How do you punch 7/16", 3/8" (and smaller) chassis holes?

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How do you punch 7/16", 3/8" (and smaller) chassis holes?

Postby sah5150 » Sat Nov 08, 2008 6:15 pm

I'm punching my own chassis from an aluminum blank and I have some questions:

So I won this set of Greenlee punches for a pretty good price. Should handle the preamp power tube, etc. holes - everything larger or equal to 1/2":

Greenlee Punch Set

For smaller holes, (7/16" and smaller), do you think this will work for a standard aluminum chassis? Says they'll punch metal, but I'm skeptical it would would with an aluminum amp chassis:

http://www.amazon.com/Heavy-Duty-12-Piece-Hollow-Punch-Set/dp/B000KE17JO/ref=pd_sim_hi_4

How do you guys do the smaller holes? Drilling seems to really mess up the chassis and I end up having to use a grinder on my Dremel to clean up the burrs, etc. I'd rather punch the holes for a clean professional look.

Thanks,

Steve
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Re: How do you punch 7/16", 3/8" (and smaller) chassis holes?

Postby dynaman » Sat Nov 08, 2008 9:27 pm

I doubt those "punches" would work. I also own Greenlee punches ranging from 1/2" and up. For the smaller holes you could use regular bits. You'd have to start small and work your way up slowly in sizes to keep chatter to a minimum. I hate doing it this way.

Now, I just use a step bit. I have this set http://www.harborfreight.com/cpi/ctaf/d ... mber=91616

I especially like using the bit on the left. I always use cutting fluid as this helps on chatter.
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Re: How do you punch 7/16", 3/8" (and smaller) chassis holes?

Postby Guitar Adjuster » Sat Nov 08, 2008 9:44 pm

Step bit cuts like butter on al. Lowes or Home Depot carry them.
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Re: How do you punch 7/16", 3/8" (and smaller) chassis holes?

Postby sah5150 » Sat Nov 08, 2008 9:45 pm

dynaman wrote:I doubt those "punches" would work. I also own Greenlee punches ranging from 1/2" and up. For the smaller holes you could use regular bits. You'd have to start small and work your way up slowly in sizes to keep chatter to a minimum. I hate doing it this way.

Now, I just use a step bit. I have this set http://www.harborfreight.com/cpi/ctaf/d ... mber=91616

I especially like using the bit on the left. I always use cutting fluid as this helps on chatter.


Thanks man - that looks like the ticket.

Steve
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Re: How do you punch 7/16", 3/8" (and smaller) chassis holes?

Postby mrkrausman » Fri Nov 21, 2008 3:35 pm

Drilling into a completed chassis? I've never done this before. Do you guys remove rear panel before drilling or do you just drill thru it? I would think cutting fluid would damage acrylic on the panel. I'm talking about 7/16" holes. I'm thinking getting an assembled chassis onto a drill press could be tricky so would hand drilling be the best for a steel chassis?
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Re: How do you punch 7/16", 3/8" (and smaller) chassis holes?

Postby sah5150 » Fri Nov 21, 2008 3:41 pm

mrkrausman wrote:[b]Drilling into a completed chassis. [/b] I've never done this before. Do you guys remove rear panel before drilling or do you just drill thru it? I would think cutting fluid would damage acrylic on the panel. I'm talking about 7/16" holes. I'm thinking getting an assembled chassis onto a drill press could be tricky so would hand drilling be the best for a steel chassis?


I had no problem drilling a 7/16" hole into a completed chassis with a hand drill, through both the aluminum chassis and the rear panel with no problem using no cutting fluid. For a hole or two, this is what I'd do with a completed amp. My issue was doing 16 holes in a blank chassis and getting them perfect for a new amp prototype. Hand drill method just doesn't scale there for me...

Steve
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Re: How do you punch 7/16", 3/8" (and smaller) chassis holes?

Postby mrkrausman » Fri Nov 21, 2008 3:45 pm

sah5150 wrote:
mrkrausman wrote:[b]Drilling into a completed chassis. [/b] I've never done this before. Do you guys remove rear panel before drilling or do you just drill thru it? I would think cutting fluid would damage acrylic on the panel. I'm talking about 7/16" holes. I'm thinking getting an assembled chassis onto a drill press could be tricky so would hand drilling be the best for a steel chassis?


I had no problem drilling a 7/16" hole into a completed chassis with a hand drill, through both the aluminum chassis and the rear panel with no problem using no cutting fluid. For a hole or two, this is what I'd do with a completed amp. My issue was doing 16 holes in a blank chassis and getting them perfect for a new amp prototype. Hand drill method just doesn't scale there for me...

Steve


Did you use standard twist bit starting small or a step drill? I would imagine steel would be a little harder to manage than aluminum.
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Re: How do you punch 7/16", 3/8" (and smaller) chassis holes?

Postby sah5150 » Fri Nov 21, 2008 3:52 pm

mrkrausman wrote:
sah5150 wrote:
mrkrausman wrote:[b]Drilling into a completed chassis. [/b] I've never done this before. Do you guys remove rear panel before drilling or do you just drill thru it? I would think cutting fluid would damage acrylic on the panel. I'm talking about 7/16" holes. I'm thinking getting an assembled chassis onto a drill press could be tricky so would hand drilling be the best for a steel chassis?


I had no problem drilling a 7/16" hole into a completed chassis with a hand drill, through both the aluminum chassis and the rear panel with no problem using no cutting fluid. For a hole or two, this is what I'd do with a completed amp. My issue was doing 16 holes in a blank chassis and getting them perfect for a new amp prototype. Hand drill method just doesn't scale there for me...

Steve


Did you use standard twist bit starting small or a step drill? I would imagine steel would be a little harder to manage than aluminum.


I used a standard twist bit. I've also used a standard twist drill bit with a hand drill to cut 7/16" holes in steel as well. Both without cutting fluid. Only issue on steel was that it took alot longer and required me to use my dremel to smooth out the burrs where the drill came through... If I'd been more patient I would have had less problems with the burrs as well... I'm sure a step bit would be better, but as I said I was pretty impatient at the time. Not a great trait for modding amps as I've now learned... :)

Steve
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