In my many years of amateur engineering and bodgery I've learnt ways to DIY most tasks, but the one that's always defeated me is cutting
large holes in steel plate.
Once again the spectre of chain drilling and filing has come back to haunt me - I need a 30mm hole in a piece of 6mm plate. There must be a way that
doesn't involve :-
a) a lathe,
b) some other hugely expensive tool,
c) taking it to some bloke somewhere.
.......so if you've found a nice, easy DIY way of doing this - I'm all ears
Hole saw in an electric drill, can produce surprisinlgy accurate results
John
30mm drillbit?
Id just go for drilling loads of holes around the circumferce and filing it back
second on hole saw (good quality for 6mm plate) and cutting fluid and lots of time 
6mm plate + hole saw= worlds shortest lived drill bit...
Been there, got the t-shirt etc etc etc....
Maybe if it's made from unobtanium!!!
i've done 6mm stainless with a starret cutter and loads of cutting fluid,
hth
Ray
My work drill holes of similar size through that sort of thickness many times a day. Hole saw everytime.
defo hole saw! Am an electrician and we use them all the time with great results, as long as you have a decent drill. if you dont fancy drilling a 30 mm hole you could always drill a slightly smaller one and widen it with a cone cutter!
I wanted a close clearance fit in 10mm plate for a 30mm diameter bar and found that a 29mm dia hole saw (a standard size) made a suitably oversize hole for the 30mm bar. A bench drilling machine on a slowish speed is good for this.
Hole saw eh? I've bought a couple, absolutely w**k at cutting holes in metal, fine in fibreglass.
Are they any better in a pillar drill ie?
Hole saw, preferably in a drill press. Use low speed (250rpm) and loads of cutting fluid. Remember to get cutting fluid on the centre bit as well as
the hole cutter, otherwise it will blunt.
Back off and let things cool down if/when it smokes.
Nick
Anyone who's had bad results with holesaws in steel plate is either using cheap crap holesaws or going too fast and not using enough cutting
fluid.
Imagine the speed a saw blade moves when you use it by hand and aim for that sort of tooth speed, 100-200 rpm would be my choice.
hole saw will be fine on a slow speed torquey drill. or one of these if you've got the equipment for it.rotobroach
Hi,
Got a selection of Sandvik (now Bahco)hole saws, no problems cutting 38 mm holes in 10mm stainless steel to make manifold flanges, but as others have
said use a slow speed and lots of cutting fluid.
David
quote:
Originally posted by BenB
6mm plate + hole saw= worlds shortest lived drill bit...
Been there, got the t-shirt etc etc etc....
Maybe if it's made from unobtanium!!!
I'd given up on hole saws for cutting steel long ago, but several of you guys are obviously having success with it, so I'll have to
re-investigate these.
If you've got a link to any that you've tried, and will cut 6mm steel, I'd be gratefull..
I would try getting a blacksmiths drill bit
http://www.lawson-his.co.uk/scripts/products.php?cat=Blacksmiths%20reduced%20shank%20drills
Has a 28mm bit but at £57 it isn't cheap
What cutting fluid would you recommend??
I've done several 35mm holes in 3mm steel with a hole saw and hand drill, but have got more accurate results with a smaller drill and round file
type hacksaw blade [can't remember what they are called].
Stu
there is a vast difference in quality in hole saws. I bought a bosch set from screw fix for £25 for a about 10 saws in a nice box with 2 arbours,
after years of struggling with cheap ones, this set is brilliant.
Using a pillar drill makes life a lot easier and as said, slow speed with a little bit of oil, or just use a water squirty bottle to cool it.
Mu cousin is an engineer and uses thick stainless all the time. He has a hole saw set that was about £60 and that has been used loads.
The little black ones you see at the market are sh1te.
We use starret at work. Very good and have drilled up to 6 inches in 3mm stainless steel before in a drill press.
One thing to bear in mind the minute it starts skidding your in trouble. It'll overheat and burn out very quickly. keep it slow and keep the
pressure on as well as the cutting fluid.
ETA these are the ones we useStarret
[Edited on 6/1/09 by omega 24 v6]
quote:
Originally posted by Antnicuk
there is a vast difference in quality in hole saws. I bought a bosch set from screw fix for £25 for a about 10 saws in a nice box with 2 arbours, after years of struggling with cheap ones, this set is brilliant.
Using a pillar drill makes life a lot easier and as said, slow speed with a little bit of oil, or just use a water squirty bottle to cool it.
Mu cousin is an engineer and uses thick stainless all the time. He has a hole saw set that was about £60 and that has been used loads.
The little black ones you see at the market are sh1te.
i went through a stage of buying hacksaw blades at 33p for 12. i now buy 2 for £3 and havnt gashed my knuckles on a vice since.
in other words, you get what you pay for
you wont regret buying a selection of holesaws, very handy things.
I've just been using the bog stock Screwfix 32, 50 & 70 mm holesaws
LINKY in round and square tube and a bit of 6mm steel plate.
