jps
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| posted on 15/9/13 at 10:05 AM |
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Hole cutters? For sheet metal?
Novice question this - how do I cut a hole in my 3mm steel pedal box to accommodate my brake master cylinder?
Is one of those 'saw blades bent into a circle - that operates in an electric drill' the answer? I guess they are called 'hole
-cutters'?
They aren't cheap - so it seems excessive to buy one to cut a single hole?
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dave_424
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| posted on 15/9/13 at 10:15 AM |
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They are called hole saws. They do work, another good thing would be a "step drill" which is like a very large cone drill the steps up in
size the deeper you drill, however fairly expensive.
If you don't want to buy anything, even just a series of small holes drilled around the circumference of the big hole you want to cut out can
work and clean it up with a file.
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iank
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| posted on 15/9/13 at 10:16 AM |
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Yes a decent bi-metal hole saw will do the job in a few seconds (drill nice and slow, with lubricant).
The alternative is to mark the hole, chain drill around it and then clean up with a file (or a flap disc in a dremel if you have one).
bah, few seconds too slow 
Bonus picture of chain drilling
[Edited on 15/9/13 by iank]
--
Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous
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myke pocock
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| posted on 15/9/13 at 10:27 AM |
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If you do buy a hole saw, get a decent one, Starret is good. The cheaper ones vibrate like stink and give a very poor cut. A bit of lubricant always
helps.
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40inches
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| posted on 15/9/13 at 10:34 AM |
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I have one of these, you can buy the arbour and saws separately. I
cut a 86mm hole in 4mm mild steel, it was slow, and I used lots of lubricant with a very slow speed.
One tip is not to cut all the way through, cut half way then turn the piece over and finish off. Also, I replaced the pilot drill with a steel rod,
this stops the pilot hole progressively becoming oval, before the saw self centres. 
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owelly
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| posted on 15/9/13 at 10:46 AM |
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I have good hole saws for the sizes I use most. These are usually Starrett. However, I bought a set of cheapy ones from Lidl and they've
suprisingly good! One has just chewed eight 3" holes through 4mm stainless. Slow cutting speed with a few breaks to allow things to cool, and
cutting paste. Ideal if you only need to make a few holes.
http://www.ppcmag.co.uk
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Ivan
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| posted on 15/9/13 at 11:08 AM |
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Slightly off topic but I have never had much success with hole cutters - the blade always comes loose from the pilot drill no matter how tight I clamp
it  - what is the secret of stopping that from happening?
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liam.mccaffrey
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| posted on 15/9/13 at 11:08 AM |
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the step drills are magic!!!
Build Blog
Build Photo Album
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myke pocock
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| posted on 15/9/13 at 11:17 AM |
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Ivan, the large sizes use two pins to locate in the top of the saw unit rather than sinply butting up against the flange of the securing thread. In
use this system can vibrate free with larger saws.
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HappyFather
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| posted on 15/9/13 at 11:21 AM |
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I used this adapted thing on the driller, with lots of lubricant and slooooowwww speed. But used it on ally not on steel. Not sure if it gets through
steel.
The nice thing is that it is adjustable to several hole sizes.
https://picasaweb.google.com/lh/photo/0qDmQd30_zaiAvEaM55o7dMTjNZETYmyPJy0liipFm0?feat=directlink
[Edited on 15/9/13 by HappyFather]
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40inches
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| posted on 15/9/13 at 11:38 AM |
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quote:
Originally posted by Ivan
Slightly off topic but I have never had much success with hole cutters - the blade always comes loose from the pilot drill no matter how tight I clamp
it - what is the secret of stopping that from happening?
The 2 pin type are much better link.
To stop the drill coming loose, mark it with the grub screw, then grind a small flat for the screw to grip.
Better still, drill the pilot hole first, and replace the drill in the arbour with a steel rod.
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owelly
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| posted on 15/9/13 at 11:42 AM |
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quote:
I used this adapted thing on the driller, with lots of lubricant and slooooowwww speed. But used it on ally not on steel. Not sure if it gets through
steel. The nice thing is that it is adjustable to several hole
sizes. https://picasaweb.google.com/lh/photo/0qDmQd30_zaiAvEaM55o7dMTjNZETYmyPJy0liipFm0?feat=directlink
Aka trepanning tool.
http://www.ppcmag.co.uk
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splitrivet
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| posted on 15/9/13 at 12:09 PM |
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The Aldi kit is bimetal as good as Starrett and a fraction of the cost with 2 arbors and a good selection of sizes use mine for work the bonus is the
arbors will also fit starrett. Its finding a store with stock thats the problem as they arent currently on offer.
Cheers,
Bob
I used to be a Werewolf but I'm alright nowwoooooooooooooo
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MikeRJ
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| posted on 15/9/13 at 01:20 PM |
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quote:
Originally posted by owelly
quote:
I used this adapted thing on the driller, with lots of lubricant and slooooowwww speed. But used it on ally not on steel. Not sure if it gets through
steel. The nice thing is that it is adjustable to several hole
sizes. https://picasaweb.google.com/lh/photo/0qDmQd30_zaiAvEaM55o7dMTjNZETYmyPJy0liipFm0?feat=directlink
Aka trepanning tool.
