How rigid is your QCTP ?

The high shear angle means the tool will not last as long as one with a less steeper angle, which may be of no consequence to the job at hand. You will be just sharpening the tool more.

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Just out of curiosity I had a play also.

Oh and it was EN8

I would imagine when Mr Stevenson and others with proper machines see this they will view them as baby lathe teething nibbles.

Edited By Nick_G on 07/03/2016 17:12:37

I've mentioned the type of tool Rod has used several times. Sharpening is easy if there is a suitable stone around as it can be done in the lathe. It takes seconds. Tools are best sharpened before they show signs of tool wear on the work or the performance drops off 'cause it's too late then.

I think Jason's chips breaking are down to the lathe not the tool. Also looks like there is more signs of tearing than Rod's.

A 1/4" depth of cut is 1/2" of the diameter. Tangental tool – interesting as some one who is using that wouldn't be too concerned about adding around 15 degrees back rake to the tool with any of the angles the others have used. Rod might be as it weakens the tool.

Sorry folks the boxford is out of use at the moment and I am not going to do that to the wabeco.

Really from the lathes point of view Rod's is the best option IMHO (if I have one – the H part, plenty of the others) as there is less load on the lathe- good for bearing life.

Nice big larger than life shots of the results would be interesting.

John

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I'd agree that there is some tearing which I would expect with less cutting angle but as for the chip breaking being due to the lathe, that is definately down to the tool.

This is the tool used for the first video, which was straight off the rack not freshly sharpened like Rods. Maybe 5deg top angle

Now this is the same tool but given some more top angle to give a sharper cutting angle on the off hand grinder no touching up with a stone.

And here you can see the increase angle which results in curly swarf that wants to wrap itself around the tool which is why I stopped the video a bit sharpish.

Swarf looks quite cleanly cut too. You can also see the better (not perfect)finish on the remaining 1/2" dia, the blue mark is where the first cut stopped and the second started. Face of the bar looks cleanly cut too.

So in answer to Rods questing – its the tool

In normal use I would not be taking cuts like this, rather use a carbide tool at 1000rpm and about half that depth of cut. Two passes will still remove the same amount of metal in less time than with one slow deep cut and put less strain on the machine.

J

Edited By JasonB on 07/03/2016 18:33:28

The main issue with the tool shown is that there is no chip control. Have you considered grinding the top of the tool so there is a rounded groove giving the required side rake and acting as a chipbreaker?

I am considering making new tool holder for my QCTP. I plan to make the tool slot at a 15 degree angle for back rake. On the surface grinder I plan to grind about 12* clearance on the front face of the tool (full length), Then grind a groove in the top face of the tool that will give me about 15* side rake (full length. I intend to keep the groove fairly narrow to act as a chipbreaker, leaving enough of the top flat for the clamping screws. The idea is to grind the worn tip of the tool and move the tool forward in the holder. Has anyone tried this approach?

Any one know how the C1 compares with the C0. I saw one for sale recently. Not sure why but I had a gut feeling that the C1 is more interesting.

John

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Which is why I have 9×20 .. sort of middle sized.

Seeing that picture of Johns lathe has set me thinking. I have a duality lathe that fits on the bed of my Tormach mill. Basically it is the same as the small Seig lathes but it has an extended spindle that has an external thread that a 4th axis gear drive is attached. I have got the 4th axis drive for the lathe but so far haven't fitted it because I have used the rotary table for my 4th axis work.

One of the things that I don't like about this mini lathe is that it hasn't got much power and can't be used for very deep cuts. I think that a 1 H.P. motor with inverter and variable speed drive could be arranged to fit the lathe using the threaded spindle to accept a toothed belt pulley. The spindles on these machines seem pretty robust and the cutting tools will be mounted to a holder that is clamped to the milling spindle nose eliminating a lot of the problems of deflection that a normal lathe is subjected to.

Any thoughts on this idea, is it goer?