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New to me Bridgeport TC22

arsenix

Plastic
Joined
Jul 28, 2011
Location
Milpitas, CA
During pandemic I bought a few "new" machine tools, including 1997 Bridgeport TC22. I was hoping to tap into some other owners here as I dig through it. I've been slowly working through servicing it and getting it running. Although "fully running", it is an old machine and a number of little things have needed attention before I start running parts on it. Lots of cleaning ancient crud... replacing o-rings and seals.

I decided I should likely change the gearbox oil as it looked a little low on the sight glass. When I drained it, only about 3/4 of a quart came out. Post draining the sight glass was the same level... ie it was likely lower than it looked. There is a fair bit of red goo around the shot pin actuator (ie it seems to be leaking there). It also looks a bit wet around the base of the motor. The "cavity" around the main spindle belt was certainly filled with a lot of goo. Makes me think the lower seal on the gearbox is likely leaking.

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Was wondering if folks had any suggestions. I was hoping to NOT have to pull the motor/gearbox... but maybe it is inevitable at this point. Does anyone know offhand about how much gearbox oil these are supposed to take?

I'll likely have more questions! The list of things I've already done is long, although I feel like I am getting close to chip time!
 

arsenix

Plastic
Joined
Jul 28, 2011
Location
Milpitas, CA
Have been working my way through the machine. Got the pneumatic system all sealed up. Rebuilt the rotary drive and replaced every o-ring in all the nylon hose junctions!

I redid the lube lines to the head and have oil flowing up there. I cannot figure out how to get to the lubrication manifold under the table though. Is there an access hatch I'm missing? Any TC22 owners have a trick to share? Still cleaning all the swarf off down there too so many areas remain deadly to bare hands!
 

arsenix

Plastic
Joined
Jul 28, 2011
Location
Milpitas, CA
After jogging the table back and forth to get all the side covers removed, and sopping up a lake of old way oil (which had been obscuring the manifold), I uncovered it. It is about 10" in from the side though. I can just barely touch it jamming my arm in there. I suppose I could undo the ends of the ball screw and move that out of the way but that seems like a fair bit of work and maybe take some setup to get it aligned again?
 

Jdub63

Aluminum
Joined
Jan 10, 2020
I can’t provide any input, but I’m watching this tread. I just bought one of these too, and I’m starting the cleanup too.
 

arsenix

Plastic
Joined
Jul 28, 2011
Location
Milpitas, CA
I ended up removing the X axis thrust bearings and screwing out the ballscrew to give more clearance to remove the lubrication manifold in the table. With that removed it wasn't too bad to remove the lube manifold and clean it all out. All back together now. Getting close to making some more chips with it.

I ended up making some custom wrenches to remove and reinstall the ball screw nuts. I listed the extras if you need a set: Bridgeport CNC Milling Machine Ballscrew Nut Service Tool Wrench Set TorqueCut | eBay

Will post some photos of the process later.
 

jj80909

Aluminum
Joined
Sep 16, 2015
As long as you're going through it, I would replace the proximity sensors / cables for the tool changer. My first machine was a TC22 and I got it cheap because the tool changer would intermittently fault out...found two cables that were old and brittle and new ones were cheap.
 

arsenix

Plastic
Joined
Jul 28, 2011
Location
Milpitas, CA
Thanks for that tip! Did you just buy the cable from bptparts? I haven't looked at the tool changer much yet other than checking to see if it worked.
 

arsenix

Plastic
Joined
Jul 28, 2011
Location
Milpitas, CA
It doesn't appear that my bijur is lubricating. I can pull the lever and it pumps, but doesn't seem to be running automatically. Is the machine supposed to apply power to the bijur only when the spindle is running or all the time? I don't seem to be seeing power to the power terminals at the pump (even when spindle is on), so maybe the control has a fuse blown or something?

EDIT: I hooked the pump directly to 115v and confirmed it works fine.
 

arsenix

Plastic
Joined
Jul 28, 2011
Location
Milpitas, CA
After wasting a fair amount of time troubleshooting I realized that the machine only runs the lubrication pump when it is running a program. So it was working perfectly all along! I'm sure I missed this somewhere in the manuals.
 

arsenix

Plastic
Joined
Jul 28, 2011
Location
Milpitas, CA
Spent the last few days running parts on the machine. So far works great! The software is a tad quirky and has a few bugs (like don't press another button after pressing quill up until it is finished raising the quill!) but they are easy enough to work around.

