Bevel Drive

[valmacmiami]

Well I fitted my new bevel drive last night and will start to put rest back together the bevel box I bought had a broken bolt where the left shock attaches I managed to drill it out after a lot of problems the bolt was 16mm for about 3/4 of it length and then with a 10mm thread at end this all drilled out easily with cobalt drills however on the parallel portion of the pin where it had broken it was very hard and I was unable to drill even with a new cobalt drill eventually this part came free when I really leaned on drill and put a lot of heat on it the pin had sheared in the hole I am not sure how this had happened has anyone else seen this happen I honestly think there was a manufacturing fault and the thing had been made too hard
and it didntly really shear but shattered

 

[warp9.9]

I wish I could answer the question but I am 600 miles from home and my bike. Sounds to me like something is hardened or some one else work harden it which developed some iron carbides. Colbalt drills will not dril thru hardened stuff only carbide drills. Of course Carbide drills need to be used in a machine with rigidity like a vertical mill. They also use a cutting speed twice that of cobalt or high speed steal. The smaller the drill size the fast the surface speed of the drill needed. To give you an idea I used to drill M300 components on the F-14 Tomcats speciffically the launch collar. I used a #41 drill at 7000 rpms and it would go thru a steal roller bearing like a hot needle thru butter.
When I get home I will look at mine to get a better idea of what you went thru, but it does not sound like it was fun.

 

[Willtill]

I once tried to drill a hole through the cutting blade of a push mower; and gave up after breaking three drill bits. Those suckers (the blades) are TOUGH!

 

[Gothlander]

I brought a drill set from Aldi and when I tried to drill a piece of mild steel the drill proceeded unwind the spiral. I ended up with straight drills, no spiral at all.:???:

 

[warp9.9]

I brought a drill set from Aldi and when I tried to drill a piece of mild steel the drill proceeded unwind the spiral. I ended up with straight drills, no spiral at all.:???:

rule of thumb when buying twist drills if they are cheap THEY ARE CHEAP!!!!!!!!!!!!!!



Its pretty bad when you buy a set made by a decent manufacturer and they were not sharpened correctly. Talk about work hardening a surface ;(