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

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.

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).

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.

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.

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.

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.

On Thursday, February 26, 2015 at 1:09:53 PM UTC-8, wrote:
...7725 bid cloth that I had lying around (a decent cloth, but surely not what Schempp Hirth used)...

I have yet to find anybody who, when presented with unlabeled samples of Hexcell 7725 and Interglas 92125, can tell them apart.

As for the instrument panel cutouts, I am firmly in the holesaw camp--the carbide grit blades are great for that. I get a fair bit of stuff waterjet and laser cut, but only where it is the most cost- or time-effective method. For a round cutout and four screw holes, a good holesaw plus a template from the Schreder library makes it a five-minute job.

Thanks, Bob K.
https://www.facebook.com/pages/HP-24...t/200931354951

Thanks, Bob K.

On Thursday, February 26, 2015 at 7:11:05 PM UTC-8, Bob Kuykendall wrote:
As for the instrument panel cutouts, I am firmly in the holesaw camp--the carbide grit blades are great for that. I get a fair bit of stuff waterjet and laser cut, but only where it is the most cost- or time-effective method. For a round cutout and four screw holes, a good holesaw plus a template from the Schreder library makes it a five-minute job.

Thanks, Bob K.

I laser cut an acrylic template off an AutoCAD file that I'd created and used a template router bit to make the panel. All the holes were good to around two thousandths of an inch - which is what I needed because everything was pretty tight.

9B

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