[J&RMachine]

I was having trouble with chatter on my mill. I could only take about .100" deep cut using a 3/8 carbide endmill without it chattering. I put an indidcator on my spindle and I don't seem to have any movement in the spindle and bearings seem good. I did take the cover off the head and there are rollers inside that roll on a rail as the z axis moves up and down. These rollers did not turn because they are all too far from the rails. There are 4 plastic plugs on each side of the head that can removed to allow adjusting of these rollers. The spindles of the rollers are eccentric so turning them adjusts them closer or farther away from the rails. I snugged mine all up until the roller just touches the rails and the machine cuts alot better now. I can take a 1/2" deep cut in mild steel now using a 1/2" endmill. My question is how close to the rails should these rollers be? I just hope that the way I have them adjusted now is not placing some kind of bind on the spindle. I can still turn the ball screw very easily when the servos are off.

[Wainford]

Hi I am having similar trouble what is the exact model of your mill, and where are these rollers located, I have KMB1x and can't see these in the manual.

TIA

Shaun.......

[bmachinist]

I have the same mill and problem. What speeds and feeds are you running? I looked in my manual: fig. 6-5, Item# 5 is the McGill Camrol Bearing #CFE-7/8-SB (Hurco PN: 2211-2603-001). I am going to check mine as soon as I can.

[Mike Stevenson]

Is the tool held tight in the holder? What about the extension? RPM? Is the part held down tight?

[Wainford]

I have the same mill and problem. What speeds and feeds are you running? I looked in my manual: fig. 6-5, Item# 5 is the McGill Camrol Bearing #CFE-7/8-SB (Hurco PN: 2211-2603-001). I am going to check mine as soon as I can.

Hi can you post the images Fig 5/6 I think there are several models under the umbrella number KMB1, in the manual for my machine their is no mention of this part number.
I would say the description tool chatter is incorrect, I think its more a sort of resonating at some speed with light cuts, due to wear in several components, splines, gear hub, and backlash in the gear teeth, I was told by a Hurco dealer to check what feels like play in the splines, in both high and low gear, the additional backlash you feel in high range is the gear hub teeth mating to the main pulley hub.
However if this Camrol bearing can take up some of the play it has to help some what.

Shaun.....

[bloke]

Unfortunately, you don't have the rollers. You have a KMB1M or a KMB1X. The rollers were only used in the KMB1 with the AC drive and swan-neck casting.

[Mike Stevenson]

How about one of you guys answering my questions in Post #4 first? If those things are not the problem call Hurco.

[Wainford]

Unfortunately, you don't have the rollers. You have a KMB1M or a KMB1X. The rollers were only used in the KMB1 with the AC drive and swan-neck casting.

Yes I figured mine would be different, however over the last few days I have completely stripped the head to see for myself what was going on, and have now determined that its nothing to do with the splines less than 0.001 play in them, Its simply an accumulation of overall play but mainly backlash in the high gear, I have yesterday replaced all the bearing in the head, simply as a mater of course (this should reduce overall play), I also removed the spindle cartridge to check the bearings and they are OK.
Whilst the machine is out of service I purchased new ball screw balls, grade 25, 5/32 for the X and Y axis and 1/8th for Z axis, and have replaced them, this wasn't as difficult a job as some make out, and the pre-load is a now restored back to speck, well as far as I can find out, but its definitely smother and feels much better.

With regards to post #4, definitely not a loose tool, and the part was securely fixed to the table, whilst keeping tool overhang to an absolute minimum, (but as stated my problem is resonating on light cuts) as far as contacting Hurco their response is we will send an expensive service engineer to have a look and tell you your machine is worn, and here is a price list of new Hurco machines. ;-)

Anyhow I expect that with replacing all the bearings etc. and adjusting everything, I should see some improvements, I should be able to get the machine back up and running this weekend, I don't expect to completely eliminate the problem, but depending upon the success or not of the above I will consider replacing the gears, or perhaps making and fitting a Tufnol pre-load gear, to take up the backlash, my lathe has one of these and it makes the gearbox run very much quieter.

Thanks to all for the pointers.

Shaun..........