If you are looking for a new type bit, Antares makes a two flute spiral cutter for stainless steel. I have used their .005 cutter at .001-.002 depth on the back of watches with perfect results. I do not think I can resharpen it in-house.

Use a spindle speed of 8,000 to 10,000 RPM and a slow feed rate. Stainless requires a far lower spindle speed than brass/aluminum. It has a much lower parting speed.

The parting speed is the speed at which the material breaks just before the cutting bit, therefore not wearing the leading edge of the bit much. In the machining industry it is referred to in feet per minute/second.

Philadelphia, PA (Really Bensalem)

When you finally understand it completely... it changes.

Thanks Harvey

I am going to stick with the half round for now as I need to regrind myself.

I have been experimenting today. I got some ugly results when I dropped the feed rate right down.

I also played with spindle speed. I found some conflicting advice on this around the net (as you would expect!)

I found the following recommedation from Suregrave:
Stainless Steel - Max. spindle speed
Mild Steel - 6000 - 8000
tool Steel - 10000

After a lot of messing about and lost material I am using 19000 rpm and set my machine feed rate at 35% of its top speed - this is only a little slower than I use for brass.

I was getting a lot of breaks on my cutter tips. I have done two things to solve this:
Reduced the plunge rate on the z axis
changed the Clearance angle on my cutters (smaller angle) so that they are a little stronger. Other than changing the clearance angle the cutters are the same as I use on brass and plastic.

I'm now getting good results at a depth of about .005". Next step is to go deeper for paint filling.

Hi David

Yes I am using a cutting oil.

Its just that I make life difficult by starting off with a domed item that needs very small text engraved. The breaks were something I was expecting as the cutter width is very small and therefore weak. it is for 2.5mm text (0.1" in your money!)
I had this problem with some commercial brass I had to engrave once - as a rule I generally use engravers brass.

The tip size is possibly too small for Stainless, however, since changing the clearance angle and the plunge rate , I have been using the same cutter all afternoon, which has a tip size of 0.2mm (.008"). I've not lost any material since them. If this hadn't of worked I would have switched to using a HSS cutter as these never seem to break on me.

The results are great, and I have sent out a few orders just now - I usually use a faceted diamond on stainless. Once I get a bit more depth I will increase my pricing and offer a paint filled finish.

I agree with you 100%.

Items I currently sell that are coloured filled retail at 25 to 40% more. I'm looking at steel to bring in some more cash for little extra work. I have the capacity for a slightly longer engraving time than the current method used for stainless, and I don't mind the paint filling - very easy on small objects.

Meanwhile - still on the same cutter, I'm getting deeper, and have upped the feed rate to the same level as brass now. Its been a good day :-)