Only issue I had was that the Z axis way cover caught the table at one point and was damaged. It rolled up during a part of the program where the table was all the way to the rear corner and the rolled up guard caught the table... bent/slid/etc. Not sure I can repair it. I guess this is why many of these machines have this guard cut short. I had just bought and installed a nice nearly new one too. Ugh. I'm not too inclined to invest in another one since it seems like a hokey design. Has anyone fashioned anything better? Maybe some of the standard rubber/fabric way cover bellows that are common on machinery?
 

arsenix

Plastic
Joined
Jul 28, 2011
Location
Milpitas, CA
Been working through the gear change system to get that working reliably. It would occasionally switch gears properly but only after a few retries. I rebuilt the Turn-Act although after getting the new seals it seemed apparent that it had been rebuilt somewhat recently. The ones that were in there seemed fine. This was not the primary issue. The solenoid was not engaging fully for one. I cleaned out the solenoid and resealed it which improved flow but still no improvement.

I took the motor off and confirmed that the transmission mechanically shifts quite smoothly. I can easily change gears by hand. No issues there. The issue is that the Turn-Act was not completing the gear change. What was happening was that the turn-act would stop producing torque after moving about 45 degrees. This would happen in either direction. It seems there was just enough leakage that the pressure across the vane was equal at that position. I purchased a used replacement Turn-Act which seemed in fine shape but it behaved exactly the same. I'm not sure if this is normal but my machine has very tiny flow restrictors on both ports of the turn-act. Like a pin hole. I think the internal leakage is overflowing these restrictions at that position, so the actuator stops producing torque.

After working through this I put it all back together with the restrictors removed. It shifts dead reliable now but the shift is pretty... abrupt. I assume Bridgeport put those in to soften the shift. I wonder how much of a problem this will be. I believe that if the "exhaust" was unrestricted there would be no issues with the slight internal leakage. You can buy restrictors with check valves in them so they only restrict in one direction. Wondering if I should try some of those to damp out the shifting but still allow unrestricted venting. I'm really not clear how the system was supposed to work with those tiny restrictors on both ports. Seems like even a tiny amount of internal leakage would cause it to not work. Both of the cylinders I have seem to be in fine shape and make great torque, but even with greasing/oiling they have a tiny amount of leakage at certain positions.

Anyone else witness this same issue?
 

arsenix

Plastic
Joined
Jul 28, 2011
Location
Milpitas, CA
I ended up buying and installing some one way restriction valves from Festo. These have an adjustment to change the flow restriction, and only act in one direction. This let me dial in a little damping into the gear change, but still leave enough flow for the change to be reliable. I dialed in more restriction until it started to retry the speed change, then backed them out a full turn. These are FESTO GRLA-1/8-B, which has the proper threads to drop in place of the existing restrictors. They restrict input flow but not exhaust. Found them for $20 for the pair on ebay. I really can't grok how this system would work reliably with the tiny restrictors it came with. Even a slight leakage in the turn-act will cause it to stick and fail to change gears.

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This machine has been running nicely. I did some checks on it this morning to check backlash and tram. It looks like there is about .0003" worth of backlash in X/Y. I zeroed an indicator, rapid out and back a few inches, then check, go the other direction. About .0003" change in reading. Doesn't seem to bad. Tram varies around .001" over an 18" sweep. The factory spec is +-.001 over a 12" sweep, so I'm within factory spec although this doesn't seem too tight to me.

One issue I'm having is that the machine has a bit of vibration on the Z axis. It varies in intensity but you can clearly see the indicator vibrating around .001" when you are indicating Z. It gets worse when you jog up, goes away when you jog down, constant when sitting. The indicated position in the control does not change. Maybe the belt is too tight/too loose? I did cinch it when I was servicing the machine. Tramming the head any tighter is tough with this vibration present. It doesn't seem to impact surface finish when machining that I have noticed though.
 








 
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