Drill/Countersinking Stainless Steel 304

[Psiron]

Hi,

Well if I cant get an answer here I doubt Ill get it anywhere!

I have to work with some stainless steel and looking for the best method to achieve the required results please.

My goal is to drill and countersink a series of holes in 8mm flat bar. Currently I use a series of cobalt drill bits starting at 3mm and increasing in 1mm increments to 10mm, this seems to work fine using my pillar drill on the slowest speed available and applying a good deal of pressure.

Each hole will house and M8 countersunk stainless steel socket screw.

My next step is to countersink the hole I have drilled. Ive never done this before and would really appreciate any advice on what tool is best for this job and what should be considered to keep the bit cool. I also only have access to my truted pillar drill to get this done.

I have searched and read lots about the work hardening which I understand. Im just not 100% on how to stop this from occuring and effectively making countersinking it near impossible.

Any advice would be greatly appreciated. Im in the UK iof anyone knows of any suppliers for a good countersink bit too.

Thanks very much in advance for any help you can offer.

 

[MechEngr07]

The keys to producing good holes, counterbores and such are sharp tools and machinging within the SFPM (Surface Feet Per Minute) range for the material and use the proper lubricant/coolant.

Stainless Steel has many different types and each has its own SFPM maching range. Check the Machinery Hanbook for those values, or the manufacture's data sheet on the material.