Quick question...what's the best bit for cutting EPP, or does it matter?

Chuck
...somewhere in Indiana...

 

Hi Chuck, I hadn't seen a reply to this, so I'll add my 2 cents. I have successfully cut 6mm EPP with the stock 1/8" bit. Everytime I use this bit on 9mm, I have problems. Using a 1/16" bit leaves less cut out area that can get hung up on the various edges of the feed table.

 

Thanks for the answer. I guess I need to get a bit-kit from Mark or something so I can experiment a little. I cut out a 9mm fuse with the stock bit and it looks okay I suppose. I was just trying to avoid any bit that would tear the EPP material out in little chunks. Aren't 1/16 inch bits too short in the cutting area to do 9mm's?

Chuck

 

Ok, i have tried the tape on the edges part, have weighted roller with a spring mod and i can't keep epp from skewing.
9MM seems ok, it's the 6MM that is giving me fits. Anyone have any other ideas?
I have a box of EPP that needs cut that I don't own and I refuse to destroy it, so I have been doing (test) cuts without a bit inserted in the dremel.

 

I remember seeing this youtube video a while back. On a side thought, wasn't those pressure mods for the hard material like wood. Maybe it's too much pressure for a soft foam like epp?

 

Nice find Kwok, and nice video by RCFlightCast.

 

One other item I might note: I put a 1/8" masonite top on my Phlatprinter. It extends from the front edge all the way to the roller, with a much smaller slot for the bit. This helps considerably, as the EPP doesn't catch on the cutting slot as much. After a quick search in the mods section - here is the example : http://www.phlatforum.com/viewtopic.php?f=107&t=1397

Greg

 

Has anyone cut 9mm EPP foam on their Pp III yet? If so, do you have any advice for me when I get my PpIII?

 

I cut out a couple of patterns in EPP 9mm last night on my Phlatprinter 3. I tried the stock 1/8" tile bit and a roto zip 1/8" saber bit. Neither one produced the smooth finished edge I was used to seeing when cut by hand with an exacto knife. I tried running the feed rates at 25, 30, and 50 inches per minute. The cuts with thestock bit actually looked better than the saber bit.

This morning I called the BitBits.com folks and spoke with them about what might be an alternative bit choice. No luck with that route either.

I'm not really wanting to burn through a stack of EPP at nearly $10.00 a sheet so, I hope someone has a good thought for bit choice and feed rates. I have maybe 7-8 partial drop sheets left to experiment with before I'm down to my good stock.

I use 9mm EPP almost exclusively, hopefully someone can impart their wisdom upon us before too much EPP is donated to the science of learning Phlatprinter cutting techniques!

Doug

 

In the past I used a Dermal 1/8" and 1/16" grout removal bit. My router is turning about 27,000 rpm. My feed rates were 60 ipm. That was as slow as I could go, any slower the foam may melt on the bit. The cuts where very smooth, even compared to a knife cut. But, this was all done on my standard home built cnc router table.

Attached files

 

With the MK3 I used the standard bit running at 40IPM any faster the foam would start ripping. However I was cutting the lightweight EPP in both 6 and 9mm.

On the MK1 I could not go faster than 7ipm and the dremel set to about half way. The 7ipm limit was not for the foam I was cutting that at 13ipm until I had to modify my MK1.

 

Do you think the max feed rate on your Pp III was do to the spindles rpm?

 

I would think the spindles fixed RPM is currently our most limiting factor. Finding the feed rate that doesn't either tear or melt the EPP is going to be the key. I haven't tried the Dremel bits yet, maybe they will produce cuts like I'm looking for. My cuts looked more like the bit was pulling small pieces of material from the face of the cut area.

 

I don't have any EPP to try, but have you tried sandwiching the EPP between two sheets of FFF?

Maybe cutting it with the burr bit or one that comes with the Dremel tools might work in that configuration. Attached files

 

After quite a bit of trial and error cutting I have found a very reliable combination for cutting designs out of 9mm 1.3lb & 1.9lb density EPP foam. I have settled on a feed rate of 35 ipm using the stock MK spindle and a Dremel brand 1/8" tile cut bit. I use a FFF carrier sheet slightly longer than the 24 x 36 EPP sheet and pin each end with (5) straight pins. I have been using V style tabbing set at 50% depths. Every pattern, no matter how complex has cut exactly as it should using this configuration. The cut edge of the EPP will appear slightly skinned over, which I actually prefer for my foamies. Hopefully this will help take some of the guess work out of setting up for EPP cutting.

(15 sheets of EPP foam were harmed during the filming.........)

 

dugd1013, Thanks fore sharing your findings. The pinning of the the epp to a backer board is a good idea. Its too bad it took 15 sheets to figure that out.

 

That 1.3lb EPP is easily distorted by nesting too many oddly shaped components on one sheet. When I cut these plans by hand I nested one complete 32" wing foamie on one sheet. However, when I tried that layout on the Phalatprinter I found that there wasn't enough material left in the "nesting frame" to keep layout intact for the last few pieces to cut correctly. I ended up leaving the wing and horizontal pieces on one sheet and moving the fuse halfs and rudder to a second sheet. There is enough uniformity in the fuse lines to nest two fuses on one sheet without getting any distortion while cutting. The end result is (2) planes per every (3) sheets utilized. That upped my waste to the 30% range but, it's a whole lot better than the 100% waste I was getting before.

One of my designs requires more than one sheet no matter how the parts are laid out so, I was kind of resolved to that option anyway. I might try a couple more nesting configurations to see if I can improve the waste loss some more but, right now I'm just passing that loss along in the final cost of the kits.

 

I haven't done a lot of cutting with the 1.3mm EPP on my Phlatprinter III yet, but what I found is that the 1/16" diamond cut bit in the Phlatprinter bit kit works wonderful. While the standard bit and the 1/8" diamond cut bit do not. I believe it has to do with the much smaller cross cut pattern on the bit than anything else. The 1/8" bits both ripped material away from the foam, while the 1/16" cut looked like it was cut perfectly with a knife. I don't really know my feed rate, but I think it was close to 70 ipm spinning at about 25000 rpm.

SlowBipe

 

Followed your guidelines for speed and feed and got a nice cut on 9mm epp of an f22. Used pink ff as a backer. Thanks for your trial and error for everyone else! Attached files

 

Glad it worked out for you!