Ml4 change gears

Hello Martyn,

Don't buy gears yet, it will be useful to know what you have already

I've sent you a PM. To read it look at the Inbox, top left hand side of this page and you will see it flashing, click and follow the directions. I can't post photos or tables in this format, there is some odd compatibility problem but I can do that sort of thing with email of course.

Regards

Brian

Wait until you get Cleeves' book on Screwcutting in the Lathe. No need to buy any odd sized gears if you use his charts for cutting metric threads with 8tpi leadscrew. He uses only the standard set of 20T to 70T in steps of 5. You don't even need the 21T that the Myford chart calls for.

The accuracy of Cleeves' charts is given for each gear combo and is usually between one in 3,000 and one in 8,000. IE, one thou per three to eight inches. That is WAY more accurate than your mass produced leadscrew would have been when new, let alone after almost a century of use.

The secret to Cleeves' method is using compound gearing, one or two sets of gears mounted in pairs on the same spindle. With the standard gear set there is something like 700,000 possible combinations of simple and compound and double-compound gearing available to choose from. Good old Cleeves whittled the choices down to the useable few for us!

I've used Cleeves' method on my 1937 Drummond imperial lathe to cut metric threads many times and never found the need to use fancy 127, 63 or 47 tooth gears.

Edited By Hopper on 10/04/2018 01:25:27

Jon Cameron,

Send me a PM please with your email address, I can't post tables or photos to this format, some irritating problem of incompatibility hides the appropriate button to upload.

A recent computer change had scrambled my tables on reloading from backed up data so it will be a little while before I can send, they need to be redrawn I'm afraid, so patience please

Regards

Brian

Here's a table I put together using an EXCEL program I wrote for a lathe with an 8tpi leadscrew:

This just uses gears from 20 to 65 in 5 steps. The first driver is on the end of the mandrel (or the output from the tumbler reverse). This meshes with the first driven gear which is pinned to the next driver on the first stud which meshes with the next driven which is pinned on the second stud to a driver which engages with the last driven on the end of the lead screw. The gears can be arranged in any order, just making sure that the drivers and drivens are the correct numbers of teeth. The table is entirely theoretical, whether the combinations can be made to actually mesh depends on the actual lathe and banjo design.

HTH,

Rod

This may be helpful to you, a full list of the different combinations for various pitches.

metric leadscrew

http://homews.co.uk/page31.html

imperial leadscrew

http://homews.co.uk/page30.html

Work out which gears you have, make sure the tumbler gears equal a 1:1 ratio and then the rest of your gear combination can be worked out from looking up the chart.

Edited By Jon Cameron on 10/04/2018 16:15:05

One word of warning, don't try to remove a chuck by engaging Back gear to lock the spindle. A friend of mine used to do this with his ML4 and broke several gears.

Clamp a bar across the chuck jaws and hit the end with a mallet. The sudden shock(s) should free it off, using the inertia of the spindle as a " brake". The converse to this is not to run the chuck onto the thread under power.

H T H

Howard