Drive milling spindle but allowing vertical movement (Myford)

Hello Everybody,

I have am in the process of building a Milling Spindle for the Vertical Slide of my Myford Super 7.

I have completed the spindle with two adjustable bearings on the cutting end, with two plain bearings on the pulley end. It has a No. 2 Morse taper to accept tooling.

I am driving it with a 500 Watt E cycle motor, with variable speed controller, it runs just great.

The set up shown which will be mounted on the cross slide has a center distance between the shafts of 250 mm.

Can anybody help me with an idea of driving the spindle with the motor...

But....

Allowing the vertical slide to be adjusted up and down.

Other than adjusting the centre distance with every height adjustment.

I put it to the brains trust.

That seems a big motor.

A lot of designs have the motor and spindle as one unit that move up and down together so the belt tension stays the same.

Another option is to have an overhead layshaft and the motor fixed behind the lathe. The long round belting upto the layshaft and back down to the spindle means that any stretch due to spindle movement is a small percentage of the overall length so not worth worrying about.

If your motor was mounted mid height of the vertical slide the actual change in ctr distance would be small and round rubber belting would more than likely take up the changes, you could always add a jockey wheel to keep tension the same when ctr distance does change if you want to use a toothed or Vee belt.

Edited By JasonB on 09/09/2018 07:51:26

You layout is quite common in clockmaking and is vitually identical to that described by John Wilding in several of his well known clock building books........ As Jason rightly observes, the spindle is almost of a perfect arc to the motor axes, so raising the motor with a small block etc would probably suffice, especially with round plastic belting as used widely in the clock trades....use the 9mm one with alluminium pulleys to the right 'V' profile....join the belt with a little tension by means of a hot knife blade (you put the knife in the vice, hold belt ends gainst the blade and slide off to make the join!) This sort of plastic belting is very forgiving in the tension dept so not dificult to encompass small(ish) changes of distance between the spindle and motor.

This is how J. Malcolm Wild does it: **LINK**

http://www.j-m-w.co.uk/tools9.html

... or you could make a full 'overhead' as seen on ornamental-turning lathes.

MichaelG.

If you use a toothed belt drive arrangement, perhaps you could introduce a spring-loaded jockey wheel into the system to "take up the slack" as the vertical slide moves up and down?

A bit like I used on my version 1 toolpost spindle:

The jockey wheel in this instance is just a bearing located in a slot to provide tension to the drive belt, but the priciple is the same, only spring load it.

John

P.S. Just a thought: If the length of the drive belt doesn't alter drastically, maybe a continuous round belt would stretch sufficiently to accommodate the slide travel? I don't have any experience of such belting, but someone who has will soon be along to quash that idea!

Mount the motor on a hinged plate and fit a big spring to keep the tension on.

When I fitted a half-horse hoover motor to my mini lathe. I just put it on a hinge bit of plywood. 98% of the time that was plenty and when I needed extra grunt I pressed down on the top of the motor

Made changing pulleys easy too!

Neil

Pic above is mine. That's £90 worth of ER11 milling spindle, adjustable power supply, clamp and collets. Plus about an hours work to adapt the mini-lathe vertical slide to the WM250 lathe and some mounting holes for the clamp(which can also bolt to the other face). That gives me height adjustment and the capability of drilling at an angle into the workpiece. My intention is to make a clock, didn't want a complex project and didn't have any motor or spindles to make one of the more traditional setups. Which look a real pain to install, setup and use.

Here's a quick and dirty trial, indexing by eye off the chuck jaws(I've most of the bits for a stepper motor dividing attachment)

If you hadn't been as advanced into the project as you are, I would have suggested you take a look here

https://www.ebay.co.uk/itm/400W-48V-Air-Cooled-Spindle-Motor-BLDC-Motor-Controller-Power-Mount-12000rpm-min/263334588965?hash=item3d4ff6f225:glEAAOSwYwJaEsXu

Umpteenth EDIT:  ***Can't be arsed with trying to get this website to display the link correctly***

Edited By blowlamp on 09/09/2018 12:19:13

Edited By blowlamp on 09/09/2018 12:22:23

.

... like this ? **LINK**

https://www.ebay.co.uk/itm/400W-48V-Air-Cooled-Spindle-Motor-BLDC-Motor-Controller-Power-Mount-12000rpm-min/263334588965

MichaelG.

A crude but effective method I've seen somewhere is to mount the motor on a board, one end of which is pivoted somehow on the RH edge of the cross slide. Tension is applied through the motor weight but the board can pivot up and down as the height of the slide varies.