turning down square blocks

[timeone]

whats the easiest way to turn down square blocks of aluminium ( to round ) in the lathe.
my 4 jaw isnt quite big enough
any suggestions

[BiggerHammer]

Are you saying that the block will not fit into the chuck? If so you will have to remove some of the excess material before chucking it up. Then you can CAREFULLY turn it down to round.

Some of the more experienced members my be of more help. I have gone from square to round but only with smaller materials. I am assuming that it will work with larger pieces if precautions are taken.

[crabsign69]

i did a trick that i learnd here and that was useing the tail stock and a spinning thingy in it and just push it up against the chuck and very carefully turn it down till it will fit . very carefully as it will spit out of that then you got a flying piece of block flying who knows where.
im just a newbie so im not that good but it did work for me.

[picclock]

Hi timeone

What size are the lathe, chuck and blocks ?

I presume you have turned the jaws round in the chuck to get the largest size ?, if not, do it but don't forget to note which position they come from (just do one at a time).

Need more info .. .

Best Regards

picclock

[andyf]

Can you turn it between centres?

Whatever method you adopt, if you have access to a reasonably accurate power saw, cutting off the corners to give an octagon will help.

Andy

[mgj]

Can you drill and tap from behind so you can bolt it onto a faceplate - with a thin spacer in between if you need to do the whole length.

[Divided he ad]

Tim',     (Tim' eone!?)



Lots of different ways to do this... Some not so safe!


Really do need pic's    


Of the chuck and the workpiece, Preferably with a rule in the shots for scale?


We can all help figure it out if we have all the info 





Ralph.

[Jasonb]

Clamping dogs on the faceplate, or something a bit fancier like this

http://homews.co.uk/page40.html

J

[Bogstandard]

The first five pictures of this post show what to do.

http://www.homemodelenginemachinist.com/index.php?topic=228.0

or ignore the first couple of pics on this one except for the bit about putting the centre in.

http://www.homemodelenginemachinist.com/index.php?topic=1809.0


If you take it steady, you don't need to round over the edges first, just take steady cuts.

You don't say how long your bar is, but I would use this method for no longer than say 4" at a time. If you do it right, and get the bar well centred at the chuck end, there is no way that the material can come out of position.

If you try to take too much off at one time, the bar will just stop turning. Put a tiny bit more pressure on the rotating centre and carry on with shallower cuts.


Bogs

[crabsign69]

thats how i did it bogs i must of got it from you . it works  very well 

[timeone]

Perfect Bogs thats some good advice there.
Ive been lucky to of been given about 2/300 aluminium blocks in varied sizes so your tip will be of great use to me.
Im so glad there are so many people willing to give advice kind of gives me hope for mankind.

[Pete.]

Does the 3-jaw hold bigger stuff than the 4-jaw? I used to round off square stock using a split collar in my 3-jaw. The collar is bored so the square fits snug inside then holding it in the jaws clamps it up solid.