Really should've asked this before I started the job but...

I just had some threaded bar made up to take the upper seat harness mounts which i am welding into a CDS tube welded across the roll bar. Talk about PITA job! I bought 2 sets of step drills, one some time ago from screwfix, they are made of cheese i think, lasted 2 mins on the CDS. The second set I bought from my local hardware guy who I use a lot and his stuff is normally reasonable, not top pro stuff but better than a lot of cheap tat. They gave me a fair bit more but eventually gave up the ghost. All they do now is make loads of smoke as they heat up the oil i use to cool the job down

I've not been running them too fast either I think it's just that the CDS is too manly for them.

Any ideas what I should have used, or need to use should i have a similar job in the future? I'm getting really P'd off using a rotary rasp and hand files still, only one left to do tomorrow night, then on to making up some templates for the panelling on the tunnel.....

I wouldn't personally use a step drill to drill my CDS tube. I tend to favour throwing a 6mm drill through then upping the drill sizes in small increments.

How big is your required hole and what is the CDS size?


[Edited on 7/4/11 by liam.mccaffrey]

What size of hole and through what thickness of material?

Davie

It's 22mm through just over 2mm thick tube

cant you use a hole cutter and plenty of cutting fluid ?