Machining CNC mill conversion project begins

@new2hpr Thanks for the kind words! I did look into the encoder question when I was planning the project since I knew that DROs all use linear encoders, but I found pretty quickly that the motor shaft encoders are the favorite for moderate cost CNC closed-loop servo conversions. Cost vs accuracy is a lot better, and Integration is way easier. Retrofitting full-travel linears onto machines that weren't designed for it can require modifying the castings. DMM provides encoders with their motors; everything is plug-n-play. If you're curious about the higher-end linear encoders, there's a ton of good information on newall.com

Let's dive into some setup. Here is a screenshot from the DYN4 drive setup utility's configuration page. The two important things here are to put "Gear Number" == 4096, and to set the "Command Input Mode" radio button to "PULSE / DIR". I think the latter is Canadian for STEP/DIR. The one hidden-yet-important fact here is that when Gear Number == 4096, then you need to apply 16k (16384) pulses to move the motor 1 rev.

You don't need to worry about the gains/filter constants yet - the defaults are fine for no-load testing. We'll run the auto-tune later when it's hooked up to the machine.


The related place in Mach4 where you need the pulses-per-rev information is the Mach4 (not ESS) config Motors tab. You select one of the motors on the right (Motor0 here) and it displays a plot of the axis velocity vs time.

The fields at the bottom are crucial. This was covered in a previous post, but the values here are now correct Assuming you set Gear Number in the drive to 4096, then "Counts Per Unit" here needs to be:

CPUnit = 16384 * leadscrew_pitch. With 5 pitch leadscrews, this value is 81920

Velocity = max inches/minute. I'm using 400 based on some user reports

Acceleration = inches/minute per second. My value of 4.0 is just a guess for now.

CAVEAT: The UI for this dialog is flaky. Be aware that changing the counts/unit for a motor will silently auto-adjust the velocity and acceleration without updating the displayed values until you select a different motor and come back to the one you're editing.

Awesome project.

Mechanical teardown time is here! I started with the Z axis; following inspiration from another video I decided to tilt the head 90 degrees CCW, crank it down to lie atop something, and then unbolt it from the Z saddle.

You can start by removing the Z axis lock handles from the side of the saddle. Easy points, and it's likely they will never go back except as dust caps for the holes.

Now you should remove the heavy motor. OK, that turned out to not be too bad. Start by opening up the electrical box and unplugging *both* cables that lead to the motor. There's a big green 3-pin power cable, and a smaller Molex style 5-pin cable, both plugged into the control board in the back of the box. To get at them you need to pull the contactor (relay) forward off its DIN rail. Here is the area before and after its removal.

In the second photo you can see the target connectors on the control board, one with the green/yellow/blue wires (R center) and the other with red/white/blue/etc wires (leading to plug at lower left rear). Unplug these and thread them back into the head through the hole in the right side of the box, and pull up through the top hole in the head.

Wait, the green connector is gone in the second photo! Yep, it won't fit through the holes in the head, you have to remove it. The first picture will come in handy when we put it back together later.

Now you can unbolt the motor. There's a big bolt that slides in an arc, and a smaller pivot bolt on the other side. Remove with 10mm and 6mm hex drivers, respectively. In case you didn't notice, the whole mill is metric...by now you will have a set of metric combo wrenches, sockets, and T-handle hex drivers. After the motor itself, remove the two small motor mount brackets. The next photo shows the situation with the motor off and the brackets about to go. It is sooooo tempting to order the Marathon 3-phase 5400 rpm motor now...


Next we want to get the electronic box off the side of the head. This in turn requires taking the control board off the back of the electronics box since one of the four attachment bolts is otherwise inaccessible. In order to to this we have to deal with a couple more cables - the spindle tach power (unplug from tach), and the safety interlock cable. The latter I pulled back thru from the head into the electronics box; recall that I previously jumpered the ends to neuter it, so it will fit. At this point this you also should remove the quill lock handle. After the electrical box was off, I put the front and back panels back on for safekeeping.

Finally here's the bare naked mill head with all the spaghetti removed.

Off with its head!! I don't have a lot of in-progress photos since the process was so simple. First I loosened the 3 head tilt bolts using a shallow 1/2" drive socket, by reaching up from under the head. The head rotates easily 90 degrees counter-clockwise and should stay put without re-tightening the bolts.

After looking things over I decided to put a ~8" thick roto-molded case on the mill table to guard against running off the end of the Z leadscrew, which didn't look to be long enough to let me crank the head all the way down onto the table. Apparently on a G0704 you can run it all the way down, but I'm pretty sure on a PM-30 you cannot. After the head is lying on its side, remove the nuts and washers from the head tilt bolts, and pull the head off. You may need to fiddle with it a bit since it rotates on a cylinder in that casting that is a fairly close fit.

Here's the result.

At this point the Z saddle is still firmly attached to the leadscrew and you can crank it up and down, reveling in the generous backlash intrinsic to the crank gear system.

Our next stage is to remove the Z crank, forever. It is not designed to be easily removed for maintenance, however I was undeterred. Especially since the new double-nut ballscrew is going to take the backlash from 20 mils to zero.

