Squeaky mk3?  

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leonardo.g3
(@leonardo-g3)
Estimable Member

Well... i will take advantage of the thread to ask someone if they are noticing vibrations noises coming from the PETG printed parts on the printer.

My MK3 has about 210 hours of printing, i've noticed that the cooling part fan vibrates and makes some noises when the X-axis is moving at certain speeds (60mm/sec makes the worst noise)

The Y-axis motor mount (printed part) also is starting to make noises (130mm/sec is the point where it makes the worst noise).

I checked the screws and they are tight enough... I tried loosening them but it didnt work. Do you guys have any idea what to use between the motor and the mount to reduce noise? I was thinking of MoonGel ( https://www.thomann.de/pt/smile_moongel.htm ) but the problem with it is that if its too much squished it wont do a thing to reduce vibrations. 😡

Posted : 05/01/2018 4:13 am
JohnOCFII
(@johnocfii)
Estimable Member


I adjusted my x-belt inside the x-carriage. It now sticks out slightly from the groove in the x-carriage housing. Maybe... 1 - 1.5mm sticking out from the little groove.

I then wiggled the belt so it was more center on the x-idler pulley. (Before when I tried this, the belt would simply wiggle its way back to the edge of the pulley again, and start squeaking)

Similar situation here (but MK2). I pulled the belt towards the rear of the printer in the extruder. It's out as far as it can go without sticking out of the extruder. I can move the belt on the X-idler wheel to the back flange. Moving the X-axis less than 120mm will move the belt again all the way to the front flange on the X-idler.

Would replacing the X-idler help? I'm not sure what to try next. It's squeaky, but worse, it seems to the source of vibrations that are negatively impacting the quality of my prints.

John

https://3dprinting.community/login #Community Discussion for 3D Printing...
Posted : 08/01/2018 4:30 am
sverker.n
(@sverker-n)
Eminent Member

I have two questions as I am waiting for my MK3.
what type of belt is used is it a GT2 belt?
What is the number of teath on the stepper drive.

I am begining to search for fiberglas belts instead of rubber. I have built a few CNC millers and there always used fiberglass belts as they do not stretch at all. When the driver changes direction it may stretch a small amount before the direction is actualy changed therefore fiberglass.

Posted : 08/01/2018 4:38 pm
stahlfabrik
(@stahlfabrik)
Honorable Member

I have contributed to this discussion and still I do not know:

Is there anybody who got rid completely of this wiggly belt problem?

I tried many hours and could reduce it, but not get rid of it. Not funny how many times I loosened the screws on X motor and its idler on its shaft.

I had an email conversation with support about this.

So far I only have heard back that maybe reprinting one part might solve the problem. What I could not find out yet: Which printed part would be the problematic part? I know that my x-motor-holder part is faulty (as the bearings in it slide up and down). Could it be the reason though (maybe the motor is also "hold wrong")? I would guess that the opposite idler holder might be the problem or of course the x carriage.

Posted : 10/01/2018 2:53 pm
jltx
 jltx
(@jltx)
Reputable Member

I am now 99% certain this theory is correct for contributing to the squeaky belt:

https://shop.prusa3d.com/forum/original-prusa-i3-mk3-f30/poor-print-quality-t12438-s110.html#p57336 '

My printer is currently torn down (see sad sight post) so presented an opportunity to examine. Sure enough, the screw hole for the X end with idler is over-sized on one side which allows the screw head to move laterally. So when the X belt is under tension it pulls that side forward and even though you have centered the belt from the carriage slot, it will dive to one side and rub the flange. The stock part hole is 3.6mm which is far too big. Interestingly the Y idler uses a 3.2mm hole which is an appropriate size.

Regarding the twisty belt, that is not a concern in and of itself, more of a symptom than a problem. My MK2S did that as well.

You want parts? I got MK3 parts https://www.thingiverse.com/jltx/designs...
Posted : 14/01/2018 3:39 pm
reid.b
(@reid-b)
Reputable Member

I looked at the STEP file for the x-idler- both sides of that screw hole are 3.6mm- so I guess I'm not sure what you are saying. Yes, the hole might be a bit large, but it is equally large on both sides so it shouldn't 'tilt'. Maybe I'm looking at it incorrectly.

