Hole Size for Belton Sockets

[The New Steve H]

I know I made it sound like this was a horror story, but it worked great once I figured out what I was doing. The next two holes will be a breeze.

[RJ Guitars]

Several of us have been down this road and there is more than one solution. I think is already a thread or two with this info... but it won't hurt to repeat ourselves will it? I really like the Belton sockets and once you get the right tool, they fit nicely from the top or bottom.

I bought a few chassis punches until i got the metric size that was right and the sockets fit wonderfully. However, I m not going to recommend this unless you only have a limited number in your lifetime. The punch was expensive and I got tired of twisting on that thing real soon after I started.

Next I went for the big step drill and a stout drill press. It made a lot less labor and a really nice hole, but it was the wrong size - either too small or too big. So I finally try measuring and find that a large metric step drill provides the correct size. I EBAY a big metric step drill and viola, it's a way perfect fit... but David Root is correct in that the step drill tends to leave a burr.

I try to deburr by turning the chassis over and running the drill into the hole from the opposite direction and just kissing it enough to clean up the burr. Works great when you can get to it... otherwise you need a deburring tool like the David showed us. In high quality aluminum like 5052 the burr isn't as prominent and lot easier to clean up. In the super soft aluminum like my "project" chassis, the burr is a bit more stubborn and it takes bit more effort to get rid of.

Ultimately I am trying to find some way that a power tool will do all the turning but if you only make a few, maybe not so important. As far as hole saws go, I prefer just to have somebody smack me a few times, at least they might feel better and I come out the same either way.

rj

[M Fowler]

I was using that deburring tool like David showed until the end went flying off one day and I haven't found it yet

Time to re-order a new tool as the replacement end is only slightly less cost then the whole unit.

[yowza]

What is the correct size for the metric step drill bit to fit the Belton sockets?

Also would a Dremel tool work for the deburring?

Thanks!

Ed

[surfsup]

RE: Dremel, sure but it depends on the bit you have. I have used one and with soft aluminum, the aluminum will usually get "pushed" down and not ground off with the sandpaper cylinders or angled stones.

Also it will crawl on you across your nice aluminum finish if you're not super careful with a strong hand.

I now just take my finger and go 90 degrees to the burr (diametrically) and rub it back and forth until the burr starts bending and snaps off.

I then take a round hole file and run it lightly across, then I take a big screwdriver and "wedge" it on opposite ends of the hole and run it around the circle to smooth the corner and provide a "knurled" chamfer, of sorts.

This is if I can't reach it with the unibit from the opposite end.

[RJ Guitars]

When I measure it I get 1.175 inches. So a 1-3/16" bit would give you a few thousandth's clearance... maybe cutting close but a good fit. I just never found an affordable 1-3/16" step drill or chassis punch. What I am using is more like 1.21 inches so you could probably use a 1.25 as well but that is getting pretty sloppy.

Deburring is a machinists art and you can mess up a good part with a slip of that tool. The inexpensive chassis are made from the really soft aluminum and generally speaking soft aluminum just sucks to work with... kinda like bubble gum. If you are really good and smooth with the deburring tool, it's like magic, otherwise it can get sorta ugly. The dremel might do you some good, but I haven't tried that. It's always tough to take off the part you don't want without getting into or onto the rest of the chassis. Also if you are talking about an abrasive wheel, those and aluminum don't generally work well together.

High grade aluminum, a sharp deburring tool, and the right touch... then just one quick pass and the hole is perfect.

rj

[The New Steve H]

Made two more big holes with the hole saw, plus three little ones with the Forstner bit and a gallon of WD40. Here it is. Still haven't made the tiny screw holes.

If you use a Forstner bit on aluminum, you have to go fairly slow, use lots of lube, and avoid too much pressure. But it does work.

Typically, I failed to notice that the top of the channel is thinner than the sides. I'd guess 3/16". That's why there is good access to the bottoms of the sockets.

This is a cool solution to the chassis problem, IF you have lots of tools and you enjoy using them.

[Structo]

Wow!
That stuff is 3/8" thick?

At first I thought that was a typo.

Is that like an extruded aluminum shape?

[The New Steve H]

It comes in long beams. I forget how long. Maybe 24 feet. It's structural aluminum. I guess they use it in construction. The sides are 3/8" thick and the top is about half that. I got it for twenty-something bucks.

[rp]

Wow! That stuff is 3/8" thick?

+2 Are you planning on dropping it a lot? Hope it sounds great as it'll last 1000 years.

Please no more mentions of metal with hole saws, Forstners, large amounts of wd40, even step bits and dremels... that was a grueling read.

I've had my Greenlee punches 20 years now. They are prized possessions. Worth every penny. Pay the rent late, juggle your bills, live on bananas and ramen and buy some punches.

[The New Steve H]

What's the thickest metal you can punch?

[rp]

What's the thickest metal you can punch?

Good question. I wonder if 3/8 would jam the punch or damage it, probably. I never plan to punch anything that thick. Maybe an electrician will know. Tell me you don't plan on doing all your amps out of 3/8 metal?

My comment was more general to those not using punches on normal chassis and working too hard to make holes.

BTW what's the metric punch size for the beltons? RJ?

[The New Steve H]

I found a company that makes aluminum chassis for a reasonable price (about 20 bucks), but they're short by Bassman standards. I discovered the likely reason for this. When you make a box larger than 19" with 2 1/2" sides, you have to discard a lot of metal, because the sheets come in lengths that are multiples of 12. Any time you go over 24", you have to throw out metal.

I wanted 20", and I didn't want to pay a ton, so I used the channel.

I can't complain. It was cheap, and now that I know how to make the holes, it's not hard to deal with.

[azatplayer]

How are you gonna mount the pots? 3/8 is about the entire threaded part.
I guess you could tap the holes and just wind the pots in? Like the XITS.

[The New Steve H]

I never even thought of screwing them in. Smart.

I got pots with long shafts. I still need the 1M pots, but I may just scoop out some aluminum and use the ones I have.