Slotting Fiberglass tube with hand tools

I have just slotted a second Hawk Mountain style tube (thanks DLB) for WeFly2 as we are both building Diab-Glo clones for Night Launch .

It came out pretty clean and thought I would post my technique. My gurus are CJ John Coker TFish and even Andy Woerner .



What is needed :

RotaryTool, mine was under $10 from Harbor Freight : https://www.harborfreight.com/80-piec...kit-97626.html

Diamond Coated Cutoff Discs (thanks OddmanRockets!) : https://www.harborfreight.com/diamond...-pc-69657.html

Tape: I used 1/4, 1/2 and 3/4 inch masking tape for marking, layout and sizing.

Pencil, Scissors and some Paper

PayloadBay tube marking template : https://www.payloadbay.com/index.php?...ction=FINWRAPS

Angle Iron : https://www.homedepot.com/p/Everbilt-...0017/204604755

Helped but not required: https://www.estesrockets.com/rockets/...-marking-guide

Slotting Fiberglass tube with hand tools , Layout

I used to try to be like the Exactimator and measure everything, exactly . But things would come out not exact..tool wander, one cut on one side of the line than the next on the other side, lining up tool on line from another angle ..ect. Probably a contributing reason to me always keeping extra LOC tubes 'in stock' ..so I could try again. And don't even get me started on Centering rings !


First up, bottom of tube slots will start 3/4 inch from the bottom to allow room for the thicker LOC Centering Rings, fillets and at least part of the Aeropack retainer to be recessed slightly - no flush rear CR and MMT sticking out like a sore thumb for me .

CJ would just grab some 3/4 inch tape, wrap it all the way around the end of the tube to mark it off -- I don't trace it with a pencil..just leave it on til all the slots are cut .

You can measure the fin, these have 4.5 inch root edge - or you can just lay up against your tube and mark it with your 1/2 tape .

Slotting Fiberglass tube with hand tools , Layout con't

Others are pro's at getting a length of tape coming around a tube and having it line up with the start point perfectly. My trail and error has shown that when I go pro style even if my tape lines up when wrapped ...the in-between is a little higher and a little lower in places. Not a full sine wave ..but noticeable a little wavy.

So I grab some paper like my paint masking paper (that gets used more for wraps than painting) and wrap around the tube

Try to get it tight , and can hold it ..but some tape will keep it in place .

Slide it down to butt up flush against my little piece of tape started in the correct position.

Now I can come around the tube with the tape using the paper as a guide . When it comes around it may not be perfect..but it is sure alot closer to true than my freehand .

Then I recheck my spacing with the fin again

Slotting Fiberglass tube with hand tools , Layout con't 2

Cut the marking guide, will need some tape here too. I usually make a 6 fin guide for my 3 fin rockets, so I can mark a 4th line for rail guides or buttons too.

To wrap 4 inches it is longer than the paper, spanning two - so put one on top of the other , to overlap a box on the guide halfs to line them up ...then tape.

Wrap tight, tape and slide down against our masking tape to mark the tick marks on the lower masking tape.

I am skipping every other line and the last mark will split one of the fin sets .

Slotting Fiberglass tube with hand tools , Layout con't 3

I haven't confirmed my tube end is completely square or my Estes Plastic Door Jamb is exactly flush at the ends ..but if marked in the same manor all lines marked will be consistent. Having a flat surface really helps too.

So grab my Estes Tube marker to extend my tick marks to the upper tape marking the tube in between also. I could use my angle iron here instead but the plastic is easier to handle here and after dropping the angle iron on its end a few times the Estes guide is probably suited to sit up straighter.

Placed near the tube I squeeze it flush gently ..and wiggle it next to the marks, want my pencil to dissect the mark when extended...start off slow when marking and if not right on , move slightly and try again.

Rotate the tube and advance to the next set of tick marks .. when you draw the rail guide lines I extend up past the tape .

Now I grab my 1/4 inch tape and lay it right up against my fin line drawn..I don't try to dissect it..

If you tape to the right or left of the line, it doesn't matter ..but you must tape on the same side for the other marks.

Slotting Fiberglass tube with hand tools , Cutting

Now its time to go inverted, Maverick !

Yes, lay the tube down and place the angle iron near your tape mark ..I also rip 3, 6 inch size or close strips of tape - ready on the angle but don't stick to the tube yet.

In the past I did tape or marking 6 lines with a gap for the fins and when cutting ..but this works better ..slots end up being the same width without as much variances and waviness.

If you keep your fin handy, you can place it right up to the tape..then slide the angle iron right up against it.

Now you can lock it down with the tape and grab the rotary tool.

Slotting Fiberglass tube with hand tools , Cutting con't

I already had the diamond cutting wheel mounted to the rotary tool , so ready to go here.

Even with the angle placed to act as a guide (or stop), I rotate the tube so the cut is at the apex and try to hold the rotary tool wheel straight up and down also ...making the cuts the same way helps for the consistancy I wasn't getting when marking things more exactly in the past..

So is best to start in the middle and just go side to side with the tool ..running the blade near or up against the guide. My angle is not prisine, starting to look a little chewed up but won't matter much .

As you run side to side you notch a line using a slight pressure..but no need to push . Enough whittling and the blade plunges through . The cut actually will help keep the blade aligned and then you are working to extend the cut or plunge again and left and right til you reach the border tape.

You will have to blow the dust off to see where to stop and you can stop just shy or to edge of the border tape.

Slotting Fiberglass tube with hand tools , Cutting con't 2

Rotate the tube and set up the next cut the same way using the fin to space the angle and your tape mark.

Keep the 1/2 inch or 3/4 tape handy as you will need to rip more strips to hold the angle secured , the tape will get fouled from the dust .

Once all three are done, flip the tube around to cut the other side of the slot in the same manor.

When starting the other slot sides: Pull the 1/4 inch tape off marking the fin line to get it out of the way. Now set the fin against the cut slot edge..covering as much of the slot as possible and still able to see a hint of the cut.

Place the angle iron and tape, ...cut the other 3 slots the same way ..it actually goes fairly quick .

After both sides are done you can can the remainder out and clean up the little bits on the edges by touching them with the rotating blade ..many small passes instead of trying to do it in one swoop.

Slotting Fiberglass tube with hand tools, complete

When the cuts are done, pull off the upper and lower border tape and take a look at slots.

These allow the fins to drop through so they are oversized by a hair.

Overall they are much quicker and cleaner than my previous attempts and I am happy with the results.

Kenny

I find that, the fiberglass reinforced cut-off wheels work better.

JD

Very nice technique and very nice writeup! Thanks for taking the time.

JDcluster said:

I find that, the fiberglass reinforced cut-off wheels work better.

Click to expand...

Me too. And I probably wouldn't use the tape--just mark the lines with a fine Sharpie, but overall I like the technique, thorough write up and using the aluminum angle as a jig.

Forget this 3/4" from bottom of tube mess! Run your slots ALL THE WAY OUT of the bottom. Attach fins to mmt and slide complete assembly into tube. That's the strongest way to mount fins. Sure you have a bit of filling to do, and this won't work with all applications, but I think it's easiest.

Looks great see you soon.

This is fantastic. Might even try it on some of the thicker cardboard tubes, too.