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Rascal CNC

Yes. Using end mill bits. I think a burr bit could possibly melt the foam part of the board.
Melting does appear to happen for longer runs, which is probably playing into the bits breaking. Would you happen to have a link to the upcut end mills you use? I've only managed to find one on McMaster Carr that fits the description you provided - but it's about $50 and I fear I may break it before I dial in my feeds and speeds which makes me cringe a bit.
 

Fidget

Active member
@flyingavocado I have something similar in mind for a vacuum table. I bought some tees and valves and am hoping to create some "zones" for cutting acrylic and things that are smaller than a piece of foam board. And hopefully an extra opening to hook a regular vacuum hose to to clean things up afterward!

I'm using Estlcam for generating g code. I like it, but I'm having trouble getting my drawings out of Inkscape (as dxf) and into Estlcam at the same scale.
 
@flyingavocado I have something similar in mind for a vacuum table. I bought some tees and valves and am hoping to create some "zones" for cutting acrylic and things that are smaller than a piece of foam board. And hopefully an extra opening to hook a regular vacuum hose to to clean things up afterward!

I'm using Estlcam for generating g code. I like it, but I'm having trouble getting my drawings out of Inkscape (as dxf) and into Estlcam at the same scale.
I have had scaling issues with DXF files as well in Easel, however SVG imports seem to work really well. You might want to try Easel to see if you can just import the SVG from Inkscape to generate the gcode. I use cncjs for interfacing with my Rascal and sending gcode. I haven't tried out Estlecam yet, but I know a lot of people on the forum use it and seem to be happy with it.
 

Fidget

Active member
I have had scaling issues with DXF files as well in Easel, however SVG imports seem to work really well. You might want to try Easel to see if you can just import the SVG from Inkscape to generate the gcode. I use cncjs for interfacing with my Rascal and sending gcode. I haven't tried out Estlecam yet, but I know a lot of people on the forum use it and seem to be happy with it.
Thanks! I'll look into Easel.
 
Melting does appear to happen for longer runs, which is probably playing into the bits breaking. Would you happen to have a link to the upcut end mills you use? I've only managed to find one on McMaster Carr that fits the description you provided - but it's about $50 and I fear I may break it before I dial in my feeds and speeds which makes me cringe a bit.
Thought you might like to know I've been using a downcut bit that works better for me than an upcut. And, they are only $12.99, plus shipping, from Inventables. The cut depth is .2" (5.08 mm).
Here's a link, if you're interested. Downcut, 1/32
 
@Addicted It's funny you mentioned that, because I ended up buying the upcut version of the same bit.

My results with the upcut were slightly better than the ball nose downcut I was using before. Surprisingly this upcut has a cleaner cut and the paper on the top surface is less rough.I still have tearout of the paper on sharp corners though, which is the main issue I want to solve. I will have to try a flat downcut as you suggested though. If that doesn't work, the only other thing I can think of is slowing down the cuts. I am running 2200-2300 mmpm which does okay for the most part.

One concern I have with the upcut end mill is it seems to get paper buildup on the endmill while cutting, and I have already seen that cause a bunch of PCB burr bits to break. The PCB ones I recall had the cleanest cuts but broke too easily and I had to run at rates which made it take too long to cut a sheet out.

This is cut using the Upcut 1/32 at 2250 mmpm. Those tail sections are the most common ones lift/tear the paper -- the cut paths try to start from the narrow end and cut inward when it happens. What I need it to do is cut the opposite direction on those cuts and I think it will fix the issue... I *could* manually hack the gcode... but I don't want to do that if I can avoid it.

PXL_20210203_051954364.NIGHT.jpg
 

Addicted

Elite member
@Addicted It's funny you mentioned that, because I ended up buying the upcut version of the same bit.

My results with the upcut were slightly better than the ball nose downcut I was using before. Surprisingly this upcut has a cleaner cut and the paper on the top surface is less rough.I still have tearout of the paper on sharp corners though, which is the main issue I want to solve. I will have to try a flat downcut as you suggested though. If that doesn't work, the only other thing I can think of is slowing down the cuts. I am running 2200-2300 mmpm which does okay for the most part.

