Drilling a Hole in Dash Panel

tlucier

tlucier

Well-Known Member
Joined
Jun 3, 2007
Location
Mebane, NC
Simple question because I don't want to eff this up since it will be very visible. I need to drill a 3/4" hole in my dash panel for a switch. Regular drill bit vs hole saw? Should I cover the area I'm going to drill with masking tape? What's the best way to cut a no fuss, no muss 3/4" hole in a TJ steering column opening cover? Thanks in advance.
 
Tj column cover, that's plastic right?
 
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Ron said:
Tj column cover, that's plastic right?
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Yes sir. PC/ABS according to the mold stampings
 
Punch it! If you don't have a punch, buy a Blair Holcutter.. If that's too much, use a hole saw. If you don't want to spend the money on that, use a step bit. Step bits are always my last resort, they just aren't a great tool for the job.
 
Sharp bit will go right thru cleanly, step, hole saw, forstner bit, spade bit, or standard twist bit. Slow is key.

.75 is a big hole for in a steering wheel cover.. what's getting mounted?
 
Are you doing it in place or is it detachable?
If detachable, I've gone as far as get a section of tubing with the desired OD, bevel the leading edge and get it cherry hot over a fire to pierce through plastic. Kinda dangerous and dumb but a guarantee it won't crack it.
 
a_kelley said:
Sharp bit will go right thru cleanly, step, hole saw, forstner bit, spade bit, or standard twist bit. Slow is key.

.75 is a big hole for in a steering wheel cover.. what's getting mounted?
Click to expand...

It's a hole for a 3 position switch. Not it the steering wheel cover, it's in the steering wheel column opening cover. Just under the steering column with tilt steering
 
XJsavage said:
Are you doing it in place or is it detachable?
If detachable, I've gone as far as get a section of tubing with the desired OD, bevel the leading edge and get it cherry hot over a fire to pierce through plastic. Kinda dangerous and dumb but a guarantee it won't crack it.
Click to expand...

It's detachable and sitting on my workbench
 
Do not use a knockout on plastic . don't.

A standard sharp twist bit turned slow or a hole saw will work fine. as will a unibit/step it. it's plastic
 
tlucier said:
It's a hole for a 3 position switch. Not it the steering wheel cover, it's in the steering wheel column opening cover. Just under the steering column with tilt steering
Click to expand...
Ah, misread there. Was thinking the steering column cover anyway, so just under that. Makes sense now. Forstner bit will cut it perfect, if you have one. It's similar to a hole saw but with two cutters instead of open between the saw and bit. Regular bit will zip thru clean too. Tsc had them for $10-15 per bit from 1/2" to 1"
 
Ron said:
Do not use a knockout on plastic . don't.

A standard sharp twist bit turned slow or a hole saw will work fine. as will a unibit/step it. it's plastic
Click to expand...

Thanks Ron. I was concerned a knockout might crack the plastic but hell, maybe somebody tried it and it's the cat's ass. Guess not. I have a step bit I'll use on it tomorrow. Thanks for your input.
 
Klein says their knockouts are for plastic too. I've used in plastic with success but Ron has way more experience with electrical related item than I.
 
rockcity said:
Klein says their knockouts are for plastic too. I've used in plastic with success but Ron has way more experience with electrical related item than I.
Click to expand...
They will work on a pvc or Masonite selectively boxes, which are way thicker.

The issue isn't the knockout. it's the Jeep plastic. it's thin and can be brittle. id bet a dollar that if would split and run from the punch point before going through. it might work, but a drill UT will work. just go slow.
 
rockcity said:
Klein says their knockouts are for plastic too. I've used in plastic with success but Ron has way more experience with electrical related item than I.
Click to expand...

The trick is that the plastic needs to be stiff enough (usually that means thick enough) to start shearing without deforming, otherwise is can crack if it starts deforming. I've punched a lot of 1/8" ABS with Greenlee stuff over the years, and it works fine.
 
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