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Topic Review (Newest First)
02-07-2012 07:47 AM
shine if there is any filler in the area a knock-out punch will crack it and most likely break the bond. not a good thing.
02-07-2012 07:18 AM
Low n' 51ow
Quote:
Originally Posted by 327 / 350 hp
I don't know about u guys but why wouldn't u use a electricians knock out punch.. Drill a pilot hole first then place punch there and screw together.. Good Luck Jim
327, I do instrumentation and electrical work for a living and even when using a knockout on an elec. panel, it tends to pull the paint from around the edge of the hole. And the enclosure paint is alot thinner than it would be on your ride. Not only that, it can "pull" the metal out around the edges and create an uneven surface that you would have to rework. Probably not a good option if you want to keep from damaging the paint and working surface.......just my two cents.
02-05-2012 07:17 PM
1971BB427 I have never kept pilot blanks. For years I've just predrilled the hole with the holesaw bit, then install the bit reversed in the holesaw so the tip is inside, and the smooth shank is out. Then just drill the hole.
I do mask off close to the hole with paper to keep hot shavings off the paint, but not close enough to drill through the tape. A spray bottle with water works well to cool the blade if needed.
02-05-2012 07:07 PM
327 / 350 hp
cutting a hole through paint

I don't know about u guys but why wouldn't u use a electricians knock out punch.. Drill a pilot hole first then place punch there and screw together.. Good Luck Jim
02-05-2012 05:49 PM
shine with the pilot hole and rod you can turn the saw in reverse to cut the paint first.
02-05-2012 05:39 PM
Old Fool
Quote:
Originally Posted by MARTINSR
And of course another tip would be to have a new or at least very sharp hole saw. If it's old it's going to "rub" on the panel and heat it up instead of cutting thru.

I am one to cut small too, cut small and using a quality burr cutter (rotary file) to slowly open up the hole to size. You can do this very slowly (with a GOOD cutting burr cutter)



And I mean picking the right one, in your case the largest cylindrical one like the sixth one from the left in the photo. I picked up a selection of these twenty years ago that were very high quality, I think I spent $20 each one them. Outside of a few that I have lost ( double ) they are still in top not working condition. Buying the best REALLY pays off.

But anyway, having a good selection lets you chose the RIGHT one for the job .

I am thinking Shines tip on removing the drill bit and replacing it with a piece of rod may take care of this somewhat. But a how saw will walk a little, it often will open the hole just a bit larger than the hole saw size. Just a tad understand, but there are times that "tad" may kick your ars.

The other day at work one of the guys (he should have known better) used the exact size hole saw on a plastic bumper to put the holes for back up sensors. The correct saw but the hole had to be EXACTLY right for the funky plastic sensor bracket to clip into, with it's little tiny clips, it needed to be very precise. Well, the hole saw opened the hole just a tad too much, wham, the sensor wouldn't say in!

The moral of the story is if you are cutting a hole exactly the size you need run a test and see if it is in deed going to work for you. If not, go to the one smaller and open the hole up to perfection with a rotary file.

And of course the one thing you have to be careful of is when using the rotary file to open that hole, don't come out of the hole and ruin the surrounding paint!

Brian
A trick I do when I need to hole saw a hole and think it might "hog" out the hole out a bit is to chuck the hole saw on an arbor and put it in the drill motor. Go over to the belt sander and turn on the belt sander and run the drill motor. Hold the hole saw side parallel to the belt sander. In a few seconds I can sand the "set" off the outside teeth.

This accomplish 2 things, the OD of the hole is reduced and by not having teeth looking to pull to the out side of the circle the saw will be more self centering.
02-05-2012 10:21 AM
MARTINSR
Quote:
Originally Posted by shine
i have no bits in my hole saw drawer . just a few rods with flats filed on them. also use the rods when working on wood. makes for a much truer hole.
and the heat is worse than the saw walking. takes very little drilling to create enough to loose adhesion around the edge. any tape will pull up paint .
Very good tip! I will be doing the same.