Posted : 14/01/2018 6:51 pm
jltx
 jltx
(@jltx)
Reputable Member


I looked at the STEP file for the x-idler- both sides of that screw hole are 3.6mm- so I guess I'm not sure what you are saying. Yes, the hole might be a bit large, but it is equally large on both sides so it shouldn't 'tilt'. Maybe I'm looking at it incorrectly.

True, but the nut holds the other side in place (fits its hex hole snugly). The screw head also has some play, which is a standard amount of clearance, but I’d reduce that as well since we want it nice and tight. In fact, my temp bandaid is to shim the head since I can’t print anything at the moment.

I’d fix it but all the step files I’ve tried, but including my own scad conversions, don’t work.

You want parts? I got MK3 parts https://www.thingiverse.com/jltx/designs...
Posted : 14/01/2018 7:41 pm
reid.b
(@reid-b)
Reputable Member

Here you go- I fixed that hole in this attachment.

Posted : 15/01/2018 12:17 am
reid.b
(@reid-b)
Reputable Member

I think I can fix this part additionally. If we were to move the x-axis idler pulley, what would the ideal amount be? I can move it 0.5mm, maybe max 1.0mm.

The thing that constrains how much we move it is the idler bolt head- we don't want it contacting the z-axis leadscrew. If moving the idler pulley, we have to additionally move the bolt the same distance, as there is very little material for the bolt head to rest against. Currently there is only 1mm material between the base of the bolt head and the face that the idler pulley touches.

Posted : 15/01/2018 2:08 am
jltx
 jltx
(@jltx)
Reputable Member


Here you go- I fixed that hole in this attachment.

Looks good. Are you able to export STL from this STEP? My CAD does not like the X idler STEP. There is a tiny bit of surface missing so it does not treat it as a solid and thus no export. I can't seem to patch it.

You want parts? I got MK3 parts https://www.thingiverse.com/jltx/designs...
Posted : 15/01/2018 3:18 am
jltx
 jltx
(@jltx)
Reputable Member


I think I can fix this part additionally. If we were to move the x-axis idler pulley, what would the ideal amount be? I can move it 0.5mm, maybe max 1.0mm.

The thing that constrains how much we move it is the idler bolt head- we don't want it contacting the z-axis leadscrew. If moving the idler pulley, we have to additionally move the bolt the same distance, as there is very little material for the bolt head to rest against. Currently there is only 1mm material between the base of the bolt head and the face that the idler pulley touches.

I wouldn't recommend moving it. Definitely don't want to contact that Z screw. I think stabilizing the screw by tightening the hole (as you did), plus setting the belt back in the carriage should be sufficient.

You want parts? I got MK3 parts https://www.thingiverse.com/jltx/designs...
Posted : 15/01/2018 3:21 am
reid.b
(@reid-b)
Reputable Member

I have attached the corrected STL.

Why do you recommend not moving it? It seems to me this would help correct a known issue that many are having.

Also- anybody have any idea why there is a slot cut through the part right next to the idler pulley? What on earth is this for?

Posted : 15/01/2018 6:49 am
ibn
 ibn
(@ibn)
Trusted Member

the slot was used as an easy way to actually strengthen the part (Joe mentioned it in some interview). Because the sides of the slot are an outside face the slicer creates perimeters, these are the "reinforcement"

Posted : 15/01/2018 3:55 pm
jltx
 jltx
(@jltx)
Reputable Member


I have attached the corrected STL.

Why do you recommend not moving it? It seems to me this would help correct a known issue that many are having.

If you are willing to test it, go for it. It's an expensive tear down just to try it. But here's my caution. They moved the back plate out 1mm, but the front only 0.5mm. Why? Because the screw head is only 1mm away from Z screw now (ideally). Any slight variation and that gap shrinks. You might get away with it, but another builder may fall out of spec. If you move it more than 0.5mm the whole belt opening needs to be widened and you get into a domino of changes, because you won't want the walls any thinner, but there's clearance concerns with the carriage, etc. Plan very carefully.

Also- anybody have any idea why there is a slot cut through the part right next to the idler pulley? What on earth is this for?

I believe it is a strain relief. There are similar hidden channels in other large parts. They used to print in ABS which is challenging. But I'd like hear from someone who knows. I would not remove it if that's what you are thinking.

