Myford Super 7 - Powered Crossfeed

Hi Guys,

Just trying to get a new toy working. Have managed to get hold of a Myford Super 7 with gearbox and powered crossfeed to replace my standard Myford 7. It had been partially dismantled to reduce weight for movement. Have repainted cabinet and just managed to get lathe onto cabinet and cleaned it all up. Now trying to fit the cross-slide. It goes on partially then stops. I'm certain this is because the key in the little drive gear is not lining up with the keyway in the cross-slide feed screw.

What is the trick/technique to get this fitted and how do I not have to go through this issue if I use the Myford Taper Turning attachment that came with the lathe.

Thanks in anticipation,

Colin

From S7 manual:-

Also, George Thomas explains how to solve this problem simply on page 281 of his  book "The Model Engineers Workshop Manual".

Best regards,

Steve.

Edited By Steamer1915 on 04/10/2016 18:54:06

Colin

This is from the S7 manual :

...If the feedscrew becomes disengaged from the pinion which slides on it difficulty will be experienced in lining up the pinion with the key way in the feedscrew. If this does arise remove the screws securing the cross slide end bracket and push the cross slide so that its front end is roughly flush with the front face of the saddle.Remove the screws which secure the crossfeed nut and withdraw the nut and the pinion. Screw the nut onto the cross slide feed screw.Push the pinion onto the feed screw. Assemble the feedscrew with feed nut and pinion to the saddle rotating the feedscrew sufficiently to allow the pinion to engage with the mating gearin the apron. Replace the screws that secure the feed nut. When finally tightening the screws which secure the end bracket , the feedscrew should be in its innermost position.

If you wish I can supply info on using the Taper attachment

Norman

Oh gee Steve I wish I' d waited!

Norman

Sorry Norman!

Steve.

Steve, Norman,

Found the GHT article. It made sense, but could not make it work. It felt as though the leadscrew was engaging but then locked up. In the end did it the Myford way. Removed the handle and leadscrew from the cross-slide, removed the bearing and gear from the saddle and fitted the screw and then the gear to the leadscrew, Very hard to het started but once into the bore and the key engaged it all moved okay, so replaced the whole assembly back on carriage. All now okay.

Just have the electrics to suss out now.

Will post a few pictures tomorrow and ask for guidance. Being red/green colour blind does not help matters.

Norman,

Would very much appreciate the info on using the taper turning attachment. I have one piece missing which is the adaptor which sites on top of the taper slide and bolts into the bracket on the cross-slide. I guess I'll have to make this bit.

I have fitted the taper turning bracket about an inch lower that the original mounting holes ( a second set had been drilled by the previous owner). This will give me space to fit magnetic scales for the DRO. Unfortunately the glass scale on my standard ML7 is too bulky.

Thanks for the help.

Colin

Do read this thread from a few years ago "Carriage (Myford Power Cross Feed stop)" , Niko.

Colin

I have sent you a PM

Norman

Guys,

Would like some guidance on wiring up the motor to Myford NVR switch.

Motor Spec plate:

Does this imply it can be wired either 440 3 phase or 240 single phase. or is this a 3 phase only motor I do have three phase but intend running this on single phase using a Myford 'Tripus' Push Button starter with NVR and overload release and reversing. ( I am aware of the issues of reversing a screwed on chuck).

Wiring Info plate on cover plate:

Current wiring to motor:

The motor currently has a 4 core cable connected:

RED to A, BLUE to B, BLACK to C, YELLOW?GREEN to Earth ,nothing to N,

So I am working on fact it is wired Delta.

:

NVR Switch Wiring Diagram

This wiring diagram implies five wires (including the earth).

Cables from NVR switch:

As I intend putting a junction box between the motor cable and the NVR cable could some kind person tell me which colour cables, OR do I need a new single phase motor.

Thanks,

Colin

Colin,

This motor will only run on 3-phase, either at 380/440 volts (Star connection) or at 220/250 volts (Mesh (more often called Delta) connection as shown on your cover plate.

You can see the Phase rating on the motor data plate at the bottom to the left of the rivet  as  "PH      3".

The colour codes on the cover plate refer to the internal wiring of the motor, and there are 3 wires visible connected to the N terminal, so it is connected for Star at 380/440 volts 3-phase

How it has run with only 2 input wires + earth is beyond me, but perhaps it hasn't.

Edited By Robbo on 05/10/2016 21:56:37

Edited By Robbo on 05/10/2016 21:58:51

You can get a three phase motor to run on single phase, but unless a suitable capacitor is added to connect to the other phase, it won't self start. I have run a shaper with the power just applied between two phases, but had to give the pulley a good push with a foot in the correct direction to start it. You don't get the full rated power from the motor either, but this is rarely a problem, you get enough to be useful.

My suggestion for the Myford would be to get a VFD for it. This would enable you to run the existing motor from single phase and would give a speed control as well, which is always a good feature on a lathe. It would also give reversing, and since a VFD will ramp the speed up and down slowly, will not tend to unscrew the chuck if you forget and reverse while it is running forward. The cost would probably be comparable to a single phase motor.

John

Robbo,

I have a feeling now that it had not been used with the lathe. I have had a single phase motor given me (which was probably the one fitted to the lathe) but the previous user has somewhat butchered the pulley and keyway with a combination of a non standard pulley with allen screw onto the top of the keyway and a couple of screws in from the side to try and make the pulley run square. It wobbled to high heaven when motor run on the floor to test. I managed to fit the correct pulley but cannot get it to lock in the correct place on shaft. But having then fitted the motor and powered it on all it would do was run very slowly. Switched on and off a couple of times, once in ran at proper speed but never again. So unless can work out why it will not run at speed, this one is most likely scrap.

I do have three phase but having just spent out of the proper single phase NVR switch, I don't really want to throw this away and fit 3 phase starter switch etc. Only other possible choice would be use the 3 phase motor and fit a VFD. Possibly same cost as new single phase motor. which is the other option.

Colin

Colin, depending on what sort of motor you have, I'd suggest, either a sticky centrifugal start switch, or dirty contacts on it.

That switch as shown on your circuit diagram is for single phase only. Also the picture of your motor terminal box shows it is wired in Star, I can see 3 wires on the N terminal, that is OK for 415 volts.You say you have a 3 phase supply, so why not obtain a proper motor starter fitted with No-Volt release and run it that way. .You would need a triple pole change over switch to get reverse. But if you do, ensure that you inter lock the starter and 3 pole switch so that you don't inadvertently try to go instantly from forward to reverse.Alternatively, as others have suggested connect the motor in Delta and get an inverter, which in my opinion is the way to go. I/we fitted a Huanyang inverter to my friend lathe and he is over the moon. John

As a further thought you might want to consider under what circumstances you will need to run your lathe in reverse.

There are some but, to date (many years!), I've not found it necessary !

Norman

( Still trying to sort the scanner!)

Edited By NJH on 06/10/2016 13:35:27

Boring and threading blind holes

John,

I must admit I'm coming to the conclusion that the inverter would be best. I'll try and do some investigation before the Midland show. I had all ready modified the cabinet to take the Myford NVR switch prior to painting, but have checked ant the pendant control (for example with the IMO XKL inverter) will fit in the same space. There is plenty of space in the cabinet for the main inverter unit.

I have just checked the 3 -phase motor and it runs nice and quite in either direction. It is a Brook Crompton Parkinson motor of 370watts, 1425 r.p.m.

Colin

Boring and threading blind holes

Quite correct Neil but not something I have yet needed. The problem with the Myford is that the chucks are the screw on variety so there is a risk ( maybe small?) that the whole lot may unscrew and fall on your foot!

N