drilling 30mm holes in Aluminium and S'Steel

gthang · Post by **gthang** » Tue Feb 23, 2010 5:23 pm

Hello everyone I'm new here and in need of some guidance.

I have to drill a 30mm hole in 4mm thick brushed stainless steel sheet and the same in 4mm think brushed aluminium sheet

I have access to a pillar drill and a hand drill.

What type of drill bit should I use, will a Bosch 30mm hole saw do the job? are there any special hints and tips you can offer for a 1st attempt. I dont really want (can't afford) to get this wrong.

Any advice here would be most welcome.
Thanks very much
Graham.

marc1106 · Post by **marc1106** » Tue Feb 23, 2010 6:48 pm

http://www.google.co.uk/products?source ... CCQQrQQwAg

try somthing like this obviously you have to find the right size!

Bob225 · Post by **Bob225** » Tue Feb 23, 2010 7:08 pm

you can do it with a holesaw as long as you center punch the center of the hole where you want it

while drilling spray the holesaw with wd40 to keep it nice and cool

gthang · Post by **gthang** » Tue Feb 23, 2010 8:16 pm

thanks for the info, i like the idea of the cone / stepped drill bit, easier to fit in the pillar drill i can use.

I only need to dill 2 holes then i'm done, I have seen these stepped drill bits on ebay for £15ish, i'll give one of these a go.

Hitch · Post by **Hitch** » Tue Feb 23, 2010 8:31 pm

You wont have much sucess on 4mm thick stainless with a step drill. They are okay for sheet, but not very good on plate.

I would buy a bahco or starret hole saw and arbour. Dont bother with Bosch if its the quick release ones you are looking at.

Drill the aluminium first, than the stainless.

Centre punch the hole, drill the pilot hole with an ordinary bit first, same size as the pilot in the holesaw arbour.
That way you can control the holesaw, putting very little pressure on it untill it has started properly.

Dont run the drill too fast. Use cutting oil on the stainless, not WD40. Some engine/gear oil will be better than wd40.
If you go too fast, you will harden the stainless and kill the holesaw. Then you will have a job on your hands!

Easy if you know what you are doing.

Just remember, keep the bit running fairly slow, but a fair bit of pressure. If your drill seems to run too fast, pull the trigger on and off.

Have a look here...
http://www.ultimatehandyman.co.uk/DIY_M ... hnique.htm

wrinx · Post by **wrinx** » Tue Feb 23, 2010 11:48 pm

I'd use the pillar drill and a hole saw.

G-clamp the work piece to the drill table if possible, using a piece of wood to protect the job. Any excess vibration will only hinder progress and lead to (more) grabbing.

As already mentioned, slow speeds with moderate pressure and use coolant.

The stainless hole will be painful

wrinx

thescruff · Post by **thescruff** » Tue Feb 23, 2010 11:52 pm

I might have considered a pilot hole and then a 30mm taper drill.

Hitch · Post by **Hitch** » Wed Feb 24, 2010 8:31 pm

Yeah....but not in the average diy pillar drill. Mine struggles to turn a 13mm through steel, let alone 30 through stainy

.

thescruff · Post by **thescruff** » Wed Feb 24, 2010 11:42 pm

Some good stuff in Here

Stoday · Post by **Stoday** » Thu Feb 25, 2010 4:41 am

Interesting, Scruff, especially the note that centre punching austenitic SS can result in local work hardening that can cause the drill to blunt.

Sparky James · Post by **Sparky James** » Thu Feb 25, 2010 6:36 am

Stoday wrote:Interesting, Scruff, especially the note that centre punching austenitic SS can result in local work hardening that can cause the drill to blunt.

Agreed with the old un centrpunching SS can cause all sorts of problems with work hardening.

We work on a lot of SS food machinery and the best thing is loads of cutting oil and going slow with tip top hole saws dont be tempted to use a cheep saw or one thats done much work.

Hitch · Post by **Hitch** » Thu Feb 25, 2010 6:36 pm

You only need centre punch it enough to get a start.
Centre punching stainless has never caused me any problems with drill entry

Bob225 · Post by **Bob225** » Thu Feb 25, 2010 8:25 pm

tbh i only said wd40 as the average diy-er has a tin knocking around as long as it keeps it cool

a light center punch wont hurt tbh it will stop the drill dancing all over the shop and who wants nasty marks all over a finished surface

wrinx · Post by **wrinx** » Sat Feb 27, 2010 11:02 pm

Hitch wrote: Centre punching stainless has never caused me any problems with drill entry

Nor me, used to do lots of sheet work in stainless and drilling holes for rivets.

wrinx

timmmers · Post by **timmmers** » Wed Mar 03, 2010 8:52 pm

Don't centre punch, use a cetre drill to start the holes. Like this
http://www2.westfalia.net/shops/tools/d ... 0ccf4ae860

You'll pick one up on carboots or Ebay really cheaply and they are essential for accurate drilling of metal really...and tough. :)

Parafin is a better coolant/ lubricant that WD40 too.