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Servo Driven 4th Axis for CNC Mill

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awemawson:
This allowed me to gently tap the table with worm attached out of the casting to reveal the very nice end thrust race and top thrust race.

The construction reminds me of a swivelling tank turret  :ddb:

The side thrust race deposited all its rollers on the bench - all eighty of them - but all were located and put in a tote bin for cleaning.

awemawson:
Those rollers look pretty grotty, but an initial inspection shows that they measure spot on 4 mm, so it is more discolouration than wear.

I'd replace them if easily available - anyone know a source of roller bearing rollers in various diameters?

So far I'm pretty pleased with progress - I need to get it re-assembled then work out just how I'm going to mount the servo motor, as its fixings are bolts into its end bearing plate, whereas the original stepper had a mounting flange with externally accessible bolts. It needs proper planning as the mesh of the gears is set by moving the motor, and if the motor has to be fixed before the cover goes on, there is no way of adjusting it  :ddb:

I'd hoped that I could make a dummy flange, but the sizes don't allow that  :loco:

 . . something will occur to me hopefully  :lol:

. . .watch this space,


Andrew

Meldonmech:
Hi Andrew

                 Its looking good, a good clean and new oil. together with your new actuator, should last for ever.

                                                           Interesting project
                                                                                              Cheers David

lordedmond:
Andrew

Is this what you are looking for
http://simplybearings.co.uk/shop/index.php?cPath=c23_5043

Stuart

awemawson:
Stuart, yes many thanks, Google got me there as well, but their 4 mm rollers are either too short at 4mm or too long at 11.8 so I decided to use the originals.

So onwards and upwards! I removed the vertical and horizontal thrust races. The Horizontal one has 80 solid 4 mm rollers all of which were ok measurement wise so they went back as is.

The vertical one on which the weight of the table and work is taken comprises 36 hollow rollers of 8 mm diameter, one of which was broken  :bang:

However I now think that this was why the table was jamming. I was surprised to find they not only were hollow, but had really quite thin walls. I've come across hollow rollers in bearings before in for instance the Gamet headstock bearings of a Colchester Student, but they were quite thick walled. So what to do?

Options - a/ Leave a roller out b/ Try and source one c/ Make one. I opted for c/ on the grounds that although it probably would be perfectly ok leaving one out, it's not very professional, and I was unlikely to be able to find just the right roller. I turned a piece of silver steel to just oversize in the hard state using carbide tooling, then lapped to size. I decided to leave it solid as no doubt the flexibility of the steel would be totally different to the original.

So here we have the broken roller with it's replacement, and the bearing back in situ:

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