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Trevor G

MH871 cutting head grinds/binds when moving.

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The cutter is approx 6 months old. The belt is still intact and in good shape. I have pulled the covers, to check the idler and the motor gear for restrictions, checked the rollers on the cutting head, all move. It moves freely by hand but as soon as I try to use the functions it does as I have added.

 

 

Any help would be great!

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I was afraid to hear this...


Is there any maintenance I should be doing to prevent further problems. I wipe out dust from the track... I dont know much else I can do...

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So I wanted to confirm the motor before I ordered anything. It turns freely on its own, I put pressure on it to simulate the cutter head and it still turns OK; however, I do notice that rarely the motor turns the incorrect direction.

 

 

 

Could there be something else causing a problem?

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"Could there be something else causing a problem?"

 

Yeah, there could be. We aren't there in your position, so any troubleshooting steps offered here on the forum are going to be just "shots in the dark" to get you to pinpoint the actual issue.

 

From the second video, that motor does seem OK.

So, now you've narrowed it down to something that's binding when the entire cutter head assembly is attached with the belt.

You say that you've taken off the left-side cover and looked at the tensioner pulley (idler) while the machine is working and it's fine, right?

 

Keep playing around and checking everything. It's not a really complicated system.

Open the cutter head box and disconnect the belt (it's just clipped on) and attach those two ends of the belt (with a paper clip?) so there's tension, and try working it.

If there's noise still coming from the unit, try to listen where it's originating from.

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I would call support tomorrow - I am leaning toward a motherboard failure or something like that but they can troubleshoot it over the phone better and suggest parts.  did you have the stand grounded to the cutter?  the cutter is automatically grounded by the plug but the stands are insulated on that model - they are known for static building in the stand/vinyl and discharging thru the carriage and causing problems with the mb.  watching how it is moving compared to the buttons pressed sure makes it look like a controller problem more than a motor - also motors almost never go out on those

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Why motherboard failure? That's a pretty drastic evaluation from just that video !!!

 

We have now seen the motor operate cleanly, so that was eliminated as a cause.

It still sounds to me like that belt is hanging up somewhere, and causing it "skipping" over the motor gears.

Maybe there's a problem in the upper track (where the control ribbon cable is)? It's worth opening that top section and looking.

 

USCUTTER support is going to run into the same limitations we are having -- namely, not being able to be right there and check things in person. For instance, they might have said (just as I wrongly advised) to replace motor part. Well, you quickly discovered on your own that wasn't where the problem comes from (and I'm glad you did, before spending $50 unnecessarily).

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slice we will see how this plays out - but I will bet it is not the motor you suggested.  looks like erratic commands given to the motor from the mb but only time will tell.  watch the movement when the different buttons are pressed - didn't look like it was gears skipping. but that is just one persons opinion and I have been wrong many times

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well here is my .02 cents!!  I bet it may be the keypad- or crossed Y-axis wires in the keypad.

 

He pressed to opposing buttons,  and it went the same direction! Then when it stuttered- I bet it was receiving both left and right inputs at the same time-.

 

Trevor- does it cut normal when you send files?-  

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well here is my .02 cents!!  I bet it may be the keypad- or crossed Y-axis wires in the keypad.

 

He pressed to opposing buttons,  and it went the same direction! Then when it stuttered- I bet it was receiving both left and right inputs at the same time-.

 

Trevor- does it cut normal when you send files?-  

Last time it cut it was cuting normally, but sounded laboured. I tried to job the cutting head after the last cut and it was binding and showing the signs as the first video. I only notices the directional problem after the fact.

 

 

Why motherboard failure? That's a pretty drastic evaluation from just that video !!!

 

We have now seen the motor operate cleanly, so that was eliminated as a cause.

It still sounds to me like that belt is hanging up somewhere, and causing it "skipping" over the motor gears.

Maybe there's a problem in the upper track (where the control ribbon cable is)? It's worth opening that top section and looking.

 

USCUTTER support is going to run into the same limitations we are having -- namely, not being able to be right there and check things in person. For instance, they might have said (just as I wrongly advised) to replace motor part. Well, you quickly discovered on your own that wasn't where the problem comes from (and I'm glad you did, before spending $50 unnecessarily).

 I ran the belt disconnected from the cutting head like you recommended and It ran smooth, no problems, other then the directional conflict being intermittent. I have not yet removed the cutting head yet but it seems to move smoothly, I will still take it off tonight to ensure its ok.

 

And yes there is a ground strap from the stand to the cutter as specified by USCutter.

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I would certainly like to see a better video than the 17-second one in the first post.

 

More operations back and forth & clearer view of what's happening.

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So I removed the cutting head to inspect the rollers. Before removing I checked for play as it sits in the track, and it appears to be tight. Please excuse the black hands, I am a mechanic by day...

 

 

This video just reviews clear smooth movement of the belt with the cutting head removed.

 

 

 

I would certainly like to see a better video than the 17-second one in the first post.

 

More operations back and forth & clearer view of what's happening.

I have the cutter apart and not able to make a better video, this is why I made the above and spoke this time (hahaha). I have yet to phone tech support as I just discovered how early they are open. I will calling them in a few hours. I will post any progress through tech support for others to review.

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OK, here's what we've learned so far ---

 

1. The motor is fine. Check.

2. The belt (without the carriage, just a rubber band holding the ends together) runs in both directions smoothly. Check.

(by the way, since it is moving without issues in this configuration, that eliminates a command/circuit failure from the MB)

3. The upper ribbon is not hanging up on anything inside the top housing. Check.

4. The tensioner (pulley) isn't binding the belt. Check.

5. The carriage wheels are spinning freely. Check.

 

The free movement of the carriage is being impeded, and when it gets jammed up, the motor gear wheel keeps spinning while the belt cannot move, resulting in the grinding sound of the belt skipping around the sprockets of the motor gear wheel -- that's what we are hearing in the first video.

 

Eliminate the hang-up, and you will eliminate the noise and be back to normal.

 

We await further details !

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personally I would keep banging my head against the wall instead of calling support for their opinion  :blink:   I still disagree that this has eliminated the control circuit completely as it appears to be only doing it under the load of the carriage, but that is what the techs get paid to figure out

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personally I would keep banging my head against the wall instead of calling support for their opinion  :blink: 

 

From his previous posting -- "I will be calling them in a few hours. I will post any progress through tech support for others to review."

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From his previous posting -- "I will be calling them in a few hours. I will post any progress through tech support for others to review."

Yeah I slept in this morning and had to bolt to work. I will have to call tomorrow morning.

 

After I made and posted those last two videos, I grabbed ahold of the belt hard and ran the motor, it ran smoothand gave good pull on my grasp.

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Sorry I ended up coming down with some flu that was going around at work.

 

So I just spoke to the tech support line. I explained my situation. He immediately asked me to look at the heat sink on the motherboard (my MH871 is a MK2) and locate the red and white pigtail on either side of the heat sink. These are for the feed rollers and the motor for the cutting head. He had me switch the pigtails, so red pigtail in white socket and white pigtail in red socket. Then asked me to turn on the machine.
 

The cutting head moved like normal and the feed rollers did not move. This indicated to him a motherboard problem. It needs a motherboard. I have ordered one already and await arrival (maybe a week?, international shipping and all...). Once I have the new mother board installed, I will post results.

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