I always knew them as "Tank cutters".
[Edited on 15/9/13 by MikeRJ]
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Peteff
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| posted on 15/9/13 at 02:13 PM |
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quote:
Originally posted by splitrivet
The Aldi kit is bimetal as good as Starrett and a fraction of the cost with 2 arbors and a good selection of sizes use mine for work the bonus is the
arbors will also fit starrett. Its finding a store with stock thats the problem as they arent currently on offer.
Cheers,
Bob
I picked some up from Aldi just on a whim and have been using them for years now. I chipped a couple of teeth in a small one but the others have been
used to cut gas cylinders and anythig up to 5mm and stood up well.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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BenB
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| posted on 15/9/13 at 02:53 PM |
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Go slowly with lots of lub and if it starts smoking stop ASAP. Lots of breaks to cool the cutter and nice slow speed and jobs a good'un. I like
Qmax type punches for sheet but they wouldn't do 3mm. 1.2mm stainless is the max I've tried with those fellas. Great for cutting holes in
the ali sides for exhausts though- such a shame you have to cover the neat edges with trim for SVA/IVA!
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ianm67
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| posted on 15/9/13 at 03:21 PM |
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quote:
Originally posted by liam.mccaffrey
the step drills are magic!!!
^^ this... ^^. I've used one of these on my Dax build and for GRP and Ali' I think they are much better than a conventional hole
saw.
[Edited on 15/9/13 by ianm67]
Always biting off more than I can chew.....
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DIY Si
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| posted on 15/9/13 at 03:50 PM |
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I'd second/third/what it is the step drills. Whilst they are expensive, they're also very versatile. As with all things though, they have
their limitations. The main one being they can only cut as thick as the steps on the drill are, usually 5-6mm. Otherwise they're excellent.
“Let your plans be dark and as impenetratable as night, and when you move, fall like a thunderbolt.”
Sun Tzu, The Art of War
My new blog: http://spritecave.blogspot.co.uk/
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neilp1
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| posted on 15/9/13 at 04:05 PM |
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We use starrett at work (offshore) and I've cut through over 25 mm plate with them taking my time. A good hole saw is worth paying the money for
and as they say use the correct tool for the job. The easiest way is always the best. Or most of the time any way!
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Alan B
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| posted on 15/9/13 at 04:13 PM |
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I'm not sure the OP has been pricing the right thing. I'm not Rockerfeller by any means, but I can buy 1.5" holesaws (decent ones)
for less than $5 (..about 3 quid?) which I think is pretty cheap actually.
I will usually evaluate tool purchases based on the time saving...I know it's supposed to be fun and not business but if I can save a couple of
hours for 3 quid then I'd say it's worthwhile...
I've seen this other threads too....spending hours to save a just few bob....but it's your time, your money..
Just my thoughts...
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MikeRJ
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| posted on 15/9/13 at 05:15 PM |
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quote:
Originally posted by Alan B
I'm not sure the OP has been pricing the right thing. I'm not Rockerfeller by any means, but I can buy 1.5" holesaws (decent ones)
for less than $5 (..about 3 quid?) which I think is pretty cheap actually.
To be fair stuff like Starrett is quite expensive, especially when you have to buy the arbor as well, but there are plenty of
lower cost versions that will do the job.
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jps
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| posted on 15/9/13 at 05:28 PM |
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quote:
Originally posted by Alan B
I'm not sure the OP has been pricing the right thing. I'm not Rockerfeller by any means, but I can buy 1.5" holesaws (decent ones)
for less than $5 (..about 3 quid?) which I think is pretty cheap actually.
I will usually evaluate tool purchases based on the time saving...I know it's supposed to be fun and not business but if I can save a couple of
hours for 3 quid then I'd say it's worthwhile...
I've seen this other threads too....spending hours to save a just few bob....but it's your time, your money..
Just my thoughts...
Yeah - I did have a Google after i'd posted and realised that the Bosch ones that i'd seen in the local Kent Blaxhill (upwards of £30
each) were phenomenally expensive for some reason - perhaps they were for specialist application and I hadn't realised...
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Alan B
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| posted on 15/9/13 at 08:26 PM |
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To be fair stuff like Starrett is quite expensive, especially when you have to buy the arbor as well, but there are plenty of
lower cost versions that will do the job.
Good point.
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Alan B
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| posted on 15/9/13 at 08:32 PM |
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quote:
Originally posted by jps
Yeah - I did have a Google after i'd posted and realised that the Bosch ones that i'd seen in the local Kent Blaxhill (upwards of £30
each) were phenomenally expensive for some reason - perhaps they were for specialist application and I hadn't realised...
I just didn't want someone to be put off a cost effective solution by incorrect or inaccurate initial info.
I do a lot of round tube work and hole saws make a big difference. I like step drill too within their limitations.
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