I thought I would check to see if anyone had a USA source for high density EVA foam material at the high density of 100kg/M3. Specifically the EVA that doesn’t shrink as much when cut with the laser. I saw a video (https://www.youtube.com/watch?v=vdgSBeRonbw&t=125s) (1:55 timestamp) of EVA 100 foam being cut with almost no shrinkage.
I purchased the plans for the Gauss rifle and have the 3D parts designed and printed, but the EVA foam mats I am using shrink and burn “a lot” when cut.
Worth some googling–but I’d be really worried about what is getting offgassed (what you’ll breath) while its cut via laser. Often pretty nasty stuff in foams!
May be better (but more time) to just use a craft knife–no shrinkage & no nasty stuff released in the air (whether yours, or out your window for your neighbors)…
But in the video did they indicate what type of laser they were using? or the settings? (power vs. speed). You may just have to test to find what settings work on the GF. Also be sure you use magnets or other hold-downs to keep the foam flat and no shifting during cuts–maybe so light the blower is moving parts?
Foam Order High Density (5.8lb) & Top-Quality EVA Cushion Foam Sheet. Perfect for Upholstery | Pneumatic Sheet, Furniture Foam Padding, Seat Replacement, or exercise (40"x 80"x 0.25")
Yes. I think the one from Amazon is going to be the close equivalent. I decided to go with the https://www.redmooncosplaysolutions.com because the thickness is stays metric (following the design details of the project) and after I checked the price and the exchange rate versus what I could get from Amazon. Thanks for the help!
I’ll post a comparison of shrinkage/burning between the generic floor EVA I get from Lowes and the 100kg/m^3 version I get from Canada. I have tried a number of combinations to try and minimize the shrinkage/burning including speeds, power, multiple power settings at multi pass as single height, multiple power settings using multiple focal point lowering passes at top surface, 3/4, 1/2, 1/4 focal heights. Just not satisfied with the shrinkage and side surface appearance.
I hope the higher density will cut like in the video.
#2 EVA “45 degree” foam from Amazon (shipped from china)
1.8m^2 of material for $62= $34.44/m^2
#3 EVA 100kg/m^3 foam from Redmoon Cosplay (shipped from Canada)
2m^2 of material for $84.40 USD= $42.20/m^2
Cut sample squares 30mm square
Actual sizes: 1) 30.00x30x12.29mm 2) 29.70x29.66x29.8x10.50mm 3) 30.10x30.10x10.25 mm
Weight: 1) 1.14g 2) .82g 3) .98g
Calculated density: 1) 103.0kg/m^3 2) 88.7 kg/m^3 3) 105.5 kg/m^3
I think #1 is has a “skewed” density due to the heat seal that is applied to the bottom of the floor mats effectively reducing the thickness. (main section of foam is likely in the 80-90 range while the bottom texture sealed area is 120+)
Test cut using 5mm focal height, 150 speed, full power, single pass
Results:
Left to right:
dimensionally square, consistent thickness, corners have visible shrinkage in mid depth
dimensionally square, significant char, shrink, burn on back
dimensionally square, consistent thickness, no charring, corners have minimal shrinkage in mid depth
Functional thin cross section part check 5mm focal height, 150 speed, full power, single pass:
1)Thinning/twist/warp at upper surface. Bottom surface retains closer to original cut patter shape. Visually distracting heat seal texture.
2) Thinning on upper surface (at bottom of circle)and some melting on back.
3) Base of circle didn’t thin. No melting in back. Some areas didn’t fully cut through.
I will further refine the number of passes and final power settings as I begin to cut the project.
Overall I’m satisfied with the #3 results, but the most expensive of the 3 options.
Nice writeup, this will be really useful information for a lot of folks!
FYI I’m moving your post to the “Beyond the Manual” section in accordance with forum guidelines relating to posting of Glowforge non-Proofgrade references/settings.
