To install them I needed a a couple of different pressing tools.
Once installed vibrations was mostly gone, I still get some resonance at specific RPM's but I hope this will be better when I get a new belt.
So now most of the mechanics is done, and it is starting to look good again.
During cleanup I noticed a tiny bit of backlash in the X-Axis, for a start I won't do anything about it, but I'll probably need a new ball screw later.
I haven't made any progress with the electronics, apart from ordering a hand full of buffer chips.
While waiting for the bearings for the spindle and motor, I might as well start looking at the electronics. The back of the mill looks like this:
It might look a bit complex, but really it isn't.. Looking at the schematics was a trip down memory lane, the design is a classic microprocessor construction with everything you'd expect to find in such a design. RAM, ROM, address decoder addressable IO chips, external serial driver etc.
The plan is to hook into the clock, step, and power down signals for the three axis, which comes from a 82C55 IP chip, so first step was to remove this.
I must admit that it does hurt a bit doing this to vintage electronics like this, but in the end it should end up being a much more versatile mill, while still being almost original.
Preserving the original electronics means that the coordinate display will still be working, but it will only be possible to display the machine coordinates, not your work coordinate system, since there is no way of feeding offsets into the machine.
Since I already had access to the electronics, I figured that I might as well take a backup of the EPROM's, and no backup is complete without also testing if you can restore it again..
For a long time I have considered building a desktop mill, I have a great deal of the parts and materials needed, and tools shouldn't be a problem either, only time, and the right design.
But then during a random search for CNC stuff for sale, an interesting desktop mill showed up. The Roland CAMM-3/PNC-3000 Computer Aided Modelling Machine.. :) The price was fair, so I phoned up the seller and made a appointment to pick it up.
It was a bit of a gamble, as it was in the other end of the country, but the machine looked relatively ok given it's age, and to the best of my knowledge Roland doesn't produce junk. And compared to sourcing linear rails, bearings, stepper drivers, all of the material and parts I was missing, and using countless hours in the garage, this could hardly be a bad option, almost no matter how banged up the mill was.
So 9 hours of driving later the mill was at the compound.
The mill had seen a great deal of use, and needed a cleaning job, it's from 1987, and designed to mill plastic, wax, soft metals, and other soft stuff. The collet is 6mm only and not fantastic, but it has apparently done the job since the mill was new.
According to the seller the spindle needed an new drive belt, which was a reasonable assumption given the amount of noise and vibration it was able to generate when it was running.
The original plan was to tear the mill completely apart and clean it, but I ended up with a more lightweight solution.
I started with the spindle, the belt vibrated like crazy no matter how tight or loose it was, and when the spindle was turned off, it gave off a strange whistling noise, for some time after. This turned out to be the top bearing, that was spinning freely inside the spindle housing.
The whole spindle assembly can be removed for servicing, when I got it apart, it was filled with aluminium dust, and someone (maybe me) had managed to loose one of the balls from the thrust bearings, I'm pretty sure it wasn't me..
No biggie, I'll just order 3 new bearings, and everything will be fine.. Well.. hmm.. The thrust bearings are 7003C, relatively innocent looking, but is, judging from the price, only available in solid platinum or unobtanium.. Most places I found was asking ~100-150€ a piece, and I ended up paying 80€ for a set of non brand name bearings, but from a German supplier. After all the spindle is only doing ~10K RPM.
After the spindle housing was cleaned up, and a bushing to make up for the lost material around the bearing was fabricated, it looked like this:
While waiting for the bearings, I started on the rest of the machine, it was clear the previous owners hadn't given it much love..
Work in progress:
One of the other problems I noted was the dust covers especially on the z-axis was curling up, so I added a pair of tig welding wires behind them, to keep them in place, this worked really well:
After cleaning It looked like this
I also decided to take the motor apart to check the bearings, which showed up to be a great idea
And one could ask.. why didn't you wait ordering the spindle bearings until you knew, if you might also be needing bearings for the motor.. well.. please don't..
Now I just have to wait for the bearings to arrive, until then I can use some time on getting LinuxCNC to control the mill, since it only understand HPGL, but more on that later.
