Back gears and tailstock quill lock myford ml4

Edited By Jon Cameron on 13/04/2018 21:58:15

Martyn and Jon,

I think there is some confusion here, which I would like to correct if I may.

The Back Gears refer to the cluster gear pair [in the case of an ML 4 lathe for example, there are other variations on other lathes] that engage with the spindle bull wheel at the chuck end of the lathe so that low spindle speeds can be obtained.

The gears at the remote end of the lathe that couple down to the leadscrew are invariably called the change gears for the good reason that they are changed to alter the rotational speed of the leadscrew with respect to the spindle and chuck holding the work

To address Martyn's two problems; first the back gear. The lever operating that is fitted on a short eccentric shaft so that the gear cluster can be swung into and out of engagement. From memory I think it fits through a split hole in the headstock which allows a nip bolt to adjust the degree of clamping to prevent the problem you describe. Strip it out and clean it up, there could be a paint dribble affecting the fit on the eccentric and spoiling the operation.

Clamping the tailstock quill is done by the short handled lever on the front end of the tailstock which I think squeezes a pair of shaped plugs together that fit over the outside of the tailstock quill. Wear on one or both of the tapered faces allows the plugs to bottom out on each other and the clamping effect is lost. Extract them, turn or file down the plain faces next to the tapers to restore the clearance and refit.

The gearing tables are well advanced and very comprehensive, they are equally applicable to non-gearbox ML7 lathes, I shall be releasing them soon as a pdf at £2.50 a copy on behalf of the Remap charity that does good work in making life easier for disabled people of all ages.

I shall post again on this thread with instructions on how to order the pdf.

Regards

Brian

Edited By Brian Wood on 14/04/2018 11:25:06

Martyn very sorry about the confusion I've caused.

On your back gears!!! A 1/8" Allen grub screw and a 3/16 Whitworth spanner is all you need.

Undo the Allen bolt in the pulley.

Tighten the Allen bolt into this hole on the bull gear

Then undo the 3/16" Whitworth bolt on the cam lever

Bring into mesh and tighten bolt again, (note position of cam in below photo).

This is your change gears as I seem to be causing confusion I'll clear it up. Though my point on your photo is still valid, you need to change that 18Tooth gear on the tumble reverse for a 20tooth gear, so your tumble reverse does not effect the gear ratio.

Now your tailstock, as far as I am aware, (never had to investigate as mine worked). The tailstock is clamped into position  against the oppsite side of the bore, the handle on top operates another cam which then comes out from the side of the bore to push it against the side of the bore.

If needed I can strip mine down and take photos of its operation if you need me to. 

Edited By Jon Cameron on 14/04/2018 13:53:23

You do know which photo I'm on about don't you in your album. You have labelled them up with the tooth count, but on the tumble reverse you have a 20tooth gear on one side of the gear, and 18tooth on the other. I have a spare tumble reverse from an ML7 and was planning to fit it at some point it has two 20tooth gears this way the gear ratios will be maintained in either direction of operation.

You are correct so long as there is not a reduction, and all the gears in between are just idler gears. But how you have it set up now if you decide to use a reduction gear train for screw cutting or fine feeds, then you'l be going quicker one way than the other.

Jon,

I'm sorry but you are confusing the situation. The two tumbler reverse gears are idlers and have no effect on the gearing ratio, regard them as a belt linking two pulleys, it can be of any length The sizes in Martyn's reverser are correct, you would not be able to fit a 20t in place of the 18T.

Martyn's album picture shows a 20T gear linked to his erroneously labelled 26 tooth gear; which is in fact 25 teeth as we know know; that 20T gear is the MANDREL gear and forms the first gear in the drive chain down to the leadscrew.

Your pictures of the back gear clamp bolt to grip the eccentric were helpful, I had forgotten the exact arrangement there

Regards

Brian

I need to go check that tumble reverse I have then as I'm sure that's x2 20 tooth gears, if not then I have an extra sized gear that I didn't know I had.

I'm glad something was helpful in my above posts, I'm not sure if that bolt is hidden by the back gear cover. As mine doesn't have one fitted.

Did no one notice the spanner was even posed in the correct direction lol righty tighty lefty loosey

As promised.

A NEW series of screw cutting set up tables for Myford lathes with 8 tpi leadscrews

For a read only pdf copy of these new tables, applicable to ML4 lathes [and similar copies of them] and the non gearbox ML7 lathes, please order through Paypal using the identtfication [email protected]

The tables are comprehensive. They cover extended imperial and metric pitches, BA, DP, Module and a number of lesser known pitches useful to restorers of antique machinery and weapons. There is also a table for the US Waltham watch screw series for 110 -254 tpi

The item is known as Remap Gears, the cost is £2.50 and all proceeds will go to the REMAP charity

A copy will be sent to the email address you use in the order

Regards Brian