I sharpen my milling cutters (end mills and slitting saws) using the HH grinding rest and am very happy with the results. Below 1/4 inch though I just throw them away and buy new.

Russell.

I hone slightly worn slot drills with a diamond hone. The worn ones I try to grind to get them sharper, as Russell I don't sharpen the small cutters. They can be used to make round HSS toolbits for tu rning or flycutting. The slot drills I sharpen is used for roughing cuts, a new one for the final.

Thor

I completed a Worden T&C grinder from Hemingway. (Completed? Is anything *ever* complete?)

Use it for lathe tools, but have not yet sharpened an end mill. I'm collecting dull ones, and this snowy upcoming Winter I expect to sit down and get proficient at it.

I really enjoyed the Worden build – although it was tough to get motivated to build a part (say, radius grinding attachment) after completion, the sense of accomplishment was really nice!

Does that help?

Another JohnS.

John' yes, AL & I have a surface grinder, have you made a jig to fit the cutter into, so you can sharpen them on the surface grinder? If so would you post pic's. We do have a jig to sharpen punches & chisels for it.

rob

> I'm about to modify my Stevenson Hex ER32 collet

Good idea Richard, but as they are hardened, let me/us know how you get on before I trash mine

Neil

Hmm. Wasn't aware of that. Anyway, we shall see. If it's too bad, maybe I'll be forced to make the adaptor I dreamt up in a mad moment – a fixture to allow a 4.5" angle grinder to pivot vertically on the toolpost (after putting rather a lot of 'something' over the lathe to protect it from grit).

As for the reason why I need to modify it.

Well, I have a little cnc engraver/very light mill (as well as my Warco WMT300 combi lathe). The cnc machine has a fairly low gantry and I want to thread pen barrels, caps and sections by using thread milling (I need an M7.4×0.55, M12.5x.8 four start, M9.5x.5 and a couple of other fun sizes unavailable as taps & dies or as thread pitches on the lathe) . That means they have to be machined upright in the collet chuck. However, the pen barrel alone is 80mm long & the gantry has a clearance of 100mm. That really isn't enough if the Stevenson collet is clamped in a vice, and the collet nut prevents clamping down on the shoulders of the collet. So, I need to machine in a groove about 6mm up, width about 4mm by enough depth for a clamp to get a grip, say 2mm. Then I'll be able to clamp it down after zeroing the cnc machine for the thread milling.

My hope is to make this:

The pen is intentionally difficult to make with a lathe – it's intended to help me learn as much as possible about cnc as quickly as possible.

Regards,

Richard.

Thanks john, i'll look into that fixture. As for slitting saws , i bought a job lot at an auto jumble a couple of weeks ago, i only wanted one or two for the occassional job, but the seller wanted rid of them and gave me the lot (about 70) for 40 euro and chucked in a few horizontal milling cutters too.

Stub Mandrel:

I machined my Stevenson Hex ER32 collet holder last night. You were correct, it is hardened. I started off with an HSS parting tool, which had the edge knocked off in short order. Then I used carbide inserts for left & right shoulders to make a 6mm wide slot. The machine was working so hard that I stopped before cutting completely though the flats of the hex. The material was surprisingly ductile despite the hardness & formed big burrs on the downcut side of the hex. Finally, I used a file to clean up the 2mm deep notches I'd made in the corners of the hex, and found the cutting rate was much higher than I obtained with the lathe!

Anyway, the collet holder doesn't look pretty (in fact it looks as if it has been assaulted by an incompetent maniac with a file fetish), but it can now be clamped on the bed of my CNC without a vice underneath it or any other fixture. With a collet in situ, the top of the fixture is 67mm above the bed of the machine. Perfect. My experiments on thread milling start this weekend…

Regards,

Richard

Additional to my post :- Sharpening Milling cutters…

Just a note of safety…

The Dremel resin bonded grinding wheels are easily damaged and bits of wheel can fly off at high velocities...PLEASE WEAR EYE & FACE PROTECTION .

Bob -.- -.- -.-

Hi Paul…

Most cutters needing sharpening will only have part of the helix available, if they are anything like the ones I have! which were used in a machine shop and thrown out when they became worn on the edges.

In order to find what the pitch of the helix is, you can put the cutter in the lathe 4 jaw chuck and set the end of one of the cutting edges horizontal with a rule or straight piece of steel set in the toolpost holder, if you have an electronic Wixey angle gauge this is set on the chuck and zeroed, this could be magnetically fixed to one of the jaws, or you could use the jaws themselves as indicators of the spindle angle … this is always 90deg or 180deg.

The chuck is then hand rotated 1/4 of a turn or 1/2 a turn (if you have that much left on the helix) and the rule is moved along using the leadscrew handle so that it lines up with helix cutting edge, the x distance is now 1/4 or 1/2 the pitch …. for example if the distance moved to line up with edge at the new position is 20mm and you have rotated the chuck 1/4 of a turn then the helix pitch is 4×20 = 80mm.

I have only used this method on 2 flute cutters and for the grinding operation will be making a fitting something along the lines of Harold Halls grinder cutter tool holder so I can rotate the cutter for grinding the other flutes without disturbing the electronic setup which indicates where the spindle will be when the leadscrew is started up.

I don't see why this method couldn't be used on a normal screwcutting lathe if large pitches are available which would provide the same pitch as the cutter helix, the only problem might be that the spindle speed is too great, I am using a spindle speed of 1 rotation every 8 seconds which gives the grinding wheel some time on the work.

Hope that helps….Bob -.- -.- -.-