Drilling holes in a chassis

TelZilla · January 2nd, 2008, 10:17 AM

Good new year to all-

My next project (wife permitting) is going to involve repurposing an 80's Fender SS combo (Harvard Reverb, but not the cool one) for use as some kind of single ended 5ish watt amp (K'zoo M1, 5F1, 5C1, etc.).

One of the things I'll obviously need to do is drill 3 holes for the tube sockets. Obviously this is something I need to do fairly precisely.

My 2 questions:

What's the "real" way to do it, assuming I have a nice workshop, but it's for home use (i.e., I'm not a manufacturer)? Drill press?
I do not have a nice workshop, and my tool budget is nada, so is there a cheapo way to do it?

Thanks all.

sjhusting · January 2nd, 2008, 10:23 AM

The "real" way is to get a coupla Greenlee (or whatever) punches. Nice clean perfect holes every time. Expensive.

The cheap way is to drill the biggest hole you can (use a drill press if possible) and file. Or cut a circle of small-diameter holes, and file it out. Unless you are exceedingly neurotic, your holes will not be anywhere close to perfect. Course, you could get lucky, but it will drive you nuts. You will probably end up with metal filings in your skin. Fun fun oh baby.

I suppose there are other ways to do it. If you're planning on building more than one or two amps, and aren't going to use prefab chassis, just buy the punches. It makes life a lot easier. I use a 25mm for octals, and 22mm for novals, from Ruko (German tool company). I used to hate chassis work, but I foolishly insist on doing it myself. Since I got the punches, I don't hate chassis work as much as I hate tolexing.

Actually, do your first chassis without the punches, so that when you do finally get them, you will treasure them and treat them the way they should be.

steven

TelZilla · January 2nd, 2008, 11:15 AM

Is therte anything like a Forstner bit, but made for Steel?

JohnnyCrash · January 2nd, 2008, 11:29 AM

You could use a hole saw bit if you have a drill press.

I'd suggest buying a pipe junction cutter from Harbor Freight. They are often the same exact punches other guys sell as chassis punches for a much higher markup!

$16 at Harbor Freight, where guys online sell the same thing for $40:

http://www.harborfreight.com/cpi/cta...emnumber=91201

Freight Twang · January 2nd, 2008, 11:30 AM

You can use a metal holesaw bit, you can get at Home Depot or Lowe's, but the best way is with a GreenLee punch. The cheapest place to get on of those is a www.tubesandmore.com. the 7/8" does the 12ax7 sockets and the 1" does the output socket.

JohnnyCrash · January 2nd, 2008, 11:34 AM

Quote:

Originally Posted by Freight Twang

You can use a metal holesaw bit, you can get at Home Depot or Lowe's, but the best way is with a GreenLee punch. The cheapest place to get on of those is a www.tubesandmore.com. the 7/8" does the 12ax7 sockets and the 1" does the output socket.

Each of their punches are $40+ which is ridiculous.

Go with the Harbor Freight SET at $16. I've used it plenty of times.

TelZilla · January 2nd, 2008, 11:36 AM

I like the $16 solution. How does that work, Johnny? I'm not able to puzzle it out by looking at the stuff in the pic.

TelZilla · January 2nd, 2008, 11:43 AM

Oops. Never mind, just saw the manual.

That is a cool tool fer sure, Johnny.

JohnnyCrash · January 2nd, 2008, 11:45 AM

You drill a hole in the chassis large enough for the driving bolt to fit in.

Then you put the bolt through the hole with the die threaded on at one side. You then thread the cut/punch/bit on the other side and tighten it all together. The die and cutter eventually meet in the middle where the chassis used to be :)

January 2nd, 2008, 10:17 AM	#1 (permalink)
TelZilla Tele-Afflicted Join Date: Jan 2007 Location: Cleveburg, USA Age: 38 Posts: 1,579 6 Photos	Drilling holes in a chassis Good new year to all- My next project (wife permitting) is going to involve repurposing an 80's Fender SS combo (Harvard Reverb, but not the cool one) for use as some kind of single ended 5ish watt amp (K'zoo M1, 5F1, 5C1, etc.). One of the things I'll obviously need to do is drill 3 holes for the tube sockets. Obviously this is something I need to do fairly precisely. My 2 questions: What's the "real" way to do it, assuming I have a nice workshop, but it's for home use (i.e., I'm not a manufacturer)? Drill press? I do not have a nice workshop, and my tool budget is nada, so is there a cheapo way to do it? Thanks all. __________________ Thanks,Nick Witless and Affected. Always.

