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First tests with new Windy Hill CNC foam cutter.
- Thread starter Wayne
- Start date
When I used to build log homes we used 3 or 4 inch Celotex in the roof as insulation. Not sure that it is the right kind of foam because it was kind of gritty... But it would be something interesting to try. Would probably have to look for a lumber yard to get some of it though.
Still in need of foam suppliers.
We were super happy with the foam cutter performance, but noticed we kept getting these "steps" in our rutting. Changed a bunch of things, but they stayed put. Here are some samples:
In this photo you can see some slightly "flat" steps mostly around the leading edges. You could just barely feel them.
Finally sean here found the magic setting in the CNC software, it was a cutting tolerance value, we changed that from the default .10mm to .030mm and now get great results. Woohoo!! My first thought was we had some sort of resonance in the cutting wire. Glad it was just software.
What do you guys think of this sample?
Finally something I am VERY proud to put our name on. VERY!
The CNC machine itself is getting a few small updates to make it perfect and then we will start offering them as complete kits. I think you will have the option of with or with out electronics.
Hmm, instructions also need to be written up, etc. That is the slow part.
Excited to put this to work on our Trix kit, and next week we will start setting up to cut EPP and we can get the Bam Bam into production (fume evacuation). Woohoo!
We were super happy with the foam cutter performance, but noticed we kept getting these "steps" in our rutting. Changed a bunch of things, but they stayed put. Here are some samples:
In this photo you can see some slightly "flat" steps mostly around the leading edges. You could just barely feel them.
Finally sean here found the magic setting in the CNC software, it was a cutting tolerance value, we changed that from the default .10mm to .030mm and now get great results. Woohoo!! My first thought was we had some sort of resonance in the cutting wire. Glad it was just software.
What do you guys think of this sample?
Finally something I am VERY proud to put our name on. VERY!
The CNC machine itself is getting a few small updates to make it perfect and then we will start offering them as complete kits. I think you will have the option of with or with out electronics.
Hmm, instructions also need to be written up, etc. That is the slow part.
Excited to put this to work on our Trix kit, and next week we will start setting up to cut EPP and we can get the Bam Bam into production (fume evacuation). Woohoo!
Ok - Found some 25 psi foam at Lowes, but we don't have a Lowes anymore, but they offered cheap same day shipping. If I selected a slower shipping option it was $99, but Sameday was $35. I would have spent that much on fuel alone. Their site didn't say anything about scoring, so hoped it would not be scored, but it was. Oh well. The local Home Depot can get the same foam but would need to be ordered, and would need to find it at their location. Our local Home Depot is not fun for normal stuff, I can only imagine how bad they would be for special order.
Will give the stuff a try soon. Sean is currently writing some custom G-code to help with blocking.
Will give the stuff a try soon. Sean is currently writing some custom G-code to help with blocking.
rcsoar4fun
Very Strong User
Which software are you using?
I need to get my foam cutter started up again, I have been using Jedicut for generating the code, but it would never connect to my controller. Guess I need to dig into that again.
I need to get my foam cutter started up again, I have been using Jedicut for generating the code, but it would never connect to my controller. Guess I need to dig into that again.
thenated0g
Moderator
Devwing foam software for design of the cutting files with the dev Cam software controlling the cnc's Arduino.
Doc J
Very Strong User
Yeah, it was a DS-19 airfoil, very smooth. It was just a setting buried away in the software.
Good afternoon, everyone. Today, I recorded a bit of our hot wire cutting machine in action. Here, you can see it working on a wing profile for a flying wing. The video is sped up 5x!! I hope you enjoy it.
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I use a 4 axis CNC foam cutter for cutting wings that I made from scratch.
If using white foam, such as you find for insulation, you should get the ones that some brands designate "300". They are higher density and usually cannot be made with regrind. They are usually certified to Type 3 or Type 4. The higher compressive strength is mainly used under concrete floors.
Type 3 Expanded Poly Styrene or EPS has higher compressive strength and greater moisture resistance.
A site with a lot of resource information for building and cutting, including firmware, is rckeith.co.uk
When I took some of my wing cores to a local foam manufacturer, I showed the production manager a sample. He took one look at it. Without hesitation his first words were "too slow, too cold". The appearance was enough to tell him what was wrong. He has a lot of experience manufacturing foam products. I was using their Type 3 foam.
He then took me to a small foam cutting machine in their production facility. He threw a large block of white EPS foam on it. The machine had multiple wires tensioned by large springs. When it heated up he turned on the motion. It sliced the foam and it had a much smoother finish then my example. It was hot enough that the foam seemed to be sealed a bit.
