Insulation Foam

[gary_sutherland]

For those who have cut insulation foam...

What are the differences, if any, between the white, pink and blue foams? Around here white is the only thing the big boxes carry, but I'm sure I could find the others is there's any advantage.

Any ideas on other 'cheap' foams for low budget projects?

Thanks...

Gary

[paco]

Gary,

I believe white bead foam to be the cheapest...

Here how they look once machined...
http://www.cooptel.qc.ca/~usinum/foams_.jpg
http://www.cooptel.qc.ca/~usinum/foam3.jpg
http://www.cooptel.qc.ca/~usinum/foams_zoom2.jpg
http://www.cooptel.qc.ca/~usinum/foams_zoom3.jpg

[Brady Watson]

Gary,
The pink and blue foams are practially identical, and come in around 3# density. They are are called 'Extruded Polystyrene'.

The white foam, while also polystryrene, is composed of many beads that are compressed or expanded...and are called 'Expanded Polystyrene'. The acronym, EPS applies to the white foam...not the pink and blue stuff.

There's probably not anything cheaper out there as far as foams go. It seems to be a regional thing...the colder it is, the more foam choices you have. Depending on where you live, you might want to look into marine and oil industry suppliers because they also use foam products that could be machined on the bot.

-Brady

[gerald_d]

Not having any idea where on this planet Gary lives, can one really have certainty what his white, pink and blue insulation foams are? Does a standard colour system apply internationally?

[Brady Watson]

Gerald,
The pink and blue, while identical in composition, vary as far as availability in the US and Canada & are manufactured by DOW Corning exclusively. EPS white foam I would bet, is available internationally, because it is used for many things in ALL phases of construction.

-Brady

[krfitz]

Gary,

I have cut both pink (extruded) and white (expanded). Pink machines better and the mess it creates, IMO, is not as nasty as the white. If you cut white (http://krfitz.com/cnc.htm), be prepared for a really irritating experience.

[joe]

I just can't do it any more.

Years trailing behing me, reviewing the successes and failures, there isn't one foam sign, left out there I'd put my name on.

Yes we've topcoated them but after fifteen years, facing the souther Oklahoma sun they just don't stand up. Even if they did, I can't say we got the right look. When we got enough of topcoat on they allways looked like cheap cast signs. Not a craftsman looking product.

I had a brilliant idea, once. Redwood was so expensive, before HDU, I'd sandblast cheap foam with a grain frame hard coat it, and make a killing. It all reminds me of a couple of young lady's I met, when I was young. Havings romantic visions of something long lasting and special. Never worked out.

Good luck with the foam anyway, I know I didn't change one mind. So why am I doing this? Because I like you all.

Joe

[davidallen]

has anyone tried using foam as a substrate for thermoforming?

in particular, cutting a positive profile then using a vacuum to form fit a warm plastic film over the top.

with an open cell foam, you should be able to pull the film into fairly sharp details. that might give a good finish and good weatherability. (at least to one side) the back could handle a good topcoat to seal without affecting appearance.



da

[billp]

David,
I did two 4 foot styrofoam turtles last year as molds for a thermoformed project. The first turtle did not have any coating on it, and they had some problem getting it to pull a good enough vacuum. So on the second one I coated it with Styro Spray and it worked fine. I think just about any good sealer would allow styrofoam to work.

[gary_sutherland]

Thanks for the replies. In the examples shown the pink and blue extruded foams certainly have much crisper edges. I'll look for some to try.

gary

[Mayo]

In addition to the pink and the blue holding detail better, (like more crisp edges), it is stronger and less fragile than the white foam if you happen to cut any thin or narrow shapes.

Around my area I have been unable to find the blue foam without it having a mesh netting on it. The pink foam has a thin clear plastic sheet on both sides, which comes off easily.

Cutting tips:
The 1/8" Rotozip tile cutter bit works really good for cutting these foams.

Speed: If you cut too fast, the bit will start to clog with foam, and then the foam begins to melt onto the bit and get progressively larger if you don't catch it right away. I have tried cutting at 2.5" per second and the bit loads up with foam. At 2" per second, all is well.

If your bit clogs with foam, soak the bit in acetone and the foam will easily clean off.

