Bridgeport used spares

I have just gotten around to looking at my series 1 vari speed 2hp motor. Having rewired it for low volts I started to look at the vari disc. It’s beyond repair. The previous owners appear to have run the machine with no inserts or retaining clip. Consequently the armature shaft has had as has the lower adjustable disc. As these are expensive parts can anyone recommend a company or person who may be able to supply serviceable used parts?

thanks

The late JS used to repair these by filling the slot with weld and remachining it.

I think there are some photos and how to over on the home shop machinist bbs. Might also be something here in the Bodgers Corner thread (think that’s what it was called)

Dave

Mark

I have a brace or three of new old stock varidisks in stock that I'd sell for £ very reasonable.

Can you measure the bore of the ones you need so I can check to see if I have the right ones for you. I think there are three or four different bore sizes out there depending on whether they are for the spindle or motor and on what power the motor is.

Put into safe storage about 15 years ago so finding them to verify what I have may take a while. My Bridgeport has a 1 1/2 hp motor so I imagine they were the wrong size for that one as I didn't use them. My disks were very decent anyway.

Clive

Hi Clive the shaft appears to be 30mm or equivalent in old money (pics below).

Hi Mark

Found my stash.

It appears that I have three varidisks from the 2 Hp 2J2 head. Both spindle disks and the fixed motor varidisk part 2J-643. Bore of the motor disk is 30 mm and someone has carefully written 2 Hp on it in red felt tip. Unfortunately I don't have the adjustable varidisk for the motor.

I'm a little surprised that your set-up is beyond repair. As Dave says fixing the motor shaft by building up with weld and re-machining is considered a standard job by folk who do such things.

Boring out the varidisk to fit an oversize plastic insert is quite practical. Delrin worked well for me. Still running well after 18 years and counting.

I found that superficially horrendous damage to mine was actually not that great in objective terms when I added material to the motor shaft and bored out the disk after discovering the box of NoS parts I'd bought didn't have the right bits. Certainly nothing approaching the examples the late, great JS has published before and after pictures of.

Clive

Thanks for looking Clive. After getting over my meltdown I’ve had think about what I’m going to do. I’m going to weld the spindle as suggested above and I think I’m going to bore and sleeve the varidisc. Just need a lathe. 😂😂

Alternatively several well regarded folk have found that a VFD and single speed belt drive using poly-vee pulleys makes an entirely satisfactory replacement for the reeves drive mechanical vari speed system on 2 Hp Bridgeports.

If I recall correctly something like 2/3 rd or 3/4 speed step-down from motor to spindle has been found generally suitable. If you are interested in this option I have details somewhere having fairly seriously considered the VFD route when mine developed a rather worrying rattle in the vari drive. Turned out the screw holding the fixed disk onto the key had wandered off. Easy repair once I'd muscled the motor off.

Clive

If I remember there is a plastic bush in the varidisk disks. I have in the past tried to bronze bush these but gave up and bought plastic replacements. Also I had the shafts metal sprayed and ground by a local company.

David

David

Yep, plastic bush.

Bronze bushes are a good way to wear the shaft. They rapidly become sticky, presumably due to inadequate lubrication and quite quickly fail. All rather odd given the amount of work they theoretically don't do.

I was told that the spring loading on the varidisc makes it a mechanical oscillator due to a combination of varying loads and the action of the cogged drive belt. So instead of sitting in one place after the speed has been set the moving disk actually rapidly reciprocates up and down a very short distance. Which tears a bronze bush apart. My informant didn't know if anyone had had success with oilite bushes.

As plastic bushes work well for a very reasonable time seems little point in re-inventing the wheel.

Clive

Metal spraying is interesting. Mind you I can weld so it would make sense to try that first.

David, yes you are right they do have a plastic bush in them, however if you look at the picture, where the disc has been rattling on the shaft it has created a tapper, so the bushes will not be big enough to do the job they are meant to do.

Mark