Square In 3 Yaw Chuck

S

Slavko

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Hello...

I want to make Norman style QCTP. But I hit into trouble as my mini lathe had only 3 yaw chuck. So how to put that 50mm x 50mm rectangle in chuck to bore 25mm hole?!?

Probably easy task for one that know... But I don't so it's hard for me...

Slavko
 
One way I know is to find a piece of pipe that is just larger than the item, Slit it and pull out just a bit, Then put the part inside of it and clamp it down it the 3 jaw. The reason you take a little out is that it allows it to clamp down with out trying to buckle or provide heavy resistance to clamping around the other piece. You can also use this method to clamp something that you do not wan to two mar when you clamp it. You can use various materials at times where it will grip the other metal etc better.
Hope this helps. I have never done it on a square piece but have seen it done.
 
Good suggestions but the best thing to do is to get a 4-jaw chuck. You will find lots of use for it.
 
Good suggestions but the best thing to do is to get a 4-jaw chuck. You will find lots of use for it.
 
I don't have faceplate too..
The 4 yaw chuck is not cheap. even chinnese one.
I try to do some offsets when installing yaws in my chuck. If I install one yaw one scroll turn latter in head then I have near centered piece. But the other 2 yaws clamp on sides and is unusable. If I do opposite and insert one yaw later in head the piece is clamped on two corners and one flat. Seems good but it's far out of center and unusable. As I look plans the true center is not needed at all. 2-3mm offset doesn't hurt.
So for now the split cut pipe seems the only option.
 
Make one of these out of some pipe with bolts every 90 degrees. It'll hold just about anything.DSC_1077.JPG
 
Bore a tube to 70.7 mm, the depth of your piece, cut it off that length. Slit it parallel the length. it will just fit over your 50 mm block. slide the block inside the tube you just made, put it in your three jaw and clamp it just tight enough to hold. You don't want it slipping when you are trying to bore it.
 
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