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Cutting 60mm Hole in Plastic

DesertG

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Sep 4, 2022
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Happy New Year guys. I am working on a car project were I need to cut a precise 60mm hole in a piece of plastic dashboard material. I am stuggling to find a hole saw blade that is not coarse or made for wood or metal. Any thoughts on how I could do this. Thank you!
 
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PCustoms

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What's your tolerance?

Material thickness?

Could think of a lot of ways, each one will work great depending on exactly what I'm doing.
 

LXCam

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Use a wood one but cut in reverse. I’d also highly suggest using a piece of metal bar stock (pre-drilled) for keeping the pilot bit centered so it doesn’t walk on you. If your piece isn’t flat then I’d suggest shaping a piece of hardwood and do the same thing.
 

mark#3

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Could you drill a small hole in it, then use a saber saw to cut the rest of the hole out?
 

PCustoms

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Being plastic, even that won't matter if there is access to the back side.
Maybe....

Unless its too thick! Then you end up with a 60mm step in each face, and a 58mm through hike. If you drill deeper it opens to the next step size.

There's reasons why a few people have asked for more details.
 

PCustoms

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Here's a partial list of ways to cut the hole:

  • Holesaw
  • Knife
  • Step drill
  • Circle cutter
  • Jigsaw
  • Body saw
  • Router and template
  • Lightsaber
  • Smaller drill, saw etc. then sanding drum to final size
  • Laser
  • Forstner bit
  • Boring bar
  • Cnc
  • Etc.
 

johnre

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If you have a set, use a forstner bit.

If you don't, you probably don't want to buy a 60 mm (closest English size: 2 3/8) for just for this application; you'll get sticker shock.

Next choice in order of decreasing cleanliness and decreasing cost: hole saw.
 

PCustoms

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Couldn't you just turn it over and drill through the back.
No. Maybe. Depends.

Say the material is 5/8", and the steps are 1/4". If you drill to 60mm in the front, and then 60mm in the back, then you have an 1/8 on the middle that is too small. Maybe the backside can tolerate being a larger hole?
 

manwithtools

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Here's a partial list of ways to cut the hole:

  • Holesaw
  • Knife
  • Step drill
  • Circle cutter
  • Jigsaw
  • Body saw
  • Router and template
  • Lightsaber
  • Smaller drill, saw etc. then sanding drum to final size
  • Laser
  • Forstner bit
  • Boring bar
  • Cnc
  • Etc.
Or you could measure it with a micrometer, mark it with chalk and cut it with an axe :)
 

PCustoms

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In plastic? :twak:
Maybe, if it's hard/brittle.

OP mentions having a hard time finding a non-course holesaw...this is about the only option I can think of. For under $10 I'd try it, odds are it plugs up.

I'd probably also have already drilled the hole by now
 
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Black300zx

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Elkton, Md
Or you could measure it with a micrometer, mark it with chalk and cut it with an axe :)
We're 16 replies deep and no one has suggested Oxy/Acetylene yet. I'm disappointed.

Details on what's being mounted and how much cosmetic overhang there is would be helpful. 60mm is a fairly common size for aftermarket gauges, so I'm guessing that's what might be going on here. If that's the case, a 2 3/8" hole saw should do just fine and leave a hole that is only about 0.01in too large.
 

nadogail

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Coronado, CA
Mark a smaller circle and drill a bunch of closely spaced holes on your marked line, then clean it all up with a file.
 

MongoTA

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What a thread!

If it's somewhat rigid, someone mentioned a hole saw but cutting in reverse. Works like a champ.

If it's a bit thin or flimsy, someone else mentioned clamping it between two pieces of wood and using a hole saw. Works like a champ.
 

ATC

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Precise?

59mm hole saw, then sand it to the correct fit.
 

ATC

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Here's a partial list of ways to cut the hole:

  • Holesaw
  • Knife
  • Step drill
  • Circle cutter
  • Jigsaw
  • Body saw
  • Router and template
  • Lightsaber
  • Smaller drill, saw etc. then sanding drum to final size
  • Laser
  • Forstner bit
  • Boring bar
  • Cnc
  • Etc.


  • Waterjet
  • Torch
  • 12ga with birdshot
  • Hot knife
  • Razor blade
  • Hammer & gasket punch
 

Zeke

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Aug 13, 2009
Messages
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Location
Long Beach CA, the sewer by the sea.
If you have a set, use a forstner bit.

If you don't, you probably don't want to buy a 60 mm (closest English size: 2 3/8) for just for this application; you'll get sticker shock.

Next choice in order of decreasing cleanliness and decreasing cost: hole saw.
2.325" is slightly oversized. If that would work there are a lot of cheap door lock boring bits available with the mandrel included. If you knocked the set off a little with a file: one, it won't grab, and 2, it would be very close to 60mm.
 

Gozo

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Oct 10, 2013
Messages
251
Location
Central VA
Not knowing the thickness, type, shape, or hardness of the plastic; I’ll toss this one into the mix: Diamond hole saw
I’ve done lots of tile work and have a set of these. Have used them for non-tiles stuff and some acrylic sheets. Just used the drill press on slowest setting and took my time. More like sanding through that drilling.
 

ambenz

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Dec 12, 2010
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NW Chicago Suburbs
...you should have mentioned you wanted to do it on the cheap!
$35 step bit, $300 router....how much do you want to spend on this hole?
I say regular old big drill bit backed by a scrap flat wood board...if you have a cheap round file, file to spec.
Man, these people love to spend our money!
 
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