[Brady Watson]

Mayo,
I have never seen blue foam with mesh in my neck of the woods...I am quickly finding out that foam insulation availability is highly dependent upon locale.

I initially was using RotoZip bits...but after finding a solid carbide bit with the same cutting length, I am convinced that the RZ bits are a false economy. They don't drill very well, they 'lag' behind with any kind of chipload, and they are down-cut spirals, so chip exraction is nil.

Get an extra long carbide end mill and I think that you will be pleasantly suprised.

-Brady

[davidallen]

I went to HD the other day and asked about the other types of insulation foam that aren't available here. they said they might be able to order some but they'd need a SKU or better yet a receipt. does anyone have a receipt for the 3" urethane sheets they could scan?

[billp]

David,
I have never been able to find the 3"stuff at any of the chain stores. I had to go to a specialty building supplier who dealt with metal buildings and roofing contractors.They even had 4" foam, but only in 2'by 4'sheets, no 4 by 8's. I even called Dow and they were NO help at all. They gave me a list of places they said would have the 3"stuff, but of course when I called them no one had a clue as to what I was speaking about.

[Jim Stephens (Unregistered Guest)]

Try this:http://www.dow.com/styrofoam/na/pro-us/products/highload_40.htm - or this -http://www.dow.com/styrofoam/na/pro-us/products/square_edge.htm -
I got these in the Dallas area - Southwest Vault Builders - (2"x4'x8') $25(square edge), $31 (highload 40)

[btk]

I have used the Square Edge (blue foam).
Approx $23 (2' x 8' x 3" sheet).

I have also used Dow Roof Mate 4" blue foam but do
not recall the cost.

My Supplier may have a branch near you.
http://www.alliedbuilding.net/alliedbranches.asp

[stargategfx]

BTK.
You might consider changing your username, there may be others on this forum who's lives, like mine have been touched by extreme violence and don't find your choice of name very funny.
Just my 2 cents.

[btk]

Boyd,

Sorry about any confusion regarding my username,
I can assure you 1000% that I am not trying to make any sort of joke. I registerd (and re-registered with each outage) on this forum
with that username before the recent publicity of those initials (incidentally, my first time hearing of that other BTK).

My company name is BTK CORP.
It has been so since 1996.
By Initials are "B.T.K." (from before the BTK incidents in the 1970's)
I am known as BTK to many.

I am truly sorry that you have been touched by violence and I am deeply sadened
by all violence and hope that you do not associate my name with violence.

Sincerely,
Brian


P.S.
Some other positive BTK's
http://www.btk.com.au/ Telecom Company.
http://www.buildingthekingdom.com/ A Church

[Mayo]

Just to clarify, the RotoZip bits I use on the foam are not the drywall or wood cutting bits. They are the TILE cutting bits, available in 1/8 and 1/4 inch. They work great on insulation foam up to 1 1/2" thick - I haven't tried cutting any thicker foams.

[stargategfx]

Brian,(BTK)
My apologies, Boyd

[paco]

Hey Brady (and all)!

Just as I'm having some issues with thick (2") extruded foaming (styrene type)...

"I initially was using RotoZip bits...but after finding a solid carbide bit with the same cutting length, I am convinced that the RZ bits are a false economy. They don't drill very well, they 'lag' behind with any kind of chipload, and they are down-cut spirals, so chip exraction is nil.

Get an extra long carbide end mill and I think that you will be pleasantly suprised."

...what bit are you finding to give you the best finish with insulation foam (styrene type)? I'm looking for 1/4" CED, 2" to 2-1/4" CEL Solid Carbide... the particular issue I'm having is that the bit get VERY HOT and melt the foam chips which create a VERY rought finish as it bounce on the cutten edge (or even clog the bit's flutes)... so far I've tested 2 (HSS) and 4 flutes (SC) up spiral and 1/2" CED 2 straight edges, various cutting strategies (multi-pass with large finishing pass stepover allowance, VERY fast and VERY slow, high and low RPM)... my best have been with this 1/4" CED, 2-1/8" CEL, HSS, 2 flutes spiral up ut it still get quite hot (without actually melting the foam chips) and tend to chatter or lagging to much at the bottom of the cut... sorry, no pics... picture a water jet finish... or plasma at high speed (not in foam!!!)...

