Hi,
I have heard and read many times about using "punches" to get the perfect holes in the top plates of DIY amp projects. Exactly what are we talking about here? Is this a big shop tool with a hydraulic press, some giant piece of machinery? Or can one get these punches in a more portable type of tool? I am unfamiliar with the punch type tool people have spoken about. Can somebody refer me to a source for a metal punch tool that I might be able to acquisition at home? Better yet, maybe somebody has a set they are willing to part with.....never hurts to ask, right?
to date I have used a Craftsman drill press and some titanium and steel blade style drill bits used for wood to cut through aluminum. Used with lots of WD-40 this has worked ok but, you can sure wear out a bunch of bits this way real quick. Even though you can buy these bits dirt cheap at Home Depot and similar, it sure seems a waste to trash a bunch of bits when there seems to be a more appropriate tool.
Thanks!
Jeff
I have heard and read many times about using "punches" to get the perfect holes in the top plates of DIY amp projects. Exactly what are we talking about here? Is this a big shop tool with a hydraulic press, some giant piece of machinery? Or can one get these punches in a more portable type of tool? I am unfamiliar with the punch type tool people have spoken about. Can somebody refer me to a source for a metal punch tool that I might be able to acquisition at home? Better yet, maybe somebody has a set they are willing to part with.....never hurts to ask, right?
to date I have used a Craftsman drill press and some titanium and steel blade style drill bits used for wood to cut through aluminum. Used with lots of WD-40 this has worked ok but, you can sure wear out a bunch of bits this way real quick. Even though you can buy these bits dirt cheap at Home Depot and similar, it sure seems a waste to trash a bunch of bits when there seems to be a more appropriate tool.
Thanks!
Jeff
Something like this.
- Harbor Freight Tools - Quality Tools at the Lowest Prices
- Harbor Freight Tools - Quality Tools at the Lowest Prices
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Greenlee punches are the way to go. They can be had on ebay for a fair price at times. The thing is to make sure you know what sizes you will need. I am sure someone here can recommend specific sizes for standard tube sockets. You can also find cheap chinese ones on places like harbor freight, but I have never heard anything to good about them. Better to pay a little more and have a tool that will last.
GreenLee makes both Hole Punches and Knock Out Punches (for electrical cabinets). I don't know if there is any difference as far as hole punching chassis. I looked on their site once but couldn't find out any real difference between the two.
Does any one know? Are the Knock Out Punches heavier duty since they expect them to be used on steel electrical cabinets?
I've got a few of the standard hole punches.
Does any one know? Are the Knock Out Punches heavier duty since they expect them to be used on steel electrical cabinets?
I've got a few of the standard hole punches.
The difference is between a hole punch made for conduit sizes, and an "actual" diameter punch. So a punch made for 1/2" conduit is actually 7/8" in diameter.
Hope that helps 🙂
Don't buy these from Harbor Fright: Knockout Punch Kit
They're difficult to use, and the sizes are all wrong for vacuum tube sockets. I've used them myself on several projects, and while they can be made to work the results are far from perfect.
They're difficult to use, and the sizes are all wrong for vacuum tube sockets. I've used them myself on several projects, and while they can be made to work the results are far from perfect.
+1 for the Greenlee punches! These are what I use to make all the holes in any metal chassis I have built. Some brands of tube sockets have dimensions that are very close to the hole sizes produced by these tools, carefully measure the ones you commonly use to make sure the fit inside the hole will be as you expect before buying one of these kind of tools, as they are non inexpensive!
