EZTRAK retrofit by AjaxCNC on a Bridgeport

[NC Cams]

Has anyone retrofitted a Bridgeport EZTRAK with an AjaxCNC system???

Interested in results, issues, regrets, thrills, whatever. Want to keep as much BPT stuff as possible so as to keep cost down... Please advise.

Thanks

[MILLMANM]

I redid my Bridgeport that had an Anilam controll, reused the power supply and the motors, and it works great,

[NC Cams]

Thanks for the reply.

Still looking for anybody who did retrofit from an oem EZTRAK system, preferrably one with a PC based motherboard.

[rsbbmw]

hi , did you ever retrofit your eztrak ? i have the same questions , i have an eztrak that needs a retrofit too ,

[NC Cams]

RSBBMW: Nope, not one single solitary reply.

Seems the "Traks are not in the hands of DIY'ers and the servicing is done by main stream system integrators. Too bad, it has a lot of charm and can be turned into a dynamite machine since the hard stuff is already DONE for you (motors, drives, external wiring, power supply, etc).

I did get hold of a guy in Carol Stream Illinois (Brian at BPT Machine) who came by and did a servo tune and he fixed some other issues which had crept it.

We had already done servo service (SEM's re-done by Clarkson) to our machine and redid ball screws with O'size balls (local ball screw service guy).

We also installed some tricked out ball screw bearings which made the table deadly accurate due to slop reduction. Redid them via help from KAF Mfg and some former contacts in bearing industry. I can provide equivalent bearing advice via P/M.

For the time being, the "Trak is running at 110% (yes, better than new due to the non-oem tune-ups we did) - the servo tune up by BPT solved our immediate "problems" (funky h/d was replaced by DOM and Brian upgraded us to version 7 software plus servo tune).

From what I learned while planning to do the retrofit, I see 2 options as being viable.

The DIY version would involve a AjaxCNC base kit.

I'd then get an Elrod Z axis drive system and retrofit my Z axis "trak servo motor to it - would have to add a feedback encoder as my Z asis is 'dumb' and uses DRO scale for feedback (woefully inadequate for true 3 axis work). I could then add 4 axis encoder to do rotatry milling but don't have $$$ to do that now.

The Ajax control would replace my P/C and older servo amps which do work just fine (did some electronic work there but it was busy work that made for better robustness) -

The DC P/S would stay as would the wiring and OEM motors et al - they're already matched and wired so why toss them??? Would consider adding more caps but this isn't necessary due to the "tune" we have on our servos (slowed down jog - less rapid but also less current spikes which seems to helped position accuracy).

Would then add limit switches etc as needed to support Ajax.

The other option considered is/was Anilam. However, the pricing seems much more substantial but it is a more elegant system - just out of my affordability range now....

Asside from the "dated" nature of the P/C and BMDC card and "old" servo amp technology, everything else on the EzTrak is pretty much a simple rewire away from being a state of the art machine... Asside from some hardware differences, the Trak could be today's Haas Tool Room Mill but BPT gave away that market with their short sighted decisions eons ago. Some 'bright' people screwed up a good machine tool company with some lame decisions and the rest is history....

Assuming the Ajax stuff works and is not junk and I had the fund$ to do it, I wouldn't think twice about doing the retro knowing what I know today.

Let me know if I can offer any advice/tech assistance should you do the retrofit...

[unterhaus]

when you do an oversized ball retrofit of the ball screws, is there any cleanup of the screw itself? From the condition of my mill, I would guess any wear is located at the middle of the travel.

I'll have to see how the rest of my machine is for slop before I dumped much money into updating the ballscrew bearings, but I'd be interested in knowing about the details.

[NC Cams]

Our ball screws were in good condition and there wasn't a huge amount of wear in middle. Thus, we only went O/S by a tenth or so.

You can't fix locally worn screw with O/S balls. You can selectively tighten it but you have to protect against brinnelling the screw when the balls/screw travels to the comparatively unworn areas. To do it right, yes, screw grinding would be needed in case of severe/uneven wear.

The bearings are size dependant and the bearing P/N's vary from machine to machine. I can provide info for a typical Bridgeport mill as that's what we tuned up.

Basically the OEM bearings are modified 6204's - barely adequate for a "drill press" but made suitable for a precision mill via "trick machining" (preloading).

First low cost option upgrade would be 7204BYG's. Have them preloaded DF to about 150 lbs by KAF Mfg in Stamford CT.

Then you go to 7204A5TYDUHP7. ABEC7's and they bolt in with a bit of shim/spacer work between outer ring and retaining clamp plate. Nothing fancy shim wise, a motor preload wave washer works fine.

Then you to to a true hard core ball screw bearing but these are in the $800/screw range. Not for the faint of heart BUT deadly accurate. With nearly 500lbs preload they turn with LESS torque than OEM's (long story explained on another thread).

Once you do all that, you need to do some iterative gibb adjustment (oops too tight, drat too loose, ahh just right) and you can turn a sloppy table into a darn accurate machine - ours can now hold within a tenth or so at mid table when machining masters...