Drilling Stainless Steel...

[Andy Walker]

Jeez, you'd think I was trying to drill into Wolverine's skull!

I'm just trying to drill some small fastener holes in my upper firewall, and the bits will NOT cut it. I've used Titanium and Cobalt bits, with and without oil as lubricant, at speeds up to 10,000pm. I have literally ruined about a dozen bits, and got about six holes out of them. They just overheat and start glowing, then they stop cutting. I try to pull them back to keep them from getting that hot, but eventually the just dull and are useless. What am I missing? Argh!!! :x

[Dan]

What size holes are you trying to make? The bestthing to use is a Greenlee punch. Hopefully you could borrow the size you need as they are very expensive. They will make a very nice hole though.

[Andy Walker]

What size holes are you trying to make? The bestthing to use is a Greenlee punch. Hopefully you could borrow the size you need as they are very expensive. They will make a very nice hole though.

5/64, not big holes at all (these are for the anchors for the camloc fasterners I'm using for the cowl). I had no trouble drilling 3/32 and 1/8 holes, but these small ones just will not cooperate at all.

[Mike53]

Andy ,from my high school days (a long long time ago)in machine shop,our teacher gave us a cuff on the back of the head if we drilled any steel at to high a speed as it heats up the drill bit and dulls it pronto.The slower the speed the better the results .Cobalt bits should be fine and a little oil helps to keep things even cooler.The trick ,slow and even pressure.10,000 rpm will ruin the bit in about 5 seconds.Good luck with the rest of them.

[MichaelFarley56]

Mike pretty much nailed it on the head...slow speed on the drill to keep it from getting too hot. Unibits seem to work fairly well too (at least for me they did).

You're right though....so far out of the entire kit, the SS firewall is the only part I hate. :?

[sonex892]

I worked with stainless for many years and have seen many drills, hole saws and metal ruined by the novice. Stainless is relatively soft until overheated when it becomes as hard as tungsten. If a hole is needed in an overheated section it can be done with a new sharp bit, but it will ruin the new sharp bit. Always use sharp bits and throw away dull ones. I always pilot drill. If no swarf is coming off the drill (it should be a nice constant curl of metal) something is wrong, so stop immediately before it gets the stainless too hot. The problem will be either, dull drill bit, not enough pressure or turning too fast. More feed less speed is a term I have heard and always lubricate. Done right one pilot drill should last for about 200 holes in stainless. If you think Stainless is bad wait till you drill the titanium gearlegs, now that was not fun.

Good luck
Steve
Sonex 892
VH-ZSX 3300 70 hrs

[Andy Walker]

Well, I got it done, but was not really happy with how it went. Because of the tight quarters I was using a Dremel with a bit chuck in it, and it can't turn less than 1000rpm. Even on fresh metal using lubricant, it took forever and killed another drill bit to do the four remaining holes. Anyway, it's done.

BTW, I had no issues drilling 3/32 and 1/8 holes using my regular hand drill. For some reason the Dremel and very small 5/64 holes (pilot holes for 3/32 rivets) were just really hard to do.

[radfordc]

You're right though....so far out of the entire kit, the SS firewall is the only part I hate. :?

Wait until you get to the canopy! :o

[MichaelFarley56]

Actually my canopy is done. I used a harbor freight oscillating saw and had no real trouble. And that was this spring before it got really hot. I was religious on sanding any edge after I cut it to keep things smooth and really lucked out. My canopy isn't going to win me a Lindy ay Oshkosh but at least it's done! :D

[Andy Walker]

Here are the results: