Small Myford problem

Hi all,
I have just bought a myford ML7 lathe, good condition and a very good price,
despite having a slight problem. (Well 2 actually, but I am asking about 1
of them here)
The problem is that the cross slide nut is not fitted or available. I have
checked the compound slide nut and that seems to be exactly the same, so at
least I can use it (apart from the other problem).
The nut on the compound slide looks to be made of aluminium. I am assuming
that if I fabricate another, it can be any material that is not ferrous, so
I could use brass, phosopor bronze etc. Am I assuming correctly?
As it is an acme nut, I am going to have to screw cut it. Trouble is, I have
not cut acme before. (I have cut square). Any tips?
Alternatively, if anyone has a cross slide nut lying around, not doing much,
I could be interested. (Saves cursing with broken internal threading tools,
mismatching threads etc.)
The other problem (I thought I had solved) is that it is currently 3 phase.
I bought what I thought was a single phase motor, though when I plug in the
motor, it buzzes. If I hand turn the armature then switch it on, it rotates
quite slowly, and I can stop it with my fingers. Doh!!!
Cheers.
Dave Colliver.
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Reply to
Dave
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Don't bother. They're about a tenner new from Myford - although phone them rather than email.
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Doesn't sound like single phase! Single phase motors should be easy to find or go the whole hog and run the 3 phase motor from an inverter - ebay usually has ones for not too much money.
Charles
Reply to
Charles Ping
I have two or three of them kicking about somewhere that I bought about six years ago and never used. Ben
Reply to
Ben
I think I only need one.
How much do you want for one? (I can pay by paypal if you want...)
Thanks. Dave. ~~ Customise your internet experience
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Reply to
Dave
Ben wrote in message ...
Can I buy the other two from you Ben?
£4 via paypal if that is OK
Bob
Reply to
Bob Minchin
There are two different threads for the cross slide nut. Mine is metric, even though the lathe is 1952, it has been "modernised".
The nuts break if you try to cut backwards (i.e. towards you) and you force the cut. Then you find out that Myford operate some continental holiday system..........
Reply to
Martin L
On the subject of motors, I need a 3 phase 1/2 hp base-mounting motor for one of my machines. If Dave (or anyone else ) has one spare for not a lot of money I'd be very interested.
Cheers
Mike
Reply to
Mike Crossfield
Where abouts are you Mike?
I am Nottinghamshire. There is apparently 3 phase to my house, but seemingly not wired in. At some stage, I will be wanting to get 3 phase into my workshop. (I have a 3 phase boxford and myford, boxford has a single phase motor on it, the myford now has no motor on it (I took the 3 phase off it...))
If I can get a 1ph motor for the myford (and I can do reverse with it) then I will consider selling the 3 phase for that (though I don't know how powerful it is without looking at it...). It won't hurt my feelings if someone else comes up with the offer of a 3 phase.
For the person mentioning about the screw threads for the myford, mine is a 10tpi (0.100 in the dial) which now means I have both a metric and an imperial lathe.
Hopefully, the nuts Ben comes up with will be imperial.
Best regards, Dave Colliver.
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Reply to
Dave
Hi again,
Did you manage to find those nuts Ben? I am not in any hurry but I thought I might mention it.
That motor I bought, I have now had a chance to have a look at it. It is a FIMEC motor. It has a spec plate on it. It is single phase, but looks like 60hz, though I imagine it should work on 50.
The RPM is 1400 and I think the HP is 1.
On the top of the motor is a box. In it, there is a connection block. Coming out from inside the motor to the block are 4 wires. 2 green and 2 black. They are connected thus...
green nothing nothing
black green black
From the plug (which is suspect is not wired correctly to the motor) It is connected thus:
Live nothing nothing
nothing Neutral Nothing
Earth is connected directly to the motor chassis.
On the spec plate (which has been scratched) is a diagram for connectivity, though I cannot make it out. However, it looks like the motor should have a capacitor on the connection block, between the two "nothing" positions on the top line. It looks like you vary the wiring in the block, around the capacitor to change the direction. However, there is no capacitor.
Can anyone help me with it?
Other info on the spec plate...
TIPO: H80c4M N.: ISCL.H/0587 CV: 1 GIRI: 1400 KW: 0.75 SER: INT uF: (empty) H: 0/60
V: 220 A: (Scratched)
Thanks. Dave. ~~ Customise your internet experience
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Reply to
Dave
Hmmmppphhh!!!!
It looks like the cross slide screw is bent slightly. Perhaps this is why the nut was missing in the first place.
I have put in the nut from the compound slide temporarily (as that will be the least used slide, especially as the main leadscrew has a dial on it) in the hole for the cross slide, wound the cross slide in and found that it gets really tight when the cross slide reaches to within about an inch of its end travel. At the same time, I notice the screw support is being moved up and down.
Still, for what I paid for the machine, it is still a bargain.
