DIY Leather Punch / Press Conversion

[kgg]

I came across a table mounted fabric hole press at auction for about $25 made by Joel & Aronoff called "The J & A Patch Press" which I believe are made at some point in England. All it needed was a little cleaning and some oil. Having a fabric hole press wasn't what I wanted, it had to do more. I only need a press to do two simple things i) accurately punch holes for rivets and ii) press my logo into leather. The main problem I came across while doing this little conversion was the 5/8 " punch bolt and internal threaded rod. The round nut, punch bolt and the internal threaded rod have an unusual thread twist of 13. Normally I would have printed a 5/8 x 11 or 12 or 14 and run a die over to clean up the thread. Noooo, not this one it was a 5/8 x13 or maybe a even 13.25 which I confirmed with a thread gauge. That sent me down the rabbit hole of designing a 5/8 x 13 thread. A proper die would have be very costly at around $400 while my time is cheap. You got to love priority threads.

Even through it has a small travel of 16mm it does work for what I need. This may give others an idea of converting other equipment to do other things that it wasn't designed for.

Photo 1:  Shows how it came, with a Aluminum 24.6 mm, another odd size, hole punch.

Photo 2: Shows the pieces that screw the three punch parts into a thread rod in the press head. I place the parts on the HDPE pad that came with the press. The round nut is use to set / lock the travel of the punch bolt while the punch is held in place on the bolt with a simple set screw that fits into a hollow formed at the head of the punch bolt.

Photo 3: Shows my 3D printed logo using the original punch bolt using and using a simple set screw attachment like the hole punch has.

Photo 4: Shows my 3D printed logo which I made in two parts so I can change to different imprinting attachments at latter date.

Photo 5: Shows the hollow hole punch that I cut down set in a mini chuck that has a 3D printed adapter so it can be screwed into the internal threaded rod.

Photo 6: Shows the cut down punch, the mini chuck and the adapter that the mini chuck screws into (3/8" X 24) and also screws into the internal threaded rod (5/8" X13).

Photo 7. Hole punched in approximately 4 oz, logo without any damping and a logo with slight damping applied to the leather.

Edited July 21, 2021 by kgg
wording

[dikman]

Nice bit of re-purposing. Looks like a nice little press, particularly at that price!

Edited July 21, 2021 by dikman

[Rahere]

You have to smile at them still using non-standard sizing to force their customers loyalty!

[kgg]

14 hours ago, dikman said:

Nice bit of re-purposing. Looks like a nice little press, particularly at that price!

Thank you dikman. I am working on strap folder using a free domestic sewing machine motor, we'll see how that goes.

8 minutes ago, Rahere said:

You have to smile at them still using non-standard sizing to force their customers loyalty!

Proprietary threading is a way but if they really wanted to have a custom thread they should have used a left hand 13 twist to really fool with customers. Sort of remains me of Singer threading.

kgg

[mdawson]

21 hours ago, kgg said:

5/8 x13 or maybe a even 13.25 

Sounds like a M16 thread, 2mm pitch.

Mark

[kgg]

39 minutes ago, mdawson said:

Sounds like a M16 thread, 2mm pitch.

I tried my metric set of dies / taps and they weren't even close. The 16 was to large, then I started with the 5/8 x 11 and worked up. The closest I could come when nothing else really worked (metric or English) was with using the tread gauge. That then drove me down into the thread design rabbit hole. Don't what to do that again, it was frustrating to do in Fusion 360.

kgg

 

[CliffM]

Oddball threads to lock the customer into buying parts only from the OEM was a widespread and common practice in the past.  In fact, machinery builders would not only use non standard pitch for the diameter, but they would also select a pitch that wasn't among the standard set of pitches available on normal engine lathes.  So, even though the customer may have an on site maintenance machine shop, he still wouldnt be able to duplicate the thread.  Popular ones I've seen in the past when making repair parts for old machinery are 17, 21, and 23 tpi, none of which will be found on a standard lathe.

Fortunately, the wide use of cnc machining now makes such tricks ineffective.  If you want to duplicate a 17.6 tpi thread, for example, you just program the pitch into a CNC lathe and chase the thread just as easily as cutting a 1/2-13.  For parts not adaptable to lathe work, the same process is used on a CNC mill where any diameter and pitch, both internal and external, can be produced via use of a thread milling cutter.