Purpose of having Reverse

K

Kroll

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Guys couple weeks ago I ask bout the wiring of my motor over on the elec section and thanks to John and other there I am ready to more to the next step,but before I do-----
What is the purpose of having reverse,won't the chuck come off running in reverse?Is this a function that the average person needs?
I have a Sears 101.28900 that came with a drum switch that has For/Stop/Rev,I am getting to the point of wiring the motor and figuring out if I need reverse,if not then I'm just going to install ON/OFF switch,but if there is some benefits that I may come across in the future of having reverse than I would like to make plans for that.
So,is it worth having reverse and please give examples and pics would be nice for this simple minded person.Thanks----kroll
 
I use reverse during threading, both for returning the carriage to the starting point when single pointing, and for backing the tap out of internal threads.

Chuck
 
More important option using collets, since they won't spin out. Also for tapered spindles instead of threaded.

Be really careful if your spindle is threaded, like all Atlas machines (?), even reversing the carriage feed etc with a chuck in the spindle, depending on what the startup is like. You could still spin it off, or worse, loosen it and not notice it is loose until you go into a fast forward speed.


Bernie
 
Purpose of reverse? Tapping and threading mostly. Drill chuck MT spins in tail stock? Slide back on Morse taper and bump reverse. Comes right off. Break a bolt or screw? Use a left hand drill to remove. Worried about accidently going past stop and right into reverse? Easy, throw away the drum switch and use a motor starter rated for the load controlled by pushbuttons. This will bring your lathe up to current code by giving the motor overload protection and you peace of mind of not creating a potential accident. Good old American lathes used drum switches because it was CHEAP at the time and legal. But not now. Pop the covers off those HF and Grizzly lathes and you will find contactors and overload relays. Why? Because they would not be allowed to sell them otherwise. This is also why it is so easy for an electrician to add a VFD controller. Except for the controller itself, a motor and a switch or two, he is COMPLETE.
 
One is not likely to be running in top rpm in reverse. Usually it is a threading operating and low rpm. I had an Atlas and my current lathe is threaded as well, and this is the way I have run my lathes.

You can use a shot pin to hold the chuck in place by simply drilling a hole into the face of the flange and a slot to the outside for a handle to retract the pin that is pushed by a spring into a matching hole on the spindle. this is just one method found on the net.
Pierre
 
I use it whenever it suits me and the job in the machine. I face down to an external boss shoulder by working a boring bar on the "far" side of the spindle, and I can turn the OD with a bar too. Sometimes cutting bevels and chamfers is done in reverse with tools on the far side. Just depends on what tool is in the holder and what I want to cut. I don't generally do the reversing method for threading, but once in a while I do power tap, so it gets reversed then.

If you happen to have left handed bars, either boring, threading, or grooving bars, nothing wrong with working the "other side" of the hole. I'd feel handicapped not to have reverse available.
 
Another reason for running the lathe in reverse is when using a tool post grinder.
 
One good reason is if you some day want to use collets . And there are also other good reasons for running parts in reverse. Cutting left hand threads is one good reason. And in production shops I have ran thousands of parts in reverse in collets and cutting tools upside down in back side of crosslide using only the bottom two rollers of a steadyrest with cycle times less then 30 seconds and never stopping spindle. It can save lots of time.

jimsehr
 
I routinely make a part that involves cutting a .425 deep pocket in 2.5" diameter .750 thick aluminum. The rough cuts are fast and deep - much faster than any auto-feed option so it is done manually. I do it in reverse because it is so much easier to see the tool approaching the far side of the pocket.
 
There is a danger with it too, as with all things mechanical if you are not careful. Yesterday I was threading some M6 blind holes on the lathe, turning the lathe manually when going in, using the motor in reverse going out. Went fine until I forgot to switch back to reverse after drilling the hole to be threaded. The tap was in the bottom of the hole and could not go in further when I started the motor to bring it out. The cross bar of the tap holder cut a deep slash in my middle finger when it started rotating. According to the doctor I had luck. A deep and broad cut but it did not touch the bone or the tendons. It will be some time though, before I can finish the mounting of the new telescope.

Goran
Canary Islands

written with my left hand
 
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