Billy Bignutz 17th November 2006, 05:30 AM I have not touched a metal lathe since high school and have just acquired a restorable old lathe 9"x36" that was certainly built to last. The 3 phase control panel allows the motor to be reversed and I have noticed that all the Hare and Forbes lathes also have a switch to reverse the motor. Before I bother wiring up a single phase motor for the lathe to be reversible I ask the question why bother??. The guy at Hare and Forbes said so that you can reverse cut threads or cut left/right hand threads but you can do this by simply reversing the rotation of the lead screw (hence saddle travel direction) at the flick of a lever. I can think of no other valid reason - any ideas?.
The lathe I am restoring I guess to be about 50+ years old with no ID apart from the number 34 on the front apron (and stamped on many of the lathe parts for ID during maintenance) which tends to indicate it came from a large industrial situation with many machines of the same type. All aluminium designation plates etc have gone through wear and tear and an apparent fire. It does have some SK brand thrust ball bearings made in UK as the only hint. When restored I will post a pic if there are any old hands out there who may be able to help ID the type or if any one has a suggestion as to how best to ID an old lathe.
Thanks
Bill
Article99 17th November 2006, 05:44 AM Internal / External cutting requires opposing directions of rotation. ;)
Billy Bignutz 17th November 2006, 05:48 AM How many left hand drills have you found as an apprentice? Have never found one myself!!
Bill
Article99 17th November 2006, 05:52 AM I'm learning to make them from carbide for a living. If it's ordered, we make it. That simple. Sometimes the flutes travel LH rather than RH. Not really a big deal, mate. :)
But hey, just so you don't have to use your head too much, I'll edit it for a slightly easier answer to understand, ay?
Billy Bignutz 17th November 2006, 05:57 AM Internal / External cutting requires opposing directions of rotation. ;)
Eureka - I think you have it.
When cutting internal threads (or any internal work) it would be a definite advantage to see easily what you are doing by cutting on the opposite side of the internal surface. Otherwise you have to be screwing your neck around to see what you are doing particularly on small jobs - yep I will go to the effort of having a reversing switch.
Good one
Bill
Article99 17th November 2006, 05:59 AM Hehehe. Thought you'd like that one. :cool:
TassieKiwi 17th November 2006, 07:16 AM Eureka - I think you have it.
When cutting internal threads (or any internal work) it would be a definite advantage to see easily what you are doing by cutting on the opposite side of the internal surface. Otherwise you have to be screwing your neck around to see what you are doing particularly on small jobs - yep I will go to the effort of having a reversing switch.
Good one
Bill
Won't the thread cutting gears go backwards too?
Wood Butcher 17th November 2006, 08:21 AM Won't the thread cutting gears go backwards too?
On some lathes the lead screw that guides the thread cutting can be reversed for cutting LH or RH threads
Andy Mac 17th November 2006, 09:14 AM There are probably many regulation tasks involving reverse direction, but I just discovered another use for the reverse switch, when re-winding MIG wire. :rolleyes: I knocked together a plywood carrier for the empty 5kg spool, driven by the chuck, and its much easier to have the wire feeding over the top of the driven spool than under, guiding feed by hand...
WB, I think an idler can sometimes be fitted in the back gear train to reverse the lead screw direction too.
Cheers.
acton 17th November 2006, 12:21 PM I use reverse all the time. It is handy for cutting a chanfer on the back of a piece without swinging the cross slide right around (tool set up the same just cutting at the back of the work-piece instead of the front), can be handy for parting off if you turn the tool upside down (acts the same as rear toolpost) which I often use for silver steel to reduce that awful screeching, and I often use it because I'm lazy when threading, and so without disengaging the leadscrew, you use the lathe to back the saddle up to the same starting position without mucking around with the little leadscrew indicator.
Some of these method may be a bit bodgy but work for me. Careful with threading because I regularly knock the tip off the tool because I didn't retract it enough. I must make a retractable toolpost one day.
My lathe has a tumbler reverse for left hand thread cutting. It also has a bolt on chuck. You would have to be careful with screw on spindles I'd imagine.
acton 17th November 2006, 12:27 PM On the topic of reverse turning, does anyone have the H&F AL300 (not the 330A)? I like the idea of backgeared belt drive, and the wide range of speeds, as well as the general look of the machine, but with my tendency to use reverse a lot, will the screwed spindle make backwards turning impossible? Can you lock the chucks on? Is there even a reverse switch?
And what do you think of the lathe in general?
Big Shed 17th November 2006, 06:37 PM Maybe so that you can undo your mistakes?:D
Grahame Collins 17th November 2006, 09:54 PM A good site to scratch around in to Id an old lathe is here
http://www.lathes.co.uk/latheparts/index.html
It may have have info on what you may want.
Grahame
Metal Head 17th November 2006, 09:59 PM I learnt a great "trick of the trade" off someone for when facing off round plates with a wall thickness of more than 6mm thick. Tighten the chuck (3 Jaw) lightly on the edges of the round plate and put it in reverse spin (@ no more than 300 revs) and bring the cutting edge of the toolbit preferably with a radius (do not use tipped tools) and lightly press on the face of the work piece (near the edge of it) and the piece will straighten up to run nearly true.
I wish I had a lathe to explain (via pictures) but I haven't:(. This is not a trick for the faint hearted.
Ashore 18th November 2006, 12:25 AM Billy Bignutz
Because you can,:cool: as well as all the other reasons given.
Article99 19th November 2006, 09:28 AM From everything I've ever tried on the baby belt-driven lathe at work, I'd advise avoiding a belt-driven metal turning lathe all together. Spend the extra couple of grand and get something decent. ;)
brianc 19th November 2006, 06:08 PM 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
arose62 24th November 2006, 07:47 PM 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
Billy Bignutz 24th November 2006, 10:02 PM 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.
Billy Bignutz 24th November 2006, 10:04 PM 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
arose62 25th November 2006, 12:45 AM 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)
joe greiner 25th November 2006, 01:05 AM Why left-hand drills? To drill pilot holes for left-hand taps:confused: :D
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.:o
Joe
joe greiner 25th November 2006, 03:07 AM 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
Billy Bignutz 25th November 2006, 05:57 AM 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.
brianc 25th November 2006, 08:32 AM 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
joe greiner 25th November 2006, 09:05 AM "close center multiple operations"
Thanks, Billy. Makes perfect sense now.
Joe
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