Drilling Filament Wound Tubes

Stable1

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How do you prevent the fiberglass from splintering when drilling filament wound tubes like WIldman Uses :confused:
 

Kaycee

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How do you prevent the fiberglass from splintering when drilling filament wound tubes like WIldman Uses :confused:

You can't by design. Drill your holes, sand the inside of the tube, then harden the holes with CA. Repeat if needed.
 

kramer714

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there are a couple of tricks to making clean holes in fiberglass (or graphite), these are some of the things I do at the 'day job'

1) back up the hole.
If you can back up the hole with high density foam or even wood, you will get a much better cut.

2) carbide or better
TiN coated or Cobalt drills are good for a few holes, high speed steel one hole, always use Carbide or harder drills.

3) Use the right drill
Use a 'dreamer' (best - we drill a few hundred holes without breakout in 1/4 inch thick graphite without sharpening), Diamond Hole saw (second best), dagger drill (not as good), or a carbide bit with a brad point (better if you use a conventional drill) or a 118 degree split point.

4) Hold It
Use a drill press or mill to drill the holes, if you do freehand it use an 'egg cup' drill bushing to help get a good hole.

5)cool it
plain water works as a good coolant for drilling. the part dosn't need to be soaked just dip the drill in water before and after each hole

6) Countersink
For countersinks (not sure if you need them) use a piloted carbide countersink, The only time I don't use a piloted countersink is if I am using a mill.

7) Break the edge
use astone to break the sharp edge. At work I have fancy stuff. At home i use a stone dremel cone bit and spin it a few times by hand.

8) Seal It.
if you do get some fraying and want to clean up the hole, mix epoxy (5 minute stuff will work) with acetone (about 3 parts acetone to 1 part epoxy) and Q-tip it on. Wipe off all that you can wipe off and the surface will have that shiny look.

FWIW
 
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GregGleason

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That look's helpful Kramer.

When you say use a stone to break the edge, are you talking about deburring the edge after the cut?

Greg
 

kramer714

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yup for deburring the edge, there is one i use it is a round wheel but where it blends to the metal shaft it looks like a bell I put the shaft through the hole and spin the bit by hand, works well and kind of self centers.
 

kinderwood

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I am very sorry for resurrecting an old dead thread but I didn't see this information anywhere else unless I missed it.
Kramer, the drill/reamer tool (dreamer) that you mentioned, was something like this what you meant?
Starlite Drill Reamer
Is is possible to do this with a hand drill? I have access to end mills and presses at work, but we don't really have any way to clamp tubing.
Also, do your recommendations apply for convolute fiberglass as well? Or is this really only needed for filament? I apologize, I've never worked with fiberglass before and I'm trying to do it right with clean holes the first time rather than screw it up and repair the frays.
 

ClayD

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I am very sorry for resurrecting an old dead thread but I didn't see this information anywhere else unless I missed it.
Kramer, the drill/reamer tool (dreamer) that you mentioned, was something like this what you meant?
Starlite Drill Reamer
Is is possible to do this with a hand drill? I have access to end mills and presses at work, but we don't really have any way to clamp tubing.
Also, do your recommendations apply for convolute fiberglass as well? Or is this really only needed for filament? I apologize, I've never worked with fiberglass before and I'm trying to do it right with clean holes the first time rather than screw it up and repair the frays.

wow, you did bring up an oldie.... but...
I would say starlights description matches the 'dreamer' the issue is that a typical drill bit cuts on the point, a reamer cuts on the side... if you want to cut the tow, its best f your bit cuts on the side as good as it does at the point.
https://www.mcmaster.com/#fiberglass-cutting-drill-bits/=is0olq

another way, if you built a press on your router would be to use this...
https://www.mcmaster.com/#fiberglass-cutting-router-bits/=is0pl2
higher RPM may help a clean hole....
 

kinderwood

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Thanks for the good advice Clay. I have used bits like those routers to cut G10 PCB's on a small CNC, never thought about it before on rocket tubing. Also what did you mean by cutting the tow?
 

G_T

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As mentioned before, backing works well. That can result in zero splintering.

Something else that works pretty well is drill a small pilot hole, and work progressively up to the final size. The first hole produces the most splintering, and a small hole produces only small splintering. One can get little to no splintering at the final hole size that way. Sharp bits work much better than dull ones...

Gerald
 

MuddAmateurRocketryClub

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My experience is all in a semi-professional machine shop on rigid machines; it won't work in hand drills or drillpresses nearly as well. Get a centercutting endmill with pronounced corners-they are often designed for glass-reinforced polycarbonate or specifically for composites-and it ill cut like butter. Coated HSS is a waste, the coating wears away too fast. HSS lasts a few holes at most, carbide quite a bit longer. Of course, the truth in machining is often that results are proportional to the amount of money you spend optimizing the setup-I'm sure these are the best you could ever do. https://www.onsrud.com/product/Item/m/itemDetail.html?itemId=86-002
 

cwbullet

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I use a small piece of wood that I have beveled a little to fit against the tube. The backing method as mentioned above works.

I have tired tape and had limited success.
 

kinderwood

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That's close to what I ended up getting. I got these from McMaster Carbide Bits for Composite Materials. I paired it with this guy Aluminum V Block to get the tubes lined up in the drill press. I also have this guy Center Punch for round material with level to find top dead center. Is all this necessary? No, of course not. I realize that it can be done with hand tools at an acceptable level. But I love tools and being precise.
 

kinderwood

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I haven't started building my first fiberglass rocket yet, the Formula 98, but I'll be sure and put up a build thread with details on how the tools I got worked. I'll put a link in this thread too.
 

ClayD

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Thanks for the good advice Clay. I have used bits like those routers to cut G10 PCB's on a small CNC, never thought about it before on rocket tubing. Also what did you mean by cutting the tow?

Always look forward to build threads!....

Tow, is the filliment that is wound on the tube... I guess i used a bad tense... Its called tow when its spooled, and filiment when its wound to a tube....

G10 is not filliment wound, G12 is... G10 would have a weave, not fillament wound.
You have less splintering with G10 than G12.
 

kinderwood

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Wow, a 1/4" bit costs more than a small I reload! :y:
Yeh, they are a bit on the pricey side. They should last though being made of carbide though. I'm only buying the sizes I need rather than a set obviously. I started a build thread here. It's in the early stages now, but it shows some of the hole drilling I've done so far. The bits work quite well.
 
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