What is this??

[skiprat]

I mentioned the other day that I was going to make one of these...

any guesses?? :biggrin:

It works fine but one day I'll get a left hand thread tap and make a better one...:wink:

 

[SteveG]

Of course...it is a RH Get-Back-Jack!

 

[magpens]

Yes, I remember your mention of making one of those machinist jacks !!!

Do not quite appreciate the significance of the thread handedness though

 

[skiprat]

Yep, of course...it's a small machinist's screw jack.

Mal, this is a two piece version. a good one is three pieces. A base, middle and top. The middle piece has a left hand thread on one end and a right hand thread on the other. So it works like a turn buckle and pushes the two ends apart as it's rotated.

With my one, you hold the V end under the workpiece and unscrew the bottom half till it's snug with the machine table.

This one is made of copper. 25mm diameter , extends from 65mm to 85mm.
Weighs approx 260 grams, which I hope also helps a little with damping.

I was going to have a RH M12 x 1.75 thread with a RH M8 x 0.75 inside it, and that would work similarly to the first one I described.

If any one doesn't know what these are, they simply offer a bit of support to a flexible / thin / long workpiece so that it can take the pressure of the tool cutter:wink:

A fun little project:biggrin:

 

[Edgar]

Cool beans!

 

[magpens]

Machining Copper

Thanks, Skip !!

And now that you have confirmed that it is copper ....

I am having trouble machining copper ... even the simple task of parting-off.

Are there specific cutting tool materials, other than HSS or carbide, that work well with copper ...

Are there special cutting tool shape profiles that work well ...

If you can cite any references, or give any tips, Skip, I would appreciate it. Thanks

 

[skiprat]

Mal, I only used this copper because it was all I had that was thick enough. I would have preferred stainless.

Copper is an absolute pig to turn. As you know it is even more gummy than aluminium and I hate that too..

I broke my first boring bit today, doing this. I haven't even broken a drill bit in years and now this crappy chuck of copper snaps my favourite boring bar..!!

I use inserts and HSS cutters and I make sure that my final few passes are very light, lubed with anything to stop it sticking to the cutter and of course a fresh cutter.

I have just ordered some TiAlN coated inserts. These newish modern coating are apparently the dogs bollocks when it comes to turning anything.
We'll see...


Sorry I can't be more helpful.:frown:

 

[magpens]

You have been *very* helpful, Skip, actually. Thanks a lot for alerting me to TiAlN coated inserts.