[dave73]

Anybody done a variable speed belt change, and, bearing change on a Hurco KM3 head.


I will put pictures up as I do it.

Thanks

First thing I did was to remove main motor at back of ram!
.............disconnect wireing from motor box
.............undo cap heads under motor on lower casting
.............undo nut holding tensioner spring, carefully, lever brake on side to stop motor turning



Wireing, note wire positions ...........
U


Bottom Plate x 3 cap heads........





Lever Brake on to stop motor turning .......



Undo nut, watch for spring?...... keeping brake on!







Undo cap heads holding motor....... remove



Check the Nylon Splined Bush, any excessive wear, change if possible.

[dave73]

Anybody done a variable speed belt change, and, bearing change on a Hurco KM3 head.


I will put pictures up as I do it.

Thanks

First thing I did was to remove main motor at back of ram!
.............disconnect wireing from motor box, making a note of where they go!
.............undo cap heads under motor on lower casting

[dave73]

Next, while holding the brake on, using a socket undo the nut holding the tension spring on.

Obviously, undo while keeping the pressure on

[macdave73]

I initially took the Head off before undoing the Spring, better to undo spring with Head still on as above.

Then removed the brake solenoid using a 10mm spanner

.

[macdave73]

Found this document online somewhere, it says put the spindle to max speed, unfortunately my machine was'nt working when I got it so I could'nt do that anyway.

I have already removed the Spindle motor cover and Spindle Motor, left the belt.

.

[macdave73]

[macdave73]

[macdave73]

I Have tried to put the pictures in some sort of order, but it was removed a while ago, so check as you go along.

took a picture of the chain length to remind me how long it was, so that it goes beck the same.

[macdave73]

I removed nut and measured it, just in case?

[macdave73]

The Head woud'nt lift off cleanly and easily, probably because the dowels were a tight fit, I tried to use Aluminium levers but I was concerned about damaging the casting, so I opted for gentle pressure using threaded rod which allowed me to lift the head equally all round.

[macdave73]

Heads finally off, here's a view of all the Belt numbers

37/10/850

40173 x 1 1/4 B9N1 (Made in UK) Powergrip

[macdave73]

With the spindle regulating (no6 in the manual) top plate and disc/variable angled plate off, I removed the belt by sliding it over the pulley-difficult, not the right thing to do but I was'nt sure if I should undo the pulley nut as I was'nt familiar with the setup, so I opted for the obvious and easiest, and I was replacing it.

[macdave73]

Finally off, belts in a right mess, so new belts and new bearing

[Rich Carlstedt]

Thank You MacDave 73
Appreciate the magnificent work and pictures !
rich

[dave73]

looks better after a clean up, next renew bearings and bushes




Change Bearing on front Variable disk






Next remove the Nylon Bushes from the front Variable disk and the back motor disk

[dave73]

Get the front drive shaft back into the Variable disk, take care not to damage the bearing, I made up some bushes and 1/2" rod.

[dave73]

Now to the Bushes, here's my drawing of the bush, now let me point out, this drawing has been altered to accommodate the bad tolerance which you get from 3D printing, in other words I have modified the drawing of the spline so that when I got the part 3D printed, I was able to make adjustments to the size, lathe turn and fettle/file.

I did ask Hurco service if they had any old stock, of course they haven't, they did say however they thought there was a firm in the US where you could have them made for $300 , not sure if that was each or the pair. So I thought I would go down the 3D Printing route.

Now, as most probably know, the concerns with 3D printing is Materials and Tolerance quality. Finding a suitable material appears to be trial and error, recommendation obviously is a good idea, tolerance however appears to be at best 0.3mm/0.012", that's huge and not very good. The other alternative is get a Broach made up - punch and die, this of course would be quite expensive, I reckon £750 +/- a chunk, $950.

[dave73]

I tried 3D printed parts in ABS, but it was so hard, I thought it would be too brittle, so I discounted that. After some search on the web I found a company who were printing a Nylon substitute, HP PA12. I was told it was similar to an Injection Moulded Part in spec, I was specifically interested in wear, friction, temperature.

Hers a comparison sheet I came up with to try and compare Nylon with 3D printed material.






Bushes Printed, modified and fitted.

[dave73]