Start by removing the four bolts holding the crank bearing casting to the side of the column. You don't need to remove the 3 bolts in the smaller ring; they just hold a cover plate that doesn't have to be come off.

Now comes the fun part. The outer casting is pressed - fortunately not too tightly - into a round hole in a flange that is welded into a cutout on the side of the column. It takes a certain amount of force to get it off, and there's no way to reach inside the column yet to tap or push it out. The joint is also painted over...a couple of whacks from a deadblow hammer broke loose the paint. I ended up driving a thin blade made from a ground-down screwdriver into the crack and then pried out the casting. I'd have been more careful if I wasn't planning on scrapping the crank mechanism, but I don't think I did any damage beyond chipping the paint.

Here it is when it was about halfway out, and again after removal, showing the gear that engaged with the leadscrew, and also a view inside showing the gear section on the leadscrew. All of this stuff is going away.

Finally it's time to disconnect the Z sled and extract the original leadscrew and brackets. First a quick look at the Z sled itself:

One thing to note is how the 3 bolts in the tilt ring have slid around toward the bottom of the ring. That's not a problem and we can leave them there.

Another thing which surprised me is the face of the sled itself, which is the bearing surface for the head tilt. The pattern of marks on the surface is "flaking", which is done to promote oil transport. I was not expecting to see this, flaking is a hand process and mostly is done after a time consuming hand-scraping adjustment of the sliding surfaces, which gets them flat and level to within 0.1-0.2 mils. I really doubt that the surface was scraped, so the flaking was pretty unexpected.

Anyway, time for business. There are *two* pairs of bolts in the middle of the face. The top pair is for the leadscrew nut bracket, and the bottom pair is for the end of a gas spring that counteracts some of the weight of the slide. If you look through the opening in the column under the slide when the slide is near the top, you can see the strut of the gas spring as a solid rod in front of the leadscrew.

My removal procedure went like this - possibly not optimal, but it worked.

• Start with the sled up near the top of its travel. Should have mentioned this before, you need to do before removing the crank! This lets the gas spring extend and reduces the total energy in the spring.
• Brace a piece of wood under the Z sled to prevent it dropping. It won't because of the spring; for me this was just a precaution because I hadn't done it before.
• Remove the four bolts holding the end plate on top of the column.
• Remove the upper pair of bolts in the face (leadscrew bracket)
• Remove the lower pari of bolts in the face
• Now fiddle with things until you can pull the square leadscrew nut bracket off of the round stud it mates with. You have to pull this out through the slot in the front of the column. The spring bracket should be able to go off to the side and extend, which will unload the sled so it can move down. This is where having some wood at the bottom of the ways is handy to prevent impact.
• After you get the leadscrew nut bracket piece out, you should just be able to lift the top plate + leadscrew assembly out the top of the column.

Here's a view down the column afterwards. The fitting at center left is the gas spring bracket; you can see the shaft of the spring going all the way down the column. The bottom bracket is fastened in a place where we can't reach yet.

Here is what the original Z leadscrew, crank drive gear, and its bearing connection to the top plate look like after removal. The square leadscrew nut bracket piece has been removed; you can see the cylinder it fits over. I did not have to disassemble the bearing from the top plate. Because of the simplistic crank gearing, backlash on the Z axis was about 20 mils. In fairness, for manual work this wouldn't be too much of a problem because you would use the much better quill downfeed for Z control anyway. These parts will not be going back in, the ArizonaVideo99 Z axis replaces everything, including the top plate.

On to the X axis removal. I took off the left end (-X direction) end plate a while ago. It turned out to have no bearing and just a pair of collars on either side of the bracket plate. The right side plate actually has bearings. Once you have all the collars off and the spline keys taken off the leadscrew shaft, the plates can be removed by tapping them off with a rubber deadblow hammer. They have press-fit alignment pins so you must drive them off along the axis of the leadscrew, directly away from the ends. This is most easily done by tapping from the underside where part of the plate protrudes. You have to break the paint, so the first couple of whacks may need to be pretty stiff.


The next picture shows most of the important parts of the right side X endplate stack, plus the left side plate (at R in the picture).

There is a 2nd spacer that should appear to the R of the ball bearing ring on the inner side of the plate with the bearing - a no-show for the family photo as it wouldn't easily come off the leadscrew. Original backlash on the X axis was about 2 mils.

NOTE FOR THOSE RUNNING A STOCK PM-30: On my unit, the X end plate bottom corners (the wide section nearest the leadscrew shaft) interfered with the Y saddle, limiting the X travel to only around 21.5", which is noticeably less than spec. This is easily corrected by grinding down the corners, which will increase the max usable X travel to somewhere around 28" (may vary a bit depending on how much weight you have on the table). I informed Precision Matthews and they said the plates were not supposed to interfere and they would contact the factory to get it corrected.

The spacer is marked "XC 51103".

As with the Z axis, all of these parts are going to be discarded or recycled into something else; the conversion kit entirely replaces the X fittings.

