I looked at your mill specs and as long as there is clearance for the drive hanging below the bed at the right hand side the weight is not going to be a problem. Move the bed to its extreme left end and look before committing yourself. The weight of the common type on ebay is 6Kg.

Edited By old mart on 24/05/2021 14:28:25

Terry

According to legend the big three phase motor and gearbox power feeds used on older Bridgeports, up to early / mid 60s, were sufficiently heavy to bend the table over many years. Was told that it was not good practice to leave the feed end hanging way out to one side. Ive seen no evidence for this but that motor and feed box unit is very, very heavy. Two man lift off the floor heavy!

No issues with the little one on your mill.

That said its still good practice to park things pretty central when finishing work for the night. Its not a bad idea to regularly give the slideways and screws a decent oiling then wind the table from one end to the other a time or four on a fairly regular basis. Keeps adequately fresh oil on things so they move smoothly, helping to protect them and scrapes off all the dust and stuff. Over many years old, exposed oil starts turning into a varnish like substance on the little travelled parts which doesn't help free movement. Once a month, every other month or thereabouts should do.

Nail the regular "deeper clean and lube" habit early like wot I didn't!

Clive

You can make a very adequate power feed using a stepper motor that will work out cheaper and considerably lighter than one of those commercial ones.

I’ve just made a 12V version loosely based on THIS video.

I intend over-driving it for a faster return ‘cos I’ve used a 19V power supply to the speed controller. Fiddly to line up but works fine. All items on stock/to hand except £13 for the generously rated speed controller.

+1 for stepper motor, you don't need to declutch it for hand winding, so all it needs is a tooth belt pulley instead of one of the handwheels and a bracket to mount it on

The advantage of the wiper motor is definitely cost. I was wondering if a window winder motor would work for a small mill.

My alternative plan was to coerce into use an old 7.2 volt ‘Skil’ screwdriver motor with an already fitted variable speed. It weighs less than half a kilogram but needed considerable speed reduction – so a couple of pulleys with a toothed belt drive. With aluminium bracketry it would likely weigh in at much less than 3kg.

The motor on my Centec 2B is only 1/8th HP, so not that much power should be needed for a mini mill?

Could you not put a simple switch into the stepper wiring so there is no circuit for the generated EMF to flow through? That way you can just flick the switch when you want to use the handwheel rather than having a mechanical clutch

Picking the wiper style motor for me is not because of cost, I wanted a simple system that if it goes wrong I can easily check and repair it, You are all discussing EMF and ways around it, I dont want that hassle.

Martin P

John I was assuming if you want to go manual you switch the drive off therefore not energised and then flick a switch to stop EMF rather than a clutch. So as the switch "disconnects" the stepper you won't be shorting anything and as controller is off you won't be energising it.

The Sherline CNC machines suggest unplugging the steppers when using the retained handwheels, would my suggested switch not do the same thing but much quicker?

I'm sure someone with more knowledge than me could do it all with only one multipole switch to do both at the same time.

Edited By JasonB on 26/05/2021 08:46:28

John, a disconnected direct driven stepper motor will offer next to no resistance and will be unnoticable when turning the handwheel. If geared then as you say it will be harder.

Mine is clutched, but if there was a way of disconnecting electrically I think it would be much easier and makes for a smaller, lighter installation…I think that's what Jason was trying to point out.

I have fitted X and Z powerfeeds to my mill with nema 23 steppers, X is direct drive to the leadscrew, the Z is belt driven with a high reduction (6:1)

The X axis can be moved easily when the power is off but the Z is very stiff unless I unplug the stepper.

I am going to install relays to power down the drivers and disconnect the steppers if I need to move manually.

At some point, when I'm feeling brave, I will drill a hole in the top of the column and direct drive the Z too but will go to a nema 34 for that one.