Thread: Why can you reverse the direction of rotation of metal lathes?

You need reverse on a metal lathe to cut left hand threads, turn the cutting tool up side down, reverse the spindle direction and away you go
easy Brian

Originally Posted by Billy Bignutz

How many left hand drills have you found as an apprentice? Have never found one myself!!
Bill

Just found this, whilst looking for centre drills, and it jogged my memory. Took a while to find your post...

http://www.engineering-tools.com.au/category587_1.htm

Never knew left-hand drills existed either. Sounds like striped paint, and other things apprentices get sent to find

Cheers,
Andrew

Originally Posted by brianc

You need reverse on a metal lathe to cut left hand threads, turn the cutting tool up side down, reverse the spindle direction and away you go
easy Brian

You don't need to reverse the motor to cut left hand threads - just flick the lever to reverse your lead screw direction of rotation - even easier.

Originally Posted by arose62

Just found this, whilst looking for centre drills, and it jogged my memory. Took a while to find your post...

http://www.engineering-tools.com.au/category587_1.htm

Never knew left-hand drills existed either. Sounds like striped paint, and other things apprentices get sent to find

Cheers,
Andrew

Begs the question - why do you need left hand drills????

Bill

Well, if my cordless drill's forward/reverse switch got stuck in reverse....

(and the cost of the left-hand drills was much less than the cost of repairing or replacing the cordless drill)

Why left-hand drills? To drill pilot holes for left-hand taps:confused:

Seriously (I think), McMaster-Carr says "Used in screw machine and close center multiple operations where spindles operate alternately left and right hand." Whatever the hell that means.

Joe

Upon further consideration, left-hand drills for left-hand taps might not be so crazy after all. For CNC with a rotating workpiece, or even with a turret lathe, you could change from drill to tap, without having to stop and reverse the workpiece. Still need to stop and reverse for extraction of tap, of course, either left-hand or right-hand.

Joe

I thought of another reason - for drilling holes in the lathe when your lathe is running backwards!!!!!!!!. The close centre multiple drilling operations requirement seems the reason - they use many chucks mounted close together each driven by a gear at the top/end of the shaft, Instead of wasting time and room with an idler gear between each gear they simply mount a left hand drill in every second chuck if that makes sense.

I agree you can reverse the lead screw to cut left hand threads but that gets a bit hard to do when you have to cut from a big shoulder thats in the chuck towards the tail stock, not easy beleive me, if you can see where i`m coming from Brian

"close center multiple operations"

Thanks, Billy. Makes perfect sense now.

Joe