Tangential Tool Holder

Diogenes II

Really nice improvements to the tool.

For simple lapping, could you skip doing the jig by using your new holder? The angles are already done. The top of the tool bit aligns with the top of the holder (nice touch) and it has a neutral rake. A suitable lapping surface and a little lapping compound (only under the tool bit face).

If you wanted to remove a measured amount by lapping, just use a shim under the upside-down holder body, loosen and extend the tool bit. Tighten. Remove shim. Lap until the lap stops cutting.

Note: Kitchen foil is around 1 thou thick as is fag paper. I have found various sheets about the house that are half that thickness.

ps: Saw an advertisement for "machinist wanted". Work with 200 foot planers and lathes. It said, "your CNC skills are useless here". Ouch!I

Thanks all for your comments -

Niels, that's a useful observation that I hadn't really considered - I guess I just drilled it halfway up the stock (and then reduced the height, anyway.. maybe I'll add that to the "to do" list.

Howard, I understand your motivation completely - I must admit that I have held on to some bits & pieces for years because I have had a destiny (loosely) planned for them, and it's the most satisfying thing to have exercised brain as well as arm in making something worthwhile. It'll be good to see it..

Paul, thanks for that - you've thought it through better than I did - I kind of pushed the idea to the back of my mind on the basis that I didn't want to abrade the top "reference" surface, and didn't think much further, but your idea makes sense and is feasible.

I'd bought a couple of Dremel diamond cut-off wheels which arrived today and which I used at slow speed to cut the rod into more convenient lengths; using the side also put a perfect flat top onto the bit, so I will see how that goes.

I had great success turning and facing without having to adjust the tool position (which was one of the things I was after) this afternoon, on an iron casting..

I'll post a description and some pics tomorrow..

Following the more-or-less successful trial of the principal, I thought I'd try and find something to cut in a more "real-world" way.
I have some "as-cast", 56mm diameter iron collars in the scrap box, and thought that cleaning-up one of these might make a useful subject.

The tool was clamped on the topslide at 45 degrees to the lathe axis to enable facing and turning without having to disturb it - it is very compact, and gives good access to the work for measuring etc. At some point I'll replace the clamp stud with a shouldered one, and can then secure the drilled holder directly to the topslide with just a nut & washer.

The carbide rod was shortened and then ground off-hand with a Dremel "Tile Cutting" diamond wheel (SC545) run at slow speed with the toolbit fitted in the holder to provide a visual guide.

Cutting performance was good - both in quantity and quality. The tool would cut to radius depth, but felt happier at a bit less than this - perhaps .8mm - which I think is okay for a small lathe spinning CI at 250rpm. The inner "roughing" cut on the face was "pushed" a bit, but still looks crisp & consistent, and the chips from the "skinning" look good. The finishing is certainly acceptable to me in the "normal" working conditions in which it was done - I'm fairly confident that with more careful hand- or fine-feeding and everything snugged up, it would improve further.

The "Tivoly" brand bit remained in pristine condition at the completion of the job, and also retained it's setting without being pushed down in the holder, so the split clamp may stay just as it is for the present.

I'm happy with the results. I have a good tool that will reduce the need to change & set (my shamefully haphazard collection of brazed carbide & HSS) tools so often, that doesn't need shimming, and in which the hard toolbit is rigidly held just off the front corner of the soon-to-be-bare topslide.

..I have no doubt a little tweaking and refinement here & there will follow, and I'll try some tougher and some softer, material soon and see what it does with that.. more anon..

Thanks for all your help, Niels.

You are wellcome.

You can always up speed and reduce deepth of cut.Try if You can beg or steel a case-hardened piston pin from a moped or lawnmover repairman.You will be astonished for surface look in the hardened zone but beware of swarf.

Apologies - I don't know what I was doing when talking about the depth of cut - it was well past my bedtime - somewhere from 0.08 to 0.15 mm reduces the strain on everything, maybe a bit less for finishing..

..light cuts for this gudgeon/piston pin, but the swarf came off deep blue and left a great finish..