I achieved a similar appearance when I made a quick and dirty 8 foot bow to cut up 3 inch thick sheets. The bow was connected to an ordinary light dimmer and 120v AC. When the wire gets to the correct temperature it stretches a surprising amount. About 2 inches over an 8 foot length.
Using a 12 or 24 volt power supply, sometimes just doesn't get the wire hot enough. I use Rene wire as does the foam plant. I use a 24 volt transformer with a bridge rectifier and a large capacitor. That results in about 34 volts ouput. I am still struggling to get the wire hot enough. The thinner and hotter the wire, the better your cut results will be.
Most wires between 10 and 20 thou should work fine. Cutting takes place with radiant heat, NOT contact with the wires. The wire should never touch the foam. If it touches the foam, the speed is too fast or the wire is not hot enough. Excess stringing can mean the wire should be hotter.
My existing 4 axis foam cutter is a modified version of this one on Thingiverse. https://www.thingiverse.com/thing:1672015
I modified it several ways. It is essential to NOT use the bearings in the stepper motors if using a lead screw design. You must use thrust bearings. The stepper motor shaft is held in position internally by magnetism. The bearings are only for side load on the shaft, not end load.
This is important if you are using using a gantry on parallel tracks or rods. It is essential that the length of the guides or carriage running on the tracks or rods be 1.5x to 2x as long as the distance between the tracks or rods. If the carriage is shorter than it is long, it can jam more easily. On mine the distance between the rods was 70mm but the length of the carraiges was only 50mm. They would rack slightly and jam. When I lengthened the carriages to 105mm, it ran smoothly without jamming. With a short carriage, it jams. When it jams, it then jumps when the threaded rods push hard enough to overcome the jam. The result is lines on the finished cut.
Here is an example of such a modification. https://www.thingiverse.com/thing:4604186
Here is a link to a gallery of foam cutters. https://rckeith.co.uk/builders-gallery/
Mine is labelled
Jim’s Foam Cutter using 3d Printed parts.
It has pictures of the thrust bearing I used on the horizontal axis.
For an aircraft foam that is virtually indestructible, there is HYBRID EXPANDED POLYPROPYLENE (HEPP). A local vendor of flying wings uses this type material from
www.polyform.com in Quebec.
You cannot believe how tough this stuff is.
Just my experience cutting foam. YMMV.
Jim Haliburton
If using white foam, such as you find for insulation, you should get the ones that some brands designate "300". They are higher density and usually cannot be made with regrind. They are usually certified to Type 3 or Type 4. The higher compressive strength is mainly used under concrete floors.
Type 3 Expanded Poly Styrene or EPS has higher compressive strength and greater moisture resistance.
A site with a lot of resource information for building and cutting, including firmware, is rckeith.co.uk
When I took some of my wing cores to a local foam manufacturer, I showed the production manager a sample. He took one look at it. Without hesitation his first words were "too slow, too cold". The appearance was enough to tell him what was wrong. He has a lot of experience manufacturing foam products. I was using their Type 3 foam.
He then took me to a small foam cutting machine in their production facility. He threw a large block of white EPS foam on it. The machine had multiple wires tensioned by large springs. When it heated up he turned on the motion. It sliced the foam and it had a much smoother finish then my example. It was hot enough that the foam seemed to be sealed a bit.
I achieved a similar appearance when I made a quick and dirty 8 foot bow to cut up 3 inch thick sheets. The bow was connected to an ordinary light dimmer and 120v AC. When the wire gets to the correct temperature it stretches a surprising amount. About 2 inches over an 8 foot length.
Using a 12 or 24 volt power supply, sometimes just doesn't get the wire hot enough. I use Rene wire as does the foam plant. I use a 24 volt transformer with a bridge rectifier and a large capacitor. That results in about 34 volts ouput. I am still struggling to get the wire hot enough. The thinner and hotter the wire, the better your cut results will be.
Most wires between 10 and 20 thou should work fine. Cutting takes place with radiant heat, NOT contact with the wires. The wire should never touch the foam. If it touches the foam, the speed is too fast or the wire is not hot enough. Excess stringing can mean the wire should be hotter.
My existing 4 axis foam cutter is a modified version of this one on Thingiverse. https://www.thingiverse.com/thing:1672015
I modified it several ways. It is essential to NOT use the bearings in the stepper motors if using a lead screw design. You must use thrust bearings. The stepper motor shaft is held in position internally by magnetism. The bearings are only for side load on the shaft, not end load.
