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tumbler gear arbours on a myford

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bricky23/04/2022 11:55:45
575 forum posts
68 photos

Following the debacle over the jiggered lathe I am trying to remove the arbours but with little success I don't know wether they are right or left hand threaded and there is little to get hold of .Has anyone had to remove these arbours,if so I need suggestions as they have been soaking in WD40 for two days and I can't shift them.


Hopper23/04/2022 12:15:49
6404 forum posts
334 photos

They have locknuts on the back of them. You have to take off the main tumbler output gear, after removing the small screw and washer in the middle of it. Then pull the whole tumbler reverse lever assembly off the stud it pivots on. Then you can get at the two 1/4 BSF hex nuts on the back of the reverse lever, one on the end of each Tufnol gear's stud. Undo those nuts, the normal right hand thread way, ie counterclockwise. Studs should then come straight out.

Assuming its an ML7.

If it's a Super 7, I have no experience, but it looks like the studs are a press fit. So you take the whole lever assembly off and press them out from behind. (Press being the technical term for whack with a hammer and brass drift while supporting the gear on a suitable round thing.) No unscrewing involved by the looks. To get the lever assembly off, it looks like you have to undo a grub screw somewhere in the headstock to let the pivot stud out.

Once you remove the old gears and install the new ones, when you press the studs back in, you will have to make sure to leave a bit of end clearance so the gears don't bind. Five or ten thou should do it.


Edited By Hopper on 23/04/2022 12:31:55

Edited By Hopper on 23/04/2022 12:36:27

Edited By Hopper on 23/04/2022 12:45:33

Swarf, Mostly!23/04/2022 12:19:07
668 forum posts
73 photos

Hi there, Bricky,

Why do you need to remove the arbors?

If you look at the illustrated parts list (aka 'exploded diagram' ) which is downloadable from the Myford web-site, the arbors appear to be an interference fit, not threaded. So you'd need to press them out.

The illuatrated parts list is here: exploded diagram

Best regards,

Swarf, Mostly!

Edited By Swarf, Mostly! on 23/04/2022 12:21:02

Swarf, Mostly!23/04/2022 12:27:33
668 forum posts
73 photos


I defer to Hopper, I misread the exploded diagram (I've never had to take my arbors out).

The bit I thought was the interference fit, I now see is the part on which the gears run.

I still wonder why Bricky wants to take them out?

Best regards,

Swarf, Mostly!

Rod Renshaw23/04/2022 12:29:15
376 forum posts
2 photos

It seem possible that different models of Myford, and perhaps different years of manufacture, have different methods of fixing so need to check.

By the way, WD40 is really a de-watering oil rather than a penetrating oil and products like Plus Gas seem to work much better for disassembly.


Hopper23/04/2022 12:34:46
6404 forum posts
334 photos

PS just added a bit to my earlier post on the press-in type of Super 7 studs. Please clarify if you have ML7 or S7.

Swarf, he wants to take them out to replace the Tufnol gears.

Grindstone Cowboy23/04/2022 12:34:59
858 forum posts
64 photos

The locknuts are fairly obvious if you look at the back of the assembly (on an ML7 at least), so if there aren't any, it may be that a differerent method was used on that particular machine. Seems unlikely though.

Swarf - I think Bricky needs to replace a stripped gear, there's another thread about it.


Edit - Hopper got there first

Edited By Grindstone Cowboy on 23/04/2022 12:44:26

bernard towers23/04/2022 13:25:39
619 forum posts
109 photos

If it’s a S7 mine are pressed in and would think that the pins are shouldered. Looking from the back it looks like there is a large dia bush with a smaller dia pin in the centre. I’ll have a go at pressing one out and see what it’s all about as I don’t use this bit anymore.

bernard towers23/04/2022 13:36:49
619 forum posts
109 photos

37a96058-ddf3-43cf-a439-9ec50b13e1ab.jpegUpdate, pins are a press fit with NO shoulder and the smaller pin in the rear is a blanking plug for the oil hole 1f4aa090-5de8-4056-8345-978a0cc86f9a.jpeg

bricky23/04/2022 19:11:36
575 forum posts
68 photos

Thanks Bernard that explains it .My lathe is a S7 Plus large bore,thanks to all who replied.


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