Question for millwrights and machinists about tool steel

[Zeke]

I want to make a press type cutter for 1" foam. I will make the die by placing a blade strip in a groove cut into a heavy laminated wood sheet and cat against a die cutting board. The pattern I'm cutting is a complex design of curves in a 2-dimentional design. so, the tool steel has to bend in radii as small sa 1.5".

Where do I get the bulk cutting strip and what do I call it?

As always, thanks.

[jim72911t]

Milt,
I clicked the link because I am a machinist of over ten years experience, and you've managed to stump me!

When I have questions about tooling, I call Western Tool and Supply. [1-800-836-4288] As opposed to bigger houses like MSC, the staff answering the phones actually have experience in machine/fabrication shops, and if they can't answer your question, they can usually point you in the right direction. Feel free to use my name as a reference (Jim at Paul Component Engineering), and good luck with your search.

Jim

[5axis]

I am not sure, but I am visualizing something like a cookie cutter? The blade will be seated into a curving groove in a wood block that will define your part shape? If this is the case you could probably get away with a heavy gage steel strapping. For a more heavy duty blade you could try spring steel. It is available as wire or sheet, and should give plenty of hardness on the cutting edge. I hope that helps?

[Zeke]

Cookie or gasket cutter is exactly right. And spring steel is perfect. I thought is might be available already ground sharp for this specific purpose.

I have seen gaskets being made and this is how they did it. Funny, a guy actually made a good living from building dies and cutting high quality unique and obscure gaskets for anyone that needed enough to warrant a short run. The fellow couldn't keep up with the demand. Lost track of him a few years back or I'd stop by and ask him. Maybe they ground thier own from steel banding.

The next level is rotary cutting where the production is very high compared to press cutting. Wait 'till you see what I have to make. It's a novelty gag item and every time I look at it I crack up.

[5axis]

Spring steel is available in many shapes and sizes. It is not my area of expertise but I have never heard of it coming ground into a knife edge. McMaster Car has a few pages of spring steel coils that may work well for you. 0.05 thick 1.5" wide 4' mini coil for $32.10 in my old catalog. BTW a 30' coil is $90

Given the "thinness" of most spring steel you may be able to simply shear your way though the foam without knife edging the blade. It's all about the pressure(use very rigid backing for the foam and the blade holder). If that isn't working you could heat the blade and it should slice through like butter.

[island911]

What type of foam? ...flexible or rigid?

Like 5axis says, it shouldn't take much to cut foam.

You could google " Steel rule die cutters" for design ideas/resources.

[Zeke]

Originally posted by island911
What type of foam? ...flexible or rigid?

Like 5axis says, it shouldn't take much to cut foam.

You could google " Steel rule die cutters" for design ideas/resources.

Open cell medium density flexible. The google terms might help, thanks.

OTOH, .05 might cut the stuff w/o any further work on the edge.

[5axis]

Originally posted by Zeke
OTOH, .05 might cut the stuff w/o any further work on the edge.

If you can sqeeze it hard enough it should shear. I have made some simple round washers and shims using a hammer and short pipe of the right diameter. I even made some 5" dia rubber seals for a boat hull fitting this way. Just wacked the pipe harder with a sledge hammer and it sheared right through.

Spring steel coils are available in various sizes Mc C lists .002- 0.062 I would think you need some thickness to maintain wall strength and fixture the strip. If you had a die set to maintain a perpendicular orientation you could probably go very thin. The only issue I see is getting off axis and folding the blade. With a bit of width .050 it should be pretty solid and hard Rc 48-51 is typ

[BRPORSCHE]

Could you use a band saw blade? They're pretty flexible. An old Do All that I used had a spot welder mounted on the side that would weld the two ends of the blade together while forcing the ends towards each other.

[kycarguy 935]

If your cutting foam you could use nichrome wire and use a form to cut around.

Here is a link to a place that sells it.

http://www.demandproducts.com/wire.html

[Zeke]

Thanks KY. There are some ideas there.

[kycarguy 935]

Anytime Milt.

When I was in college I use to work at a large hobby shop in Lakewood and would cut foam all the time with nichrome wire. It worked for the model airplanes and even shaped a few surfboards too.

[island911]

Doesnt sound like you want Hot wire . .. that would be more for free-forming, and cutting thick stuff.

If you want to "cookie-cutter" a bunch of "parts" then steel-rule is the way to go.

'll suggest that you find some .030-.060 thick steel for the die.If you try to count on thin stuff holding-up, you'll be pissed when it folds on ya. . .(AND have with a sharpened edge. . .why cut with a dull knife)

You'll want the heavier walled steel for thicker (taller) material, and/or big lazy profiles. (flexable foam is compresses to "thin' when cut) If, otoh, you have tight countours, the thinner steel can utilize the support of the tight folds (and be okay).

maybe search under steel rule die stock for base materials.
http://www.schroederinc.com/materials/

[Zeke]

Thanks for all the help guys. I'll use a router to cut my pattern into a block to be pressed against the cutting board. The smallect cutting bit is a lot bigger than the knifing material, but I should be able to secure it with some epoxy. Embedded in the wood like that should produce some lateral stability. Following an aluminum template with a drawn knife should make enough pre-production prototypes.

If I follow through (and this has been developed for 6 years and I haven't moved forward yet), I will send all who replied a sample of my novelty gag item.

[RickM]

Here's the ultimate way to cut foam or other materials to any shape: http://www.cnczone.com/forums/forumdisplay.php?f=48

[island911]

Originally posted by Zeke
. . . I will send all who replied a sample of my novelty gag item.

Well thanks .. . I think.
Why is it I get the feeling that you're going to give us all the big foam finger?

[Zeke]

Originally posted by island911
Well thanks .. . I think.
Why is it I get the feeling that you're going to give us all the big foam finger?

That's been done. Nope, way more silly and fun.

[deanp]

Call your local folding carton / box company ask them to point you in the direction of the company that makes their cutting / scoring dies. They should be willing to point you in the right direction or even supply a small amount of the steel they use. I'll attach a pic to a separate post o show you what the rotary cutting dies they use look like.

[BGCarrera32]

How big is this thing? If your part is going to be the size of one of those big foam hand/finger things you'll have an awfully tough time making a nice part with a die and trying to shove it through the foam. At the very least you'll need a large press, and then you'll have to do a little work getting the part out of the die when you are done, risking breaking the part. Dies can be tricky if you haven't built one before.

The "ultimate" way to make your part is to find a short run shop that does abrasive waterjet cutting. No heat is introduced to the foam, its blindlingly fast, leaves a nice edge, minimal mess, etc. Rather than spend time on a die it might be to your advantage to have a 2d line drawing of your thing sent to a shop, pay a $100 setup fee, a few bucks a part and let them bang out hundred of them for you by tomorrow...

http://www.emachineshop.com/machines-kerf/water-jet-cutting.htm

If you've ever seen the Flow Corp's "Flying Bridge" on the show "American Chopper", that would be an example of waterjet cutting machine. High pressure water mixed with an abrasive slurry is shot through a sapphire tipped nozzle at an obnoxious amount of pressure. The cnc end of it is similar to laser or plasma, except it has the ability to cut plastic, wood, foam where the others can't.

-BG

[deanp]

Material used on box cutting die...