As a previous poster noted, make sure the actual size of hole produced is what you need. The Greenlee punches are often sized for electrical conduit fittings, which have actual dimensions that are often slightly larger than the stated "size" of the punch being used. For example, a 1-inch Greenlee die will produce a hole of 1.362 inches diameter. You can download their PDF catalog for the various hole-making tools from this link: http://www.greenlee.com/cat_docs/Holemaking08_lowrez.pdf
HTH-
As a previous poster noted, make sure the actual size of hole produced is what you need. The Greenlee punches are often sized for electrical conduit fittings, which have actual dimensions that are often slightly larger than the stated "size" of the punch being used. For example, a 1-inch Greenlee die will produce a hole of 1.362 inches diameter. You can download their PDF catalog for the various hole-making tools from this link: http://www.greenlee.com/cat_docs/Holemaking08_lowrez.pdf
HTH-
me has bought a cheap made, but not cheap sold, set of hole punches several years ago. Totally junk! I should have bought a stepped drill instead.
Regards
Regards
Hi Jeff
I'm surprised to learn that your bits are wearing out so quickly from cutting aluminum, which is pretty soft stuff. I wonder if the WD-40 might be counterproductive, in that it may be causing the bit to spin without cutting, then overheat and dull. You can buy cutting fluid designed for aluminum, but for intermittent use I often cut without a lubricant - you need to clamp the aluminum well since the bit can grab. Feed pressure should be reasonably high and steady, so the drill cuts its way through and doesn't sit at one point just skating.
You likely know this, but in case not: when drilling in larger sizes, you need a pilot hole larger in diameter than the flat bit at the leading edge of the drill, so the cutting edges can get to the metal and do their job. If it takes a lot of pressure to make the cut, this could be part of the problem.
I speak without a lot of knowledge in this area - any machinists in the group want to chip in (sorry about that) on why this bit-dulling is happening?
Regards.
Aengus
Vent holes
Another thing I have seen done so beautifully is the ring of smaller vent holes drilled around the base of a tube socket. I have often mused at how these guys are able to space these holes so precisely, evenly, and spaced perfect from the centerpoint of the tube socket. Does anybody have a good technique for getting such a nice job? I am sure I could come up with something that would work but appearently there is a surefire way of getting this result and I want to know how it is done!
Thanks,
Jeff
Another thing I have seen done so beautifully is the ring of smaller vent holes drilled around the base of a tube socket. I have often mused at how these guys are able to space these holes so precisely, evenly, and spaced perfect from the centerpoint of the tube socket. Does anybody have a good technique for getting such a nice job? I am sure I could come up with something that would work but appearently there is a surefire way of getting this result and I want to know how it is done!
Thanks,
Jeff
Re: Vent holes
Probably they use a CNC machine. To do it by hand is tedious and requires a lot of careful aligning and drilling to a layout you've done with a straightedge and protractor (drawing).
Hmm, wonder if someone might start offering small square or round aluminum plates pre-drilled in this way and mated to a tube socket? These could be inset into rabbets (rebates for the British members) in wooden or teflon top plates, or bottom-mounted to copper (etc.) top plates - could look quite cool (my day for bad puns, it seems).
Regards.
Aengus
Probably they use a CNC machine. To do it by hand is tedious and requires a lot of careful aligning and drilling to a layout you've done with a straightedge and protractor (drawing).
Hmm, wonder if someone might start offering small square or round aluminum plates pre-drilled in this way and mated to a tube socket? These could be inset into rabbets (rebates for the British members) in wooden or teflon top plates, or bottom-mounted to copper (etc.) top plates - could look quite cool (my day for bad puns, it seems).
Regards.
Aengus
Attachments
Actually, WD-40 is an excellent cutting fluid for aluminium and plexiglass. Not much good for anything else though. It is not a good rust protector as it drys out and leaves a gummy residue.I learned that in the machine shop 20 years ago.
The way you space the holes perfectly is (1) use a turret vice on a mill, or use a CNC mill. I suspect the really nice holes were done on a CNC machine.
Alternatly you can lay them out by hand with a scribe, protractor, etc. However this method is less precise.
I don't yet know if I will be able to fit my plate in my Mill-Drill (Jet PDF-18) since I havn't tried yet. I suspect I won't be able to because of the size of the plate and locations of the tubes.
I've got 0.135" thick Al plate I'm thinking of using for my amp. It looks like only the Standard Round punches are specified for Al, whereas the SlugBuster and SlugSplitters are rated for mild steel and SS but not Al.