Thanks in advance for any advice. Anybody else is invited to join in for any good tips about this.

8-)

[jay]

Paco, I am surprised to hear you are having a problem with very hot bits.

I believe I run the same router, a PC, as you. I have no problem with hot bits. Now I did have a problem with super hot collets until I got my third set of replacement router bearings from the PC Service Centre.

When cutting foam 1, 2, 3 and 4 inch, I use the same bit and step-over I would use when I cut the same file out of wood. Never get any melting and always get a nice clean cut. Many times I will run my move speed at the fastest my PRT will cut at, as the foam offers very little resistance. I should mention that the majority of the bits I use are from Onsrud.

I question whether you may be having a bearing problems? You must need a glove to protect your hand when you touch the collet to change bits, right? If so go get new bearings from your PC service centre.

Jay

[billp]

Paco,
It's also hard to tell from your description above, but have you tried ball end , bits/end mills? I think the upcut spiral will "tear" some foams. And many foams don't tolerate "plunging" very well either. As Jay points out however, it's not very difficult to get a smooth edge on almost any foam (except for that popcorn white EPS stuff on occasion...). Have you tried going back in after the file has run, and then just "skimming" the edges about .01" ? Got any pix?

[jhicks]

Interesting thread. I have used the PINK foam for pilot verification but this sounds like some of you are using it for finished product. Is that what I'm reading here? I would never imagine this material would be suitable for anything but pilots before the real thing in HDU or other materials. Can anyone share what types of applications are folks using this pink foam for?

[Brady Watson]

Paco,
I mostly use a sharp upcut spiral ball and dedicate it to only cutting foam. I run it at 8,500 to 11,000 RPM max depending on move speed. I have never seen foam melt from routing. This could be as Jay points out, your collet getting hot and transferring that heat to the bit or excesive RPM. Turn the router down to 10k.

Low density EPS requires very sharp tools to get a nice finish...but even so, you will still get some ragged edges. Be sure that the foam is held down well with DS tape.

Finishing the foam is a whole other matter...and an art in & of itself. At this point, Trupan seems to be my choice for 3D, when it is possible to hog out the back side of the part to keep it light.

-Brady

[paco]

Thanks all for fast reply!

VERY relevant suggestion about the collet/bearing but... not! I now run the SUPER Milwaukee and the collet never get more than warn even at 22 000 RPM. I've sure consider this while troubleshooting this issue... and discarded it.

As wrote, so far I have used/tested HSS spiral 2 flutes up cut with a single pass cut; that is 1/4" CED, 2-1/8" CEL in 2" thick blue and pink insulation (and white too). I've tried a SC 4 flutes spiral up cut with worst results; I've come to believe that the flutes are too small to remove the "chips" efficiently with this 4 flutes... the HSS 2 flutes is better but tends to be a little more flexy (since the bottom of the cut is less good than the top/upper part)... I've tried a 1/2" CED, 2" CEL 2 flutes straight edges too with no better finish and MUCH MORE heat... this heat build up is mostly at the tip/end of the tool bits I've test/tried. I run the RPM at the lowest (8000)... the melting mostly begin when the tool bit as cut a certain lenght of material; say 4 to 10 inches... I've found that the best feed for the better finish is at about 1.5-2"/sec. which I think is quite slow... I wish I could go FASTER!

Anybody snap their 1/4" CED, 2" CEL Solid carbide tool bit from too fast a feed in styrene foam?! I'm now more confused about this... I plan to order a SC of this 2 flutes spiral up to see if it's less flexy... but that does'nt solve the heat buid up... what feed are you guys using at around 8000-11 000 RPM?

By the way, I do not have any problem of this kind when I do some 3D carving with a ball end tool since the stepdown and kerf allow for more room to remove the chips... same when V carving, pocketting and such... I do have some heat build up when profiling thick HDU (1.5-2" in a single pass) but not as much as in styrene type foam... The less thick is the foam the les I have a heat build up... I don't have this problem with my HSS 1/8" CED, 1-1/8" CEL?!?!?!?

OH, all thoses tool bits are quite new and sharp...

