Questions about DIY Centering Rings (BT-60 to 4 inch)

[Gunstar]

So I'd like to make my own centering rings for body tubes BT-60 up to 4 inch, with 18mm and 24mm engine tubes. I would prefer to make them from thin plywood. I know a laser cutter would be perfect for this, but that isn't an option unless someone can point me to a $200 unit that would do the job. I have a drill press however. What I'm thinking of is using a circle cutter like in the link below for the outer edge of the ring:
https://www.amazon.com/dp/B00004T7OZ?ref=ppx_yo2ov_dt_b_product_details&th=1

I could use that for the hole as well I think, but there are 18mm and 24mm spade bits, hole saws and forstner bits. Would any of those be a better option?

I do have a 3d printer and could print the right shapes, but how would they hold up under use long term? I don't feel confident that is a good option. I'm not going to print in ABS, I can do PLA, PLA+ and PTEG.

Would love to hear from anyone who has experience in any of this.

 

[cwbullet]

So I'd like to make my own centering rings for body tubes BT-60 up to 4 inch, with 18mm and 24mm engine tubes. I would prefer to make them from thin plywood. I know a laser cutter would be perfect for this, but that isn't an option unless someone can point me to a $200 unit that would do the job. I have a drill press however. What I'm thinking of is using a circle cutter like in the link below for the outer edge of the ring:
https://www.amazon.com/dp/B00004T7OZ?ref=ppx_yo2ov_dt_b_product_details&th=1

I could use that for the hole as well I think, but there are 18mm and 24mm spade bits, hole saws and forstner bits. Would any of those be a better option?

I do have a 3d printer and could print the right shapes, but how would they hold up under use long term? I don't feel confident that is a good option. I'm not going to print in ABS, I can do PLA, PLA+ and PTEG.

Would love to hear from anyone who has experience in any of this.

Both 3D printing and the wheel cutter will work. I have seen successful flights with 3D printed centering rings from low to level 3. The key is the right material, wall thickness, infill, and fill pattern.

https://www.rapiddirect.com/blog/how-to-make-strong-3d-prints/

 

[RokitFlyr]

I've been using hole saws for years in a drill press. Just get a quality set.

 

[David Schwantz]

The trick to using spade bits and holes saw is just drill half was through and then flip it over and use the now pilot hole to start the second cut. Finish this way and you will never get a ragged edge.

 

[lakeroadster]

Fly Cutter... easy peazy

 

[Gunstar]

Fly Cutter... easy peazy

Where do you get a fly cutter like that? The ones I find either only have just one blade, or they are huge.

 

[Gunstar]

Both 3D printing and the wheel cutter will work. I have seen successful flights with 3D printed centering rings from low to level 3. The key is the right material, wall thickness, infill, and fill pattern.

https://www.rapiddirect.com/blog/how-to-make-strong-3d-prints/

What matrials/thickness etc. did you use? What glue did you use?

 

[lakeroadster]

Where do you get a fly cutter like that? The ones I find either only have just one blade, or they are huge.

Amazon has 'em​

https://www.amazon.com/Adjustable-Circle-Woodworking-Cutting-Drywall/dp/B0CJV555KQ/ref=sr_1_28_sspa?crid=QIMA9E3PCHDQ&dib=eyJ2IjoiMSJ9.TlpMoPkW7nWCwvzlTi1wdjmvSHttFAxPg9COBz11xTzBTVdouiBrTuUoim-kU9MgOJvpEypFGCENCj-aeqVB18NzLQn_Xj1Ol3JCDajvrglS2atP3NzJ2uGVH2N5t5RPn3h4l2BRgJzcRfjzbZPJY1Bny1Il2RkpiDdyuf3JitZHDUCXFa4KkDcK23ynH7K6q0rgelCBAEHj0k0fo1tnPSq0db8GVYwOPgnGR2Yaa94eGZTVHBDqCRrMnEc5AFjqA0hTrBzHBljSySUafE2Y3j-6yQ518KUWeew_A8PMZ5M.IgNAqloPJozHkuHws88DXuAu0YA3wr4B7zL2e_7ox2o&dib_tag=se&keywords=circle+cutter&qid=1712188435&sprefix=circle+cutter,aps,419&sr=8-28-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9tdGY&psc=1​

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[cwbullet]

What matrials/thickness etc. did you use? What glue did you use?

