Making a punch press and dies for small parts

Status
Not open for further replies.
Bill DeShivs

Bill DeShivs

Knifemaker / Craftsman / Service Provider
Joined
Jun 6, 2000
Messages
12,554
I'm interested in die punching my own small parts. Nickel silver (1/8"), some brass or stainless for liners, etc. Maybe even steel, if it's feasible.
I know it probably would be cheaper to just have the parts waterjet cut, but if I had more knowledge of making dies it might be fun to do this in-house.
I assume I could use a hydraulic press, but how are the dies fixtured? What size press?
Anybody have any knowledge of this stuff?
Thanks,
Bill DeShivs
 
I used to make dies for punch presses. It's great and a very cost effective option if you need a lot of one part. The dies I used to make were meant for millions of parts.

Waterjet or laser cut parts are often better for the short run. They can be changed much easier than rebuilding a new die.

Jamie
 
Bill,

I recently stumbled on a website that i found interesting. I was thinking about making a few of my own dies for punching out shields.

http://www.potterusa.com/index.php?...=shop.browse&category_id=14&Itemid=53

Mr Potter uses a jewelers saw to cut these pancake dies. He thought that punching .040 thick 410 into slipjoint shields would be handled by his smallest press. 12 ton. He used mild steel for his dies intended to cut brass and nickle silver. He suggested I use a tool steel and heat treat it.
 
You can do it, it isn't impossible. You don't need to make something built like production tooling. You just need an upper (generally male), a lower (generally female) and alignment by dowel pins. I think that for what you're doing, that's all you'll need. You do want hardened steel, even for brass. I used to use O1 for this sort of thing, but knowing what I do now, I'd choose A2.

You can estimate tonnage by multiplying the circumference of the cut by the thickness by the yield strength. A 12 ton hydraulic should be more than enough for shields etc. Just be sure to keep things centered.

Your biggest difficulty is going to be keeping the clearance between the two halves in an appropriate range. The thinner and more ductile the material being stamped, the tighter the gap (and it is possible to be too close). So you may be grinding and filing a fit to within a couple thou or you'll have problems with burrs. I think you'll find it easier to make the female first and fit the male to it than the other way around (much like married life). Then you have to get your alignment pins in the right place, which is a little harder to do if you're making these by hand, though there are reliable techniques for it. (Which I can describe if anyone is interested.)

It should be a fun project that will test your skills. There is a chapter about this in the Machinery's Handbook, which you can probably borrow from someone if you don't have a copy.
 
Last edited:
I don't want to discourage anyone from learning, but punch pressing parts usually involve several operations (i.e. progressive dies, progressive presses) and lots of tonnage with flywheel presses. This is only cost effective if you are Buck or Schrade companies, making thousands of the same pieces per year.

If you move forward in your plans, look at S7 or D2 for tooling steels.

Mike L.
 
I have a copy of Machinery's handbook around here somewhere. I'll look for it.
Interesting site, Ken!
I'm just digging for information right now. Just got a Taig CNC mill, but am waiting for the remainder of the parts. It may be what I need to use.
Waterjet makes the most sense, but the logistics of shipping, and outsourcing leave me sort of cold. I want to do as much in-house as possible.
Bandsawing is OK for custom stuff, but I have a project in mind that will require multiples of several parts.
 
logem said:
I don't want to discourage anyone from learning, but punch pressing parts usually involve several operations (i.e. progressive dies, progressive presses) and lots of tonnage with flywheel presses. This is only cost effective if you are Buck or Schrade companies, making thousands of the same pieces per year.

If you move forward in your plans, look at S7 or D2 for tooling steels.

Mike L.
Click to expand...




Oh lord, it was exactly the kind of point I was trying to make that you really don't need fancy tooling, progressive dies or a "real" press to stamp out a few part. I used to make these all the time for punching, forming and staking existing parts where a laser or waterjet aren't the right tool. I'll see if I can find anything around here to photograph that illustrate the simplicity of these tools. Bill makes automatic folders and now has a CNC. He's up to this. (I think) :thumbup:

S7 is a high shock steel, I don't think it will be necessary on a few hits from a hand crank hydraulic press. D2 is abrasion resistant and what I used to make real tools from, but not just a few parts. A2 sure is a lot easier to machine...
 
Okay, I dug around the shop this morning and found a few examples of "simple" press type tools than can be made by anyone without a lot of difficulty.

First, I trudged down to the dank shop at the back of my property. I seldom go in there, there are spiders. But I knew there would be something in the old press. This used to be a tool that punched holes from two directions into aluminum C channel. Then I needed something to cut out some disks, so I pulled the guts out and slapped this together. That's one way to get things aligned, build it, assemble it, then weld everything down while it's closed...

23.jpg


Hey, I think I found my C clamps...


Moving along, I found this old gem up on a shelf. I'm sure you can relate, I seldom get to keep any of the cool stuff, this being an exception. This was little forming tool to draw some deep dimples in an existing part. Hand included for scale.

24.jpg


This has an extra piece, a stripper plate that was drawn down with screws whos function was to apply pressure to the part so areas on it could be drawn. The draw was done in a hand crank bottle jack press.

25.jpg


26.jpg


27.jpg


and I found this little guy

28.jpg


29.jpg


It was a shear tool used to cut the flare of flared tubing to specific dimensions.


So, I don't have have any little tools laying around that are exactly like the type of tool you're talking about, but the construction could be the same. For what you're talking about, really simple tools, nothing to it.