This is important if you are using using a gantry on parallel tracks or rods. It is essential that the length of the guides or carriage running on the tracks or rods be 1.5x to 2x as long as the distance between the tracks or rods. If the carriage is shorter than it is long, it can jam more easily. On mine the distance between the rods was 70mm but the length of the carraiges was only 50mm. They would rack slightly and jam. When I lengthened the carriages to 105mm, it ran smoothly without jamming. With a short carriage, it jams. When it jams, it then jumps when the threaded rods push hard enough to overcome the jam. The result is lines on the finished cut.
Here is an example of such a modification. https://www.thingiverse.com/thing:4604186
Here is a link to a gallery of foam cutters. https://rckeith.co.uk/builders-gallery/
Mine is labelled
Jim’s Foam Cutter using 3d Printed parts.
It has pictures of the thrust bearing I used on the horizontal axis.
For an aircraft foam that is virtually indestructible, there is HYBRID EXPANDED POLYPROPYLENE (HEPP). A local vendor of flying wings uses this type material from
www.polyform.com in Quebec.
You cannot believe how tough this stuff is.
Just my experience cutting foam. YMMV.
Jim Haliburton
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thenated0g
Moderator
thenated0g
Moderator
I need to come down and check out the new cnc table Martin designed. The v1 is getting pretty old but still going strong. Im sure the 3d printed parts will fatigue at some point.
Flying fpv on the Defiantwings d52 at los banos reminded me that fpv wing flying is fun. Kind of a take my time project, but im going to build a copy of the Graugans Thinkflight (youtubename) designed and has built a couple of. The d52 flies great but I want a 6s 90mph'ish setup for some fast zooming. So instead of messing up the d52 i started looking at other things i could do. The Graugan is a pretty big 80" wingspan ship with removable wings and a huge bay.
@Wayne what cutting wire have you guys settled on? For myself the 1mm travel time is fine as im not in production and the very tiny kerf from the 27g wire is great, but i imagine you guys want to cut things a little faster.
Flying fpv on the Defiantwings d52 at los banos reminded me that fpv wing flying is fun. Kind of a take my time project, but im going to build a copy of the Graugans Thinkflight (youtubename) designed and has built a couple of. The d52 flies great but I want a 6s 90mph'ish setup for some fast zooming. So instead of messing up the d52 i started looking at other things i could do. The Graugan is a pretty big 80" wingspan ship with removable wings and a huge bay.
@Wayne what cutting wire have you guys settled on? For myself the 1mm travel time is fine as im not in production and the very tiny kerf from the 27g wire is great, but i imagine you guys want to cut things a little faster.
We have been using the same wire since we started. I do not know what size it is, but I know I bought 2 different sizes to try out. I will say our kerf seems a little large when cutting the pink stuff, especially at the tip when tapered.
Martin has drawn up some updates for the design that should give the machine a much longer life span and make it more adjustable. I'm looking forward to testing the new design. I really like what he has done and think it should be the final version and we can start production of the kits.
Martin has drawn up some updates for the design that should give the machine a much longer life span and make it more adjustable. I'm looking forward to testing the new design. I really like what he has done and think it should be the final version and we can start production of the kits.
thenated0g
Moderator
If you use a screw design, you must not use bearings in the stepper motor. You must use thrust bearings. The stepper motor shaft is held in place internally by magnetism. The bearings only carry side loads on the shaft, not end loads.
This is important if you are using a gantry on parallel tracks or rods. It is important that the length of the rails or brackets running on the rails or poles is 1.5 to 2 times the distance between the rails or poles. If the penstock is shorter than long, it is more likely to jam. On my car, the distance between the bars is 70 mm, but the carriages are only 50 mm long. They wobble and jam slightly. When I lengthened the carriage to 105 mm, it ran smoothly and did not jam. When the carriage is very short, it clogs. When it jams, it jumps when the screw is pushed hard to overcome the jam. The result is lines on the finished cut.
This is important if you are using a gantry on parallel tracks or rods. It is important that the length of the rails or brackets running on the rails or poles is 1.5 to 2 times the distance between the rails or poles. If the penstock is shorter than long, it is more likely to jam. On my car, the distance between the bars is 70 mm, but the carriages are only 50 mm long. They wobble and jam slightly. When I lengthened the carriage to 105 mm, it ran smoothly and did not jam. When the carriage is very short, it clogs. When it jams, it jumps when the screw is pushed hard to overcome the jam. The result is lines on the finished cut.
Hawaii Sloper
Very Strong User
This particular design by Martin at Windy Hill is a proven, tried and true machine with many hours of use on it. Those are good design points if someone is doing a DIY setup though.
