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CNC Waterjet cutting instrument holes



 
 
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  #1  
Old February 26th 15, 09:05 PM posted to rec.aviation.soaring
[email protected]
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Default CNC Waterjet cutting instrument holes

Hey All,
Does anybody have any experience with getting a fiberglass instrument panel CNC cut with a waterjet (or any other CNC cutter for that matter)? I called several local shops and I couldn't get a definitive answer whether the waterjet will delaminate the composite around the cut holes or not.
I've previously cut with bi metal hole saws and the hole turned out quite a bit too large and I trust a robot to measure a lot more accurately than myself. I was also interested in laser CNC cutting, but I'm pretty sure that will burn the composite around the edges of the cuts.
Any input would be appreciated.

Thanks,
Omri
  #2  
Old February 26th 15, 09:29 PM posted to rec.aviation.soaring
Darryl Ramm
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Default CNC Waterjet cutting instrument holes

On Thursday, February 26, 2015 at 12:06:01 PM UTC-8, wrote:

Does anybody have any experience with getting a fiberglass instrument panel CNC cut with a waterjet (or any other CNC cutter for that matter)? I called several local shops and I couldn't get a definitive answer whether the waterjet will delaminate the composite around the cut holes or not.
I've previously cut with bi metal hole saws and the hole turned out quite a bit too large and I trust a robot to measure a lot more accurately than myself. I was also interested in laser CNC cutting, but I'm pretty sure that will burn the composite around the edges of the cuts.
Any input would be appreciated.

Thanks,
Omri


Just about any decent waterjet shop should have some experience cutting composites. Carbon Fiber generally cuts very well. If the shop can't even answer this question I'd find somebody else.
  #3  
Old February 26th 15, 09:49 PM posted to rec.aviation.soaring
Darryl Ramm
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Default CNC Waterjet cutting instrument holes

On Thursday, February 26, 2015 at 12:29:07 PM UTC-8, Darryl Ramm wrote:
On Thursday, February 26, 2015 at 12:06:01 PM UTC-8, wrote:

Does anybody have any experience with getting a fiberglass instrument panel CNC cut with a waterjet (or any other CNC cutter for that matter)? I called several local shops and I couldn't get a definitive answer whether the waterjet will delaminate the composite around the cut holes or not.
I've previously cut with bi metal hole saws and the hole turned out quite a bit too large and I trust a robot to measure a lot more accurately than myself. I was also interested in laser CNC cutting, but I'm pretty sure that will burn the composite around the edges of the cuts.
Any input would be appreciated.

Thanks,
Omri


Just about any decent waterjet shop should have some experience cutting composites. Carbon Fiber generally cuts very well. If the shop can't even answer this question I'd find somebody else.


With the right laser it is possible to cut carbon fiber sheet, but smaller systems won't cut it, and some shops may not want to touch it. And the edges are unlikely to be really great like you can get with a waterjet. Waterjet is what you really want.

.... now back to tweaking a CAD file for a G10/fiberglass laminate laser cut part (1/8" sheet cuts easily on 60W CO2 laser, just a little scorching).
  #4  
Old February 26th 15, 10:09 PM posted to rec.aviation.soaring
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Default CNC Waterjet cutting instrument holes

Thanks Darryl, this is a fiberglass panel, not carbon. So not quite as stiff or strong and any delamination damage is quite a bit more obvious.
I did a layup of approximately the same thickness as the panel blank from Schempp Hirth. It's made out of about 6 plys of Rutan 7725 bid cloth that I had lying around (a decent cloth, but surely not what Schempp Hirth used) and US Composites laminating epoxy which is quite a bit lower grade than the MGS epoxy the factory used. I'm sure also mine has more air bubbles than what the factory made.
One of the shops suggested I bring that and do a trial cut and see how it turns out. My guess is if it would cleanly cut a laminate with weaker epoxy and worse craftsmanship, it'll probably cut the real thing well.
  #5  
Old February 26th 15, 10:27 PM posted to rec.aviation.soaring
J. Nieuwenhuize
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Default CNC Waterjet cutting instrument holes

If you're unlucky, count on delaminations extending up to 1/3rd of an inch extending inboard. A good shop can put a soft material underneath to prevent delam, but it'll for sure require a few test runs, typically initial pressure is way too high.

A glass plate twice as thick underneath will certainly be adequate to solve any delaminations issues once they get the pressure right.
  #6  
Old February 26th 15, 10:47 PM posted to rec.aviation.soaring
Darryl Ramm
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Default CNC Waterjet cutting instrument holes

On Thursday, February 26, 2015 at 1:09:53 PM UTC-8, wrote:
Thanks Darryl, this is a fiberglass panel, not carbon. So not quite as stiff or strong and any delamination damage is quite a bit more obvious.
I did a layup of approximately the same thickness as the panel blank from Schempp Hirth. It's made out of about 6 plys of Rutan 7725 bid cloth that I had lying around (a decent cloth, but surely not what Schempp Hirth used) and US Composites laminating epoxy which is quite a bit lower grade than the MGS epoxy the factory used. I'm sure also mine has more air bubbles than what the factory made.
One of the shops suggested I bring that and do a trial cut and see how it turns out. My guess is if it would cleanly cut a laminate with weaker epoxy and worse craftsmanship, it'll probably cut the real thing well.



