Bridgeport J-Head Rebuild Kits?

[jdelaney44]

So my question is - Where can I get a rebuild kit, if such a thing exists? If not what should I replace? OR - Is this just a process of openning it up and seeing what you think is bad and just replacing that, like I would do with an old car.

Here's what's going on:

My J is like 20+ years old. It's noisy to me but I don't know how loud one of these should really be. I know machine shops can be noisy places that's about it. I thought I had a big problem yesterday with something. But I found a loose motor bolt. Tightenned that up and things are back to normal. Actually I put a lock washer in there too. So my strange noises could have been that loose motor slapping on the casting of the vari speed.

Running it in low gear is a little noisier, but not much. Forward and reverse are the same.

Also when I reduce the motor speed with the VFD, the belt is squeaky, that's gotta be a lot of the noise at full speed. There's just some noise inherent to a 2 hp belt drive and all those gears going round.

When rev'd up to 4200 I can no longer hear the radio on the other side of the garage. 30db maybe? It's pretty loud. But not as loud as say my worm drive DeWalt circular saw.

So anyway, I've seen posts about the keys on the motor pulley assembly being worn. I need to check that. then I saw a similar post about the same thing on the front. Need to check that.

Then I saw something about adjusting a clutch and the directions are in the manual. Need to look that up.

Then I see that the back gears are s'posed to be lubed for "life". Well 20+ years is close to life I figure. I gotta imagine the grease is breaking down in there as I type. So that needs to be done I expect.

So at this point I'm thinking I may be getting pretty deep into this thing so maybe I should just overhaul it.

I would think that new bearings would be in order. I know I have one on the top of the vari speed that's dried up. I force grease into it around the seals every couple of months. Seems to work. But it should be replaced. So that tells me that any other sealed bearings in there are running on borrowed time too.

I found this place on the web

http://www.alternativemachinetool.com/

I also have a refferal from the Yahoo Bridgeport group for a Dee Reel.

But....that's all I got.

I am in Orange County CA. I might be looking for someone to re-scrape the machine too. Maybe. They are not that bad. Could be I just need new Gibs or something. Not a clue what that costs either.

Thanks,
-jd

[machintek]

It is most common for the motor adjustable varidisc to wear out and start to rattle. Be aware that the original ones had thin black plastic inserts glued in. Later ones and current production uses a green material that is a lot thicker and wears a lot better. But the green versions are not repairable. They are only replaced. Note that there were two different HP motors and they had different diameter shafts. Therefore order the correct parts. The front varidisc is common to all, and still has the thin black plastic inserts glued in. There is a lot to get correct if you try and glue in new inserts. The varidiscs cannot wobble and must run true or you will have vibration issues. If the plastic inserts wear out, they will destroy the shaft, so it is crucial to replace the varidiscs before that happens. When I rebuild a head for a customer, I have to use new parts, as I guarantee my work. Also I usually replace the 3 top bearings and replace the vari-drive belt. This ensures that I will not be turning in the near furure and the customer is well taken care of.
By the way. A "J" head refers to the step pulley head. The vari-drive head is referred to as a "2J' head.
The boottom end may be worn out or not. You will be the judge of how much play you can tolerate. The ways may or may not be chromed. If chromed, it complicates a rescrape. Most way surfaces get dished or worn in the center. A new gib will not help. Be aware that gibs are ordered raw. they are not fitted and lack oil grooves. That is an additional cost. Check the backlash, that is a rather easy adjustment or you can replace the brass nuts. Be aware that just like the way surfaces, the screws wear in the center first. If you take the backlash out of the center, you may not be able to reach the ends of travel.

George

[jdelaney44]

George, thanks very much. I think I need to open it up soon and see what's going on at least. How much does a rebuild typically cost by the way?

-jd

[machintek]

Too vague. I have repaired heads for as little as 600 dollars and as much as 3,500. Rescraping a machine varies almost as much depending on what needs to be done. At that point, the machine goes up for auction and the company buys a new one with all the tax advantages that comes with the purchase. This allows the rest of us to have a bridgeport in the garage. When you tear into it, we can price it out.

George

[Cold Fusion]

Machintek,

Could you tell me the business that sells you the top bearings, as well as the numbers? I've got a 4J head that needs them to be replaced.

[machintek]

A 4J head has different bearings than a 2J. All the bearings on a 2J can be purchased at a local bearing house EXCEPT the two bearings in the bull gear housing and the spindle precision bearings. I would have to dig in the 4J book and get a list together of the bearings. Then see if the generic numbers are listed next to the Bridgeport part numbers. They are for the 2J head. We buy our parts from Bridgeport. When I rebuild a head, I send the spindle out to C & M precision spindles in Tualatin Oregon. They load new bearings, preload them correctly and regrind the R-8 taper so the spindle runs true inside the new bearings. I cannot do this in the field. They also sell bearing kits very reasonably for the head. They have what is caled a 5 pack. Instead of the spacers between the bottom precision bearings, they install 2 additional bearings.

George

[jdelaney44]

OK, thanks very much. Good info as always. -jd

[jdelaney44]

George, I got another reply that said it might be the splines. With the machine stopped and say a chuck in the R-8 that I can grab hold of, I can rotate the shaft back and forth several degrees "stop to stop" It shouldn't do that, right?

Thanks in advance for the 2nd opinion.

-jd

[machintek]

On a Bridgeport head, both J and 2J there are 2 places for such play. The play between the spindle splines and spilned gear hub is usually minimal. This should be checked with the head in back gear.
I believe your play is coming from the "clutches". The bottom of the spindle pulley hub and the top of the splined gear hub have teeth that mesh when the head is in high gear. These teeth are tapered. When a head is new they may mesh into each other about half way. As the teeth wear the mesh gets deeper and deeper untill the teeth bottom out. Then they wear in such a way that there is a gap between the teeth ends and this is where most of the play is.
In the process of these teeth wearing, the head has an adjustment to allow full engagement. On the lever for selecting back gear, there is an adjustment so the pin will engage the hole and allow full mesh. Typically all one need do is loosen the screws on the clamp block and the springs beneath the bull gear will bush the mating parts together. Older 2J heads have this clamp block pinned so instead the plate with the plunger hole has a set screw locking it and can be adjusted up or down.

George

[jdelaney44]

Perfect. I will check it out. Thanks VERY much for the advice.

-jd

[densman]

Hello Machintek
I have my J-2 1 1/2 HP head torn down waiting for some replacment parts.Can you tell me from your experience ,other then the plastic pully bushings what can make a mill run loud. Thanks for any advise you can share.
Dave Ensman

[machintek]

There is a lot of factors with regard to a "noisy" head. Bearings, balance, fit of parts, speed, and enviroment. A machine is louder in a quiet garage.
As I mentioned just above, it will be difficult to replace the bushings (front or rear) and maintain a true running varidisc, and keep its balance. The bearings are a factor. The fit of the clutches. The play in the spindle spline. The spindle bearings. Make sure you float the head in when reassembling. This is where the nuts that hold the belt housing to the bull gear housing are kept a touch loose to allow the pieces to float in while the head is running, and then they are tightened. The same is true for the quill housing to the belt housing. Sometimes the quill will move up and down with a choppy motion while the spindle is turning. This is because it is not centered in the spline gear hub and needs floating in.

George