I want to machine a larger(2 1/8") hole punch for putting holes in a custom gauge panel and would like to see any homebuilt ones you have. I was also wondering approx. what the cutting angle might be on the face for use in light gauge aluminum . Thanks, Jeff.
I have a set of greenlee punches up to 1 but I'm not paying $$ for one as large as I need that may or may not be used again. I would however like to model mine after them but was wondering if the same acute cutting angle would work on larger holes. I had thought of the hole saw but because of where it is the holes need to spot on and burr free.
If you look closely at the Greenlee type, you'll see that the punch face has a shape a lot like the notch you'd put on the end of piece of tubing. That allows it to cut a small section of the circle at any given time. Shouldn't be too hard to fab something like that if you have a lathe. Otherwise, your biggest problem will be finding material with the right O.D.
I have used a adjustable boring bar type for the big dash holes. It has a center drill bit and a sliding and lockable arm with a 3/16 lathe type cutter. Old time hardware stores should carry them. Not totally burr free, but real nice round holes. If using in a drill press clamp the dash to a wood backup piece to keep the drill from walking. Good luck. DT
You can drill a lot of small hole in a circle and then take a bigger size and nock the middle part out and grind the edge
The only cheap hole saw I've had good results with are the rigid line at home depot, they cut steel well. there are better ones but those will work, did the new hole for my column. 2.25. Just stay away from the really cheap ones. I'd like to see the boring bar set up mentioned earlier in the thread, sounds pretty slick.
You may want to check out your tool shops. Here in Sacramento we have a place called Cal Service Tool that rents out a lot of different tools. Also check with any of your Electrician buddies. Alot of us have a couple that are worn out but they will go through thin guage aluminum no problem.
That is the style of my others and the one I'll probably try, just thought maybe somebody might have done this before. When you have a lathe,mill and snow on the ground you tend to look at spending the $150plus a little different.
If it is just thin guage aluminum I would use a hole saw. Clamp the piece down really well use a lot of cutting oil and file any burrs off when done. Are you putting guages in the holes? If so won't the bezels cover the edges anyways. Seems like you are overthinking this.
Tried posting picture from the net of tool. Could not. General Tool makes two versions heavy duty and light. It is called Circle Cutter. If you log onto a search site and type in Circle Cutter Metal, in images it should show up.
I can't believe your unable to do a hole with a hole saw and not be able to leave an almost burr free finish (which can easily be dressed to final finsh with a round file and careful work). New saw, light pressure very slow speed, lots of lube, done. Making you own knockout punch will involve a lot of time, expensive materiel, and the need for heat treating folowed by grinding to final size. You are aware of this aren't you? If you neglect the heat treat and final grind you won't have a cutting edge up to the task. Frank
If you need holes for gauges the el cheapo holes saws to drill a door for a lock assembly are 2 and one eighth. Turn it slow and you can mount a lot of gauges.
A 2" conduit punch won't work, according to the Greenlee catalog a 2" conduit punch makes a 2 3/8" hole. I would do the hole saw and deburring tool. A good sharp hole saw will cut a very nice, clean hole. If you can drill a small pilot hole so you know you have your hole centered where you want it, start cutting with the hole saw from one side and then flip the piece and finish drilling from the other side. I do this when I have a thick piece of metal and it eliminates the rough burr on one side.
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