Newbie Question: How to use hollow punches for making gaskets

[Sleazey]

I recently acquired a hollow punch set, the kind that allows nesting different size punches in the working end of the handle. Thus, with one operation you can punch out a washer-type gasket, with no worries about centering the smaller punch in the larger punch. For reference, it's a Mayhew 16 piece metric punch set.

However, there were no instructions about how to use it. It also did not give any warnings about maximum thickness, materials that can be punched, or the most effective means of using the punch.

I do my punching on top of a soft wood surface to avoid damaging the cutting edge of the punch. Running a sharpening rod 'round the outside and inside edges of the punch to hone it a bit helped it to penetrate better. Doing that before each gasket made punching quite a bit easier.

For thin enough material, I can just put my weight on it and punch out what I need. However, for thicker material, that becomes harder and harder.

Is using a wooden mallet to strike the handle a safe and effective way to punch slightly heavier material? The handle is chromed and does not appear to be designed to be pounded with a metallic hammer (maybe a lead hammer would be ok). Should the punch be rotated as you bear down on it to help it cut?

I found that for the heavy rubber vibration absorbing mat that I was punching bolt holes in, and also punching out home-made anti-vibration washers, could only be punched by rotating the punch as I bore down with my body weight. This led to significant distortion of the washer shape due to the twisting of the material as the punching proceeded.

What is the most accurate way to use a hollow punch? I want to avoid creating gaskets or washers that are tapered or bell shaped. I also want to avoid producing a work item whose axis is not normal to the top and bottom surfaces either.

Any hints and tips for using a hollow punch will be greatly appreciated!

 

[Stan]

I am not familiar with your brand and model of punch so I will just offer two suggestions. You need a hard resilient material to punch on. A hardwood block is common or some of the plastic materials.

Punches are made sharpened on the outside or the inside. The punches sharpened on the outside are for the outside of a circle. For the inside hole you need a punch sharpened on the inside. Otherwise, you expand or break the material you are punching. You can get away with the wrong punch on thin material, but not on thicker gasket paper if you are close to an edge or making a washer with a thin ring.

 

[Sleazey]

Stan: Thanks for the pointers about proper sharpening techniques. I am doing my punching on top of a wood working bench, made of birch.

A process of trial and error (multiple errors) will be the means of traversing the learning curve.

 

[agr]

I was taught by my grandfather many years ago that you always use punches on the end of a hardwood block such that when the punch goes through the material it enters the end grain of the timber. I believe that this prolongs the sharpness of the punch as the edge simply separates the wood fibre/grain rather than cutting into it,

Tony

 

[Sleazey]

That is a very good tip. Thanks AGR.

 

[Captain Jerry]

If the rubber material is deforming when you rotate the punch because of drag, you may want to try some lubrication. Surprisingly (to me anyway) water makes a fine lube between rubber and steel and it doesn't contaminate the material.

This was first shown to me by a mech from Gates Rubber when repairing conveyor belts.

Jerry

 

[Kermit]

An extra soapy solution of water and dish detergent will really lube the rubber up too!

I used that method when making washers for some 18 inch subwoofer mounts.

 

[Sleazey]

Thanks, Kermit & Captain Jerry, for the lubrication tip. I should have thought of that!

I think I may recut a couple of them using the soapy water trick. The very first one I cut came out nice and square, but each succeeding one was more and more deformed.

 

[Maryak]

The very first one I cut came out nice and square, but each succeeding one was more and more deformed.

Maybe it would help if you cleaned the punch between cuts. Very small bits from the previous cut may still be attached to the punch causing uneven drag with the next cut.

Hope this helps ??? ???

Best Regards
Bob