Kitamura Mycenter 1/485 Rebuild and Retrofit Diary

[travasky]

I picked up a Kitamura MyCenter 1/485 this past weekend and moved it into my garage for a full retrofit before moving it to my shop for permanent use. Working on it at home rather than at work should hopefully give me less distractions and a much faster turn around time.

As the machine sits today. We had to remove the enclosure for transport:

A machine of similar vintage in decent condition. The retrofit should surpass this level of cleanliness by a large margin.

The machine has the following specifications:

Fanuc 0M control

Fanuc red cap servos all around @ approximately 1.8kw per axis. Spindle motor is a 3.7kw continuous, 5.5kw 30 minute rated servo.

13k rpm spindle with air oil lubrication and refrigerated oil cooling.

Box ways

16 tool ATC.

Plans for the rebuild and retrofit:

Strip down to core components for paint stripping and then repaint with a 2k urethane. Ive great luck with a Sherwin Williams product previously and will try it again on this project.

Spindle rebuild with grease packed bearings to eliminate the air oil system and chiller. This is possible thanks to new greases and a switch to steel ball angular contact bearings as opposed to the existing ceramic units. This aids in thermal transfer of heat out of the spindle.

Way inspection and repair. If there is any bad Turcite bonds theyll be replaced with Moglice. Ive used this previously with fantastic success.

Swap ATC geneva drive to a servo and belt system to speed tool changes.

Oak board with ADD1616.

Complete replacement of servo drives and motors. Spindle drive and motor will also be updated with a true servo spindle and drive as opposed to a VFD.



Ill be updating this post regularly with details of the rebuild in photo, video, and timelapse form.

Travis

[travasky]

Got the way covers, axis motors, and spindle cartridge off. No plates on the motors but manual lists them as 5M series. I’ll start sizing motors soon and ordering replacements.

I can only assume the machine was used with straight oil as coolant. The chips are held together like syrup under the way covers. What I can see of the ways so far looks to be in very good condition.

[martyscncgarage]

Looking forward to watching your progress....
Marty

[travasky]

I got the motors sized. Originally the 5M motors on the X and Y axes produced 0.9Kw and are 2000rpm. The Z was a 10M motor which produced 1.8Kw and was also 2000rpm. The X and Y motors are 130mm frame size and the Z is a 180mm frame size.

In order to make the retrofit as simple as possible and eliminate the need for motor adapter plates and odd sized shaft to ballscrew couplings I've chosen motors with the same frame sizes. What that means, however, is that the motors will be oversized. The new X any Y motors are 1.5Kw units, and the Z is a massive 4.5kw motor. Just goes to show how much servo technology has progressed in the last 32 years. Over sizing the motors isn't the best practice from an energy consumption standpoint. Typically the inertia mismatch of a motor to load should be 10:1 or better. Im now well under the 10:1 ratio and should have good performance. The new motors are a bit faster RPM wise and so rapids may increase by 20%.

The original spindle motor is 3.7/5.5kw (S1/S6 ratings). The new motor is 4.0/6.0Kw. A little extra umph which given that the machine is stout as a tank wont be a bad thing. I assume the BT35 taper will be the limiting factor as far as speeds/feeds are concerned.

Axes drives run off of single phase 220. Spindle runs off of 220V 3 phase. Motors and drives will be ordered tonight. Ill post pictures as soon as they come in. Will likely be a few weeks.

I picked up the paint today. Its a 2 part acrylic urethane. Goes under the brand AIC, but its manufactured by Sherwin Williams. The system consists of a base, hardener, and reducer. When mixed together they begin to harden. Pot life is somewhat short but full cure is under 24 hours in balmy Arizona and the end result is a tough and durable finish resistant to chemicals.

Tonight Ill begin gutting the electronics cabinet. As far as I can tell the current electronics are mounted straight to the enclosure. Ill probably tig weld some standoffs in the enclosure and mount a removable subpanel which will make wiring much easier.

[travasky]

Electrical cabinet before and after. Some pretty nasty stuff in there.

[travasky]

Making good progress on the tool changer assembly. All the parts have been cleaned and primed and will get a coat of paint. The only remaining part in need of priming is the umbrella itself.

I took some time to model up the existing way covers for the x axis in CAD. They’re made of fiberglass and after 31 years aren’t in great shape. Why they made them out of fiberglass I don’t know but I get the impression they handed this part of the machine over to the new intern with a Fiero obsession.

I welded up a replacement cover today to test fit. Works well. I’ll finish up the other side and the telescoping parts tomorrow.

[travasky]

All of the ATC parts are cleaned and primed. Will paint them this weekend. The spindle is starting to come apart for a whole new set of belleville springs and all new spindle bearings. Ill post photos of that soon.

In the meantime Ive ordered all the necessary parts for converting the ATC umbrella to servo drive rather than geneva drive. I couldnt find a HTD pulley the right size with the correct hole patterns, so I made one. See below:

[martyscncgarage]

Very nice!
Marty

[travasky]

When I was initially taking the head apart I noticed the spindle bearings didnt sound great. The noise plus my dislike for the ancillary cooling and lubricating equipment convinced me to take the spindle apart for a rebuild. This weekend I got the spindle apart to clean and inventory the parts. I have new bearings ready to go in and will tackle that next. The bearings were definitely contaminated with both dirt and water at some point. The top bearing was the worst, being the least protected and the machine not being cleaned well. I think a lot of material sat on top of the spindle for a long time collecting dust and coolant sludge. The lower bearings seemed to be in ok shape, but weren't ceramic as the parts manual suggests. They were likely replaced at some point but from what I can tell about the markings on the bearings, they weren't replaced at the same time which means one of the bearings has likely been in and out a few times. This is problematic from a cleanliness standpoint and also that the bearings arent a matched pair. Most P4 bearings are going to be very tight on tolerances so buying a matched set isnt super critical. In any case, both bearings came out.

The drawbar was next and, as you can see in the photo,s was quick a shocker. 10 or so of the 131 belleville springs were completely shattered. Im glad I took the time to dig this deep now. It would have been a let down to have poor finishes right out of the gate once the machine is running. Without a legit drawbar force tester finding the problem could have taken some time and led me down some wrong roads. New springs have been ordered. McMaster of all places ended up being the least expensive. Ill be replacing the whole stack.

Motors and drives are about 20 miles from my house now. Customs is holding them up for a clarification on the HTS code. I might end up paying an additional 25% thanks to the new section 301 tariffs. Not super jazzed about that.

[DICKEYBIRD]

Great thread! Thanks very much for taking the time to post all the great pictures & details. Being a hobby guy, I'd otherwise not get to see the innards of a quality machine. I'm loving it!