The way you space the holes perfectly is (1) use a turret vice on a mill, or use a CNC mill. I suspect the really nice holes were done on a CNC machine.
Alternatly you can lay them out by hand with a scribe, protractor, etc. However this method is less precise.
I don't yet know if I will be able to fit my plate in my Mill-Drill (Jet PDF-18) since I havn't tried yet. I suspect I won't be able to because of the size of the plate and locations of the tubes.
I've got 0.135" thick Al plate I'm thinking of using for my amp. It looks like only the Standard Round punches are specified for Al, whereas the SlugBuster and SlugSplitters are rated for mild steel and SS but not Al.
vt4c has some cool stuff. (std disclaimer : no connection to them)
HiFi DIY Site - VT4C/211 Power Triode
Ha, you beat me to it Aengus. I was looking up the Greenlee manual for acceptable metal thickness.
Ya know that gives me an idea. One could use a 2" square aluminum template with the hole pattern in it, and use a hardened guide in the holes. Similar to the way B-Square scope mount jigs work.
I can't find a picture but basically you take a square al plate say 2" on a side. Center drill it, mount it in a rotary drill press and drill 3/8" holes. Then you turn a peice of 1/2" drill rod to accept a 1/4" drill, and turn a shoulder on it so it will fit in the 3/8" holes. Cut it off and heat treat it to harden it.
The aluminium plate gets bolted in place with a bolt in the center hole before you open the tube socket opening up. Put the bushing in one position, drill through it, pick it out and move it to the next position, drill, repete till done.
Ya know that gives me an idea. One could use a 2" square aluminum template with the hole pattern in it, and use a hardened guide in the holes. Similar to the way B-Square scope mount jigs work.
I can't find a picture but basically you take a square al plate say 2" on a side. Center drill it, mount it in a rotary drill press and drill 3/8" holes. Then you turn a peice of 1/2" drill rod to accept a 1/4" drill, and turn a shoulder on it so it will fit in the 3/8" holes. Cut it off and heat treat it to harden it.
The aluminium plate gets bolted in place with a bolt in the center hole before you open the tube socket opening up. Put the bushing in one position, drill through it, pick it out and move it to the next position, drill, repete till done.
I've used them, they're actually a pretty good size. The smallest one is 7/8" which was just right for my 9 pin sockets. The problems is that while they are the right size, they're built like crap. The punch cracked halfway through my first hole! I managed to carefully make it through 3 1/2 holes before it finally cracked in half. 🙁
The way I do my top plates allows for easy hole alignment. I use a program like Front Panel Designer or PowerPoint to lay out the holes. I then print it out and tape it to the plate. Use a spring loaded center punch to mark the centers of the holes and guide the drill bit. Very simple and effective to make accurate patterns at home.
I made the mistake of buying them. I didn't understand the way they are sized. You have to drill a huge hole to use them anyway. Instead I used step bits on aluminum and they worked great.
I lay it out in cad (use whatever drawing program u know), print it, and drill it. To get perfect holes, pre drill it w/ a tiny bit, or punch a little divit in the middle of each future-hole.
I got a nice delta drill press on clearance for about $100.00, and it's probably the best tool purchase Ive ever made.
I got one of these to cut any size circle I need
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Love this idea. A little front end work and then you have a tool for life. Thanks Gimp!
aaaah - but with such a range of hammers, wonders can be performed!
I currently have to climb over the model railway and the stacked console and jukebox chassis and past the stacked furniture to get to the roller door that must be opened to put the drill stand outside before i can drill one hole. I normally trip over the arc-welder or the drop saw on the way.
I understand your dilemma...
I currently have to climb over the model railway and the stacked console and jukebox chassis and past the stacked furniture to get to the roller door that must be opened to put the drill stand outside before i can drill one hole. I normally trip over the arc-welder or the drop saw on the way.
I understand your dilemma...
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