- Stan Pope
- Pine Head Legend
- Posts: 6856
- Joined: Sat Jul 05, 2003 7:01 pm
- Location: Morton, Illinois
http://derbytalk.com/viewtopic.php?t=66 ... ght=stubby
"If it's not for the boys, it's for the birds!"
I would probably use a 1/8, then 1/4, then 3/8, then 1/2" to get the desired hole. You could also stop at 3/8 if you wanted to use the punch listed earlier in this thread. The smaller bits you can spin faster (200-ish RPM's), then slow down as you drill bigger (100-ish RPM's). The trick here is to limit the linear speed of the cutting surfaces so as to not work-harden the stainless (overheat). Ask the supply house for a drilling fluid that isn't runny and put a quarter-sized blob over the cutting area. When one-bit drills through it, change the bit then wipe the new bit down with cutting fluid using a rag. If the steel scarf (shavings) start to turn blue as you are drilling then you are going too fast and should slow down. The stainless you are drilling is thin and will heat up quickly if you aren't careful. If you do blue the stainless then stop, let everything cool down (bit included), re-oil, and SLOWLY drill past the blue.
The last thing I want to mention is to not break these cobalt bits https://mechanicguides.com/best-cobalt-drill-bit-sets/ while drilling. Unlike the cheaper bits these do not flex. What they will do instead is shatter if you use too much force or dont hold the drill steady.
Hope that helps!
- Site Admin
- Posts: 4759
- Joined: Fri Jun 20, 2003 12:46 am
- Location: Highlands Ranch, CO
Awana Grand Prix and Pinewood Derby racing - Where a child, an adult and a small block of wood combine for a lot of fun and memories.
But to share something that works for drilling
Hardened steel like an broken off ez out tool in a bolt.
Tried several different types and makes of drill bits to re drill into the ez out. The drill bits just would not cut in to it.
So I broke out a masonry drill bit
Used Constant pressure and drilled with a slow speed
And was able to drill threw the ez out tool that had broke off in the bolt.
It was slow going and the shavings were more of a powder instead of shavings.
Any how just thought I’d share something that worked for drilling into the hardened steel
ez out tool that had snapped off.
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