What motor to get for my Craftsman lathe 12x36

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
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
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!!!!!!!!!!
bob in phx (who is just learning to use his newly re-bush'ed lathe)

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I dont recommend reverse on a threaded spindle
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
My atlas is a 10x36 but they are very similar
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Brent wrote:

I had reverse on my first Myford.
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. <shrug> 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.
Cheers Trevor Jones
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

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.
John Martin
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
    [ ... ]

    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.
    Enjoy,         DoN.
--
Email: < snipped-for-privacy@d-and-d.com> | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Oct 2, 5:23 pm, snipped-for-privacy@d-and-d.com (DoN. Nichols) wrote:

Don, I don't know for sure exactly what he was advocating. Hard to tell without a Ouija board...
He did, however, recommend not having a reversing switch on a lathe with a threaded spindle. That's his choice, but an awful lot of machinists wouldn't be caught dead without the reversing switch - threaded spindle or not. I'm one.
You are, of course, right about fractional vs. metric leadscrews and threading.
John Martin
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
    [ ... ]

    There is that. I guess that I was just assuming. :-)

    As am I. (Well ... I do have three lathes without reversing switches -- but they are the small ones, the Unimat SL-1000, the Taig (though I am going to be switching in a small three-phase motor and VFD which will give it reversiblity), and the Emco-Maier Compact-5/CNC, which would have no problems with the chuck coming off under power, because the chucks mount to the flat nose of the spindle by three or four screws which pass through the body of the chuck. But I'm not sure how well the CNC could be adapted to reverse running of the DC motor. I've been more tempted to use some of the extra control outputs to switch between two speed control pots in place of the single one which is fitted as it comes from the factory.

    Which is why I am very glad to have the Compact-5/CNC, since all it requires is rotating a switch to go between metric and imperial threads (and everything else). So -- so far - it is what I use when I need a metric thread, though I do have the transpose gears set for my 12x24" Clausing. So far, I have not had a project which needed metric threads large enough to require that machine.
    Enjoy,         DoN.
--
Email: < snipped-for-privacy@d-and-d.com> | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
    [ ... ]

    This applies to gear headstock lathes, but not to belt drive ones, such as the Craftsman listed above, or my 12x24" Clausing, so it does not apply to the person who originated this thread.
    Those are reversed by reversing the motor, which drives nothing but the spindle and (though the threading gears) the leadscrew and (if present) feed rod.
    Enjoy,         DoN.
--
Email: < snipped-for-privacy@d-and-d.com> | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Bob in Phx wrote:

Plus the speed range you can get from each gear in the gear box????

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Fred, no those numbers are from the top to the bottom, in terms of back gears, dual pulleys on the jack shaft and the 4 pulleys on the head... It can go lower then 26 with the back gear, but the torque just isn't there.
bob in phx

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

what does your nameplate on the motor say exactly (in its entirety).
i
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Thanks for your reply...That is the bad part, no plate or number anywhere on the motor.....also no on and off switch either....Peter
wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I'm wondering what kind

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.
Bob AZ
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

    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.
    Good Luck,         DoN.
--
Email: < snipped-for-privacy@d-and-d.com> | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

<snip>
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.
Mike
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I have single phase 1/2 HP and 3/4 HP motors. regular frames like 56 etc.
i
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

    [ ... ]

    Are the back gears Zamac as well as the threading/feed gears? If so, then I would worry about stripping them.
    But I still think 1/2 HP is a bit too small for a 12" lathe. It might be reasonable for a 10" one. Perhaps go for 3/4 HP or 1 HP for the 12" lathe.
    Enjoy,         DoN.
--
Email: < snipped-for-privacy@d-and-d.com> | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
PeterM wrote:

1 horse 3-phase 208/220 + 1 horse VFD.
You'll never look back.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Peter,
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.
- Bruce

kind

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.