I would have a simple question for thoses who've cut styrene foams; if you cut out (profile) a 20 inches tall letter out of 1-1/2" to 2" thick blue/pink/white styrene foam in a single pass with a 1/4" CED tool bit, can you grab your tool bit without actually burning your fingers?!?! If yes, what setting are you exacly using (all specs)?

Jerry,

some of my customers use the foams for thickning their large acrylic lettering; they use it as a backing for the colored acrylic letters and designs and paint the edges... which is why I (we) need a smooth finish...

[gerald_d]

"if you cut out (profile) a 20 inches tall letter out of 1-1/2" to 2" thick blue/pink/white styrene foam in a single pass with a 1/4" CED tool bit, can you grab your tool bit without actually burning your fingers?!?! " There will be a burning feeling unless you switch the router/spindle off first!

[Brady Watson]

Paco,
What you are saying is almost impossible if you are talking about blue/pink insulation foam like they sell at home centers. I'm not doubting you, it's just that I have never encountered the foam actually melting regardless of RPM.

Cut quality will be drastically improved if you just use a straight bit to do profile passes. Make sure that you are running the tool in Conventional on the outside....

-Brady

[paco]

Brady,

It is this kind of insulation foams that one can find about anywhere around here... Melting occur, mostly with the 4 flutes up spiral... I still get "hard chips" from the 2 flutes spiral up... note that thoses are 1/4" CED tool bits with a cutting lenght of 2-1/4"... I've test a 1/2" CED straight edges last evenning with a less smooth finish than with the 2 flutes up spiral... all become enought hot that one cannot touch it right after a certain lenght of cut.

I plan to order a solid carbide of this 1/4" CED 2 flutes up spiral in the hope that I will improve the finish of the cut edge... maybe try a 1/2" CED up spiral too...

How fast could/should I go with the feed BEFORE snaping the long bit (mostly the 1/4" CED solid carbide ones)?... thoses are no cheap bits to break!... in foams...

I'll try to post some pics of what I got so far for you (all) to give me a feed back appreciation about it... I made SEVERAL tests...

I'm quite suprised (and confused) that no one else seem to have encounter this issue?!

Still thanks for any help!

[Brady Watson]

Paco,
Please do posts several pics. It is clear that we are not talking about the same type of foam...this must be something other than the insulation (pink/blue) foam that many of us use. It is nearly impossible to break a bit in this stuff. If you took two pieces of the foam I am referring to and rubbed them together, they would sand each other down. The pink/blue foam is only 2 to 3 pound density...Do you have a density rating for the stuff you are cutting? Still baffled by this one...

-Brady

[paco]

6035

What else could it be?! I must admit that I have test/tried several density of this stuff (blue and pink) lately; the later is called "high load" blue extruded styrene.

Here some pics, which I hope will make it clearer of what I've got so far... could it be better?!... than my best so far... and why is it getting so hot?!

Thoses are from a 1/2" CED straight edges (2) wood router type bit, 2" CEL...


6036

Thoses are from a 1/4" CED 2 flutes spiral up cut HSS 2" CEL...


6037

This is the same test as the previous in pink (2" thick)... along with the previous blue one, IT IS the best I could achieve so far in thick (1-1/2" to 2") blue/pink extruded styrene... you can see that the bottom of the cut is not as good/smooth as the upper part...


6038

This is what I've got with the 1/4" CED, 2-1/4" CEL, 4 flutes spiral up bit in blue styrene... I can cut some longer in pink one (few more feet) before it begin to melt?!?!?! WHY?!?!?!


6039

This is what is creating the problem... and it is not the worst I've got!!!


6040


This is with a 1/4" CED, 1-1/8" CEL (shorter) HSS spiralup in white expanded styrene... much better, but needed to be cut with two pass because of the cut lenght of the tool...


6041

Thoses are the BAD tools (in my case) for thick styrene... from top to bottom; 4 flutes SC, 1/4" CED, 2-1/4" CEL, spiralup; 2 flutes HSS, 1/4" CED, 2-1/8" CEL, spiralup; 1/2" CED, 2" CEL, straight edges CT (actually this is a 1-1/2" CEL of the same since the 2" is on the machine right now)...