With the X endplates and associated bearings/collars off, we can now just slide the table off to the left side. I chose this direction because it enables removal of the gib before the table is completely off, which is pretty much essential. The leadscrew will be removed after the table. Here is what I did to get the table off:

• Slide the table left until there is only 3-4" of mating remaining on the ways.
• Loosen both of the gib adjusting screws
• Get a reasonably strong assistant to hold up the end of the table (it weighs 80-90 lb IIRC) and move it out to where it's only engaged by an inch or so. You will not be able to move it out that far unless someone is holding up the end.
• Pull out the gib. You'll probably have to wiggle it around a bit, but make sure not to apply too much force or ding it up.
• Now the table can be removed easily.

Here's the result.

Now the X leadscrew bracket can be unbolted via two socket head screws on the right side of the saddle (lower edge in this picture).

Finally we're down to the Y axis. Here's a photo of the saddle showing the Y leadscrew underneath, and two oval slots on the right hand rail where the Y nut bracket bolts reside. Note the oil distribution slots and holes in the ways for the X axis. These connect to four ball oiler valves on the sides of the saddle. The original backlash in Y was about 7 mils.

Disassembly of the Y axis is almost trivial. Remove the nut, pull off the handcrank, remove the spline key, unbolt the bracket plate and dislodge it with the deadblow hammer. It has alignment pins just like the X axis plates and thus must come out straight to the front. The front bearing ring and spacer will slide out as you move the plate; they aren't a super tight fit. You don't need to remove the silver collar. Here is the Y bracket plate mostly off:

Now unbolt the leadscrew nut (in the oval slots in the rail towards the column). You can now slide the saddle off the ways towards the front. For this one I didn't even have to remove the gib beforehand, though I did loosen the gib adjuster screw first. Now you are left with this - here the column is at bottom:

Finally, unthread the leadscrew from the nut - there's no other way to get it out - and pull the leadscrew out to the front. The nut gets taken out through the slot in the base.

We will soon be making a small but significant mod to the base to increase Y travel considerably. In the above photo, the extent of the slot governs how far forward the saddle can go in the Y direction. In the factory machine, the saddle will not go past the point where it's flush with the end of the ways. However, the ArizonaVideo99 conversion bracket will permit some overhang, with the travel limited by where the table would contact the motor bracket. There is a video from a PM-30 user who extended the slot by 2.2", obtaining a total travel of a bit over 11". His casting had a rib that limited the slot extension to that amount. Mine does not have the rib in the same place so it's possible I could get a bit more. The new brackets provide 3.0" of clearance in front of the ways, but there will be some loss for the thickness of the X home switch. Overall I'd say that 2.25 to 2.5" of bonus Y travel looks feasible - a big win for being able to use larger mill vises. Here is the area that will get cut out:


The other modification - and this one is mandatory - is to mill out a 1 x 3 x .140 deep pocket in the saddle for clearance of the X axis double ballnut. The stock single nut fits in the existing slot, but the new double ballnut assembly is much longer and needs some thickness removed from the saddle to avoid mechanical interference. There's a video on ArizonaVideo99's channel explaining exactly what's required. The following picture shows the approximate area that will be milled. A local fellow TRF'er with a *serious* mill is going to help me do this.

Whaddya know, I've caught up to real time on posting the mechanical mods, though I've still got a backlog to filll on the Mach4 software setup. Tonight's activity is modifying the base for increased Y travel.

After measuring all the geometry, it looks like I'm only going to need to extend the Y nut slot by about 2.25" for max Y travel. The key dimension is the distance on the saddle from the mounting bolt hole centers (where the two bolts in the shiny block above will go) to the front of the saddle. That distance is 7.7". Not coincidentally, when I move the Y ballnuts to match that position as in the photo, that is the exact point at which the lower ballnut is just starting to disengage from the screw threads. Looking down from above, that works out to extending the slot by about 2.25". The dimensions aren't critical; I just marked with a Sharpie after cleaning off the oil with some Goof-Off. I will still get more than 2" of extra Y travel since in its original configuration the Y travel stopped short of the end of the nut slot. The final Y travel isn't going to be known until I get everything stacked up again and see how the X table interacts with the structure at the back by the column.

Following the example video, I'm cutting down the sides with a Hackzall and across the end with a thin grinder disc, then finishing the end cut with the Hackzall. In the next photo the left side has been cut - which took about 10 minutes - and the right side started. At the end I'll stone the surfaces to get rid of any slight cruft around the edge. There's a crossbar about 2" below the surface, so you have to stay in the outer 1/3 of the blade once you get there; you don't want to cut the crossbar. You also should tilt the far end of the blade inward slightly to avoid cutting too much into the thin vertical wall in the casting along the edge of the opening.


It's worth noting that this is the smaller of the two reciprocating saws Milwaukee has, and most of the cuts seen above were done with a carbide blade (important) on a partially discharged medium size M18 battery. Pretty impressive for cordless!

Well I actually got to make some chips - just not with my own machine yet. Here's WarnerR's Kondia mill cutting the recess in my Y saddle for the X ballnut assembly. The Kondia is a Spanish, yes Spanish!, clone of a Bridgeport knee mill.


Afterward the X ballscrew assembly mounted on nicely with plenty of clearance for alignment variations. On my casting (and I'm assuming they are variable), I didn't need anywhere near the 0.140 depth that ArizonaVideo99 gave, I think about half that would be fine.

