.007" diameter reduction on Aluminum

[Jim F]

Measured it at .622 to .624 so it's going to be tight. Maybe a big file?

Start with 3/4 stock.

 

[Aukai]

I think Jim is right unless you already have it, and you are willing to discard the ones that do not clean up at .007. I'm turning 2" bars, and will go as far as .020 to get them round. I think this one cleaned up at .010

 

[martik777]

Already have 5/8. Tolerance is between 616 and 618 but no spec of being perfectly round

 

[Aukai]

Chuck one up, and you will soon determine your course of action.

 

[Parlo]

Using a collet will automatically average out any deviations from the centre of the bar so they should clean up ok in a collet.
I would use a clamp on style grooving tool to turn the face then o/d and then part off in one setup. You can also use it as a pull out stop.

 

[martik777]

Used a ER25 collet, so far all have cleaned up at about .004" then I dial in another .002-.004". Annoying part is drilling thru .377" as 6061 gums up after 1.5"

 

[Aukai]

I have been drilling 6061 with the Noga mister using alcohol to help keep the part cooler from the outside, WD inside.

 

[epanzella]

Use your ER chuck. Cut the pieces 4" plus the width of your parting blade. Turn half, flip it, turn the other half, then part. An ER collet will have the range to hold .618" to 625". Nothing you can do if it won't clean up but it'll be close.

 

[martik777]

Use your ER chuck. Cut the pieces 4" plus the width of your parting blade. Turn half, flip it, turn the other half, then part. An ER collet will have the range to hold .618" to 625". Nothing you can do if it won't clean up but it'll be close.

I have a part-off jig I use to cut within a couple thou. Then will cut to exact size and debur with a spindle stop. 12' long stock supported in chuck and V block about 1' out so it doesn't whip.