I've got a Myford Super 7 with a Brook Crompton 550W single phase moto that's just stopped working. It turns (slowly unloaded if spun by hand but it won't start or reverse and it gets hot with a distinct smell o burning. There are five wires exiting the motor, the usua brown/blue/striped and two black wires going to the drum switch. Anyon know exactly what the black wires do? The motor was working fine an then refused to work. No, it's not got a thermal cut out
More than one possibility. The most likely one is brown and blue for the motor main winding. The two black wires then connect to the two ends of the starting winding via the centrifugal starting switch and also, if one is used, the starting capacitor.
As Andrew has pointed out,the most likely fault is a dud starting switch which fails to close when the rotor is stationary.
I have a virtually unused motor and switchgear from my S7B, which was removed a couple of months after I bought the lathe new, so that I could fit a 3-phase motor and inverter (a move I have not regretted for one microsecond).
If you would like this motor, you are welcome to it in exchange for a bottle of the _very best_ red wine you can find in your local supermarket. I need the house-room.
Single-phase Brook Crompton, 550W, shaft 5/8" dia x 2" long. Switchgear is a box having Forward/Reverse, Emergency Off, and ON/OFF switches.
I'm located in the south-west Midlands. I'd ask you to collect.
Can I have first refusal on this if he doesnt want it? My ML7 came with a super-powerful errrr 1/4hp motor on it..... How does a Barolo sound in exchange?
Oh dear, I'm not going to be very popular but I'd like to take you up o
that offer Clockie since it sounds like an easy change over. Sorry Pete (you're welcome to the old one if you fancy a fiddle).
Red or White? What the hell, how about one of each? I'm driving up t Telford this weekend so would Saturday morning be convenient? This i very much appreciated
No problem, at least mine works (if a little underpowered) whereas yours is hors de combat, so you're more in need of it than me. As for fiddling with your old one to fix I fear that is beyond my skills. I'm grateful for the fact that 3-pin plugs come pre-wired these days:). Charles (Ping) has provided me with some information on recommended reading to counter my lack of skill here, but it will be Christmas before I have the free time to get around to it.
I don't suppose anyone else has one of these myford motors - 1/2 or 3/4 hp - that is surplus to requirments? I actually got 2 motors with mine, the 1/4hp (British Thomson-Houston co.) thats fitted and an original
1/3hp Brook 3-phase. The Brook is available if anybody wants it. The Thomson is actually a nice smooth quiet motor, but I worry that it may be a bit underpowered with a 6" 4-jaw and anything large-ish in it.
Peter, I can't recommend highly enough the inverter method of driving a small home workshop lathe. As you have a 3-phase motor, it seems a shame not to use it to get the benefits of this system.
Since installing mine, I rarely have to change belts, hardly ever resort to backgear (though admittedly most of my work is light duty) and have infinitely variable spindle speed within the range concerned. In addition, the motor runs very cool. It's 400W but has always provided all the power I need, and I regularly use a 6" 4-jaw chuck.
I'll also agree with this. I built some special purpose machines that use invertors. These go on machines operated by people who don't care and run 24/7 I can count on one hand the number that I have had back that have failed, usually there is physical damage present as well and bear in mind we are buying 100 to 150 per year.
A few notes: They take in single phase at 240v and output 240v at 3 phase and not at 440v. If you are running a two speed motor an invertor won't fit the bill. You also need to swap the wires over on the motor from star to delta. Late motors have 6 wires usually connected to brass or copper strips that you can swap over [ more later].
Early motors are often wired in star with the star point buried in the windings. Unless you are lucky or have done this before it can be hard to find the star point and bring the three extra wires out. Often best to consult a rewind company. Next alternative is to get a late motor as there are usually cheap enough secondhand.
Here's a link to how a motor needs to be wired in delta.
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Now for invertors. There are many types and they all follow the same lines. I have used many different types over the years and there are no bad ones but there are different features.
The biggest trap to fall into is to buy an invertor that is just an invertor on it's own, filters and programming panels are extra. Mitsubishi are one of the worst for this. By the time you have bought the whole kit , plus VAT, you are double what some others are.
For the home shop use one of the best, features v cost is the Telemechanique. Because you only ever want one or even two off you can't get a good deal from a supplier. For this invertor RS do a good deal to anyone. Do a search on
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and type in 431-9178 and you get a
0.55Kw invertor complete with everything for £95.00 less vat. That will run anything up to 3/4 HP
It's also cheaper than a lot of people are selling S/H units for. I have had these and fitted them in various applications and they are good. I don't use these commercially as they are missing two features that don't matter to a home shop guy, one being you can't lock the keypad off. To the home shop guy this doesn't matter but when night shift get bored and decide to see if they can't get 24,000 rpm out of the machine then it's a different matter :-)
I know, I know:) I really should go down this route as it makes a lot of sense, but at the moment I'm still in the playing with the new toys mode where every bit of swarf that comes off without leaving chatter marks or breaking the tool is a plus.
You gotta remember chaps that I'm re-discovering skills (hah!) that I haven't used for 25 years,and I don't need to be that good yet, although as a matter of pride of course I try to be. Back then I remember taking huge cuts at high speed off nickel chrome bar when they let me play with those 'new' ceramic bits (remember them - they looked liked an oversize asprin tablet?), but that was on some pretty rigid Colchesters, and I'm happy to be a bit less ambitious now, and suit the work to the smaller capability I've got. I'm under no illusions and the truth is that the tools I've got are probably more capable than I am at the moment.
And its always more fun looking out for a bargain ( 'free' is never too much for me to pay ) like a cheap single-phase motor for 25 quid or so. As I get better and get on to some more serious work I'll probably wish I'd listened to you both, but for now I'm happy to go down the scrimp & scrounge route.
One feature I have just come across is that they are problematic if your wiring system uses a rcd (earth leakage trip). The inverter will probably cause nuisance tripping and require the rcd to be changed to a Type B device. Of course you are deemed incompetent to fit this and must get a Part P approved electrician to do so for you at vast expense.
The other feature is the ability to program a variable into the invertor so it reads rpm and not Hz. As these are single speed machines it works. Even with this facility on say a Myford with three step pulleys it's irrelevant.
They are probably missing a few more but all the home shop guy wants is single in, three out, reliability and variable speed and these give it. One added note, modern invertors have a setable parameter inside where you set the motor amps. This replaces all those curly wire and trip over loads that never worked correctly anyway. Usually they will give 10% overload for xx seconds then say stuff it that's enough and come up with a OC display [ over current ] Leave for a minute, hit stop or reset and it good to go again.
No this is the first I have seen about these although the yanks have had 110v in 220v out for a while. I have also heard rumors but again from the States. Interesting that he's not quoted input mains, got to be a fair size.
Looked thru his feedback and past sales and he does sell lower units, saw a 2Hp one for £300 and some decent deals. He's based in Nottingham but no contact numbers except a weird fax number and email. Feedback is good, only one neg from someone who can't read.
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