Drilling hard parallels

[roofman]

I have a pair of parallels that are now out of tolerance and i want to use one for my diesel injector puller...question is i need to drill two 10mm holes through it, would a normal drill go through or will i need the Cobalt troops to the front line?

 

[hotponyshoes]

I don't expect the parallels will be made from anything that work hardens so should be safe enough to try a normal drill first..

 

[oldbikedavey]

I have a pair of parallels that are now out of tolerance and i want to use one for my diesel injector puller...question is i need to drill two 10mm holes through it, would a normal drill go through or will i need the Cobalt troops to the front line?

Just make something proper out of EN.8 bar...
Harden, then temper to dark straw.

 

[pressbrake1]

Depends who made them
If a tool maker had they’ll be toolsteel(silver steel) and dead hard
Carbide will drill just but any stress like a puller will make them snap

 

[6ply]

I have a pair of parallels that are now out of tolerance and i want to use one for my diesel injector puller...question is i need to drill two 10mm holes through it, would a normal drill go through or will i need the Cobalt troops to the front line?

I have repurposed several old parallels and have had no issues drilling them with a regular HSS drill. But maybe they were cheapies?

 

[Rrobson]

With the state of some “parallels” I’ve seen over the years, it would be safe to say HSS tends to cut them fine…

If they are hardened, you could anneal them and that should allow a standard drill to run through. They’ll not be as brittle then either.

 

[roofman]

Found some 25mm steel plate today which is perfect...i probably would of shed a tear going through a Moor&Wright even though they arnt the best...

 

[Agroshield]

Could you find someone with a surface grinder and reduce the parallels to the next size down or to a metric size smaller?