In gearing up for my first build of a 6BQ5/EL84 single ended amp, I did a lot of searching for advice on cutting 3/4" tube socket holes in my chassis for 9-pin tubes. I had thought that about the only good option would be a Greenlee punch, but I really did not want to spend $60-$100 for a single punch. The advice I found varied widely, and the threads were pretty old, so thought a refresh on the topic might be useful.
I learned a lot about what not to do, like buy cheap shoddy hole punches from Amazon. They are not even heat treated, let alone tool steel, and should really be considered as counterfeit. Customers stated a myriad of problems in the feedback- sometimes, on the very first hole, the bolt threads gall, or strip, or break. On one the die cracked in half. Others were off the stated size by small amounts, and many had tiny socket head bolts that required reefing on a tiny Allen wrench while cutting. On thin aluminum and other soft metals some said they got perhaps a few holes, but they quickly blunted and stripped. Do yourself a favor and do not buy these.
I found a great solution I wanted to share- TEMCo Industrial. They carry a range of knockout punch sizes in both actual, and conduit sizes. Don't buy the conduit sizes unless you are doing electrical work. For tube sockets, purchase the ones that say Actual. They are hardened tool steel, have a larger size bolt head, and includes a thrust bearing to make cutting a lot easier, a feature the Greenlee punches have as well. The few that TEMCo sells on Amazon (for a few dollars more, cheaper to buy direct from TEMCo) have stellar reviews, quite a difference from the ones above.
The one I purchased for my 9-pin holes cost $31.45, with free shipping at their website. This is half to a third as expensive as a Greenlee, and they look to be identical quality.
Once I have a chance to use it a few times, I'll pass on some pictures and my results. Have you tried these, or do you have an alternate recommend? I'd love to hear.
I learned a lot about what not to do, like buy cheap shoddy hole punches from Amazon. They are not even heat treated, let alone tool steel, and should really be considered as counterfeit. Customers stated a myriad of problems in the feedback- sometimes, on the very first hole, the bolt threads gall, or strip, or break. On one the die cracked in half. Others were off the stated size by small amounts, and many had tiny socket head bolts that required reefing on a tiny Allen wrench while cutting. On thin aluminum and other soft metals some said they got perhaps a few holes, but they quickly blunted and stripped. Do yourself a favor and do not buy these.
I found a great solution I wanted to share- TEMCo Industrial. They carry a range of knockout punch sizes in both actual, and conduit sizes. Don't buy the conduit sizes unless you are doing electrical work. For tube sockets, purchase the ones that say Actual. They are hardened tool steel, have a larger size bolt head, and includes a thrust bearing to make cutting a lot easier, a feature the Greenlee punches have as well. The few that TEMCo sells on Amazon (for a few dollars more, cheaper to buy direct from TEMCo) have stellar reviews, quite a difference from the ones above.
The one I purchased for my 9-pin holes cost $31.45, with free shipping at their website. This is half to a third as expensive as a Greenlee, and they look to be identical quality.
Once I have a chance to use it a few times, I'll pass on some pictures and my results. Have you tried these, or do you have an alternate recommend? I'd love to hear.
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