# Square In 3 Yaw Chuck



## Slavko (Oct 31, 2015)

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


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## Charles Spencer (Oct 31, 2015)

You could mount it on a face plate.


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## kvt (Oct 31, 2015)

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.


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## John Hasler (Oct 31, 2015)

Good suggestions but the best thing to do is to get a 4-jaw chuck.  You will find lots of use for it.


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## John Hasler (Oct 31, 2015)

Good suggestions but the best thing to do is to get a 4-jaw chuck.  You will find lots of use for it.


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## Slavko (Oct 31, 2015)

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.


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## epanzella (Nov 2, 2015)

Make one of these out of some pipe with bolts every 90  degrees. It'll hold just about anything.


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## T Bredehoft (Nov 2, 2015)

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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## planeflyer21 (Nov 2, 2015)

Watched this the other day.  Making one of these was a final exam at the local CC for your CNC Programming final.

This dude does it on a manual lathe, with a 3-jaw chuck.


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## T Bredehoft (Nov 2, 2015)

planeflyer21 said:


> This dude does it on a manual lathe, with a 3-jaw chuck.



That's where I got the idea.  I tried to make a cube from 13/16 diameter Aluminum.  too small. not enough contact area with my numbers.


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## Slavko (Nov 3, 2015)

That's amazing. But the guy actually does hold square in 3 yaw chuck without splitted pipe. At 2:47 is that clearly visible. I can hold piece in that way if I shift jaws in chuck and be near in center. (I don't have that big piece of round material to make jig.) Seems that I just need to try and work with slowest RPM if something fly away.


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## janvanruth (Nov 10, 2015)

2:47 only to square up, not concentric
3:10 to hold the square, concentric
easiest is the split pipe


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## Slavko (Nov 10, 2015)

I already do. Like on 2:47. I do offset one yaw for one scroll spiral and got piece near the centre. Just right for job needed.


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## Rozwell55 (Nov 25, 2015)

planeflyer21 said:


> Watched this the other day.  Making one of these was a final exam at the local CC for your CNC Programming final.
> 
> This dude does it on a manual lathe, with a 3-jaw chuck.


Thanks for sharing this video. The machinist is incredible at his task and I have learned a new way to hold something in my three jaw chuck.


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## Wreck™Wreck (Nov 27, 2015)

Ran 2400 square parts in a 3 jaw, 2 fixtures with square recesses milled in the, face, four tapped holes to hold the parts in place, repeat again and again.

Happy Black Friday


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