Warner showed me (and we used for this job) an interesting hold-down riser pad and pin registration kit called TruHite from LeeDion Tool Company that lets you instantly align things parallel to your T-slots, as well as stand them up off the table if needed. This is a hard to find item - they were being made by a small tool company in Auburn WA and sold on Ebay about 10 years ago. The company seems to still exist but has no web presence, and Ebay search currently comes up empty. Too bad, they are nicely made and weren't too expensive.


Warner's also got some real turkeys. Really.

Thats a Wild Turkey. Your mills really moving along! Hope I can get a working VFD for mine to replace my noisy rotary converter!

That converter is noisy for sure - I heard it in action. Too bad we didn't have time to debug your solid state unit. Here is the output from our work yesterday.

The longer double ballnut is nestled into the recess in the Y saddle and everything looks good. This photo also shows the oil distribution channels in the ways quite well. More to come on that topic later - I'm planning a post or two dedicated to looking at how to possibly add a one-shot oiler system. It is not as easy as on some mills due to the low-profile saddle.

Yesterday my VistaCNC pendant came! On first impression it's really nice - good hefty feel, the switches are very tactile, and the wheel is ultra smooth with nice micro-clicks. To use it you need to download the Mach4 firmware into the device, and install the Mach4 plugin. It needs a different firmware load according to what CNC program you use - Mach3, Mach4, LinuxCNC. The constant feed rate button gives you "manual power feed", which when combined with the full jog function provides full manual milling capability. And having the position displayed on the screen and spindle control makes it easy to drill a sequence of regularly spaced holes without having to look away to the main computer screen.

Setting up the VistaCNC pendant. Go to their site, click the Downloads link, and grab the Mach4 P4-S zipfile. Be sure to get the Mach4 version for the correct product, not the Mach3 version which is at the top of the list. For Mach4, everything is in a single zipfile. There is PDF of instructions inside the zip - be sure to read it first. There is one slightly fiddly part in getting the device's bootloader to activate when you plug in the USB cable, and the the instructions don't explain it too well - they talk about holding the wheel in between click positions. That didn't really work for me; I found that you just need to spin the wheel slowly at a few clicks/second to get it into programming mode. The device programming itself is really fast, just a couple of seconds.


Back to mechanical stuff. This photo turns out to be one of those perception-benders. Is the grey part higher or lower than the white?? This is the base with the slot extended to allow maximum Y travel.

The column is off and the base is mounted atop the stand and chip pan, so I've finally turned the corner from disassembly to reassembly! One of the column bolts was pretty tight and I had to take the deadblow hammer to the 3/8" socket drive handle (12mm bit) to loosen it. A breaker bar would also have worked but I didn't have anything suitable. Based on this experience, I'd say that a socket drive type wrench is a must for that operation.

The base is the heaviest single part of the mill at around 100 lb., but I was able to get it up there myself with reasonable care in lifting. I think though that putting the column on top of it will be a 2-person job since it will have the Z saddle and leadscrew assembly attached when it goes on, probably totaling about 120 lb.

Afterwards I cleaned all the remaining yellow gunk off the base with Goof-Off and de-burred the newly cut edges of the slot with a fine stone. There's still a little bit of a paint line where the ways transition to the column mating area; a little more Goof-Off should remove it.

A little EMI shakedown...I was getting fairly frequent false E-stop triggers when madly jogging around with the VistaCNC pendant. This is pretty common when putting together CNC electronics since you have servo drives switching pretty high voltages and current. Looking around at things I found that the DC power input lines to the I/O breakout board weren't twisted, and neither were the wires going out to the actual E-stop switch contacts. So I twisted them up rather tightly to block induction.

For good measure I also ordered some shielded Cat6 cables for the RJ-45 connection from the BOB to the limit switches, and checked that the servo motor cases were connected to earth ground (it turns out they are already in the DMM design).

Even without the shielded limit switch cable and with everything still lying on the table, the false stops seem to have disappeared - none seen in 25 mins of active motion. Things will be yet better when the electronics tray is in the metal case, shielded from the motors. If there's any more trouble I will probably put filter caps across the inputs. Hooray, another debug item down.

Busy weekend so far, and it's only half over, with some time out for a DART launch.

Let's start with the wiring harness for the 3 aux 120V outlets on the back panel of the electronics box. Connectors on and fully insulated with 1/4" heatshrink.


Adding wiring to hook up a couple of not-yet-used breakout board ports (2_1 and 2_14) to the CNC4PC C55 dual-relay card, which will end up controlling solenoids for mist cooling and (maybe but kind of doubt it) flood cooling. I couldn't use the nice RJ-45 connector on the relay card b/c the signals on the last available plug on the BOB don't line up. Soooo....twisted pair wiring. Here's an old trick for consistently twisting wires that I learned from a Linkabit electronics tech about 35 years ago. You can make wires as twisty as you want this way:

That's a Madcow Nike-Apache upper stage on the bench.