I use plastic epoxy from Lowes. Thickness depends on the bird, but I have gone as thick as 1/2 inch and as high as 60% infill.

 

[JimByrne]

I have made quite a few (1/8", 3/16" & 1/4") and used holesaws.
As mentioned above cut halfway through then cut from the other side.
I feel that a fly cutter is dangerous (too easy to hit your hands).
Don't forget that when cutting the outside diameter you need a holesaw that has the correct
inside diameter. I often need to buy oversize then sand the centering ring to fit.
Cut the outside first, then use a 1/4" bolt & large washers to hold the centering ring in the drill press for sanding, then cut the center hole. I have a lathe, so that part is easier.

 

[lakeroadster]

I feel that a fly cutter is dangerous (too easy to hit your hands).

Temporarily screw the part to the drill press base as shown in the video... then your hands are no where near the cutter.​

 

[cwbullet]

I have made quite a few (1/8", 3/16" & 1/4") and used holesaws.
As mentioned above cut halfway through then cut from the other side.
I feel that a fly cutter is dangerous (too easy to hit your hands).
Don't forget that when cutting the outside diameter you need a holesaw that has the correct
inside diameter. I often need to buy oversize then sand the centering ring to fit.
Cut the outside first, then use a 1/4" bolt & large washers to hold the centering ring in the drill press for sanding, then cut the center hole. I have a lathe, so that part is easier.

Definitely better not to adjust them. They tend to loosen over time and can result in a neutering.

 

[bjphoenix]

I have made CR from 1/8" plywood by drawing circles on the material with some form of compass, cutting out the rings to rough shape using a saw then sanding the ring to the pencil line using a disk sander. I have a tool for my drill press that uses sandpaper tubes so it works for sanding the inside hole.

 

[rharshberger]

So I'd like to make my own centering rings for body tubes BT-60 up to 4 inch, with 18mm and 24mm engine tubes. I would prefer to make them from thin plywood. I know a laser cutter would be perfect for this, but that isn't an option unless someone can point me to a $200 unit that would do the job. I have a drill press however. What I'm thinking of is using a circle cutter like in the link below for the outer edge of the ring:
https://www.amazon.com/dp/B00004T7OZ?ref=ppx_yo2ov_dt_b_product_details&th=1

I could use that for the hole as well I think, but there are 18mm and 24mm spade bits, hole saws and forstner bits. Would any of those be a better option?

I do have a 3d printer and could print the right shapes, but how would they hold up under use long term? I don't feel confident that is a good option. I'm not going to print in ABS, I can do PLA, PLA+ and PTEG.

Would love to hear from anyone who has experience in any of this.

The General Tools circle cutter you linked will work fine, I own a number of them and just leave them set to specific sizes instead of constantly resetting the size as it takes a bit of trial and error. One thing to keep you fingers safer is to use small brads and tack the ring down to a board big enough to keep your hands clear of the cutter.

 

[Nate G]

Plus one for fly cutter.
1. it's adjustability is unmatched.
2. it is a little tricky to set up and takes some practice.
3. yes, it is dangerous... all really powerful tools are. affix the part well. also can lock it against a fence if you have built one for a drill press that is solid ( what I do). Keep hands well away from that bar!!!
4. CWB has a lot of experience and his suggestion of 3DP sounds like a good option. - but I go back to the flycutter since I cannot get my darn Zortrax M200 back up and running - ERROR #032 despite replacing all the electronics. sigh.

good luck.

Nate