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SL motor heats up and..

Fran All Messages By This Member #64845 Hi,? These days I am having more time to get used to the Unimat SL I purchased months ago. I have started working on some new stumps for a watchmakers staking set, and After 5 to 10 minutes, the (SL original) motor heats up a lot, and then suddenly shuts down the house’s fuse. It happens again and again until I quit and leave the thing alone to cool down completely.? Any ideas about what can I do to improve this? TIA
phill005 All Messages By This Member #64846 Hi Fran, Unfortunately that is the main problem with the SL/DB lathe you only have a short working time before it overheats the only way is to replace the motor with either a 24V DC? or a 118-220V one with controller have a search on the forum there is a lot has been written about to do it. ? Regards Phill??
Carl All Messages By This Member #64848 开云体育 Hello Tia: I think you have a bad motor. To trip the house breaker, 15 amp or larger, is a huge current for a motor that should draw 1 amp. I think your motor has shorted windings, will run but overheats, burning more insulation off. I have the plastic case motor that has never stopped for me. I have a spare 24 volt replacement motor that is still waiting in store. Knowing more about motors I would look for a small 3 phase motor and a Variable Frequency Drive (VFD). This would give you full power at all speeds. Lowering the voltage to slow a 24 volt motor also cuts the available power. Ebay motor: Ebay controller: This is only one possible combination. I put a VFD in to run my surface grinder and it works great. The easiest option is to just buy a new Unimat motor that bolts on. But they can be pricey. Good luck, Carl. On 4/6/2025 5:39 AM, Fran via groups.io wrote: toggle quoted message Show quoted text Hi,? These days I am having more time to get used to the Unimat SL I purchased months ago. I have started working on some new stumps for a watchmakers staking set, and After 5 to 10 minutes, the (SL original) motor heats up a lot, and then suddenly shuts down the house’s fuse. It happens again and again until I quit and leave the thing alone to cool down completely.? Any ideas about what can I do to improve this? TIA
OldToolmaker All Messages By This Member #64849 I replaced the original DB200 motor with a 24 volt DC motor. I will never go back to the original noisey motor ever again. In fact I have (2)24volt motors. Most of my work on the Unimat these days is done by hand crank. I can use that any place I go. Dick -- http://www.homemadetools.net/forum/?OFF-SET-tailstock-center-65965#post105972 ?SMALL TURRET TOOL POST PLANS? ?LARGE TURRET TOOL POST PLANS ?MINI-LATHE CARRIAGE LOCK PLANS ?SMALL QC TOOL POST PLANS? ?QUICK CHANGE LATHE TURRET ?MINI LATHE COMPOUND PIVOT MODIFICATION
Jkle379184 All Messages By This Member #64850 I think that the SL motor is only rated and so minutes of run time before it has to cool down. ?Jeff On Sunday, April 6, 2025 at 05:39:03 AM EDT, Fran via groups.io <frodriguezpc@...> wrote: Hi,? These days I am having more time to get used to the Unimat SL I purchased months ago. I have started working on some new stumps for a watchmakers staking set, and After 5 to 10 minutes, the (SL original) motor heats up a lot, and then suddenly shuts down the house’s fuse. It happens again and again until I quit and leave the thing alone to cool down completely.? Any ideas about what can I do to improve this? TIA
John Entwistle All Messages By This Member #64851 开云体育 Which motor do you have? I don’t have that problem with the U100 but the older motors had a limited duty cycle. The hot setup (sorry) is to replace the motor with a scooter motor - there are dozens of discussion threads on here about how do that. Best Regards John toggle quoted message Show quoted text On Apr 6, 2025, at 9:24?AM, Jkle379184 via groups.io <jkle379184@...> wrote: ? I think that the SL motor is only rated and so minutes of run time before it has to cool down. ?Jeff On Sunday, April 6, 2025 at 05:39:03 AM EDT, Fran via groups.io <frodriguezpc@...> wrote: Hi,? These days I am having more time to get used to the Unimat SL I purchased months ago. I have started working on some new stumps for a watchmakers staking set, and After 5 to 10 minutes, the (SL original) motor heats up a lot, and then suddenly shuts down the house’s fuse. It happens again and again until I quit and leave the thing alone to cool down completely.? Any ideas about what can I do to improve this? TIA