One concern I have with the upcut end mill is it seems to get paper buildup on the endmill while cutting, and I have already seen that cause a bunch of PCB burr bits to break. The PCB ones I recall had the cleanest cuts but broke too easily and I had to run at rates which made it take too long to cut a sheet out.

This is cut using the Upcut 1/32 at 2250 mmpm. Those tail sections are the most common ones lift/tear the paper -- the cut paths try to start from the narrow end and cut inward when it happens. What I need it to do is cut the opposite direction on those cuts and I think it will fix the issue... I *could* manually hack the gcode... but I don't want to do that if I can avoid it.

View attachment 191401
With the downcut bit I linked, there is far less of a rough edge, which is now on the bottom of the cut, and the top of the cut is very smooth and clean. And, the downcut bit has a deeper cutting depth. I've cut far more than 150 planes with an upcut, and after using a downcut bit, I will not use an upcut bit to cut foam board again, unless it's an emergency.
To get rid of the tearing, you can place full depth tabs in the acute angle, or change the plans to not cut those areas, then hand cut them afterwards. (y)
 

nerdnic

nerdnic.com
Mentor
@Addicted What I need it to do is cut the opposite direction on those cuts and I think it will fix the issue.
This is what I do and it works well. It's a pain to configure for each file, but the end result is very clean and no tears.

With the downcut bit I linked, there is far less of a rough edge, which is now on the bottom of the cut, and the top of the cut is very smooth and clean.
Can you show a picture of the top and bottom of your foam after a cut with a downcut? I've been using upcuts and while the top of the foam (inside of the plane) is fuzzy, the bottom (outside of plane) is clean and not seen on an assemble plane.
 

Addicted

Elite member
This is what I do and it works well. It's a pain to configure for each file, but the end result is very clean and no tears.



Can you show a picture of the top and bottom of your foam after a cut with a downcut? I've been using upcuts and while the top of the foam (inside of the plane) is fuzzy, the bottom (outside of plane) is clean and not seen on an assemble plane.
With the downcut bit, the bottom of the cut is still fuzzy, but not like the top when using an upcut bit. I think it's because the waste board beneath it holds the paper against the foam and reduces the "fuzzy". I usually sand the edges of the parts anyway, but with the downcut there's less to sand.
I don't have any pics of it, but I'll post some when I can, Nic.
 

nerdnic

nerdnic.com
Mentor
With the downcut bit, the bottom of the cut is still fuzzy, but not like the top when using an upcut bit. I think it's because the waste board beneath it holds the paper against the foam and reduces the "fuzzy". I usually sand the edges of the parts anyway, but with the downcut there's less to sand.
I don't have any pics of it, but I'll post some when I can, Nic.
That makes sense. I'll have to give it a try. I'll be happy if I get better results.. but also sad that my 20+ upcut bits will go to waste :p
 

Addicted

Elite member
This is what I do and it works well. It's a pain to configure for each file, but the end result is very clean and no tears.



Can you show a picture of the top and bottom of your foam after a cut with a downcut? I've been using upcuts and while the top of the foam (inside of the plane) is fuzzy, the bottom (outside of plane) is clean and not seen on an assemble plane.
Here are a few pics using a downcut to make an EZ Raptor.
These are the top of the cut.
IMG_20210207_212525437.jpg IMG_20210207_212453388.jpg
IMG_20210207_212511721.jpg IMG_20210207_212659353.jpg
IMG_20210207_212549078.jpg IMG_20210207_212611337.jpg
 
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Addicted

Elite member
This is what I do and it works well. It's a pain to configure for each file, but the end result is very clean and no tears.



Can you show a picture of the top and bottom of your foam after a cut with a downcut? I've been using upcuts and while the top of the foam (inside of the plane) is fuzzy, the bottom (outside of plane) is clean and not seen on an assemble plane.
Bottom of the cut. In the last photo you can see the fuzziness is the worst of all the pics. I think it was due to the material being slightly lifted, or bowed above the waste foam board, or the waste foam board had a low spot.
IMG_20210207_213318092.jpg IMG_20210207_213127572.jpg IMG_20210207_213132592.jpg
IMG_20210207_213234994.jpg IMG_20210207_213255314.jpg IMG_20210207_213155115.jpg
IMG_20210207_213326391.jpg
 
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