How to Cut Mask Foam?

[estogoalie]

I bought a large square sheet of mask foam from McMaster to re-pad my mask. I took out my existing foam (easily, it's velcro'd in) and traced it onto the new foam. I tried cutting along the outline with a box-cutter, but it cuts the foam kinda jaggedy, or choppy, or whatever you call it, but it's not smooth. Is there some trick to this? How can I cut the foam with smooth lines? I can't think of any other way than using a box cutter.

[benner33]

1 hour ago, estogoalie said:

I bought a large square sheet of mask foam from McMaster to re-pad my mask. I took out my existing foam (easily, it's velcro'd in) and traced it onto the new foam. I tried cutting along the outline with a box-cutter, but it cuts the foam kinda jaggedy, or choppy, or whatever you call it, but it's not smooth. Is there some trick to this? How can I cut the foam with smooth lines? I can't think of any other way than using a box cutter.

 

I used a foam hot knife. It’s not perfect and I’d love to know better tricks but it worked better than a box cutter for me. 
 

https://www.amazon.com/gp/aw/d/B07H28SCC9?psc=1&ref=ppx_pop_mob_b_asin_title

[estogoalie]

11 hours ago, benner33 said:

I used a foam hot knife. It’s not perfect and I’d love to know better tricks but it worked better than a box cutter for me. 
 

https://www.amazon.com/gp/aw/d/B07H28SCC9?psc=1&ref=ppx_pop_mob_b_asin_title

Wow, I didn't even know something like that existed. Interesting for sure, I'll have to look into that more, thanks.

[TDS-MN]

I had luck using a knife, but taking the cut in several passes rather than trying to get greedy and do it in one pass.  It seemed to get a cleaner cut as long as I followed the first pass closely.  Stray from the previous score and it got a messy edge like you describe.  I have only done the job once, so I am not an expert by any means, but just sharing what worked for me.  I actually used a small scissors to clean up the edges in any place where my knife work left it uneven.  I was working on the Eco Pro foam or whatever they called it.

[jacksork]

On 9/6/2020 at 9:19 PM, TDS-MN said:

I had luck using a knife, but taking the cut in several passes rather than trying to get greedy and do it in one pass.  It seemed to get a cleaner cut as long as I followed the first pass closely.  Stray from the previous score and it got a messy edge like you describe.  I have only done the job once, so I am not an expert by any means, but just sharing what worked for me.  I actually used a small scissors to clean up the edges in any place where my knife work left it uneven.  I was working on the Eco Pro foam or whatever they called it.

second this. Use a new blade with no nicks and several passes should help. Try and flex the foam a little (watch your fingers) and it can be a little easier to follow your previous cuts.

[big_tommy68]

If i recall correctly, one of the foam resellers who posts on GGSU has some videos about cutting foam, including some interesting ideas like using a copper pipe to make perfectly round holes. I hate trying to find anything on FB once you've seen it and lost it, but will try to find them and post them here if I can...

[MrGoalie]

I use a 1” round drill bit to cut the holes.  Go at a steady, medium pace.  Holes come out very clean.  

[RichMan]

I found that using a bread knife worked kind of well on equipment foams (HD/LD) as long as the blade isn't crazy serrated. I'm guessing it would work well on EVA foam, as @estogoalie uses, as long as it is in a cold state. Rubertex might need something more like the hot knife. 

It would be a hell lot easier if we could buy the die cutters, right.

Edited October 5, 2020 by RichMan