Brian
02-05-2012 10:19 AM
shine i have no bits in my hole saw drawer . just a few rods with flats filed on them. also use the rods when working on wood. makes for a much truer hole.
and the heat is worse than the saw walking. takes very little drilling to create enough to loose adhesion around the edge. any tape will pull up paint .
02-05-2012 10:03 AM
MARTINSR Oh and on your idea Shine, I am thinking of getting a short piece of 1/4" drill stock today and putting it in the hole saw box so I don't get tempted to do without because I can't quickly find some when I am ready to drill a hole.

Brian
02-05-2012 10:00 AM
MARTINSR And of course another tip would be to have a new or at least very sharp hole saw. If it's old it's going to "rub" on the panel and heat it up instead of cutting thru.

I am one to cut small too, cut small and using a quality burr cutter (rotary file) to slowly open up the hole to size. You can do this very slowly (with a GOOD cutting burr cutter)



And I mean picking the right one, in your case the largest cylindrical one like the sixth one from the left in the photo. I picked up a selection of these twenty years ago that were very high quality, I think I spent $20 each one them. Outside of a few that I have lost ( double ) they are still in top not working condition. Buying the best REALLY pays off.

But anyway, having a good selection lets you chose the RIGHT one for the job .

I am thinking Shines tip on removing the drill bit and replacing it with a piece of rod may take care of this somewhat. But a how saw will walk a little, it often will open the hole just a bit larger than the hole saw size. Just a tad understand, but there are times that "tad" may kick your ars.

The other day at work one of the guys (he should have known better) used the exact size hole saw on a plastic bumper to put the holes for back up sensors. The correct saw but the hole had to be EXACTLY right for the funky plastic sensor bracket to clip into, with it's little tiny clips, it needed to be very precise. Well, the hole saw opened the hole just a tad too much, wham, the sensor wouldn't say in!

The moral of the story is if you are cutting a hole exactly the size you need run a test and see if it is in deed going to work for you. If not, go to the one smaller and open the hole up to perfection with a rotary file.

And of course the one thing you have to be careful of is when using the rotary file to open that hole, don't come out of the hole and ruin the surrounding paint!

Brian
02-05-2012 09:47 AM
MARTINSR
Quote:
Originally Posted by shine
forget the tape. wont stop a hole saw or anything else from going through but most likely will pull up paint when removed. if you get the paint hot it will loose adhesion.
drill your pilot hole then change the drill bit to a piece of rod the same size. the drill bit will wallow out the hole and let the saw walk. first turn the saw backwards slowly to cut the paint. then cut the hole very slow to keep the heat down. heat is the thing to avoid. good luck .
Absolutely brilliant Shine! As soon as I started reading this I am thinking NOOOOOO on the tape. Then thinking, drill a pilot hole! LOL Your idea on replacing the drill with a piece of rod was worth coming to my computer and reading this stuff, that will be written on the inside of my hole saw box, that is a good one!

Brian
02-05-2012 08:57 AM
shine i'll stick to what i know .
02-05-2012 08:49 AM
stich626 heat.. ya I guess if you are use'n a dead hole saw..
a sharp hole saw will not heat the metal anymore than the summer sun does..
I'd still use painters tape and if you're worried about heat.. light stream of water from a hose.. if heat lifted paint, we'd be repainting every fall..
it's sheet metal not 1/8" plate he's cutting.. as long as the saw isn't dull..it never build enough heat.. nowa dull saw.. well..
02-05-2012 07:03 AM
shine just remember the heat. hole saws cut better at a slow speed. when metal heats it tempers itself and gets harder. go slow and monitor the temp . i'd rather take all day to cut a hole than repaint a fender .
02-05-2012 07:00 AM
StreetKruzer
Quote:
Originally Posted by shine
forget the tape. wont stop a hole saw or anything else from going through but most likely will pull up paint when removed. if you get the paint hot it will loose adhesion.
drill your pilot hole then change the drill bit to a piece of rod the same size. the drill bit will wallow out the hole and let the saw walk. first turn the saw backwards slowly to cut the paint. then cut the hole very slow to keep the heat down. heat is the thing to avoid. good luck .
Thanks to all. Shine, looks like that is how we'll do it. Never thought that the tape might be the bad guy!
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