Sorry I was just taking about CF with soembdy else and got my wires crossed..

Yes try a test cut, but this is something that I'd hope whoever you go to either water jet or laser has some experience with this. Laser will likely scorch up fairly badly on the edges, but you can usually sand this back with wet and dry and get a nice smooth (if darkened) edge... that is what we are doing with G10 at the moment, a little sanding with 600 grit wet and the edges are great. We could probably tune down some of the scorching by playing with laser pulse settings etc., but it's not worth the time. Smaller shops/those not set up for it may not want to cut fiberglass composite sheets becasue of fumes from the epoxy.

A "low-tech" option is to laser cut a template (e.g. 1/4" clear acrylic sheet) and then use that as a router template with solid carbide router bits intended for fiberglass (Whiteside make some nice ones).

Again, my first choice would be waterjet company with some experience with this. Although I love laser cutters as it's so easy to cut quick cheap tests, e.g. in corrugated cardboard.

  #7  
Old February 26th 15, 11:03 PM posted to rec.aviation.soaring
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Default CNC Waterjet cutting instrument holes

If you use a hole saw (Lowes or Home depot variety) you can get really nice results if you do a couple things.

1. Buy a hole saw holder with the replaceable center drill bit. Remove the center drill bit and replace it with a (seems like 3/16 or 1/4") smooth rod. This helps avoid the center drill from oversizing the guide hole as you go.

2. Drill the center hole with the appropriate sized drill bit first.

2a. Make a template for the 4 screw holes that centers off the center guide hole. Drill the screw holes before you cut the 2 1/4" or 3 1/8" instrument hole.

3. Once you switch to the hole saw with the smooth rod center guide, place the panel on something like a 2 x 4 with a matching 1/4" hole to keep the hole saw from torquing out of position as the cut starts to make it's way through the last bit of the panel thickness. You may need different shapes of 2 x 4 if you are cutting holes in a corner of the panel.
  #8  
Old February 26th 15, 11:05 PM posted to rec.aviation.soaring
Craig Funston
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Default CNC Waterjet cutting instrument holes

On Thursday, February 26, 2015 at 12:06:01 PM UTC-8, wrote:
Hey All,
Does anybody have any experience with getting a fiberglass instrument panel CNC cut with a waterjet (or any other CNC cutter for that matter)? I called several local shops and I couldn't get a definitive answer whether the waterjet will delaminate the composite around the cut holes or not.
I've previously cut with bi metal hole saws and the hole turned out quite a bit too large and I trust a robot to measure a lot more accurately than myself. I was also interested in laser CNC cutting, but I'm pretty sure that will burn the composite around the edges of the cuts.
Any input would be appreciated.

Thanks,
Omri


A CNC router should be a good option with fiberglass. You can run a 1/8" dia. cutter and do pretty well. There are quite a few sign shops that have small CNC routers & they might be a good resource. Depending on where you live, there may also be a fabrication co-op (Makerspace, etc.) that has the equipment to do this. No need to get exotic with lasers, etc.

Craig
7Q
  #9  
Old February 26th 15, 11:24 PM posted to rec.aviation.soaring
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Default CNC Waterjet cutting instrument holes

After designing the panel on AutoCAD, I sent the .dwg file to Severn Valley Sailplanes in the UK. They made the fibreglass panel and CNC cut the holes.. They did an outstanding job, produced a delamination-free panel and shipped it to my door. If I was to try to find a negative it would be the wait before starting as they had a number of jobs on. But for experienced pros, definitely worth the wait.

CJ
B3
  #10  
Old February 27th 15, 03:54 AM posted to rec.aviation.soaring
jfitch
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Default CNC Waterjet cutting instrument holes

I have cut a lot of fiberglass on waterjets. It will delaminate a small circle around the hole pierce, this can be avoided by drilling thru holes where they can start the cut. A backing board will not prevent it, it is a consequence of the waterjet pressure forcing between the laminate layers before the pierce is complete. The edge will be very nice and clean. You can also cut the panel in a conventional CNC machine, however fiberglass is pretty abrasive and so many CNC shops don't want to deal with it (dust gets into the machinery and wears it out). I will cut it on my open mill so I can vacuum up the dust and chips as it is cutting (but I still don't like it), I will not put in the VMC with coolant etc. - no way to collect the dust.
 




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