Setting wheel train on ML7

[GrottoParticipant @grotto]

I've finally decided to have a go at cutting an external thread on my ML7, but am stuck before I've even started. Hope I don’t sound too stupid….

I need to cut a 19 tpi external thread.

I've consulted Ian Bradley's Myford manual and sorted out my change wheels, but am a bit stumped as to what goes where and how to fit them so they mesh.

I need to use Set Up 2 according to the chart, and have the 40 tooth as the Driver, but can’t work out which shaft takes the driver.

I've got the 50 tooth on the lead screw.

I've got the 55 tooth on the 2nd Stud (do I need to adjust the shaft so it meshes with the 50 on the lead screw?)

I've got the 38 as the driven, & the 20 as the driver on the 1st Stud (do I need to adjust the shaft so the driver meshes with 55 on the 2nd Stud?).

I've put the 40 where I guess the driver should be.

i can’t seem to get all gears to mesh.

I can get lead screw, first Stud, & second Stud to mesh, but can’t get driver to mesh with first Stud?

 

any ideas?

I'll try to add a photo

thanks

 

 

Edited By Grotto on 25/07/2019 10:45:02

[GrottoParticipant @grotto]

Help!

[Kiwi BlokeParticipant @kiwibloke62605]

40T driver. This meshes with 38T, which is keyed to 20T, both on 'first' stud. The 20T wheel lies outboard of the 38T wheel. The 20T meshes with a 50T 'idler' on the 'second' stud, which in turn meshes with 50T on the leadscrew. My chart suggests a 50T idler. You have a 55T idler, which seems OK, if it fits – obviously, the number of teeth is unimportant. The first stud is on the higher slot on the banjo, the 'second' stud on the lower slot. So your setup looks nearly there, the driver seems to be where it should be, so it's just a matter of getting the 20T and 55T into mesh.

Meshing adjustment. Slacken the banjo clamp nuts, and swing the banjo downwards, to give you 'wriggle room'. Get the mesh of the idler 55T and leadscrew 50T wheels correct, then the mesh of the 20T wheel on the 'first' stud with the idler, then swing the banjo up to get the mesh of the 38T correct with the driver and clamp the banjo. To align with the idler, the leadscrew gear will have to be spaced outboard with a spacer or small dia. gearwheel acting as a spacer (you seem to have done this).

Don't mesh the gears 'tightly', but allow a little backlash. Some advocate a strip of thin paper between gears when setting up, to ensure some clearance. Lubricate the gears. Slideway oil is good – it doesn't get flung off as readily. Lubricate the studs too.

Hope this works – working from charts and memory, and haven't checked the maths (it's getting late). I have the luxury of a gearbox, so haven't done this very much since the gearbox arrived…

Edited By Kiwi Bloke on 25/07/2019 11:25:51

Edited By Kiwi Bloke on 25/07/2019 11:27:30

Edited By Kiwi Bloke on 25/07/2019 11:31:19 (I said it was getting late…)

Edited By Kiwi Bloke on 25/07/2019 11:38:37

[Howard LewisParticipant @howardlewis46836]

Being me, I would set the mesh between the first driving gear and the compound gear on the first stud first of all. Then set the mesh between that and the gear on second stud next, finally the mesh between the idler and the gear on the Leadscrew. This method allows the position of the Banjo to be fixed, early on.

For meshing, a piece of paper or thin card, about 0.003" ( 0.075 mm ) should be run into the mesh before tightening the stud into place, to ensure backlash, and freedom from noise and wear.

HTH

Howard

[GrottoParticipant @grotto]

Thanks

managed to get it sorted.

I didn’t appreciate you needed to loosen the 2 nuts holding the banjo(?) at the end of the lead screw.

I suspect that setting the change wheels may the easiest part of the operation. I’ve always shyed away from cutting threads using the the lathe, preferring to use taps & dies, but don’t have the correct die for what I need to do so will give it a go.

[Kiwi BlokeParticipant @kiwibloke62605]

Glad you're now all geared up. My apologies, my chart in fact suggested a 55T idler, not 50T as I said. I should have gone to bed instead of posting when tired…

Cutting the thread is easy enough – don't be scared. There's plenty of info out there. It's best to ensure that the cut is made primarily by only one side of the tool, either by making a small lateral movement for each in-feed, or by feeding down the flank of the screw, by setting the topslide round by half the included angle of the thread. Take a very shallow cut first, and check the pitch is what you intended, then gently does it…

Good luck.

[GrottoParticipant @grotto]

Turned out to be less difficult than I’d anticipated.

Thread isn’t pretty or precise, but works fine. I had threaded the inside of some ancient conduit using a 1/4*19 tpi tap, and needed to cut a thread on a bar to fit in it but had no die. I think I cut the tread a little too deep on the lathe, but l feel more confident for my next effort.

[Pete RimmerParticipant @peterimmer30576]

Posted by Howard Lewis on 25/07/2019 11:54:31:

Being me, I would set the mesh between the first driving gear and the compound gear on the first stud first of all. Then set the mesh between that and the gear on second stud next, finally the mesh between the idler and the gear on the Leadscrew. This method allows the position of the Banjo to be fixed, early on.

For meshing, a piece of paper or thin card, about 0.003" ( 0.075 mm ) should be run into the mesh before tightening the stud into place, to ensure backlash, and freedom from noise and wear.

HTH

Howard

I do it the exact opposite way Howard. I mesh the gears from the leadscrew up. That way the last thing you do is set the last meshing by securing the banjo swing bolt.

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