Any ideas on making a double D Heyco hole without a $3000 punch?

[Charlie Wilson]

Hello, I have decided that I want a hardwired AC cord in my amp and want to use a Heyco strain relief but I am wondering how to make a decent looking double D hole in the chassis without spending $3000+ on a Heyco punch. The chassis is aluminum and I could use files but it may end up looking like Fred Flinstone did it. Any ideas?
Charlie Wilson

[Yoda]

The Greenlee double D punch seems to be about $160. I would just buy that. At least you’re not looking for a C14 IEC punch like me! I gave up and went with an IEC connector meant for replacing the old Bulgin AC plugs, because I only have to make a round hole for it rather than a rectangular one.

[jabguit]

What is hole size? Aluminum cuts easily with a router. You can get a 1/4" pattern bearing bit if the hole is larger than 1/4" and do it on a router table. Aluminum routs beautifully.

cheers,

[Stevem]

Since I also do high performance cylinder head work I have high speed grinding Burr’s for cast iron that I use to enlarge two wire sized double D holes to accept bigger holes for 3 wire for Hayco grommets.


These 30 dollar Burr’s will work in a hand drill, but it may take you 10 minutes to get the job done if it’s a steel chassis, Aluminum about 5, but you need a Aluminum Burr not a fine cut one as for steel.

Stop I bit shy of the final size you need a file the rest to get a nice clean edge.

When I have the room inside the chassis I make a big hollow Teepee of clay around the hole I am reworking to catch all the filings and when done I just throw the whole mess away.
The only thing is that sometimes you need the Hayco plyers to get the new parts in as at times a big Needle nose or adjustable plyers just does not work.
Another way to go is to just carefully drill out the inside perimeter with a small drill bit and have the holes almost connect.
Then you drill a far bigger center hole and then just rat tail file it out .
Note that Aluminum will load up a file easily so keep it well lubed.

If you have a friend or family member who may have even a hobby type drill press you can do the job by loading a mill cut tool bit in it once the center hole is drilled to drop the mill bit through.
Another option is if you know a high school shop teacher.
They have the needed gear and might help you out!

[Charlie Wilson]

Thanks guys for the ideas. I have not seen even a Greenlee double D punch in the correct .625 size, so I think for now, that idea will have to wait. I am going to take a aluminum enclosure and use it to try some of the other ideas on before I start drilling my amplifier chassis.
CW

[sluckey]

You may be interested in these cable glands strain relief cord grip from Amazon. Also available in white, steel, or nickel plated brass. PG11 and PG13.5 should cover any amp power cords.

[FUCHSAUDIO]

Why kill yourself trying to make a D hole ? Get some ear plugs, get a metal cutting sabre saw bit, and put in an IEC outlet and be done with it.

[Charlie Wilson]

The amp has an IEC receptacle, I (really) don't like them. I have dealt with trying to figure out where the staticy ground noises are coming from and found it to be loose ground contact to the AC cord. I just really like the idea of a hardwired AC cord to the amp.
CW

[Reeltarded]

Why kill yourself trying to make a D hole ? Get some ear plugs, get a metal cutting sabre saw bit, and put in an IEC outlet and be done with it.

Lol I bet someone knows where Hoffa is.

[ChopSauce]

In the early times of metal working, many precison works were filed by hand.

I don't really like doing that and it takes time to adjust properly, but aluminium is a soft metal and provided you start by drilling a hole slightly too small, you can use even a cheap set of small files to do that.

One thing I often do when filing thin material is moving the file along the edge, nut just moving across. The combination of movements avoids irregularities and that awfull (squeal ? ) sound I guess you know.

Of course this is not something you do routinely, but the edge being hidden by the plug, who knows in the end?

[bepone]

Hello, I have decided that I want a hardwired AC cord in my amp and want to use a Heyco strain relief but I am wondering how to make a decent looking double D hole in the chassis without spending $3000+ on a Heyco punch. The chassis is aluminum and I could use files but it may end up looking like Fred Flinstone did it. Any ideas?
Charlie Wilson

round hole + round file? 15min of work?