Tangential lathe tool holder

I have just finished MY version of a tangential lathe tool holder. The shank is the parallelogram type the idea which I copied from Michael Cox's design (thank you Michael).

I have read on here and in ME or MEW that these tools can allow the HSS bit to slip under load so I have come up with my own design of tool bit clamp.

I have tried the tool out and having put on what I consider to be a heavy cut - as heavy as anything I would ever use in future - I am able to report that the HSS stayed in place.

I wanted to get the two 4mm caphead screws as close to the slot as possible but I got a bit to close and JUST broke through the slot with the clearance drill. Never mind though, I machined the threads off in the fouling area and Bob's your uncle.

The only other thing I have done that I have not read about is to take a whetstone to the operational corner of the HSS bit and stone a small radius the whole length of the bit. Dressing the bit in an end to end stroke makes sure any striations are running in the right direction cutwise.

I had considered machining the clamp in gauge plate followed by a little heat treatment but I decided instead to simply use a piece of scrap that was lying around. It wasn't gauge plate but it wasn't MS either - something a bit tougher!

I have never been heavy handed when it comes to tightening screws so for the trial cut I just "nipped" the screws up. Anyone using this design who delights in stripping threads would be ever so pleased Rik http://www.model-engineer.co.uk/albums/member_album.asp?a=27519

Or try **LINK**

Very neat Rik!

Neil

P.S. Have you tried using the 'camera' icon to embed pictures from your albums, not the 'picture' icon?

Neil - Thanks for the compliment and your tip, I'll use the camera icon next time. ----- Rik

Looks good

Thanks for shaing.

MichaelG.

Alan has PM'd me for drawings - sorry but I did it by feel using the basic design from Michael Cox's article in MEW. As you can see, the main difference is the tool bit "bridge" type clamp. This was a little tricky to make as the bit nearest the cutting point needed to be "thinned" so that the clamp would not foul on the work piece before the tool bit could start to cut. As in ladies I prefer curves to angles so the necessary "thinning" was done by eye (ooerr!) using a file and emery cloth. With the face plate (or shall we say work piece) mounted on the lathe and the tool clamped in the tool post it was easy to see when the tool was advanced if the clamp or the tool tip came into contact with the faceplate first. If the clamp hit first then it needed more thinning.

Very difficult if not impossible to draw, the only thing I would add is that on my first attempt the shank of 14mm thickness would not allow the tool bit down to the correct centre height. The solution (in my case) was to remove a further 3mm from the underside of the shank and that solved the problem. (This using a WARCO standard tool holder on the QCTP on a WM250 V-F lathe).

So Alan, was it worth it? I'll say so! I have always been a bit windy about heavy cuts but I have just chucked up a 1" rod of tough ole' stainless, applied a 1/8" deep cut and set it going. Alright, I was feeding by hand (I'm not THAT daring - yet!) but with brush applied cutting oil the swarf curled off very smoothly and left a superior finish. I am WELL pleased with this tool, you will not regret making one for yourself.

Rik

> the bit nearest the cutting point needed to be "thinned" so that the clamp would not foul on the work piece before the tool bit could start to cut

This seems to be the challenge with tangential holders; it;'s the bit i've found tricky - the lower the holder, the less you need to remove, as you found.

Neil

Hi Rik,

Thanks for the posting. This looks to be a worthwhile enhancement to the tangential toolholder design.

Mike

I really must get around to making one.

My bright idea is a snail cam under the bottom end of the tool bit, to stop it being hammered down. Or even a shelf on the toolholder to support the bottom of the bit, if the tool holder is to be mounted on a QCTP which can be set a little higher after each sharpening.

Andy

Holder looks very well made. How about making a sketch of sizes and posting it

Thanks Kenneth - I'll do a sketch or 3 in a day or 2. ------ Rik

Kenneth and Alan have asked me for more details about my version of the diamond tangential tool. Please bear in mind that this version of the tool has been made for MY lathe - a WARCO 250 family fitted with a WARCO QCTP.

I have just been up the workshop and offered it up to the standard tool post that WARCO supply. It may work on this but it is so close that a combination of a little more clamp thinning (the curvy bits at the end nearest the tool bit) and a reduction of the shank thickness (the underneath bit) may be necessary. Sorry I cannot be more specific but as I have no intention of using it with the fixed tool post further investigtions have come hard up against the buffers. (I can't be bovverd!).

Have included a not very special pic showing how I determine if I have enough clearance to prevent "clamp rubbing" something to be avoided (even talcum powder won't help you here!

Hi Rik

Thanks, Give me a couple of days and I will draw a nice CAD drawing and upload it. Can you make a sketch of the sharpening fixture.

Hello Kenneth - Sketch as requested.and I use this to sharpen. I don't find a guide necessary.

Kenneth - Sorry but I left an angle of the sharpening fixture. The "v" shaped groove that holds the tool is 30 degrees from the horizontal. --- Rik

This is how the holder come out. I am using Solidworks

Front and left view. If the design looks ok I will upload drawings with dimensions

The Only Caution I might suggest is the same as Gary Sneesby of Eccentric Engineering, the use of the double V enables the bit to be clamped on four sides giving a much improved grip on the tool bit.

Another thing I have been experimenting with is the grind and as Des Burke detailed the use of the round grinding disk provides a concave surface to the tool bit. This Concave profile of the tool bit can privide a chip breaker.

I have found without the concave profile I can easily create 4 to 8 foot curled chips of viruually any cut depth I choose.

It has been over fourty years since I last touched a lathe and the first tool I bought was the Diamond Tool holder. It is much more interesting to only have to touch the lathe as a hobiest now that I am retired from my career after 37 years.

The extreme detail and helpful hints and excellent layouts of the MEW is a testimony to the best of the British legacy in Engineering.

Please have a look and see if there are any mistakes. I will add the clamp and screw details tonight. Any ideas as to what would be the easiest way to make this holder. I was thinking with starting with a piece os 30x20x100mm (1 1/4 x 3/4 x 4 inch) bar material to start with