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Myford motor

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Nick Taylor 203/01/2017 10:19:22
102 forum posts

Hello! Long-time lurker, first time poster!

I'm a complete newbie to motors when it comes to ratings and frame sizes etc so please excuse any stupid questions!

I've had my super 7 a few months now, it came with a Clarke 1hp single phase motor which sounds like a knackered 2-stroke engine, vibrates like nuts, runs very hot and is making the machine un-pleasant to use basically.

I’ve been given a 1/2hp VFD and would like to buy a motor to replace the clarke that I can use with this inverter.

My problem is I know nothing about motor frame sizes etc. The clarke seems to me to be a B3 80 frame foot mount, 100x125mm foot print with 19mm shaft. The problem is I can’t find any 1/2hp three phase motors in this frame size. Whenever I look at motors which are advertised at direct mount for Myfords they are described as B56, I’ve looked at the dimensions for this but none seem to match the clarke that I have now.

I’m on a budget so the easy option of buying a 1hp motor/VFD package isn’t open to me.

What size motor should I be able to fit? The motor plate on the lathe has not been re-drilled or anything, and everything looks standard.



KWIL03/01/2017 10:39:27
3563 forum posts
70 photos

Ignore the physical size of your present clarke motor, you are looking for a 1/2 hp machine to match your VFD. You could call Newton Tesla 01925 444773, or Transwave 0121 708 4522 for advice, both sell motors only or complete packages.

Bizibilder03/01/2017 10:45:32
126 forum posts
7 photos

Super 7's were fitted with 3/4 HP motors originally. 1/2 HP may not really be enough.

KWIL03/01/2017 10:55:49
3563 forum posts
70 photos

3/4 hp is the correct original motor but the OP has a budget and is committed to the gift VFD. I fitted a 1hp + VFD many years ago and is the way to go.

Nick Taylor 203/01/2017 11:21:19
102 forum posts

Many thanks for the replys,

I've seen that 3/4hp single phase or 1/2hp three phase were the original specs.

Just had a look on newton tesla's website and they do a good selection of 1/2hp motors in 56 mounts.

I like the look of

I understand that it is not fully enclosed so I will have to protect it against coolant etc, will it have a cooling fan built in?

Many thanks,



Edited By Nick Taylor 2 on 03/01/2017 11:21:59

KWIL03/01/2017 12:46:41
3563 forum posts
70 photos


Not necessary to fully enclose as you will not (should not) have that amount of coolant around, you will be drowning as well! Newton Tesla are a very helpful lot and advertise to model engineers in ME/MEW etc. Go for it.

Swarf, Mostly!03/01/2017 13:27:48
682 forum posts
78 photos

Hi there, Nick,

I agree with Kwil's advice.

However, it's a good idea to fit a simple baffle plate to protect the motor from flying swarf entering its ventilation ports which will be just behind the lathe spindle nose. Some will say 'but metal swarf is too heavy for the motor fan to draw it in' - I'd say swarf doesn't always seem to obey the laws of physics! Besides, somewhere in the future you might be turning plastic and plastic swarf is a lot lighter but just as bad for the motor's innards.

My real point, though, is that fitting such a baffle or screen (sharing the motor's mounting bolts) is very, very, very much easier while you are in the process of fitting the motor, it's a real pain if it means removing a motor that's already mounted and aligned. So now is the time to think about it. As part of this topic, is your lathe mounted with it's back to the wall? If I had my time over again I'd position mine at right angles to the wall.

Best regards,

Swarf, Mostly!

Edited By Swarf, Mostly! on 03/01/2017 13:29:20

Nick Taylor 203/01/2017 15:32:35
102 forum posts

Posted by Swarf, Mostly! on 03/01/2017 13:27:48

I'd say swarf doesn't always seem to obey the laws of physics!


is your lathe mounted with it's back to the wall? If I had my time over again I'd position mine at right angles to the wall.

Hi Swarf,

Agree 100% on both counts! I find the stuff ruddy everywhere, luckily I have a knackered old vax hoover so its easy to keep up with clean up, but i have started covering my cup of tea now... or putting it on the other side of the garage!

Mounting the lathe back to the wall was a bad idea, like you I would move it if I had the space!

Many thanks for all the replies gentlemen, think I have some 2mm ally sheet which will make a nice motor guard.



Hopper04/01/2017 08:39:17
6690 forum posts
347 photos

A half horse motor should work OK. I have a half-horse on my Drummond, basically same size lathe as an ML7 and have never managed to stall it or even slow it down. Will power a .100" deep cut in steel at 500rpm no worries. In back gear it will bore a 4" diameter hole in 1" steel plate without faltering.

I would put a swarf shield on a ventilated motor though. When I pulled my motor apart a few years ago, the insides were packed solid with swarf and took quite a bit of cleaning out. It was a wonder the thing still worked at all. So I moved the motor down to below the bench, which suited my countershaft set up better but probably not a simple option on the ML7 set-up.

Nick Taylor 206/01/2017 14:36:57
102 forum posts

Thanks for all the replies gents, have now taken delivery of a 1/2hp 3 phase resilient mount motor from newton tesla.

Cleaned up the gifted VFD and had a quick skim of the user manual I found online, all wired up and worked first time!

I cannot believe how smooth the motor is, even at full speed there is zero vibration coming through the mounting. Quite a lot of electrical noise so I need to tweak the frequency settings in the VFD I think. It was being used on a planer before so some of the settings are specific to that, very fast acceleration and aggressive braking etc.

Speaking of which I disabled the DC brake because the noise when it activated was horrendous! It’s probably perfectly normal but I have no idea about these things so I’m erring on the side of caution at the moment.

Now just need to get it mounted on the lathe then knock up a motor guard to stop the chips and oil/coolant doing any damage, then it’s a look around for any spare switches I have to build myself up a remote-control panel and sort out the wiring!



KWIL06/01/2017 14:53:29
3563 forum posts
70 photos

Reset your ramp up and ramp down times to remove agressive acceleration and braking. Both at around 5 seconds not unreasonable. DC injection braking should cut in late on ramp down when almost at rest, should be quiet. Yes tweek the setting to reduce the electrical noise, again should be reasonably quiet. Jog function helpful when clocking.

Nick Taylor 206/01/2017 15:01:30
102 forum posts


Yep that's pretty much what I've done - I set the accel/decel times to 3 seconds, now have a nice steady ramp up and down.

The DC brake has a lot of different settings like time/torque and the like. It was only cutting in like you say just before stop but was VERY loud. I'll see if I can post a video of what it sounds like, but not sure if I'll get into the shop this weekend - work is getting in the way!



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