View Full Version : Some advice needed on X-Axis belt issues.

02-17-2007, 04:08 PM
Hi All,

A little background on my machine. I purchased the turn key machine from Industrial Hobbies. When I got the machine, there were certainly some pretty big issues with it that Aaron helped me get sorted out. Well, the one issue that has yet to get sorted out is an X-Axis belt issue and I'm wondering if someone can help me get it sorted out. I've contacted IH about it and the response I get is, "my x-axis belt has been on there for years." Doesn't really do me any good.

First, the issue. I put a brand new belt on and in a matter of a couple of weeks, when there is an X move, at the start of the movement and the end, the servo vibrates really bad and makes kind of a sqeeking noise, this noise could be because of my encloser but it creates a pretty serious vibration. Then, a couple of days later, the vibration will last longer through the movement, lets say the first third of the movement, still vibrating badly at the end as well. After another day or two, it vibrates throughout the whole movement. Another day or two and it vibrates so violently, even when it's finished moving, that it sounds like the machine is going to rip itself apart.

So, after this happens, I tighten the belt on the X-Axis. That will fix the problem for a couple of days and then the whole process starts over again. I can only adjust it once because there isn't much available adjustment to begin with. After the second adjustment and cycle of vibrating again, it's now time for a new belt.

As you can see, every couple of weeks, I'm replacing the belt. I'm beginning to buy them in bulk because I go through them so quickly. I'm probably buying more belts than IH right now.

When this initially happened, Aaron said to adjust the gibs and bearing. I did all of that so I could turn the little nob all the way through the length of movement of the table with no kind of tight spots. A few weeks later, the same problem.

Recently, while changing the belt, those four little screws holding the motor on the bracket, that got so corroded finally let go and broke. Now, I have a new servo and gear on the X-Axis. The whole cycle is now happening sooner after I did that. I called Aaron again and asked him if I could purchase the new X-Axis mounting brackets because it would make changing belts a lot more efficient. He told me he didn't have time to deal with me at that particular time and would call me on Monday. After about 3 weeks, I've given up on him calling me back. Understandably, he did sell the company.

I've been following the IH forum for a while now and it seems like there are some really smart people who purchased the kit/machine and was wondering if anybody could help me solve this problem. Since I've owned the machine, the Y-Axis has worked fine, no belt changes or anything. I did have some issues with the Z but that's probably for another day.

If I would have known I'd have so many problems on a turn key machine, I would have probably taken my $10k somewhere else.

Thanks for any help or suggestions you might have, I've just kind of reached the end of this and don't know where to go.


02-17-2007, 11:52 PM
are you sure thats its a mechanical issue and not an issue with the acceleration of the servo motor that might be causing your problems? from what your describing, the vibration at the beginning and end of a run kinda looks like a problem with the driving software.

i would try slowing down the acceleration in the software and go from there. if the vibration persists, then start checking stuff like the motor brushes, or start looking for a loose connection. unfortunately i know the last comment is kinda nebulous as the cnc has a lot connectoins, but make sure your getting the 5 volts to the gecko.

02-18-2007, 05:42 PM
Are your belts actually breaking?
with the belt disconnected how does x-axis feel in the area
it begins to have this trouble?
any loosness between table and the ball screw , is the ball nut ok ?
do the bearings in the mounting blocks st each end of the x-axis screw feel ok? any radial movement?
is the table gib adjusted firm enough so there's no excess
table movement from front to rear?
did you check these things already , we just don't know what you have done yet?

i think Runner4404spd is right
it sounds like a tuning issue not mechanical

if your going thru that many belts you would think if it was mechanical it would be easy to find

Mike Nash
02-18-2007, 09:14 PM
There's one other thing I wonder about. My understanding is that the servo encoder is on the screw, not the motor, on the IH kit/machine. Any chance the encoder is loose or bad? Whether it's on the screw or motor maybe shouldn't make any difference if the belt is tight, but then again...