A quick note about the last four output pins, which are 2_1, 2_14, 2_16 and 2_17. The breakout board functionality affects how you can use them. They are individually configurable as TTL or open collector. If you are running the "safety charge pump" interlock (SCHP, selectable by a DIP switch on the C62 BOB), it wants to be on P2_17. The third onboard relay on the C62 is jumper-selectable between P2_16 and P2_17, so you should jumper that to P2_16 if you also want SCHP. That leaves P2_1 and P2_14 for misc outputs, which is why I chose those for the dual relay card. In Mach4 I have those labeled as flood cool and mist cool. The jumpers at the center of the photo of the BOB are the TTL/open-collector selectors, pictured before I switched things from 2_14 and 2_16 to 2_1 and 2_14.



If I really needed one more output pin, I would turn off the SCHP to reclaim P2_17. The charge pump interface is a bit of an artifact from the days when CNC usually involved a PC directly controlling parallel port pins. The SCHP signal is a digital square wave at some frequency ~1 KHz that was supposed to be driven by software so that if the SW crashed, equipment that was listening for the SCHP signal would stop. Newer systems that now use motion control cards like the SmoothStepper, UCCNC etc. are set up so that if the stream of packets going to the motion controller stops, the motion controller will stop commanding any motion.

In the hardware I have, the SmoothStepper can be configured to generate the SCHP signal, and if configured, the C62 will go into stop mode if it doesn't see the SCHP waveform. This might have a little value since the SmoothStepper and the C62 BOB are separately powered, so the SCHP detection in the C62 will stop things if the SmoothStepper loses power but the C62 doesn't. However in my rig everything including the spindle operates from STEP/DIR commands, which will stop if the ESS croaks for any reason, whether or not there was an SCHP signal.

Here's the wiring for the dual-relay card, which is at bottom. The 1/14/16/17 connectors on the C62 BOB are towards the upper left.


The next thing I got to do was re-load a ballnut after I extended the Z axis a bit too much while measuring travel. There's a nice video about this over on ArizonaVideo99's YouTube channel, where he demonstrates it using the exact same ballnuts used in his conversion kits, which apparently can need a lot of fiddling with different ball sizes to get smooth movement. I don't have any photos, but the basic idea is to stick the nuts in place with petroleum jelly and a screwdriver. Putting them in the right place is important. The video I mentioned does *not* quite give you enough information about this. Here's the skinny:

• The plastic "recirculator" fittings connect one thread to the one above it, creating a single track each (there are 3)
• You *only* want balls in the recirculator racetracks.
• You do *not* want balls below the bottom recirculator nor above the top one. Otherwise things will jam badly (voice of experience)
• You also do *not* want balls in the two small spaces (that would hold about 3 balls each) right between the recirculator fittings.
• The video suggests inserting an appropriately sized tube or rod through the ballnut while you thread it back onto the screw. I tried this once but then switched to incrementally threading the nut onto the screw as I loaded each row of balls. That worked great and minimized the risk of balls falling back out of place as you go.
• The little lockscrews used to hold the plastic end seals in place are 1.5mm hex slugs. The $4 Harbor Freight jeweler's screwdriver set has this; the usual metric hex wrench sets don't.
• If you are having trouble picking up the balls with the screwdriver, just stab the screwdriver blade into your tub of vaseline. That will pick up just the right amount of goop to grab the rascals. Tripled my speed after discovering that.

Finally back to a bit of mechanical stuff. in connection with converting to a one-shot oiling system, I'm planning to eliminate 2 of the 4 oil ports on the X axis slides by milling oil distribution channels between the two existing lateral channels. The photo below shows the planned cuts as black lines on the ways. These will be pretty shallow, maybe 20 mils.

Here's a reference shot of the Ethernet SmoothStepper (small board on the R) and the C62 breakout board showing what I think is probably the final position of the connections, DIPs and jumpers. The only change that will happen when the A channel is added (rotary table) is that the corresponding Driver Fault jumper will get enabled. I have a bunch of input pins left over because I'm not using the parallel port style control pendant, but basically no more free outputs. However, I will be able to change the spindle speed/direction control from the present 0-5V setup to drive an AC inverter VFD.


Remember that nifty TruHite fixturing kit shown a few posts above? WarnerR contacted the owner of the now-closed tool company that made them, and snagged the *last two sets in existence* for us. They've been off the market for several years. How cool is that?

Onwards to oil and grease. First off, a really good starting point for reading about doing one-shot oil systems on bench/knee mills is here: https://www.cnccookbook.com/way-oiler-automatic-machinery-lubrication-vactra-2/

As a starting point, I ordered this fairly inexpensive Chinese lever-style one-shot manual oil pump from Supra Machinery in Fullerton. The make and model is iShaw YML-8 and is a clone of the kind often seen on Bridgeport machines.

It is described as having 4mm and 6mm bore outputs; I'll just have to look at it to see what that means for the tube sizes. I need two branches, one for X-Y and another for Z, so with this pump I shouldn't even need a splitter manifold.

A big question was whether to go with grease or pumped oil on the ballnuts. They are set up from ArizonaVideo99 with 6mm straight zerk grease fittings. After a lot of fiddling and measuring I've concluded that given the dimensions of the PM-30 castings there is no very reasonable way of converting them to one-shot oiling, or even to replace the zerks with grease line extensions. So I am going to rig things so the grease fittings can be accessed as well as possible, and use the one-shot oiler for the ways.