6042

Thoses are my "good guys" for foam cutting since I can't complain about 'em... from top to bottom; 1/4" CED, 1-1/8" CEL, HSS spiral up; 1/8" CED, 1-1/8" CEL, HSS spiralup (I love this one
6043)


6044

This what I can get when I carve styrene... quite smooth...?


6045


6046

This what I get with the 4 flutes in HDU at about the same feed speed than in styrene?!?!?!
6047


6048


6049

While I'm at it, this a moulding carved in white styrene for a customer's sample... with 2 tool bits...


6050

Looking to hear/read about your feed back... please!

[btk]

Paco,

We have definitely seen a difference in the quality of finish depending on RPM and Move Speed when cutting Foam (2", 3", 4").

Slower better in both cases. When I want a nice finish on 2D profile cutouts, I use 1.0 ips and 8000 RPM (Dow Blue Foam).

If you are doing deep cuts and stepping down and doing multiple passes, the second pass will most likely have the bit completly submerged in the foam. The insulating factors of the foam will keep the bit hotter that normal.

In the case of a tappered bit, it is possible depending on the stepdowns that the first pass will not fully "clear" the entire Diameter necessary so that the Shank of the bit above the CEL (with no blades) could "drag" through un-cut foam on the subsequent pass. If you can, I would avoid using a tapered bit for the profile cutouts.

Have not seen a problem with faster speeds when doing 3D surface contours with ball-end mills (assuming single stepdown)

Have only seen burnt foam when inadvertently drag hot collet into foam or step down more than the CEL while moving fast at high RPMS.


Brian

[paco]

Brian,

what bit are you usually using for profiling big letters and designs out of thick styrene foam? Do you do it with a single pass?

I always respect the CEL capacity of my tools... or do more than one pass... still, I most admit that the kerf is pretty much always packed with foam "chips"...

Have you gotten better finish than I did in styrene?... better than #3-4-5 of my tests?

Thanks!... I feel a little less alone now...

[btk]

Yes, we get a better finish that 2,3,4, however only when required.
Slow Down the move speed and Router
If the part is just a prototype, I do not generally care about the finish.

To reduce vibration, First Pass cut all the way through except for
1/4 "skin", then do a final pass (we experimented with a small offset on cleanup pass, however find it to have a neglible advantage).

I can get you exact specs on Monday when I go
back to shop, however I think specs are:
Solid Carbide
Double Edge Spiral
1/4" CED
3" CEL
Approx $50 USD @ Hartlauer Bits

I will see if I can post some pictures this weekend.

[btk]

Paco,
I could not find any closeup pics.
I will look for some others.

Cutouts (these were initial prototypes, purposely cut quickly, not with great surface quality, however final batch was done with very good finish)

6051

Contour (done with ball-end mill).
Note: Edge ("skin") was broken off by hand, not cut with machine.

6052

Brian

[paco]

Thanks Brian!

I use (and found to be my best so far) the same bit as you but HSS material (Hartlauer Bits)... I plan to order the SC one from Onsrud soon...

I'm already at the slowest RPM but I seem to be faster than you about the feed (1.7"/sec.)... I'll try 1"/sec. next time...

I've tried making a final/cleaning pass with a quite large allowance (1/8") to see if I could improve but not very much better... at 1.7"/sec.

Your 3D looks VERY good; was it hairy?!

So far, how do you like cleaning up this stuff from your shop/machine??!!!
6053

[nic (Unregistered Guest)]

Maby your router turn faster than what it suppose to.

[Mayo]

Here's a tip in case you have bits with melted foam on them. Soak them in acetone. The foam will then be easy to clean off.

My hold down method is 3M Super77 spray glue - a light misting on the back of the foam, then firmly press it onto the spoilboard everywhere. You'll quickly discover how much spray is too much (when your foam won't release from the table) and how much isn't enough (when it moves and lifts while cutting).

One "bit" I have used on the thick white foam is sold in hardware and home center type of stores - it's called a 1/4" high speed steel saw drill bit. The edges are serrated. The tip resembles a regular drill bit, so you need to cut deep enough so that the tip is past the bottom of the foam if you want your foam edge to look uniform. When I do this I use a 3/4" sheet of foam as a spoil board.

[paco]

Thanks for the tips!

Keep posting; I'm watching it...