Myford ML7 Backgear jammed

This is my first post - please be gentle.

I have purchased a Myford ML7 (s/n 20206) and a small number of accessories. The lathe has seen a lot of work but is in reasonable condition with the former owner having replaced the leadscrew and generally having looked after it.

I have access to a manual for the ML7 but I find that I am unable to use the backgear. I have used the references in section B of the manual to identify various parts.

The problem is that when I loosen the cap head screw (B19) and move the backgear key (B16) to allow the Vee cone pulley assembly (B14) to freely rotate on the spindle (B24) - it doesn't freely rotate. In fact it doesn't rotate at all. Consequently when I operate the tumbler release lever (B43) to engage the backgears it locks the spindle. It is as if the Vee cone pulley assembly has seized on the spindle. No amount of firmly applied force (by hand) will get the Vee cone pulley assembly to spin on the spindle.

Has anyone else encounted this problem?

Have I overlooked something?

How do I fix this?

I have removed the oil nipple (B15) on the vee cone pulley assembly and have introduced into the hole as much wd40 as it would hold but after two days this has had no effect. I have checked that the backgear cluster (B50) turns freely on its shaft when not engaged.

Looking forward to your imput.

Reply to
ungifted amateur
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Two things come to mind. First is that the spindle may have been run without lubricant and seized. More likely is that the spindle is seized from the dried up mung of oil that was there but never got used, essentially varnishing the parts together.

Have you a heat gun? The WD40 and some heat might do it. I would suggest a temperature in the range where it is uncomfortable to leave a hand upon the part, but not to the smoking oil range. A hair dryer or a proper heat lamp would do it, though it takes a bit of care to get enough heat out of a hair dryer without cooking the thermal fuse.

Worst case scenario. You pull the spindle assy off the lathe and see to whatever you must on the bench rather than in place. Nothing to fear but fear itself, eh! IIRC the ML7 manual covers the removal and installation. As I remember, there was nothing to it other than to take care to not introduce grit between the spindle itself and the bearing surfaces on assembly, and to take care not to overtighten the caps.

Cheers Trevor Jones

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Trevor Jones


Thank you for your prompt reply.

I immediately tried the heat gun approach and used a high power hair dryerheated the vee cone pully assembly to a point where it is too hot to touch (although no burning oil fumes) and still the pulley cannot be moved.

Am loathe to remove spindle unless I have tried all options. I took the name ungifted amateur for a reason

Assuming that the backgear was run without lubrication and the vee cone assembly has seized on the spindle, will I need a new spindle and vee cone assembly?

Reply to
ungifted amateur


My pulley has a oil "port" to lubricate the bushings. I imagine that yours does too. You might try *forcing* a solvent in there in case it is a matter of being "gunked up", as Trevor suggested it might be. If that works, you will need to displace the solvent with the correct oil, but that would be less work than pulling the spindle. Nothing to lose.


Reply to
Bob Engelhardt

Hard to say without seeing it.

It will also depend a lot on whether the parts can be separated without much in the way of violence.

In any case, the spindle will have to come out, if the parts cannot be freed up in place. If it does come to violence, I'd suggest a careful cost comparison of the parts, and a right effort to restrict the damage to the less expensive. Offhand I'd think that that would mean cutting the pulley, rather than the spindle.

Before resorting to cutting things, though, I'd suggest some cleaning fluid or solvent and a good washing down of the area in question. Have a good look over all the bits and peices with a close eye on the parts manual, looking for "extra" screws or the like. I have resorted on an occasion or two, to prying parts apart, only to find that some wiser soul than I thought that a second setscrew under the first was appropriate. I have also found the odd user modification made to lathes by folk that saw this as a way to get an otherwise non-runner running, such as the pin that was quite tidily placed in the clutch of my current Super 7. It was there when the previous owner aquired it, and he did not know that there was supposed to be a clutch there.

Know anyone in your area that can help you out?

I think pulling the spindle is not avoidable from the sounds of it, and it really is not something to fear. A nice clean towel or cloth to lay the parts out upon, and keep an eye on the shims under each of the caps, and there should be no worries.

Once the spindle assy is removed, there is opportunity to try a few other things before cutting parts.

With all the screws removed, the drive belt or a strap wrench can be used to attempt to turn the pulley while the spindle is held securely (soft jaw liners in the vice, wood blocks, or even placing the chuck or a faceplate on the spindle and securing it to something solid).

Heat can be applied while so doing.

Some judicious tapping with a soft faced hammer might be in order.

Or you can just use the lathe as is, though that leaves you running pretty fast for some stuff.

Cheers Trevor Jones

Reply to
Trevor Jones

Trevor and Bob

Thank you both.

I will attempt to follow your lead. I will try to force more WD40 into the union through the oil nipple screw hole and allow the rest of the week for it to have an effect. If not I will attempt to remove the spindle and remove the various components as per the manual.

I will post the results when I have finished if I haven't drowned in WD40 beforehand.

regards ungifted amateur

Reply to
ungifted amateur

--My Super 7B has experienced similar problems and I've been rebuilding it sporadically over the past few months. One thing I've discovered is that it tends to bind up more when it's been on for a while and when it's warm. Also, there's a tendency for it to bog down when the load is heavy along the spindle axis; i.e. when drilling a big-ass hole with, say, a 1/2" bit. Armed with this bit of info I backed off the two nuts at the left hand end of the spindle; i.e. I reduced the load on the taper bearing at the front of the spindle. This made a huge difference and it runs much more easily now. Not sure how much of this you can apply to your predicament, but you might just stick a barring tool in the slots in the nut and ease off a bit. Then make *sure* the Myford hand-pump oiling dingus doesn't have a plug of old oil keeping it from working properly, give the lathe a good dousing of oil and let 'er rip. --Now, if all of the above doesn't help you'll have to tear it apart. It looks daunting, but if you've got the manual in front of you while doing it it's not so bad, heh.

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I don't think WD40 is the best penetrating oil, it is more of a water displacer. Try another brand. I have had good results with Kroil. see

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Uncle George

Reply to
F. George McDuffee

It is amazing what vibration over a long time will sometimes loosen up. It might help to just use the lathe for a while with the lock released and the siezed area lubed as much as possible. I have also found that tapping/forcing along the axis will sometimes get things moving when rotating will not. If you can even get any movement in any direction it will eventually come free unless it is seriously gouged. I am not familiar with your lathe but some spindles can not be removed without sliding them from the pulley.

Lots of Luck, Don Young

Reply to
Don Young

Thank you to all who replied.

I may not be able to fix this problem but I now am far better informed as to the problem and it's possible solution.

ungifted amateur

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ungifted amateur

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