• Grease life is supposed to be in the range of 600-800 operating hours. If I do 100-200 hours/year on the machine, I can run it a few years in between grease replenishments.
• On Y there is not enough clearance between the ballnut flange and middle of the base casting to allow any push-connect 90 degree elbow to be installed in place of the zerk. Game over for oil on that one.
• On Y it IS possible to install a 6mm 90 degree zerk facing aft, which will make it reachable through the slot with the saddle out near the front. So that's the plan there.
• On the X ballnut, a 90 degree zerk will definitely help the cause for either of the next 2 options:
• On X it may be feasible to get a short grease gun 4-jaw extension hose and leave it connected to the 90 degree zerk and hang slightly out the side of the saddle. This would allow X greasing without any disassembly. I'm definitely going to see if this can work.
• If the X extension hose trick doesn't work, you will need to undo the angular contact bearings at one end to move the table far enough to expose the bare zerk. A small bit of a PITA but still much less work than a full teardown.
• On Z, a 90 degree zerk should allow it to be reached with a flex grease hose through the hole left by removal of the Z crank.

So the conclusion is that all the ballnuts are going to get 6mm 90 degree zerks installed in place of the straight ones. I ordered this $16 assortment set so I'll be swimming in zerks for future projects: https://www.amazon.com/dp/B07F3Q16MW/ref=sspa_dk_detail_13 They don't have to be expensive, they just have to work OK.

For oiling on the saddles, as soon as I drill out one of the press-fit ball oilers I will know what size of push-connect elbow fittings can be used. I'll need two fittings for each axis, a 4-output manifold for the XY saddle, and a 2-output manifold for Z, plus some tubing and Parker / Legris / Jupiter pneumatic flow control valves (yes you can use pneumatic flow controls for oil). Those manifolds will ride with the saddles and one will be plumbed back to each sides of the oiler pump with a fairly rugged flex tube. The shopping list is going to depend on the fitting size and what tube sizes they will connect to, so I'd better get to drilling away the ball oilers.

The peculiar case of the zerks and the Y ballnut channel in the base - a tale of mechanical interference.

The box o' metric zerks and grease gun showed up today. Hoping to find a way to grease the ballnuts without taking the mill apart and having already ruled out oil fittings, I started checking how the right angle 6mm zerks and a grease line coupler would fit. The short answer is, for the Y axis, they don't, and there is basically no hope. Here's most of the situation:

The right angle zerk is a good 2-3 mm taller than the straight one, and the coupler fitting (knurled thing) makes it yet another mm or so taller. That's about as tall as a 90 degree push-connect oil fitting would be, and there is no way this extra height has enough clearance in the Y channel in the base. The outcome is that the Y axis zerk is going to have to remain as-is, and XY saddle disassembly is going to be required to reach it. In turn that means there is no point in doing anything with the X axis, since the X has to be removed to get to the Y. That is not super hard but it does mean that re-greasing the X and Y ballscrews is going to take an hour or two.

The good news is that this rig *is* going to work on the Z axis, where disassembly is a much bigger pain because you would have to remove the motor (un-wiring it) and head before you could disconnect the Z sled from the ballnut bracket and get at the zerk. There's enough room inside the column that I'm confident I can use the 90 degree zerk, put a hard-to-dislodge Milwaukee coupler on it, attach a 12" hose and use a female thread zerk fitting on the other end of the hose (Alemite PN 1618-B) to create an extension hose that will just remain attached to the ballnut flange. It hangs down below the ballnuts inside the column; the bottom of a 12" hose end up about 4-5" below the sled so you can fish the end out through the slot slightly for re-greasing. At most you'll need to tilt the head over somewhat for convenience. Another detail is that grease coupler fittings differ wildly in the amount of force needed to disconnect them. The 3-jaw coupler that came with my nice Lincoln Industrial grease gun disconnects fairly easily. OTOH I got a pair of Milwaukee 4-jaw couplings that are really hard to take off...just what the doctor ordered for something that is going to remain permanently installed!

One more thing to mention is that the extension grease line needs to be filled with grease before installation so that you don't end up with air in the line as you are trying to pump in the grease. I ordered a tube of Lube USA MT-1 (hah Japanese product despite the name) already so the initial greasing is going to happen Real Soon.

While looking more closely at the Y channel in the base I found another easily corrected problem, shown in the next photo:


On the lower (left) edge there is a bunch of sloppy flash in the casting that impinges on the area through which the ballnut bracket and zerk need to travel. Even using the small straight zerk, if the ballscrew ends up centered evenly it looks like there is interference with the zerk as it crosses the center crossbar. I was able to reach the worst of it with an angle grinder...here's what it looks like after a few minutes of grinding:

Let's talk assembly sequence since the parts of the mill are mostly scattered over the floor of my garage. Here's the battle plan:

1. Initial greasing of all ballnuts.
2. Z first - want to get the column and Z sled in place to remove risk of dropping them onto the table
   1. Put column on its side...no need to fight gravity with the Z sled
   2. Unbolt aluminum bracket from ballnut flange
   3. Replace zerk with 90 degree version and attach grease extension line
   4. Put ballscrew/motor bracket assembly into the top of the column
   5. Insert aluminum bracket thru slot in column, slide over ballnuts and bolt onto the flange. This is the tricky part, do up near the top end of the column
   6. Bolt motor bracket onto top of column (loosely)
   7. Put Z sled on the ways, insert gib strip and retain loosely with gib adjuster screw
   8. Jiggle things around until you can bolt the sled to the aluminum bracket
   9. Work on alignment and progressively tighten things until smooth motion is obtained across whole range
   10. Pick the whole column/sled up (probably need exactimator to come help me!) and bolt onto base.
3. Y axis
   1. Undo ballscrew connection to angular contact bearing by removing shaft couplers. This is shown for a PM-25 in an ArizonaVideo99 clip.
   2. Put ballscrew into Y slot and bring the end out the front.
   3. Replace shaft couplers (do first so motor bracket can be upside down while you do this)
   4. Loosely bolt motor bracket on front of machine
   5. Slide XY sled onto ways, insert Y gib strip, and get sled bolted to Y ballnut bracket
   6. Adjust everything to get smooth motion
4. X axis
   1. Remove shaft couplers from motor end of leadscrew
   2. Mount X ballscrew bracket to saddle. As usual, don't fully tighten yet. Ballnuts should be positioned roughly in middle of screw.
   3. Slide X table onto saddle. Insert gib strip and fasten.
   4. Slide X table over to meet non-motor end bracket (already on ballscrew) and bolt to bracket.
   5. Put motor bracket over leadscrew and bolt to other end of table
   6. Re-attach shaft couplers.
   7. Adjust for smooth motion
5. Motors
   1. Put motors on at the end...they are heavy and interfere with checking for smooth motion
   2. You can use short sections of 1/2" rod in the shaft couplers to move the axes with a 1/2" cordless drill

Perhaps a steel brake line with bent 90 and threaded fitting to extend grease fitting to accessible spot under table?

The Y is so tight that I think I probably can't do anything more than leave the straight 6mm zerk there, it's by far the lowest profile possibility; any fitting+bend will be a fair amount taller. Some chance I will have to do more grinding to even get that to pass. Meanwhile I've discovered I'll need to cut a shallow channel in the aluminum Z bracket to pass a grease line downwards; the bracket is kinda fat and interferes by a couple of mm.

The oil pump arrived and I found the outputs have M8 straight threads, with adapters to M5 straight (the product description only said "4mm and 6mm bore" which referred to the tubing sizes that are usually used with M8 and M5 threaded connectors). So for that I'll be using some push-in connectors for 6mm (1/4") tube with M8 threads.

Usually you avoid grease on machine tools, as it holds in chips and other metal bits. Which then accelerate the wear on your parts. With that said, some machine centers have special grease formulations that the manufacturer specifies.

I would also not count on just the functional life of the grease alone. Typically a large reason grease intervals are somewhat short is in order to push out contaminates from the bearing surfaces. Greases and oils also break down due to age, not just mechanical reasons. It gets oxidized, some of the additives come out of suspension, etc. About the longest greasing interval I have seen on a major machine was 6 months, and it used PTFE grease as well.

So it might be wise to have provisions to grease things a bit more frequently than once every few years. Though it sounds like your expected use time is low enough you could probably make it quite few years before you start seeing the extra backlash.

@Xrain I did go thru the tradeoffs on grease (see a few posts up). Besides the fairly low expected use rate, the conversion kit designer intended grease and provides seals so it should be retained pretty well and swarf kept out. And I'm using Japanese grease specifically intended for ballscrews. Also as noted above the XY teardown is reasonably quick so I can probably do that at least annually if I want.

On to the Y axis setup. After noting the possible base-vs-zerk interference issue (see post #49) I decided to set up the Y axis first. Here is the Y motor mount showing the setup. Coming upwards from the bracket, you can see a short section of the angular contact bearing, then some of the threaded part of the screw, a Belleville disc spring (concave washer), and the inner shaft coupler. The plastic coupler insert and the outer coupler are not shown. Of note is that the Belleville spring has the concave hollow side towards the coupler.


Here's what happened to the outer coupler and insert: they've been mounted on a scrap piece of 0.500" round stock that can be chucked into a 1/2" cordless drill. In the picture you can see that the Y motor mount has been test-mounted to the base casting. To mount things you need to run the ballnut out toward the far end of the screw, and then insert the threaded end of the ballscrew back through the slot in the base and out the hole in the front. Then you put the Belleville washer on and screw on the inner coupler, which does not need to be more than finger tight to compress the washer. While pushing the screw through the mount, be careful not to push out the angular contact bearing...saves trouble if you can avoid having that come apart. Lock down the inner coupler tightly using the screw going through the split. Do all this *before* bolting the motor mount to the base so you can have the mount upside down for access to the coupler.


After this I used the drill to run the Y ballnuts back and forth, and confirmed that there was some interference where the tip of the zerk passes the part of the casting that supports the middle crossbar. The next picture shows the exact trouble spot. You can just see the tip of the zerk there where it touches the casting. If the ballscrew alignment ended up exactly down the middle or to the right of center, you might be OK, but there is no room whatsoever for the adjustment to end up left of center.


