Drilling Stainless Thread

[jgarrett]

I "thought" there had been a thread or two on drilling stainless but after several searches on the group I have not been able to find any.
Can anyone "jog" my memory???
Thanks,
Julian G.

 

[gilessim]

Hi Julian, I don't remember the thread but the important thing to remember is that most types (there are quite a lot!)tend to "work harden" very easily, i.e. if you centre punch to drill a hole , that small area around the pip can become so hard as to seriously dull, or even break a good drill bit!, it's better to touch your marked hole with a very small centre drill first and then go in with say a 2mm bit first, depending on the size of the required hole, say 6mm, go 2-4-6, go in steadily,not too slow, and don't peck, as this can have the same hardening effect, if you use intermediate sized bits too close ,say 0.5mm, the webs will tend to follow one side of the hole and you'll end up with an off centre hole!, even on the lathe.

I personally don't mind stainless, especially as I was given about 25lbs of it recently!, I know that a lot of people hate it, but I am by no means an expert and I'm sure others will be able to add to my observations....Giles

 

[compound driver 2]

Hi

Much the same as Giles wrote but just adding always use coolant and keep the feed and speed reasonable. Check your tables for both.

Cheers kevin

 

[Circlip]

You're not telling us what grade of stainless you're using Julian, but if it's 303,304 or 316 machine and drill as you would for silver steel (drill rod) and just like Kevin, coolant, I use water soluble oil. For the tougher grades drill slower but keep the drill cutting. Ian

 

[jgarrett]

Ian, I have no idea what grade it is. It is a HF caliper frame that I need to drill for mounting on my mill. I drilled one hole Tues. with no problem using a battery drill and I needed to drill another with precision so I tried it in the mill. Work hardened almost instantly. Finally figured out battery drill was almost dead and therefore drilled very slow. Mill speed was about 870 RPM. I slowed the mill down as low as it would go and drilled another hole with no problem. I guess VERY slow with lube. is the key.
Thanks for the inputs.
Julian G.

 

[compound driver 2]

Hi
At 870 rpm in SS I would imagine with out coolant the drill bit was glowing.
SS needs a lot a care when machining no matter if its drilling or turning.

caliper frames are tough not always hard but tough is the guide for them. You did well to drill them the way you did.

Cheers kevin