Favourtie Finishing Tools

What are people's favourite finishing tools for doing final turning, facing or boring cuts?

Pretty much anything will do for hacking off metal but different authors seem to suggest different shapes of HSS tool to get a good finish on the final cut. Harold Hall's books suggest one shape of finishing tool while the articles in Model Engineer by Tubal Cain (I'm not sure who this is an alias for in Model Englineer) suggest a different shape of shaving tool to give a good finish. It may vary depending on the material - I'm not sure.

Other people seem to use indexable carbide tips for the final finishing cut.

Would be great so see what people's favourite finishing tools are. Photos welcome!

The "Diamond Toolholder" is my personal favourite for most jobs, then a "Shear Grind" bit if I need/want a superior finish both use HSS tools.

Regards

Paul

Will,

For fine finishing, the most important feature is that it should not be sharply pointed in plan view. A very sharp-nosed tool will leave minute screw-cut lines on the work, whereas one of rounded shape will smooth these out with ovelapping cuts as it goes. I cannot say I have found much difference between a round shape, or a knife tool (with a small radius at the leading edge) applied so that the front face is at a few degrees to the work.

Most indexable carbide tips have a cutting lip which has a very small radius on it*; this is to make it more durable, as a dead sharp lip would be liable to chip easily. You can refine this with a diamond hone if you wish, but I have found that a new tip will take a finishing cut of around half a thou without too much difficulty. Around this depth of cut it will stop cutting and start rubbing, which leaves a lot of chatter and an uneven cut. Others' experience may vary. For the very finest of cuts a well-honed HS knife tool is hard to beat. However, you may find that the best finish is actually obtained if you leave a few thou to be removed at the last cut - I know in our world we often approach size on our one-off jobs rather tentatively. For removal of the last few tenths with excellent finish, I find the most reliable approach is to use a No 4 or No 6 cut genuine Swiss hand file (must have handle fitted) well soaked with cutting oil - an approach recommended by no less an authority than G H Thomas, and I have found it works splendidly to get good shaft fits.

Tubal Cain was the nom-de-plume of Tom Walshaw, who spent his working life as a professional engineer, and who wrote many excellent books and articles. I met him once, very briefly; very nice chap he was too.

David

*This time I don't mean in plan view, I mean a (very small) a radius on the horizontal cutting edge - sorry if that was confusing.

Edited By David Littlewood on 28/07/2012 16:41:39

I use my tangential tool (**LINK**) for almost everything except left handed cutting and interupted cutting. It can make deep cut with a reasonable finsh and fine cuts with a good finish.

Mike

Will you don't say what size machine you are using, if its a minilathe or smaller then the tangentals may not fit and its unlikely to be rigid enough for insert tooling.

Myself I've mostly gone over to CCMT style tips and the ali cutteing equavalent, can't see the point in changing to a finishing tool as these will handle 0.100" roughing cuts and 0.001" finish cuts. If there is a lot of waste to come off then I may use my holder that makes use of the two spare corners from blunt CCMT inserts.

J

Edited By JasonB on 28/07/2012 17:44:00

My home made tangential tool uses 1/4"square and fits my mini lathe nicely, I slightly round the tip for finishing.

My best finishing tools are hand ground with a large radius, about 1/16" or more.

I understand taht an exceptional finishing tool can be made like a straight ended d-bit, but angled slightly so that the centre of the edge on the end is all that contacts the work. Someone (GHT?) claimed this generates swarf like cotton wool with very light cuts and leaves a mirror finish.

Neil

Same as Jason here. I don't differentiate between roughing and finishing as far as the tool is concerned. I use mainly insert tooling. Standard depth of cut for roughing is 0.1" to 0.2" off the radius, for finishing more like 0.01" to 0.04" off the radius. I will, however, normally reduce the feedrate for finishing cuts, from anywhere from 4-12 thou/rev for roughing down to 2-4 thou/rev for finishing.

Regards,

Andrew

Favourite at the moment is my small 14mm Ceratizit Eco cut. Tryed in anger last week with coolant, 6082 works like free machining aluminium with small chips and mirror finish even at low rpm.

To help thing s along i just whacked a 28mm drill through then one pass ending up 35.8mm dia leaving 0.2mm to come off as a final pass in reverse = every one a gem cock on 36mm bore 80 off. XCNT tips

http://www.youtube.com/watch?v=Mygkm07j1o4&feature=colike

On flimsy machines such as mini lathe or Myfords etc decent HSS % cobalt works best, had no end of trouble with tipped cutters. Often dragging in reverse traverse a ground up tool worked best for all materials.

A lot more substantial machines such as Harrisons, DSG, etc pretty much anything will give a decent finish unless traversing too quick. Preference here is CCMT, CCGT, CNMG all variants of XCNT used in the Ceratizit for drilling, boring and turning. They work better than the round style, forgot the tips RCO?

Will .....Regarding Tubal Cain (the late Tom Walshaw) you can see a good summary in **LINK**

Cheers

Dennis

This 'shaving tool' illustrated by LC Mason in 'Using the Small Lathe' is a good'un:

**LINK**

Joe

Tom Walshaw also has other gifted engineers in the family. I think it was his nephew I once saw at Roy Lever's place at Burnley, and he was exhibiting a Rolls Royce Merlin model engine of about quarter scale. Everything on it worked including the generator. He had a huge folder with pictures of all stages of manufacture. The amazing thing was that there were no castings used. It was all chopped from the solid, even the large sump. Even more amazing was that he had built several of them, and had sold some to famous personatlities.

His son (Anthony?) is an accomplished professional model builder; I don't think he enters shows.

Neil

Sorry Mike, but the link doesn't work - it tries to go to http://,ikesworkshop.weebly.com/tangential-tool-holder.html

which doesn't exist.

Regards, Gary

Edited By Gary Wooding on 08/08/2012 17:39:29

Change the appostrophy before the i to an m and you will ge to Mikesworkshop

Hi Gary (and anyone else inconvenienced by the wrong link),

Jason has now provided the correct link, see previous post)

Thanks Jason for making the correction.

Mike

Thanks Jason, and thank you Mike - I've made 3 tool holders (1 for me an 2 for friends) based on your design, but for larger lathes; they accept 1/4" square HSS bits and work very well. I made a different sharpening jig to yours.

I use the tool for most turning ops,and found that rounding the tip a little extends its life.

Gary

Edited By Gary Wooding on 09/08/2012 08:27:49

That's an awesome piece of tooling, Jon

The other videos by Ceratizit are worth a look, too.

MichaelG.

Can someone put me right on the issue of diamond turning.

As explained to us when I was doing production engineering at college back in the early 50's, the method of diamond turning involved adjusting a multi-faceted diamond cutting tool under a microscope so that one of the facets was perfectly parallel with the diameter of the workpiece.

The width of the facet was slightly larger than the feed pitch such that no feed marks were generated. Please see my diagram.

By comparison, I would rub a tiny flat across the tip of a single point cutter, and parallel with the workpiece. This seemed to do a similar job.

Hi Mike,

Thanks for correcting the link.

Edited By Will Robertson on 09/08/2012 21:50:57

Hi David,

Thank you very much for all the information - very interesting and helpful. I hadn't thought of using a Swiss file on a bore. Have you any advice on how to choose a file fine enough and good enough?

Does this work with both ferous and non-ferous metals?

Edited By Will Robertson on 09/08/2012 21:53:04