So I got an angle grinder and attacked the offending part of the casting. It wouldn't quite reach down far enough so I used a Dremel with a grinding stone to do a little more. Here's the resulting shallow channel in the casting. There's over an inch of iron behind this so no worries about weakening anything very much. The bottom looks ragged but that's due to eating thru some very thin casting flash.

Another detail in shaving this big ol' yak. The footprint of the Y mount is in some places larger than the original factory mount. Because they painted directly around the Y mount, the new mount overlaps some of the paint. The paint layer is rather thick, so the paint lying under the new footprint is going to have to be removed. Here I've traced around the new mount.


After taking the mount back off, here's the new outline.


A few minutes with a sanding disc in the trusty Dremel tool got rid of the paint. A note of curiousity here - the upper right and lower left holes are for the locator pins on the factory mount, which don't really have much purpose (and might even compromise adjustability) and are not used by the conversion kit.

When installing the Y mount you must be sure to use the main bolts provided with the conversion kit, which are 5mm shorter than the factory ones.

Finally I put the Y axis ballscrew and mount back in again (getting some practice there), and rechecked the zerk interference - I now have plenty of wiggle room for adjustment. Just on inspection it looks like I'm going to need to yaw right and tilt down a bit, so I'll get over to Marshall's HW this week and pick up some thin shim stock.

One last thing from the above picture - now that I can actually check the travel of the Y ballnut and bracket, it turns out that I could have extended the slot in the base about 1/4" less. The little black mark near the lower left corner of the slot indicates the slot length needed to clear the bracket's mounting bolts at the point where the near end of the ballnut touches the inside front wall of the main casting.

For reference, here's a quick summary of mods to the base casting. Bear in mind that the rough sides of castings can be inconsistent; a casting that had the slot channel walls truly vertical would not require any grinding.

• Extend main slot forward by 2.0"
• Grind off flash near center of left side of slot
• Grind shallow channel in left side of casting inside slot to clear Y zerk fitting
• Trace outline of conversion Y mount and remove paint underneath
• Remove thin paint lines from the ways back near the column

OK we're going to go nonlinear here...I realized I totally forgot to fully document removal of the pesky gas strut; it got glossed over at the beginning of post #44. Here are the column and base still bolted together with the strut inside the column:

At this point I was able to single-handedly flop the ~200 lb assembly over on its side. The bottom of the base is open and allowed me to unbolt the bottom end of the gas strut and pull it out of the column. The gas strut is going on the discard pile since the servo is very strong and we won't be hand-cranking the Z axis anymore. Another post I found on a CNC forum indicated that it restricted travel a little and the CNC'd machine will definitely work fine without it.

After this I stood the base+column back up again to unbolt the column.
[return to present]

Last night I drilled out the ball oilers from the XY and Z saddles. Here is what they look like at the start:

The oilers are simple press-fit widgets that consist of a brass tube containing a coil spring and small ball bearing, formed at the ends to hold the spring and bearing in. To remove them I started with a #25 drill and went progressively larger until the brass tube finally came out. After doing a couple I came up with the sequence #25, #14, #7, #1. This has the virtue of not enlarging the hole yet, in case it turned out to be a convenient size.

If you don't already have sets of the numbered and letter size drills, you will need them for any kind of machine work...get decent ones, try https://drillsandcutters.com/. You really need 3 sets - fractional inch, #1-40, and A-Z, and optionally a 1-13mm metric set. Generally there are two choices of length, "jobber" and the shorter "stub" or "machine" sets. Machine length is nice for metalwork and particularly in lathe drilling. Jobber length is handy if you are going make deeper holes in aluminum / plastic / wood. HSS is fine for anything non-ferrous and cast iron; for drilling hard steel/stainless, cobalt is a good idea. If you stay at this long enough you'll eventually be drowning in drill bits.

Here is what the residue looks like after drilling one out. The spring is gonna get mangled and the ball bearings are gonna roll away. You can push everything out from the back of the hole. Just make sure to get all the stuff out of the hole. Be aware that the through hole is smaller than the ball oiler diameter; there is a ~8mm deep counterbore to hold the oiler. Also note that there is a perpendicular hole that carries oil up to the ways; make sure nothing gets stuck in there. I didn't really have any trouble. I ended up just doing all this with a cordless drill since the saddles wouldn't quite fit under my benchtop drill press.


Finally I gauged the hole sizes (roughly) using the ever-handy drills. It turns out a B drill (0.238" == 6.04mm) is a fairly close fit in the ball oiler counterbore. I think it's safe to conclude that these were drilled as metric 6.0mm. That is the correct tap drill size for 7.00x1.00 metric threads, but push-on fittings are not available in such a size; they are common in 1/8 NPT thread, which takes a Q tap drill (0.332), which in turn would require expanding the hole a fair amount. Possibly a better option is an M5 to M8 threaded bushing which will only require a 1mm expansion of the holes, though the M5 pneumatic fitting is going to have a small bore to carry the oil.

WarnerR comes through! Here's one of the two last-of-the-Mohicans TruHite standoff pad fixturing sets he got from the original owner of LeeDion Tool Co. I will need to get some 14mm - 9/16" t-nuts for it since the stock ones were 5/8" and the others were special order.

just mill them to size! Lol- couldn’t resit! Your mill is about ready to go online! going to be fun seeing your creations