January 2nd, 2008, 11:15 AM	#3 (permalink)
TelZilla Tele-Afflicted Join Date: Jan 2007 Location: Cleveburg, USA Age: 38 Posts: 1,579 6 Photos	Is therte anything like a Forstner bit, but made for Steel? __________________ Thanks,Nick Witless and Affected. Always.

January 2nd, 2008, 11:29 AM	#4 (permalink)
JohnnyCrash Poster Extraordinaire Join Date: Mar 2005 Location: Lost Angeles and Orange County Posts: 7,134 39 Photos	You could use a hole saw bit if you have a drill press. I'd suggest buying a pipe junction cutter from Harbor Freight. They are often the same exact punches other guys sell as chassis punches for a much higher markup! $16 at Harbor Freight, where guys online sell the same thing for $40: http://www.harborfreight.com/cpi/cta...emnumber=91201 __________________ . Learn about safety before building/repairing/modding an amp. When in doubt, take it to a shop. Never drink yellow snow. Have fun.

January 2nd, 2008, 11:36 AM	#7 (permalink)
TelZilla Tele-Afflicted Join Date: Jan 2007 Location: Cleveburg, USA Age: 38 Posts: 1,579 6 Photos	I like the $16 solution. How does that work, Johnny? I'm not able to puzzle it out by looking at the stuff in the pic. __________________ Thanks,Nick Witless and Affected. Always.

January 2nd, 2008, 11:43 AM	#8 (permalink)
TelZilla Tele-Afflicted Join Date: Jan 2007 Location: Cleveburg, USA Age: 38 Posts: 1,579 6 Photos	Oops. Never mind, just saw the manual. That is a cool tool fer sure, Johnny. __________________ Thanks,Nick Witless and Affected. Always.

January 2nd, 2008, 10:23 AM	#2 (permalink)
sjhusting Tele-Holic Join Date: Jul 2003 Location: Germany Posts: 502 11 Photos	The "real" way is to get a coupla Greenlee (or whatever) punches. Nice clean perfect holes every time. Expensive. The cheap way is to drill the biggest hole you can (use a drill press if possible) and file. Or cut a circle of small-diameter holes, and file it out. Unless you are exceedingly neurotic, your holes will not be anywhere close to perfect. Course, you could get lucky, but it will drive you nuts. You will probably end up with metal filings in your skin. Fun fun oh baby. I suppose there are other ways to do it. If you're planning on building more than one or two amps, and aren't going to use prefab chassis, just buy the punches. It makes life a lot easier. I use a 25mm for octals, and 22mm for novals, from Ruko (German tool company). I used to hate chassis work, but I foolishly insist on doing it myself. Since I got the punches, I don't hate chassis work as much as I hate tolexing. Actually, do your first chassis without the punches, so that when you do finally get them, you will treasure them and treat them the way they should be. steven

January 2nd, 2008, 11:30 AM	#5 (permalink)
Freight Twang TDPRI Member Join Date: Dec 2007 Location: Montgomery,Al Age: 40 Posts: 94 2 Photos	You can use a metal holesaw bit, you can get at Home Depot or Lowe's, but the best way is with a GreenLee punch. The cheapest place to get on of those is a www.tubesandmore.com. the 7/8" does the 12ax7 sockets and the 1" does the output socket.

January 2nd, 2008, 11:45 AM	#9 (permalink)
JohnnyCrash Poster Extraordinaire Join Date: Mar 2005 Location: Lost Angeles and Orange County Posts: 7,134 39 Photos	You drill a hole in the chassis large enough for the driving bolt to fit in. Then you put the bolt through the hole with the die threaded on at one side. You then thread the cut/punch/bit on the other side and tighten it all together. The die and cutter eventually meet in the middle where the chassis used to be :) __________________ . Learn about safety before building/repairing/modding an amp. When in doubt, take it to a shop. Never drink yellow snow. Have fun.