Odd Size counterbores

Grind a pilot on a 6.3 dia drill. If you dont have the gear to do this any Tool and cutter grinding company could do it.

Wayne...

Get a bigger counterbore and bring it to a tool & cutter grinder. They will be happy to do that job for you. Should not make you poor.

Nick

Try making a D bit from silver steel and hardened. As long as its normal material and not very hard stuff you are cutting it should do the job. Another factor is of course use, don't expect it to do millions! If the counterbore is being put in after the work is removed from its drilling position then put a centering spigot on the bottom of the D bit otherwise if its done immediately after the drilling operation on the same centre it will not need centering. Keep the D bit stubby for rigidity.

Thanks for the replies.

The job already has the 3.3mm holes in when it comes the counterbore operation. The best solution seems to be getting a drill bit ground up with a spigot to correctly centre it. Is anybody able to supply a drill bit (or couple of) ground as above?

Thanks again for speedy replies

Paul

Look in yellow pages for a local tool and cutter or formtool grinders, you may be lucky as I am in having a local firm that does the work the old fashioned way at a good price.

I've got some nice grinding gear but rarely use it now as it's easier to pop down to them for the odd special.

Wayne...

Thanks for replies everybody.

I remembered a guy I had bought oddments from before including a ER25 collet holder and I knew he did tooling as well. Anyway droped him a email got a prompt reply and job was sorted for aroung £7.00 inc first class P&P. Excellent service. No connection just a satisfied customer. Here is a link to said site:

Paul