The motor on my newly acquired lathe doesn't look good to me. wires hanging out, the cover for the fan is gone things like that. I'm wondering what kind of motor to get. I know nothing about motors, and like to know what kind I should get, can I have or need a reversible motor. I have 220 and 110 volts only. It is in my garage. Strictly for hobby use. I think the reverse is only used when one threads? I'm not sure.......Peter The model # of the lathe is 101-07403
I can tell you as a beginning metal lathe trainee, I love the 1/4 horse 90 volt dc variable speed motor I put on my 6" atlas/craftsman lathe..... I get speeds from 26 rpm all the way up to 3300 rpm, with plenty of torque. I sure like it!!!!!!!!!!
Mark the leads and remove the mot or from the lathe. Take it to Grainger or a motor shop and find out what they have for you. You need a motor with the same frame number, voltage etc. Hopefully it will be
220 capable and reverse capable. Be sure and get the wiring directions or diagram.
you dont need reverse on the lathe because the forward and backward movement you need to cut threads (Right and left handed and inside and outside) is done by the gear train linking the spindle to the leadscrew.
the Atlas lathe i have uses an AC motor spinning at around 1750 and its 1/3 HP if i remember right
I'll try and remember to read my nameplate rating in the morning and post it for you
just dont forget to not modify the speed reduction ratios on the belts so that you maintain the same speeds
O.K. For a 12" lathe, I would suggest a 1-1/2 HP motor.
And while you *can* run that from 110-120 VAC, you will probably trip the breaker more often than you would like when starting the motor with the lathe set for high speeds. You halve the current if the motor is wired for 220-240VAC instead. That is what I am using on my
12x24" Clausing -- at least until I get around to swapping in a three phase motor run from a VFD.
There are times when reverse is really nice to have. But the first question is whether this is a threaded spindle or something else. If threaded, you have to be careful in reverse, or you are likely to unscrew your chuck. I changed mine from a 2-1/4x8 threaded spindle to a L-00, which has no danger of unscrewing.
But even with a threaded spindle -- it is possible to make up a locking backplate so the chuck won't unscrew. (Quite a few Myford lathes have that feature.
And -- if you are using collets to handle rod stock through the spindle, there is no problem running in reverse, since there is nothing using the spindle thread.
Note that the typical single phase motor *must* be allowed to spin down to a stop. If you simply switch it to reverse while it is at speed, it will keep going the direction that it was already going. (This is one reason for changing to a three phase motor, where reverse is *sure* to be reverse. :-) I do a lot of switching between forward and reverse when using a releasing tap holder in the bed turret for internal threads (like 1/4-20 or 10-32), since there is otherwise no way to back the tap out of the hole which it has just tapped. The releasing tap holder at least keeps you from driving the tap in until it breaks. :-)
As for reverse with threading -- other than when threading with a tap or a die, it is only necessary when you want to cut a left-hand thread, or when you want to cut a normal thread from a shoulder to the free end to avoid running into the shoulder.
But no matter what -- get a motor which you can reverse. I would suggest (assuming that you don't want to go for a three phase with a VFD to drive it) that you get a dual voltage (120/240V) single phase motor at around 1-1/2 HP. Once you have that, it is fairly easy to reverse the motor with the wiring to the drum switch. (When the time comes, post again, and I (or someone else) will go into the details of that wiring.
Oh yes -- if you can't mount the motor somewhere where it won't be hit by the metal chips, you want a TEFC (Totally Enclosed Fan Cooled) motor, so the chips can't get inside the motor where they can do damage.
And you probably don't want to buy a new motor -- get a used one from eBay or somewhere local if you can -- the price is a *lot* better.
I miss having it, as I do not, on the one I now have.
Single phase motors, at least the one I had, will quite happilly carry on in the direction they are running, if the switch is thrown while it is running. About the only time there was a risk of unscrewing a chuck, was if the motor were strarted in high rpm mode, and in reverse. Net result, chuck potentially walks off the end of spindle, and lands on bed, or cross slide. Never had it happen, so I say, potentially.
A metal tab, or other safety device blocking the reversed setting on the switch will go a long way to prevent that, if you set it up correctly. If you do not, you will learn from experience, or you will always remember. I never had a problem with it.
Being able to reverse the spindle was very nice, when I had to do a wee bit of grinding in the lathe. Feeding the work against the stone rather than with it was a benefit.
Reverse is also handy if you want to thread metrics or worm pitches, as you will be able to run the whole works back to the start without having to disengage the gear train, potentially losing your indexing, and you will not then have to crank it all the way back by hand, two dozen or more times.
1-1/2 HP is way more than may be advisable for a Craftsman 12x36, especially in the hands of someone new to machining. ISTR that the lathes originally came with at most a 1/2 HP motor which is better suited to the design of that lathe. The Zamac gears in the Craftsman won't be quite as forgiving of a mistake as the gears on the much heavier Clausing that you have have. Just MHO.
I bought my Craftsman 12x36 new from Sears in 1974. I put a Dayton 3/4hp single phase motor in it wired for 220 and gave it it's own 15A per-leg circuit (mostly so the lights won't flicker upstairs every time I turn it on down in the shop - I know I'd hear about that). I wouldn't recommend any more power though, as this is a really light-weight lathe for a 12".
I have a reversing switch, and I use it. There are times (like winding a spring) it's just plain easier. To get the chuck mounted solidly though, you have to be meticulous about keeping the threads on both the spindle and chuck clean. Set the back-gears to lock the spindle and seat the chuck by giving it a good half spin BY HAND. Release the back-gear, and you're good to go. Never power the chuck on - really bad for the lathe and you could end up with a permanently mounted chuck.
There's always a risk working in reverse with a threaded chuck - use very light cuts, and NEVER an interrupted cut. Even so, it's always better to take the time to create the proper tooling and do the job running forward, but in all the years I've used this lathe, I've only knocked the chuck loose in reverse twice. YMMV!
There's also another need for reverse: tapping in the lathe (I can hear the gasps from here). However, using ONLY gun taps, working in non-ferrous metals with proper lubrication, and having plenty of clearance in the bottom of the hole (or better yet, a through-hole), I do it all the time. Heck of a lot faster and more accurate than doing it by hand.
"PeterM" wrote in news:lMudnXsxCoMpwGHbnZ2dnUVZ email@example.com:
And -- a lot safer with a releasing tap holder made for a turret. You'll need to adapt it to fit in the tailstock chuck -- or with a well centered boring bar holder in the carriage, and set a carriage stop to stop the holder, and thus force it to release and spin with the chuck and workpiece. Then you stop and reverse the spindle (two separate steps with a single phase motor), and pull back on the releasing tap holder to cause it to pick up a separate dog (or with friction) to back the tap out.
I use my releasing tap holders in a bed turret, because I have one, and the other stations do other steps in preparing the workpiece for tapping and other things like knurls on the outside, and perhaps external threads with a Geometric die head. That, at least, you don't have to stop and reverse the spindle -- the chasers are mounted like the jaws of a chuck, and retract quickly clear of the workpiece at the end of the threading operation, so you can back it off with the workpiece still spinning forwards.
Well thanks Don, I think I just started my Christmas list. All this time I've been trying to hold my mouth just right to stop the lathe at the right time. "Usually" it works fine. Time for another upgrade to the basement shop...
firstname.lastname@example.org (DoN. Nichols) wrote in news:fdk5in1ea9 @news5.newsguy.com:
And exactly what trick do you use to get the spindle in synch with the leadscrew each time you re-engage the tumbler? The threading dial is used to determine when to close the halfnuts, but it's useless if you have disconnected the leadscrew from the spindle by disengaging the tumbler gears.
You don't need reverse because it is easiest to disengage the halfnuts and crank the carriage back using the handwheel.
I don't think that he is advocating switching the tumbler when in the middle of threading -- just using it to choose between right-hand and left-hand threading.
And note that *some* lathes have a dog clutch between the threading gearing and the leadscrew, so you can halt the leadscrew and re-engage it without losing sync. Some of these even handle the reversing, I believe.
This is fine *if* you are cutting imperial threads with an imperial leadscrew, or metric threads with a metric leadscrew. If you are crossing systems, you need to use transposing gears in the headstock, and you can't disengage the half-nuts without losing sync, so you pretty much *have* to run the lathe in reverse.