HSS vs carbide inserts

Thanks to all who replied about the Eccentric Tool holder, I now understand that there are many devotees of this bit of gear out there, it can do anything a conventional HSS tool can do and that it has some pretty significant advantages when it comes to tool sharpening. To get the Eccentric Toolholder in perspective,only one question remains: does this toolholder offer any improvement in finish or other performance attribute?

Of additional interest to me is that I have a roller-box attachment for my capstan lathe which uses tangential tooling and I should be able to use the sharpening jig for this also

Regards, Chas

The Eccentric or similar toolholder makes it dead easy to get the right geometry, but if you grind the same geometry on the end of a tool held conventionally you'll get the same results. It just takes longer, and sooner or later you have to grind away the whole end of the tool and start again. There is another one called the Wimberly

http://www.wimberley-tools.com/

I have no experience of this but the concept appears to be sound, in fact I'm thinking of making one for my Perris.

If you're a member of an ME club ask if anyone has got a tangential holder you could borrow to try.

Edited By duncan webster on 01/09/2016 23:20:46

Thanks Duncan,

I'm now convinced I should buy one!

I made my own tangential tools (left and right handed) as per "mikesworkshop.weebly.com"

The flat on the front of the right hand tool is machined to my lathes centre height, which makes setting the tool height dead easy.

Yes, they're easy to make on the mill. This is one of mine.

I have a Wimberly but I'm still trying to figure out a practical way of holding it - the size of the head of the casting plus excess HSS sticking out of the back gives it about an inch overhang in a four-way toolpost and means it could only be used for small diameter work. Equally it would need a 'special' holder for the QCTP and still overhang too much. This is off the Wimberley toolholder website:

To compare I measured the overhang (beyond toopost front) of a few tools:

• Hand ground HSS 10mm
• TCT tipped tool in QCTP holder 12mm
• Tangential built into QCTP holder 10mm
• Wimberley as supplied 25mm
• Wimberley with HSS cut in half (estimated) 17mm

So the wimberley as supplied reduces the diameter of work I can tackle by 26 -30mm.

What sort of overhang does a 'normal' tangential holder have?

Of course I could cut the HSS in half but that would only give a small gain and defeats the object of an easy sharpen. long lifetime tool bit.

My conclusion is that the Wimberley is a great idea in principle but in practice it will be best for small work on large lathes unless you have a long-travel topslide or are willing to use a custom toolpost to hold it.

Edited By Neil Wyatt on 03/09/2016 10:20:51

Just a note, the tangential lathe tool is not exactly new, there is an article in volume one (1898) of ME about such a tool.

Ian S C

Hasn't there been an article in one of the magazines not so long ago about making something like the Wimberly? I'm sure a mate said he was making some type of tool holder but it wasn't a Tangential.

If the Tangential appeared in ME in 1898 then it's probably quite a bit older than that even. It's just that it was "reinvented" quite recently!

I looked at the Eccentric Engineering on-line instructions and am not very convinced because the back rake looks far too big to permit easy grinding and checking to cut accurate 55 or 60 degree thread angles unless I'm missing something?

So, trying to follow Martin Cleave's 5 degree side rake recommendation for steel (page 119) which is pretty much all I thread and inspired by Jacques Maurel's article in MEW I came up with this to take 1/4" toolbits.

The toolbit is held at 30 degrees and so only one flank of the toolbit needs a lot of work (the business end for RH threading) and the 1/4" groove and screw in the holder are tilted back at the 5 degree angle so the top is held flat and doesn't need more than a hone. Sharpening is with the toolbit in the QCTP holder for speed.

...not had time to try it in anger yet though.

Jon