I will be going to Elvastan (Derby) tomorrow, there is a steam rally on. If anyone here sees me, say "Hi". I will be fairly easy to spot. I will be wearing a T-Shirt with
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written on the back of it.
Best regards, Dave. ~~ Customise your internet experience
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Reply to
Dave
From the Data Plate the HP is 1 (0.76kW = 1HP). If the speed is quoted as 1400 then it is almost certainly rated for 50Hz. (It would be around 1700RPM if it was a 60Hz motor.) Service rating is intermitant - probably not a problem on a Myford as the usual motor fitted to an ML7 is only 0.5HP. More of a problem might be that on an ML7 with no clutch you will be stopping and starting the motor too frequently and could burn out the starting windings. With nothing quoted for the capacitor value it is almost certainly not a capacitor start or capacitor run motor - even worse for a clutchless machine.
Dave wrote:
snip
Reply to
Dick Ganderton
Dave. Might see you there if it's not pissing down. If you see a tall, fit good looking bloke that won't be me.
The cross slide screw will most probably be able to be straightened. I've done quite a few that have got bumped in transit. Something that small can usually bent by hand and a check with a dial gauge to get straight. Can't help with the motor, just been and had a look in the Fimec book but it's all three phase stuff. The local Fimec agent is against you at Mansfield, MGC Systems.
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Regards,
John Stevenson Nottingham, England.
Reply to
John Stevenson
Can't be sure because there's not enough info. First have a look inside to see if there's a centrifugally operating starting switch. If there's no switch it's capacitor run. If a switch is present it's capacitor start or split phase start.
Make sure you've got a good fuse in your supply. Apply power for a few seconds, neutral to the green/black terminal, live to the separate green and black terminals linked together.
If it starts and runs normally it's split phase
If it just buzzes or has very little starting torque it's capacitor start or capacitor run.
Let us know how you get on.
Jim
Reply to
pentagrid
Hi,
I connected each black to each green and started it. It did rotate but quite slowly. Looking from the shaft end, it rotated anti-clockwise.
I couldn't find any centrifugally operating start switch (not that I know what one looks like...).
From my diagram, there are six places for connections.
1 2 3
4 5 6
The original setup was
1 green + live 4 black 5 green + neutral 6 black
4 and 6 had wires on them, though they had been cut off. I suspect that the wires were for reversing the motor.
Thanks. Dave. ~~ Customise your internet experience
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Reply to
Dave
We obviously missed each other then, though you may have seen our car (if you walked around the vintage car section). Two cars had
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posters in them. The one on the end of the row was mine. (The other, my dads.)
I had a look at the website. Not much technically (and their website layout was all broken) so I sent them an email asking for a little help.
Any suggestions as to how to straighten out the screw? What I have been trying is on a flat plate and finding the high spot, grabbing in a vice and pulling against the high spot, check and repeat. Getting there but not perfect.
Cheers. Dave. ~~ Customise your internet experience
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Reply to
Dave
Dave wrote in message ...
Dave,
Ben already replied saying he could not find the nuts seehis post 27/ june at 21.42
Bob
Reply to
Bob Minchin
Hi Bob,
Yes, I already saw that post. As it was a few days, I thought I might remind him (whilst I was posting a message to the group...) in case he had his hands on them again since.
Best regards, Dave.
Reply to
Dave
Unless dud it's a capacitor run motor- my guess is that it's a motor that has been dumped because the capacitor blew up!. Because both pairs of wires are coded green and black it's probably a symmetrical winding and either winding can be used as the capacitor fed phase.
Check the resistance of the two windings. The higher resistance phase is the capacitor fed phase.
The problem now is the capacitor. For a symmetrical winding I would expect 30 to 40 uf or maybe half that for an asymmetric winding. The capacitor must be suitable for continuous AC working- not an electrolytic. Paper or plastic dielectric and at least 250vac working.
The lower resistance winding should connect directly across the supply. The second winding should be fed via the capacitor.
Jim
Reply to
pentagrid
Worked it out...
I straightened the screw a bit better than it was (though I may have bent it before I even started...) though it probably wasn't the screw that was causing the problem.
The handle support looked like it had been bent slightly. When I took that off and stuck the screw into the handle, the face that mates with the actual crossslide table was not perpendicular to the screw, so I milled it and that seemed to allow the screw to line up with the hole better. I put it all back togethor and found it was still tight.
Eventually, I discovered that the handle support was slightly lower than the dovetail, so it will have been this that was causing the tightness.
However, I think it was a combination of all three. I suspect the last user (wether it was the owner or someone who borrowed it.) had dropped something fairly heavy on the handle support. When I got the lathe, the handle support was loose and the nut was missing.
All I need now is to sort out the motor and get a replacement nut to replace the one I borrowed from the compound slide (oh yes, I also need to get some M6 screws to fasten the compound slide unit to the crossslide table. The previous user looks like he lost his screws and just jammed another (not M6) screw in. Prat.) Apart from that, the lathe looks to be in good condition and is fairly clean.
Best regards Dave.
Reply to
Dave

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