Bill in OKC too All Messages By This Member #64852 Use? pulse width modulation (PWM) controller to control your DC motor speed. It uses pulses of variable width but very close to full voltage to control the motor speed with minimal loss of power. Lots of options on ebay and amazon. Bill in OKC William R. Meyers, MSgt, USAF(Ret.) Aphorisms to live by: Good judgement comes from experience. Experience comes from bad judgement.? SEMPER GUMBY! Improvise, Adapt, and Overcome. Physics doesn't care about your schedule. The only reason I know anything is because I've done it wrong enough times to START to know better. Expect in one hand, expectorate in the other. See which one gets full first. On Sunday, April 6, 2025 at 06:31:42 AM CDT, Carl via groups.io <carl.blum@...> wrote: Hello Tia: I think you have a bad motor. To trip the house breaker, 15 amp or larger, is a huge current for a motor that should draw 1 amp. I think your motor has shorted windings, will run but overheats, burning more insulation off. I have the plastic case motor that has never stopped for me. I have a spare 24 volt replacement motor that is still waiting in store. Knowing more about motors I would look for a small 3 phase motor and a Variable Frequency Drive (VFD). This would give you full power at all speeds. Lowering the voltage to slow a 24 volt motor also cuts the available power. Ebay motor: Ebay controller: This is only one possible combination. I put a VFD in to run my surface grinder and it works great. The easiest option is to just buy a new Unimat motor that bolts on. But they can be pricey. Good luck, Carl. On 4/6/2025 5:39 AM, Fran via groups.io wrote: Hi,? These days I am having more time to get used to the Unimat SL I purchased months ago. I have started working on some new stumps for a watchmakers staking set, and After 5 to 10 minutes, the (SL original) motor heats up a lot, and then suddenly shuts down the house’s fuse. It happens again and again until I quit and leave the thing alone to cool down completely.? Any ideas about what can I do to improve this? TIA
Keith S. Angus All Messages By This Member #64853 These motors are getting quite old now, and many are marked 80 minutes on, 2 minutes off, or something like that. They do get hot in continuous use, and when they get to hot the windings start to burn. Is it tripping the current overload, or the earth leakage trip? Actually it doesn't matter. It's on its way out. ? Get a 24 V DC motor rated at between 100 to 150 Watts (I use 130 W) like this one - Ebay item 146489217625. It takes a bit of work to fit it, but not too much. You can use a speed controller with them, but I found I ignored mine and just changed speed with the belts. But id f you do want one, I'd look at something like this - Ebay item 405526646363. Then you need a 24 V power supply like this, 24 V 10 A, Ebay item 355025807336. ? All these bits are from China so there may be some confusion, but I think you will find them, or se very like them, from more local suppliers. There are a few descriptions of how to fit the motor, including mine, in the Photos, ? /g/Unimat/photosearch?p=updated%2C%2C%2C20%2C1%2C0%2C0&q=Keith%27s%20SL ? There are variants of the motor. The one I found on Ebay is very like the one I used. If you can find one with a longer shaft that's a big help, also having the lead at the opposite end to the shaft. Some have a tooth belt pulley on them, and it's a pain to get it off. Others have a sprocket for a roller chain, and a lot of the shaft is threaded for it. In both those cases the shaft is a bit too short. A longer plain shaft is much better. ? With the DC motor I was running the lathe continuously for an hour at a time and the motor got a little bit warm. That was for polishing, which is a low power load, but I also used it for fairly continuous turning, and it never got hot doing that either. ? Avoid high power motors - they are too big and with excess power you also get excess damage when things go wrong. Using the 3 phase motor with a variable frequency drive will, I think, give trouble if you overload it to the point of slowing the motor down. My experience of motors like this is that they don't slow down gracefully as the load increases, but reach a break point where the drive can't cope any more and you get a lot of noise and vibration. n advantage with the simple DC motor is that you don't really need a speed controller - you can run it straight from a 24 V DC power supply, and that's one less thing to go wrong. ? Also it's a change many of us have made, and it simply works.
Keith S. Angus All Messages By This Member #64854 On Mon, Apr 7, 2025 at 03:50 AM, Keith S. Angus wrote: These motors are getting quite old now, and many are marked 80 minutes on, 2 minutes off That should, of course, have read 8 minutes on, 2 minutes off!
Fran All Messages By This Member #64855 Thanks everyone for your replies and helpful advice. I have purchased a 24 V DC motor, 150w and 4000rpm, as well as a 10A power supply and vsc. I will adapt Keith’s drawings (thanks for sharing those!) to build a mounting bracket and spindle adaptor. I hope I have some spare time during Easter for this. ? regards, Fran
Fran All Messages By This Member #64856 Yes, I have seen mine is marked like that.
Keith S. Angus All Messages By This Member #64857 If you hit any snags or want any advice, post your questions here.

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