I use high speed as well but hone the tool to a smooth finish with an oil stone & use bags coolant
Nobby

inserts were initially made for nc and cnc tooling, they were manufactured for high speed work on different materials that's why there are different grades of inserts .secondly they are power flooded with special coolants that cost the earth some £750 + per 50 gallons and more . For our purpose hss is more than sufficient if, like nobby said you keep it honed ,and keep the speed down ,even on none free machining stainless. you wont have any problems providing you stick to the rules of the materials your machining and you decrease the cuts as you near the end size or diameter, finishing cuts should be no more than a couple of thou. This applies to milling as well ,if your machine does not come down to a slow enough speed just take finer cuts the same with drilling ease of the pressure and slow down if you have no coolant facilities use a washing up squeasy bottle. ian c

Jason I was thinking the same, I find when machining stainless with insets that its better to use high relative feed rates and run dry, I've watched friends try these insets and invariably they are far too timid with them, resulting in what looks and feels like a torn surface, I have a ton of HSS tooling but very rarely use it now, apart from for form tools, as stated in other posts you need to know your machine and develop a feel for the metal, on inch 316 stainless I will never take less than 0.5mm doc, at 900rpm, I have Harrison with 3hp, but as I said you must know your machine when taking cuts this deap or you will cut under or over on final pass, the finish I get is like Chrome, the above probably doesn't help Dave, however the offer is still open for you to visit and see for your self, or I can pop round and try and point you in the right direction…

HTH

Shaun

I have used both HSS and carbide over many years and both have served me well. HSS tends to be more forgiving and cuts well when sharp and thus has a lot going for it. Having said that, I rarely use HSS these days for a number of reasons. Modern carbide ( not the old stuff that many have complained about ) is so convenient to use and keeps sharp for much longer. I use a lot of ground and polished inserts with high positive rake, which are designed for aluminium, but work a treat on steel and freecutting stainless and can give a beautiful finish.

Doug

I am definitely not an expert on these matters, but rifle builders who profile stainless barrels tell me that they use carbide tips and, for a good finish, like to take a deep cut. Apparently a final finishing cut of, say, 5 thou, is a recipe for disaster. Can't tell you which grade of stainless is used for barrels, but modern manufacturing methods suggest it is considerably hardened by cold working.

.

Dave,

It is a bit of a performance, but not really difficult:

• Create an Album [or several]
• Add photos to Album[s]
• When creating a post, use the camera icon
• Select photo from those in your Album[s]

go on … give it a try !!

MichaelG.

.

Albums only accept jpg/jpeg files

… might that be the problem ?

MichaelG.

.

Edit:  evidently not, because you have a picture in your Album

Edited By Michael Gilligan on 23/02/2014 16:29:00

You want to be taking bigger cuts and running the lathe faster, don't slow it down for the last few cuts, speed it up if anything as you are removing less material.

It may also be that the feeds on te lathe just don't go low enough to get a super smooth finish in which case honing as Michael suggests may be the answer, Bit of Emery cloth backed with some MDF works well for that final sizing operation.

J

This always polarises opinion but I'll reiterate what Mike, Shaun etc said above. If you take a fine (and / or slow) finishing cut you'll most likely end up with a worse finish. Ideally you'll take nice deep cuts and run your machine near max speed. You don't always need a lot of power – my Bantam is only 1.5HP and manages quite happily. I use power feed on both axes where possible and increase the speed as the tool approaches the centre line.

This is what I manage using carbide inserts. The 2 disks are 4140 carbon steel (rather like silver steel) and the shaft is some sort of mystery stainless steel I recovered years ago from the Ark. Not a touch of emery paper in sight. With experience, frequent measuring as I go and careful use of the micrometer dials I can get the final dimensions within a thou or so despite taking a decent final cut. If I undercut it, I take a shallower finishing cut and get out the emery paper but I try to avoid that.

It's a good idea to sacrifice a piece of material for some experimentation, rather than learning the hard way on something that matters. Discovering that increasing speeds and feeds improves the finish significantly with indexable tools is a major step forward. Same goes for indexable parting tools, which I also used for parting off those disks with power feed. Stuff takes a lot less time to do this way….

Murray

Having done much the same thing when making reloading gear as Al. I agree with his choices. Get near to size and then polish with what are called, 'Buff sticks', much used by watchmakers to polish spindles. They come in several grades 00, to 3 grit. Can be ordered and bought from watchmaker sites. If you are seriously worried about wear on the sizing die then case harden it and re-polish. Non of the commercial ones I have seen have any really fine finish at all. They look as if they have been finished off with a fairly coarse diamond paste by lapping. You have to get the size right as if the int. size is too loose then the bullets will move on recoil if in a magazine.

Clive