Automatic Center Punch Fix

[bmac2]

I have a center punch that lives in my garage, it’s was a cheap one I’d picked up and I have had a love/hate relationship with it for years. The picture below shows just how the trigger on this type of punch works.

 

[bmac2]

It had this habit of missing a beat and then catching after 4 of 5 hits usually producing a nice pop mark just to the side of where I wanted it. For most of the work I do in the garage it really doesn’t matter but it’s annoying so this morning I decided it was time to come up with a fix or bin it

 

[bmac2]

The basic action looked like it was working starting with the pin cocked over to one side and coming to the center when depressed.

 

[bmac2]

Like a lot of things out of China the machining is on the rough side so the first thing I did was polish the pin and the end of the hammer with some emery. The end of the intermediate pin was also slightly mushroomed so I just touched it on the grinder to flatten the end.

 

[bmac2]

When I got it back together it was better catching 2 out of 3 times. Looking at the punches I have I found one in the shop with the same style of hammer trip and saw that it had a pronounced dome to the end of the punch I assume this is to encourage the intermediate pin to rock over to the side.

I thought I’d try putting a small stainless steel ball between the intermediate pin and the punch. I used the smallest one I had on hand that could not slip between the punch and the cap.

 

[bmac2]

After chasing the bearing around on the floor a couple of times I found that if I compressed the intermediate spring I could grab the pin with a small pair on hemostats. Back together I’m happy to say it’s hitting a solid 10 out of 10.

 

[DJP]

I like your determination and analysis to find a solution for a better mouse trap. That is probably why most of us have gathered on this site to share ideas that work.

Your dexterity can be challenged further if you decide to repair an iPhone. I recently changed the charging port connector on an iPhone 5. The part was $15 but the time invested was priceless. It was one of those jobs that couldn't be paused and restarted the next day due to short term memory decline.

You only need a Pentalobe screw driver and suction cup to open it up. That's all of the hints I'll provide.

I enjoyed your fix for a centre punch. I also have the same model but have gone back to the old solid style punch. You have given me a reason to open it up.

 

[Herbiev]

Well done. Great pics. I've often wondered how those things work

 

[Wizard69]

You have a wonderful sequence here! Between work and home I have several of these punches but never had an idea or even a clue about how they worked. You solved that with a great series of pics and a nice write up.