02-18-2007, 11:49 PM
Hi guys,

Thanks so much for your ideas. To answer a couple of the questions above:

The belts aren't breaking, it does look like they are starting to come apart though. I think this is due to the belt rubbing on the screws that hold the motor in place. It looks like the belt skims the bolts and eventually starts to wear.

The table movement seems smooth throughout it's entire range, no tight spots or anything. I can grab the table and not move it away or toward me but when it's homed, I can take the far end and move it a little.

After I read the posts, I went out and played with the motor tuning some. I think you guys might be on to something here. When I got the machine, the settings were:

Velocity = 1.25
Acceleration = 5

I played around with those two settings and finally got it to work noise free by setting them to:

Velocity = 1
Accelleration = 1

There is a problem with this though, I was cutting some parts and when it cuts circles or radiuses, it actually pauses. I even changed the Y-Axis to the same values and then both axis pause. It does work but where it pauses it leaves machine marks in the part. I guess begars can't be choosers, at least it's working right. Any suggestions on how I can find a happy medium? Any higher on the settings and it will start to make the noise again.

Thanks again for everyones help with this,


02-19-2007, 07:19 AM
this does not sound right, you are set at 20,000 right ? if so 1 & 1 is out of order, I run 20,000 135 & (5 or 7) with mach set at 45,000 and it runs fast and strong. The pausing sounds like exact stop set, but slow responce. how does your machine sound when static or just sitting there idling, noisy or quiet ? if noisy then the geckos need a fine tune, if quiet then they may be ok or set too soft. these setting are global and all have an effect and all have to be right.

02-19-2007, 08:43 AM
Yes, the steps are set to 20,000 with mach set at 45,000. The exact stop checkbox is also selected. If I change the belt every couple of weeks, I can change the settings and it will run fast and strong too. The Gecko's are quite when the machine is sitting idle.

Thanks again,


02-19-2007, 08:03 PM
the noise i was refering to would be coming from the servos, not the gecko's, but the gecko setting would be the cure, you'll figure it out someday !

02-20-2007, 09:00 AM
I had the same problem with my mill, first on the y-axis, then later on the x-axis.
I would tighten the belt, it would last a few days and the oscillation would be back. I even modified the motor mount for more adjustment. I went through two belts. What I found was the coolant I was using would make the belts go soft and stretch.
To fix it I switched coolant brands, and made aluminum covers and sealed them to replace the plastic covers, and moved my coolant nozzles to spray the coolant away from the drives.

Been working fine since.

02-20-2007, 10:12 AM
can someone post what all of their motor settings are in MACH 3? i'm getting my IH mill setup and would like some place to start so i'm not chasing my tail.


02-20-2007, 06:25 PM
Youngfg, So this sounds important to me, what coolant was the offender ?
Runner, I'd be glad to help you and better yet i'd be willing to send a copy of my xml file which would cary it all then it would be simple to expain the few changes you would have to make !

02-20-2007, 08:07 PM
Here is what I was using. I have an unopened gallon left if someome wants to try it.
Universal® Metalworking Lubricoolant

I am using Tri-Cool TC1 right now, I haven't had any problems with it, but I have much better belt covers now. The original plastic weren't much more than splash gaurds.

02-20-2007, 09:57 PM
Thanks for the infor youngfg, do you by any chance have some pictures of the new covers that you made? I've been using SynLube GM, which Aaron recommends on his site, I figured it was ok.

Thanks again,


02-20-2007, 10:48 PM
cruiser you can send the xml file to




02-21-2007, 09:47 AM
this does not sound right, you are set at 20,000 right ? if so 1 & 1 is out of order, I run 20,000 135 & (5 or 7) with mach set at 45,000

Surely the original numbers were in inch/s units while these are in i/min units. Although 135 ips rapids would be pretty awesome :) Since the poster said this is a turn-key system is it corect to assume that Mach2 is being used? However, wouldn't a 1ips^2 acceleration be something like 3600 ipm^2?