Centering Holes in End Discs

[nater]

I use an AllPax gasket cutter to cut out end discs. When cutting a 1/2" hole in the center for a spolette, the hole for the pin often enlarges making the ID cut poor. Arch punches work great, but are difficult to keep perfectly centered. The hole for the spolette does not need to be perfectly centered, but they do need to be consistient across your discs so they stack right when building your shell.

 

I made some templates out of thin plywood to help guide the arch punch, but they don't work quite as well as I had hoped. I am considering a gasket punch set which has a center punch guide or making some sort of jig to align the discs in a press to punch the hole. Has anyone made something similar?

[Shadowcat1969]

Hey Nater, I haven't done it yet, but I've been kicking around some ideas for something to do that too. I haven't settled on a final prototype yet or I'd certainly share.

 

I'll share once I have something going.

[dagabu]

For work I did. The machine shop turned the end of a gasket punch down to fit the arbor press hole then use a disk of delrin with a pin the same size as the gasket cutter pin, centered the whole thing and punched the holes with great consistency. These were round cork gaskets with four round holes for a screw compressor head that had to be cleaned every few months.

 

Not sure if that is helpful since the holes are all off set. ..

[nater]

That gives me an idea, Dag. If I bought a gasket cutter with a centering pin, I could make a base with a hole that the pin can set in to keep the discs on target.

 

My first idea was to make a wood base with Vee stops to hold the discs centered under the chuck on a drill press and a means to mount the jig to the table in the same place each time.

 

I have to leave for a meeting before work soon, then a break before my shift starts. I will have to see what I can come up with on Friday or Saturday.

[Mumbles]

I generally use a spade drill to make my spolette holes. I drill two disks at a time, so that the inner and outer disks for a specific break would match up, spinning the disk if I had to in case of a slightly off center drill job. I included a picture of the one I use. It has wing spurs, which helped out keeping the cut a little cleaner, as it starts to bite into the disk before the bulk of the head hits the cardboard. The holes in the receiving end of the next break are always larger for me to accommodate the match on my spolettes. This extra 1/8-3/16" of space always gave enough play that I never had to worry too much about keeping everything centered from disk to disk. Depending on how you build multi-break shells, this may or may not be the same for you.

 

http://www.alliedboltinc.com/productimages/Spade%20Bit.jpg

[nater]

As long as each disc for each break mate up, I am happy. You are right that preceding breaks need a slightly larger hole for the matched spolette. I have not worried about them being perfectly centered either, "close enough" works here as long as each break can stack neatly.

 

I thought about using a spade bit, but was worried about the cardboard catching on the bit and tearing. I will give that a try too.

[Bobosan]

Nater,

 

I use this set which has a centering pin.

[pyropro]

simply take the punch that makes the 1/2 inch hole now take a dowel with a nail centered in the dowel place that into the hole punch.You now have perfect centers,the pin in the dowel thats sitting into the hole punch fits into the apax cutter or like the disk kutter I make.lol Can supply pics if needed.The easy peasy way.

Edited August 15, 2014 by Mumbles
Removed irrelevant video