[TheForge] Punch press dies

Mon Jul 18 21:22:03 EDT 2011

My understanding isthat the  clearance needs to increase with the thicness of the stock.

-----Original Message-----
>From: Bob Ehrenberger <eforge at centurytel.net>
>Sent: Jul 18, 2011 2:44 PM
>To: Ries Niemi <rniemi at fidalgo.net>, Blacksmithing List Sponsored by ABANA <theforge at mailman.qth.net>
>Subject: Re: [TheForge] Punch press dies
>
>Ries,
>
>Thanks for your reply. Yes, that is what I want to do.
>
>I have a home made press and was planning on making my own punches and dies. 
>Right now most of my sheetmetal work is in 16 ga and 14ga material.  I don't 
>expect to go past 1/4" plate.
>
>I have already made a holder for 1" rd tools, it is a pretty loose fit, I 
>hold the top tools in place with a set screw. I chose 1" rd because that is 
>the same size my kick press uses, and the top tools could be interchanged. I 
>have already made 3 round tools for making bowels and plates, 5 different 
>sizes of fullers for making grooves and creases in sheetmetal, and a veining 
>tool.
>
>Drilling large holes in light sheet is a pain because it tends to bind, so I 
>thought it would be nice to be able to punch them. I also make several 
>sconces that have key holes for hangers, which require drilling and filing 
>also a pain. A key hole shaped punch would save a lot of time.
>
>It sounds like 1/32" clearance or a little less would work. I was concerned 
>that if it was too close the punch would get stuck.
>
>Robert Ehrenberger
>Shelbyville, Mo.
>eforge at centurytel.net
>
>
>----- Original Message ----- 
>From: "Ries Niemi" <rniemi at fidalgo.net>
>To: "Bob Ehrenberger" <eforge at centurytel.net>; "Blacksmithing List Sponsored 
>by ABANA" <theforge at mailman.qth.net>
>Sent: Monday, July 18, 2011 2:37 PM
>Subject: Re: [TheForge] Punch press dies
>
>
>
>On Jul 18, 2011, at 10:45 AM, Bob Ehrenberger wrote:
>
>I'm thinking of making some hole punch dies for my press.  I know that there
>is a formula to determine the clearance between the punch and the bolster.
>Do any of you know how much oversized the bolster needs to be?
>
>Robert Ehrenberger
>Shelbyville, Mo.
>eforge at centurytel.net
>
>Are you are talking about punches and dies?
>
>If So you want to know "punch clearance".
>
>this varies depending on the material being punched, and the thickness.
>
>Here is a quick chart for mild steel-
>
>
>CLEARANCE FOR A-36 and MILD STEEL MATERIALS
>Recommended clearance for punching
>
>MATERIAL THICKNESS              RECOMMENDED CLEARANCE
>
>1/4" to 1/2" / clearance- /1/32"
>
>1/2" to 3/4" /clearance-  /1/16”
>
>3/4" to 1”  /   clearance-  /   3/32”
>
>1” and over/ clearance-  /1/8”
>
>So, for the vast majority of blacksmith needs, 1/32" total clearance is 
>good. That means the punch is 1/32" under the die size.
>
>If you order ironworker punches from someplace like Cleveland punch, they 
>will ask you thickness, and size your punch and die accordingly.
>
>If you are asking about the punch holder, that you slide the punch into, it 
>can be a loose fit, oversize, just as long as you have set screw that holds 
>the punch in place. This works for smooth shank punches, which were used on 
>many older, lighter duty punches like pexto, niagara, and whitney. Usually, 
>I grease mine, so they will come out again, so clearance is probably .010 or 
>so.
>
>A better system is a quick release system, which uses a lock nut to hold the 
>punch in, and relies on the lip at the top of the punch to hold the punch in 
>place. This is for ironworker style punches, which have that lip on  top. In 
>this system, its the accuracy of the threading of the retaining nut that 
>centers the punch, not the diameter of the hole and the clearance between 
>the hole and punch.
>
>What type of punches will you be using?
>homemade, or storebought?
>For round, square, and oval holes, storebought are better, and pretty 
>reasonably priced. For oddball, specials, you will probably make them 
>yourself, but it makes sense to pick a standard size/type so you can 
>interchange with commercially available stuff.
>
>there are several major suppliers of punches and dies, and most stock 
>coupling nuts as well.
>http://www.americanpunchco.com/punch_stems_coupling_nuts.htm
>
>
>Ries Niemi
>Industrial Artist
>http://www.riesniemi.com/
>
>
>
>
>
>Ries Niemi
>6988 Bayview Edison Road, Bow, Wa. 98232
>360.766.8004
>www.riesniemi.com
>rniemi at fidalgo.net
>
>
>
>
>
>
>
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