Drilling stainless steel bumpers?

alastair

I've bought a set of stainless steel bumpers for my Volvo 1800ES, after weighing up the pros and cons of replating in the UK rather than going the stainless route.

Happy with the bumpers and fit, but I need to drill holes for rear under-riders, licence plate lights, and a spotlight bar on the front.

Can anyone recommend somewhere/someone in the Dublin region that can do the job? Initial drilling would be on bumpers not yet installed, but the spotlight bar probably needs the holes drilled after installation (critical positioning needed on split bumper).


Mosney is looming, and I'd like to get this done in time.

w124man

Can you not do that yourself? All you need is a decent set of cobalt drill bits, a centre punch and a power drill.

alastair

w124man wrote: »

Can you not do that yourself? All you need is a decent set of cobalt drill bits, a centre punch and a power drill.

Considered it, and opted not to. I'd rather not risk learning the craft of drilling stainless on pricey bumpers. Much happier having someone with the talent and better kit do it.

The Red Ace

if you have to do it yourself use tape akin to elastoplaster over the spot that needs drilling to stop drill slip, that way you wont mark the bumpers as the bit cant wander

Max Headroom

IMO You'd be lucky to find someone that would even bother to do this....if they did they'd probably charge you €100 ...they'd say it was for "setting up " etc..:rolleyes:.....

mb1725

+1 on the cobalt bit, that's the secret. An added bonus is you could drill through the bottom of a drinking glass with one, great for pranks!

alastair

I'm coming around to the notion of doing it myself. Checked out a few videos on drilling stainless 304/1.4301 with cobalt bits, and it looks less fraught then I imagined.

jimgoose

mb1725 wrote: »

+1 on the cobalt bit, that's the secret. An added bonus is you could drill through the bottom of a drinking glass with one, great for pranks!

No,the secret is cutting oil or a drop of full-synth at the drill tip, and keep the drill-speed around 1,500 RPM.

w124man

jimgoose wrote: »

No,the secret is cutting oil or a drop of full-synth at the drill tip, and keep the drill-speed around 1,500 RPM.

1500 rpm? What size is the drill bit?


No. The secret of cutting stainless is using the right drill bit, with the right cutting edge and angles and using the right cutting speed. Cobalt drill bits on 303 or 304 stainless should use about 30 m/min cutting speed*. higher if its coated. The chips that are cut should be yellowish through to blue in colour. Tapping fluid is the best lubricant for drilling stainless in a DIY situation.


* cutting speed = D x 3.142 x n
1000
D = dia of drill
n = revs


I'll get my coat!

jimgoose

w124man wrote: »

...No. The secret of cutting stainless is using the right drill bit, with the right cutting edge and angles and using the right cutting speed. Cobalt drill bits on 303 or 304 stainless should use about 30 m/min cutting speed*. higher if its coated. The chips that are cut should be yellowish through to blue in colour. Tapping fluid is the best lubricant for drilling stainless in a DIY situation.


* cutting speed = D x 3.142 x n
1000
D = dia of drill
n = revs

Good stuff. Yes, quite right as well. But I know one particular idiot <HARRUMPH!!> who destroyed an expensive cobalt-steel bit on a relatively harmless bit of stainless by running it at full machine-speed with no oil.

Max Headroom

jimgoose wrote: »

Good stuff. Yes, quite right as well. But I know one particular idiot <HARRUMPH!!> who destroyed an expensive cobalt-steel bit on a relatively harmless bit of stainless by running it at full machine-speed with no oil.

I've sooo many t shirts on the subject its not even funny ........:o

w124man

I know one idiot who ran the drill backwards .............

Max Headroom

w124man wrote: »

I know one idiot who ran the drill backwards .............

...as i said....................................:D

alastair

Got a couple of cobalt drill bits and a can of tapping fluid. Job done, and without too much drama. Dulled the smallest/guide bit after a few holes, despite keeping it nice and slow, and regular re-lubricating, but I'd bought a second bit in the same size, which worked a charm for the last couple of holes.

Spotlights bar hasn't gone back on, as the new bumpers have bracket mounts in slightly different positions, and they obstruct the mounting point for the bar. I'll source a different width bar and get them back on later.

Thanks for the advice and DIY encouragement.

Max Headroom

alastair wrote: »

Got a couple of cobalt drill bits and a can of tapping fluid. Job done, and without too much drama. Dulled the smallest/guide bit after a few holes, despite keeping it nice and slow, and regular re-lubricating, but I'd bought a second bit in the same size, which worked a charm for the last couple of holes.

Spotlights bar hasn't gone back on, as the new bumpers have bracket mounts in slightly different positions, and they obstruct the mounting point for the bar. I'll source a different width bar and get them back on later.

Thanks for the advice and DIY encouragement.

Glad it worked out for you and i bet youre chuffed you did it yourself too...great satisfaction in DIY....most guys with too much money will never enjoy this feeling..;)

w124man

result

jimgoose

Daycint. Well fixed, chief.