A pillar drill on it's slowest speed and cutting fluid is the way to go.
I used a mix of paraffin and engine oil as cutting fluid/coolant coz that's what I had.
HTH
Neil
As above, get a good holesaw from an engineering merchant - the yellow ones. I've done 80 mm holes in 5 mm stainless by hand with them before
(using an air drill so can run it very slowly, and the red cutting compound usually used for tapping)
Cheers
Fred W B
Use a local engineering firm - much easier and accurate.
I use a good quality stepped cone cutter, faster than a hole saw on steel and it always leaves a nice edge. I have a set like these, tbh their a must
really for working on cars and the holes they cut are more accurate size wise than can be done with a drill bit as they don’t vibrate when cutting. So
fast on GRP that you need to watch how hard you press but also can leave a nice chamfer through the gel coat at the same time to prevent cracks
forming, very handy
[Edited on 7/1/09 by Mr Whippy]
Problem with using stepped holesaws on 6mm plate, is the steps might not be 6mm, if they are less the top of the hole would be wider than the
bottom.
Easy to overcome by filpping the work over though.
Use a holesaw, but make sure it is the solid type that goes onto a threaded arbor, rather than the poo flexible metal ones where several can slot
into the base plate for storage.
My only problem is my pillar drill only goes down to 450rpm, so am limited in the size I can cut (although my cordless is fully variable)
I drilled a load of 38mm holes in 3mm plate on Saturday and the screwfix own brand holesaws did fine.
Sean
What you need is A Practool super drill.
It will drill any size hole from 1/2" to2" in steel wood or ally. I have had one for 10 years and it is a super bit of kit. It will cost
less than 1 large drill and drill any hole you will ever need.
Check the website practool.com
They are made in Australia but avaliable in the U.K.
For info tel. 01944 240978
Cheap hole saws are scrap within seconds of going near steel IME, they are a waste of money unless you want them only for wood or plastic.
A decent quality bi-metal hole saw will easily go through 6mm of mild steel with no problems provided you drill slowly enough and use cutting fluid,
but then again they aren't particularly cheap.
how,s about cutting a square hole in the plate with an angry grinder and making a 3mm plate with said hole to fit over the square hole? 3mm will be
strong enough for the master cylinder mounting
I use Starrett for metal and those cheapy rubbish ones for fibreglass. The FG seems to take the cutting edge off the saws so I'd rather fudge a
cheap one!
I have cut many holes through lots of thicknesses of steel from 1mm up to 10mm floor plates. Drill press is best but a good, slow hand held drill will
work. If you need an accurate sized hole, drill the hole through a piece of 12mm plywood and clamp it to your steel. It stops the blade from wandering
about!
I use Rocol Cutting paste. It's like grease. If it starts to smoke, your getting too hot. Stop, let things cool down and start again. If the
metal turns blue, you've already hardend the steel so when it's cool again, go very careful, slowly and with plenty of cutting paste! Make
sure the cutter is cutting and not rubbing it's way through! If it starts to rub, stop, check your teeth(!) and let things cool! When the device
is cutting correctly, the material that is being removed (swarf) carries heat away from the cutting edges so aim to keep them cutting!
Good luck.
I use the Bosch "Progressor" hole saws. They arent cheap, but them havent let me down on any job yet. They are quick release changeable too.
here is a link to somewhere that sells a good range:
http://www.axminster.co.uk/product-Bosch-Bosch-Progressor-Holesaws-19863.htm
didn't someone say recently that once the drill has done its job, replace it with a steel rod to prevent the hole from wandering?
quote:
Originally posted by 02GF74
didn't someone say recently that once the drill has done its job, replace it with a steel rod to prevent the hole from wandering?
I've used my Aldi bimetal cutters to cut 4mm mild steel with some 3 in 1 type oil applied while it was cutting and it went through no trouble
Just to update, went to see Mr Screwfix today and treated myself to an Ebauer cobalt holesaw of the requisite size.
My hole is now cut, it took about 10 mins with my DIY setup of a crappy old drill and stand, and I quickly found out that, as mentioned by many
people, slow speed big torque is what you need, and what I didn't have.
Anyway, after about 10 mins I was through (I never realised that 6mm was such a long way...) but gave the cutter some abuse TBH in the process - you
definitely need a good pillar drill for this. Hats off to Ebauer cobalt holesaws though, it felt as sharp after it's ordeal as it did at the
start.
Glad to see you chaps have a healthy interest in a nicely engineered hole though, thanks for all the input
quote:
Originally posted by LBMEFM
Use a local engineering firm - much easier and accurate.
Oxy torch?
go with the bi metal hole saws... when the stuff gets thick I chain drill round the perimeter and then use the hole saw. the chain drilling gives the
hole saw space for the chips to go.
agree on all the above, with the caveat that if you have a few to do, its not expensive to hire a rotabroach and the right cutter