If you'll reference the Machinery's Handbook, it will tell you how much clearance you'll need for a particular part and explain the mechanics of it.
 
ken erickson said:
Bill,

I recently stumbled on a website that i found interesting. I was thinking about making a few of my own dies for punching out shields.

http://www.potterusa.com/index.php?option=com_virtuemart&page=shop.browse&category_id=14&Itemid=53

Mr Potter uses a jewelers saw to cut these pancake dies. He thought that punching .040 thick 410 into slipjoint shields would be handled by his smallest press. 12 ton. He used mild steel for his dies intended to cut brass and nickle silver. He suggested I use a tool steel and heat treat it.
Click to expand...

I totally forgot about these kind. You could definately make this kind with a jeweler's saw. The ones pictured on the website are laser cut.

Jamie
 
Nathan is right on. A-2 is where it's at. On something like this allignment and clearance are your biggest issues. Something the size of a folder liner might require more attention. If there is a competant tool and die shop in your area I'm sure they could help. You would just be charged an engineering fee if you want to build it yourself.
 
ken erickson said:
I recently stumbled on a website that i found interesting. I was thinking about making a few of my own dies for punching out shields.

http://www.potterusa.com/index.php?option=com_virtuemart&page=shop.browse&category_id=14&Itemid=53

Mr Potter uses a jewelers saw to cut these pancake dies. He thought that punching .040 thick 410 into slipjoint shields would be handled by his smallest press. 12 ton. He used mild steel for his dies intended to cut brass and nickle silver. He suggested I use a tool steel and heat treat it.
Click to expand...

Kevin [Potter] is a frequent contributor on PracticalMachinist. He's good people.
 
So, the dies are not affixed to the press with pins?
I understand the dies are self aligning, but you just stick them in the press and squeeze them?
BTW- I can't weld! And I have no clue how to use the CNC! I'll learn the mill, though-once the guy delivers everything!
 
Bill DeShivs said:
So, the dies are not affixed to the press with pins?
I understand the dies are self aligning, but you just stick them in the press and squeeze them?
BTW- I can't weld! And I have no clue how to use the CNC! I'll learn the mill, though-once the guy delivers everything!
Click to expand...

On a real production setup, both sides are generally attached to the press. However, for your use, that isn't really necessary.

I have a little OBI "flywheel" press, but for most stuff like you're talking about I'd just put it in my cheap $100 bottle jack press from HF.
 
Punching out parts and forming dimples are technically the same but not really. Dimples will self center to a degree. Brass will need smaller die clearance than stainless, also less tonnage. When you start getting into details and sharp corners there are other clearance issues that need to be designed into the punch/die.

What type liners do you want to do? do you want the liners to come out with all the holes? If so you will need to make a compound die that includes some sort of knockout mechanism. Or you will need to make more than one tool. punch the holes then use the holes to locate cutting out the profile. Do you have a mock up sketch of what the end product would include feature wise. Of course I do not mean posting a picture of your new design, only something that incorporates some of the same features such as holes and any funky shapes.
 
Nathan

For those little dies sets you are showing

What kind of fit tolerance would be appropriate on the dowel pin holes - not the press fit end

The sliding fit end ?
 
Liners would not need to have holes.
I'm familiar with how die-punching works and what you can do with it, but I have no personal experience with it, other than doing simple things like punching a sheet metal button with a home made punch and die and whacking it with a hammer.
I have designed production knives with die punched parts. The manufacturers had the die work done.
I just thought it would be interesting to discuss this to see if it's something I want to do. I think I have been sufficiently discouraged!
I may try a few things in the future, but by the time I buy/build a press and dies it doesn't seem feasible.
Thank you all for your input, and if anyone else would like to contribute it would be welcomed. I love to learn stuff.
Just wait till I get the little CNC machine hooked up-THEN I'll have some questions!
 
Carl_First_Timer said:
Punching out parts and forming dimples are technically the same but not really. Dimples will self center to a degree. Brass will need smaller die clearance than stainless, also less tonnage. When you start getting into details and sharp corners there are other clearance issues that need to be designed into the punch/die.

What type liners do you want to do? do you want the liners to come out with all the holes? If so you will need to make a compound die that includes some sort of knockout mechanism. Or you will need to make more than one tool. punch the holes then use the holes to locate cutting out the profile. Do you have a mock up sketch of what the end product would include feature wise. Of course I do not mean posting a picture of your new design, only something that incorporates some of the same features such as holes and any funky shapes.
Click to expand...



You can put holes in a part in a single setup on real basic prototype style tooling, though the finished parts have to be manually removed from the tool. The female side ends up being blind with the punch in it, pressing into the male side. The times I've tried this, there often wasn't enough room to mill that feature directly so I'd insert it. You do want some holes so you can knock your part back out. But it is possible to get features in your part with a simple two piece setup. It just doesn't look very conventional and you have to manually remove your part.

It sounds like you've had a lot more experience than me, is there a better (easy) way for something like this?

As far as small holes go, I've had trouble with the tool breaking and have always ended up drilling holes smaller than about twice the material thickness.
 
12345678910 said:
Nathan

For those little dies sets you are showing

What kind of fit tolerance would be appropriate on the dowel pin holes - not the press fit end

The sliding fit end ?
Click to expand...

If I understand your question, the diametrical clearance between the dowel pin and the hole is (nominally) .0008"
 
Last edited:
Status
Not open for further replies.
Back
Top