First Bridgeport need info and opinions to get it up and running

[OldBlue56]

Hello everyone,

I've been searching around and researching on the site for a while now, but this will be my first post. I recently acquired what I believe is a 1984 Bridgeport (going off serial #'s) with the SWI PROTO TRAK MX2 CNC setup on it. I just happened across this at a local online auction and ended up winning it. I have no real experience with machining other than my self taught research and trials and errors with my PM-25MV and my 1966 13" South Bend lathe I just finished restoring.

My first order of business is going to be figuring out how to power this thing. I did plug in the MX2, since it is 115v, and was able to verify it does work. I was able to jog the table on both the "X" and "Y" axis. Now to my question, obviously I will need a VFD or some type of converter to run off of my single phase 220v I have available in the garage. The mill motor is obviously 3phase. Since this is a variable speed head and the CNC is powered from the setup on the mill itself, it seems my best option would be to simply feed power to it from a VFD and not use any of the fancy features available on many of the VFD's. I assume this is the best method because the VFD will also be powering the CNC portion therefore I can't be controlling the motor or anything from the VFD without affecting power to the CNC correct? This being the case do I still really need to go with the more expensive VFD modules or can I get away with a more basic one since I have no use for the fancy features?

Secondly based on the pictures would it be a good idea to do some disassembly of the table and knee and do some cleanup of the ways and check lubrication lines? You can see some wear on the ways, doesn't seem to be too bad to me but I'm no expert. I don't want to make it any worse though. If I do take it apart how does the installed CNC motors and such affect the process? I have the rebuild guide for a standard manual Bridgeport, but I would like to know what I'm getting into with the SWI system on there before I go tearing into everything. I would hate to accidentally destroy some part of it since it currently works and I'm sure getting any replacement stuff from a 1993 CNC system would not be easy.

Please feel free to offer any suggestions, experience tid bits or warnings that might be useful for me.

I'm sure I'll come up with more questions as I get into this, but this should get me started I'm thinking.

Cheers,
Brent

 

[memphisjed]

The vfd goes between 220 wall plug and the motor. It does not go to the controller. The controller (likely, sw would know) has a low voltage wires to vfd to turn motor on, and how fast, and which direction. No switch between vfd and motor.
Your drive power is unrelated to cnc power in this case. Two plugs, one 110 for the nc, one 220 for the spindle. You can split the 220 and feed cnc, but why?

 

[OldBlue56]

You can split the 220 and feed cnc, but why?

Thanks for the reply. My thinking was since it is already all wired up with a surge protector and transformer stepping it down to 110 mounted to the mill why not just use what is already there and wired up, just need to feed it power. That's what the Sentrex and Square D boxes pictured above apparently do. They feed 110 to the outlet mounted to the back of the mill and that is what the CNC monitor and control box are plugged into currently.

 

[memphisjed]

Your vfd does not output power unless told to. You can use one as a phase converter, set at 60hz. Doing that negates 99 percent of the advantage of a drive in this usage.
The drive outputs variable frequency to make motor go variable speeds. The control (likely, not positive on that control) sends a low voltage variable voltage/amp/or frequency to the drive. You will need to know what type of signal controller sends, it will be a setting on the vfd.
No switch between vfd and motor! Ground errthing.
Keep it simple when you can. 2 plugs, one 110 one 220 is simple.
Southwest industries has a good reputation on support. They will have all your controller information.

 

[rons]

My first order of business is going to be figuring out how to power this thing.

Make a simple RPC 5Hp to start off with.

Secondly based on the pictures would it be a good idea to do some disassembly of the table and knee and do some cleanup of the ways and check lubrication lines?

No.

 

[OldBlue56]

Thanks for the replies. Much appreciated. These give me some options to look at and start running with.

Cheers,
Brent

 

[specfab]

I would also recommend a rotary phase converter rather than VFD for this specific situation, since everything is set up to run from a single power input. One thing to make sure of is the voltage range the control system can tolerate, and whether a given RPC will give you what is needed. A rotary converter can also be used for other 3-phase machines if you size it properly.

 

[OldBlue56]

Is there a way to identify without doubt what spindle taper my machine has? I've tried doing some research, but I end up just confusing myself more with what I find.

I assumed it was an R8 and I still think it is, but I want to verify that. The draw bar is the standard 7/16-20 thread and I can insert my R8 collets, chuck and face mill, however when tightened they don't seat near as deep as they do in the spindle of my Precision Mathews 25-MV bench mill and the key I can see has been sheared off at some point as I can spin the collets inside the spindle until I tighten them up. I can see and feel the remnants of a key there. There does not appear to be any spindle damage from the sheared key, that I can see anyway. I would assume if it was a different taper the collets wouldn't even be able to be inserted, but I don't know that for sure and don't want to be destroying my spindle by using the incorrect tapered tool holders.

I ended up going with a VFD just for cost simplicity and quickness of getting up and running. It works great and I've been playing around with learning how to use the MX2.

 

[4GSR]

Don't worry about that sheared off pin. You'll thank your
self later for the reason it's sheared off. I did not install the dog point set screw when I rebuilt my Index mill twenty years ago. All that dog point set screw does is prevent the collet from turning when screwing the drawing bar into the collet or arbor. IT DOES NOT provide any holding torque like a driving key on a NMTB 30 or 40 spindle does.

 

[Mr.Honeybone]

I was pretty much in the same situation you were in when I [picked up my first Bridgeport by accident. I decided early on to go with the simplicity of a VFD for the 208V three power supply motor requirement. I plan on using the Bridgeport speed controls on the lathe and the stock drum switch to turn the mill on and forward/reverse. Unfortunately the installed Anilam Crusader M series numerical control system was non functional as disclosed by the seller. It took almost six months to find a repair person familiar with a repair person able to work on an obsolete vintage pre CNC system. It's up and running since last week. Currently going through the operating manual learning how to program.the system. The VFD cost around $200, don't know how mush a RPC will cost .

 

[neanderthal mach]

While I can't offer any advice about what to watch for as far as the cnc and removing the drive motors. It would be a sure yes on pulling the table and Y axis for a through cleaning, manual re-lube as you put it back together, and gib adjustment. For whatever reason, most machine tool manufacturer's don't seem to even mention anything like this would be just yearly - semi yearly maintenance depending on how much the machine is being used. In theory it's a total loss oiling system that should help flush itself clean. In practice that isn't as true as some seem to think.

Chips and debris will get in under the table somehow. And discolored or black lube oil is a sure sign it's full of both tiny chips and wear particles from using it. And catching any failed lubrication issues from any broken lines or plugged line restrictor's as early as possible is common sense. Even more so on a cnc since there's no hand feel that a slide is starting to take a bit more effort to move. On my manual BP clone, I'll usually pull the table after I get enough wear a slight adjustment on the gib or the nut backlash starts climbing a bit. Yours should have ball screws so that won't be needed. But flushing the exposed X,Y screws clean from any chips, congealed and discolored oil can only help. And all of that crap running back and forth further accelerates even more screw, nut and slide wear.

Yeah the first time you do it might take a few hrs, once it's been done a few times it really doesn't take much time on mine. Just don't try and remove the ball screw from the nut unless you understand what your doing and have the correct ball retainer that goes into the nut and keeps all those balls in place as the screw comes out and is put back in. A spray can of brake cleaner or even electrical contact cleaner does a good job of de-greasing and flushing all the crap off the screws and slides and it's what I use. Depending on how well that mill was maintained you might be surprised at just how filthy what you can't see is.