Change Gears on Myford ML7R

Hi, I am trying to figure out the gears in my gearbox to thread 24 TPI. I have the gear chart and the manaul, however its says to use 20 tooth driver, 70 tooth idler, and 60 tooth on the lead screw. The problem is they will not fit in the configuration it shows on the chart? If anyone is familiar with this machine any help would be appreciated. Thanks,

Mike

Hello Mike,

Welcome to the forum, I hope you will find it helpful and informative. Turning to your question, I don't see your problem yet, you say gearbox which already caters for 24TPI as a built in setting.

Or is this a non screw cutting gearbox lathe? If that is so, then the gearing you list of 20 driver on the mandrel with a 60 driven on the lead screw, linked by a 70 idler wheel is quite correct. You do have to rotate the gearing quadrant and move the stud position [for the 70 idler] about to get the wheels to mesh; maybe you hadn't appreciated that.

Regards

Brian

Hi Mike,

Have you a manual? You need to use configuration 1 on the diagram leading up to the chart which just calls for one of the studs to be on the banjo. On this stud is mounted the 70 tooth gear along with another one just to make up the thickness (any one will do). It's easier if you remove the other two studs from the banjo but you can sometimes move them to the ends of the banjo out of the way.

You need to put the leadscrew spacer outside the driving gear so that it can mesh on the same level with the driver and idler gear. With the banjo slack, position the 70 tooth idler so that it meshes with the leadscrew gear and tighten the nut on the stud and then position the banjo so that the idler meshes with the 20 tooth driver and tighten it down.

[Edit: When meshing the gears don't push them up tight but leave a small gap (say 20thou or 0.5mm) between the teeth to prevent wear. Oil the bushings as you assemble and keep them lubricated if you're running it for the first time or for extended periods. ]

HTH

Jon

Edited By Jon Gibbs on 08/01/2016 09:32:48

To ensure just a little backlash, when meshing gears, I run a piece of paper into the mesh, and then tighten the fixings. (IF it needs to be said, as a general rule, no gears should be run without backlash. Yes, there are special set ups to eliminate backlash, such as split gears pushed in opposite directions by springs, and the like)

On my lathe it is a messy job, since everything is kept covered in grease or gear lube, to minimise wear

Howard

Swapping change gears must be one of the jobs where throw away latex gloves could be used then. I know what you mean about messy. People who have Norton gearboxes and have never changed the headstock gears don't know how lucky they are. Feed rate changes were more likely than screw thread changes for me. If made me tend to leave the feed rate at a low value and suffer the time delay this resulted in. It is part of the reason I put CNC on my machine. Not to be wonderfully clever with what I could do but to be able to thread and feed without changing gears. I also was missing some gears from the set required to do all common threads (no 127 tooth amongst others so approximate metric was the order of the day). I did make some aluminium gears when I really needed them. Not running change gears even when perfectly set up is also quieter but that is just a pleasant by-product.

Martin