Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: 92Volts on December 13, 2017, 09:43:49 am
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I'm considering a turret-based layout similar to some terminal-strip layouts, with (many) components on or very near the tube socket. The tubes would be "in" the turret board with a ring of turrets or eyelets around it to run components directly from the socket to the turret/eyelet.
So my question is about drilling the various board materials Hoffman offers. I'd need about a 1" hole for small tubes, larger for octal tubes. I can do this in thin aluminum chassis with a step-drill, but it can be rough and sometimes warps or tears the metal if it doesn't go smoothly. I'm assuming this could crack or shatter epoxy or fiberboard but I haven't worked much with those materials. Any thoughts?
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I have successfully drilled multiple tube socket holes in 1/8" G10 with step bits from China. No issues, ever.
I put 2 small 2"x4" blocks under the board around where I'm drilling for support.
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You could use a 1" hole saw; leave the holes as-is or bore out further with the step bit.
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+1 to keyhole saws. you'd typically need a 7/8" for preamp tubes and 1-1/8" for octal power tubes. i use hole saws to drill chassis as well - clamp the material to the drill press WELL.
--pete
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I screwed 3/4 Oak, 12ga semi-perf Steel box, two sheets Hoffman FRP, and another Oak, and ran a 2-inch hole saw through.
My real worry was the steel- it was the wrong corner of a fusebox and had a scad of 1/2" knockouts. I feared the teeth would snag a part of a knockout slug, bind, cock, and go very wrong. So go slow with just enough pressure to keep cutting. Small snags but no problem.
I do not recall the FRP being any issue.
It probably blunts the saw. The fiberglass dust is bad for you. (But I only did this once.)
I would *certainly* back-up with hardwood. If you go through tough stuff with a hole-saw, at the end you break-through only half the circle and it can snag bad. Going into Oak is not such a shock, and you can stop when you feel you reached all-Oak.
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Thanks everybody! Sounds like I can go ahead with thinking up this layout. The idea of clamping it between layers of wood to stop snagging does sound like a good idea.
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Any bit will work on my epoxy board
The only thing you need to be aware of is that it will burn and stink if it gets too hot
So you want to have sharp bits and take your time
If it starts getting too hot, just splash some cold water on the material to cool it down
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Thanks for the confirmation!
If I order a turret board from you I would consider having you install the turrets... I don't have tools or experience installing them (though I'd be willing to figure it out if needed). If they were pre-installed this would prevent clamping it against another material as PRR suggests. In your opinion is it a good idea to drill the board empty, to have the ability to layer it with something, or will drilling usually work with a "loose" (clamped to the drill press) board?
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Thanks for the confirmation!
If I order a turret board from you I would consider having you install the turrets... I don't have tools or experience installing them (though I'd be willing to figure it out if needed). If they were pre-installed this would prevent clamping it against another material as PRR suggests. In your opinion is it a good idea to drill the board empty, to have the ability to layer it with something, or will drilling usually work with a "loose" (clamped to the drill press) board?
turrets are relatively easy to install, eyelets even more so.
buy the staking kit from doug and you're set.
follow the board build directions doug has posted online and building your own board is a snap.
--pete
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I haven't drilled any 1" holes in the 1/8" board material. If I needed a big hole I'd drill all the turret and other small holes first. No need for a clamp for those. Then screw the circuit board to a length of 2x4 for a backer. You really don't want to sandwich this between two boards. Then clamp the 2x4 to the table. I'd use a brad-point bit or hole saw, the hole saw will produce less glass fibers in the air. Step-bits will not work well with a backer board. If you want to use a step-bit then don't use a backer board. You can easily hold it if using a drill press.
Installing turrets is really easy if you have a drill press. I use a small tabletop model. Doug sells the tools and he has a webpage with a lot of howto info.
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Sorry, late for the dance on this. Years ago I used to work at a factory that produced finished insulative materials for the electrical industry. We worked with everything from all sorts of glass polyesters (Glastic to G materials) to fiber and laminated materials to even asbestos. All our tooling was either diamond or carbide - and the carbide kept the sharpening house very busy. Sandwiching is a great idea. However for larger holes, if you can lock the board in place (as there is no pilot) on your drill press, these would work fine and the price is right. Set up a vacuum and work slow. Remember, the larger the hole, the slower the RiPuMs. Even better, make a playdoh dam around the area to be drilled and fill with water. I think I am still blowing red Glastic dust out of my nose 40 years later....
Jim
https://www.walmart.com/ip/Elfeland-16Pcs-Diamond-Hole-Saw-Drill-Bit-Set-Hole-Saw-Cutter-For-Tile-Ceramic-Glass-Marble/508467053?wmlspartner=wlpa&selectedSellerId=4654&adid=22222222222080870359&wmlspartner=wmtlabs&wl0=e&wl1=o&wl2=c&wl3=83769044094231&wl4=kwd-4587368670691334&wl12=508467053_10000004931&wl14=diamond%20hole%20saw&veh=sem
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Jim,
Dang! That deal was too good to pass up. Thanks for the link.
Barry
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> That deal was too good to pass up.
Now showing out of stock. How many did you buy??
There's a similar set on Amazon, only 10-pc:
https://www.amazon.com/LOT-Pcs-Diamond-Hole-Drill/dp/B00AEVUGAY
More from the same brand (https://www.amazon.com/s/ref=lp_10511229011_nr_scat_8106328011_ln?srs=10511229011&rh=n%3A8106328011&ie=UTF8&qid=1513884420&scn=8106328011&h=48abd5a2974f17be06f57cadbe0f2eb86cd5946a).
AND there's a jig I have never seen which could be very useful:
https://www.amazon.com/DRILAX-Fixture-Vacuum-Suction-Coolant/dp/B00V3UONCW
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I only bought one. When I click on it I see 4 left
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> I see 4 left
Now I do too!
Walmart's e-order system must be wonky. Thousands of last-minute gift-buys of diamond-saws for Xmas. Poor server can't keep up.
Thanks for the pointer! (and re-point!)
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Something else I forgot to mention - and if I am preaching to the choir, ignore this. Unless you have a Bridgeport or equivalent mill, run your drill press table and work piece up as close to the bit as possible. The further you have to extend the quill/spindle, the sloppier they tend to be. You don't want it waving in the wind as the non-piloted bit is trying to find it's way. Also, snug down the quill/spindle lock as this will also take some play out as you extend it. You want it all to be as solid as possible. Again, the slower the RPM, the better.
Jim
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> You don't want it waving in the wind
OFF-TOPIC....... I put a chain-saw into my good kitchen floor.
We've moved cabinets around. We can *never* replace the wide aged oak boards. So any time I put a cabinet over good floor, I "harvest" the board to use elsewhere and fill under the cabinet with scrap. Up to a point I could pry whole boards out, maybe trim and put part back. But I ran into a couple long boards into the rest of the floor, only wanted to harvest a few feet of each.
And it is the dead of winter. I don't want to make sawdust in the house, we will be hacking til Spring.
Sharp chainsaw is more chips than dust. Electric (no fumes), and actually battery. Whirrrrr... whoops. As you say, if you don't have Bridgeport arms, the cutter will bounce and skip. Ah well, we'll put some varnish on that scar.
Yeah, nails. I had a chain that had already kissed a couple stones so I was willing to risk it.
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PRR, I just find that hard to believe.....
Jim
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I use a step drill bit to drill large holes in the garolite boards without any problems.
Mark
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keyhole saw cut sample.
--pete