You want parts? I got MK3 parts https://www.thingiverse.com/jltx/designs...
Posted : 15/01/2018 3:59 pm
jltx
 jltx
(@jltx)
Reputable Member


the slot was used as an easy way to actually strengthen the part (Joe mentioned it in some interview). Because the sides of the slot are an outside face the slicer creates perimeters, these are the "reinforcement"

Thanks. You answered while I was typing. Makes sense.

You want parts? I got MK3 parts https://www.thingiverse.com/jltx/designs...
Posted : 15/01/2018 4:00 pm
stahlfabrik
(@stahlfabrik)
Honorable Member


I have attached the corrected STL.

Why do you recommend not moving it? It seems to me this would help correct a known issue that many are having.

Also- anybody have any idea why there is a slot cut through the part right next to the idler pulley? What on earth is this for?

Hi Reid!

very interesting! May I ask what your changes to the original design were? Did you only change the diameter of the screw's hole?

And even more interesting: Did you have the wiggly belt problem and did printing and installing your redesigned replacement part solve the issue for you once and for all?

Would be great to hear back from you. I need to reassemble larger parts my MK3 for various reasons - I would love to reprint this part before if this would help me getting rid of this problem!

Best regards

EDIT:
I played around with the scad - I have never used it before so I might be wrong here. But am I wrong that in order to change the screw holes opening from 3.6 to 3.2 mm one has to change these three lines:

diff -w x-end-idler.scad x-end-idler_mod.scad
16c16
< translate(v=[0,-19,30.25]) rotate(a=[0,-90,0]) cylinder(h = 80, r=1.8, $fn=30);
---
> translate(v=[0,-19,30.25]) rotate(a=[0,-90,0]) cylinder(h = 80, r=1.6, $fn=30);
64c64
< translate(v=[0,-15.5,30.25]) rotate(a=[0,-90,0]) cylinder(h = 80, r=1.8, $fn=30);
---
> translate(v=[0,-15.5,30.25]) rotate(a=[0,-90,0]) cylinder(h = 80, r=1.6, $fn=30);
119c119
< translate(v=[-8,-15.5,30.25]) rotate(a=[0,-90,0]) cylinder(h = 20, r=1.8, $fn=30);
---
> translate(v=[-8,-15.5,30.25]) rotate(a=[0,-90,0]) cylinder(h = 20, r=1.6, $fn=30);

EDIT2: With these changes the STL is this:

EDIT3: Attention, my changes are solely based on the discussion here - I have not even measured the real diameter of the used screw - so beware before you print!

Posted : 15/01/2018 9:13 pm
reid.b
(@reid-b)
Reputable Member

I don't even have my MK3 yet- not till next month if I am lucky. Yes, all I did was change the bolt hole diameter to 3.2mm. But I did this in Fusion360 with the converted STEP file that was provided by jitx on his github site. I can say whether your steps are correct, as I am not an OpenSCAD user.

Posted : 16/01/2018 2:32 am
jltx
 jltx
(@jltx)
Reputable Member


I don't even have my MK3 yet- not till next month if I am lucky. Yes, all I did was change the bolt hole diameter to 3.2mm. But I did this in Fusion360 with the converted STEP file that was provided by jitx on his github site. I can say whether your steps are correct, as I am not an OpenSCAD user.

Just to be clear, the GitHub repo is all the hard work of jzkmath.

You want parts? I got MK3 parts https://www.thingiverse.com/jltx/designs...
Posted : 16/01/2018 5:51 am
jltx
 jltx
(@jltx)
Reputable Member



I have attached the corrected STL.

Why do you recommend not moving it? It seems to me this would help correct a known issue that many are having.

Also- anybody have any idea why there is a slot cut through the part right next to the idler pulley? What on earth is this for?

Hi Reid!

very interesting! May I ask what your changes to the original design were? Did you only change the diameter of the screw's hole?

And even more interesting: Did you have the wiggly belt problem and did printing and installing your redesigned replacement part solve the issue for you once and for all?

Would be great to hear back from you. I need to reassemble larger parts my MK3 for various reasons - I would love to reprint this part before if this would help me getting rid of this problem!

Best regards

EDIT:
I played around with the scad - I have never used it before so I might be wrong here. But am I wrong that in order to change the screw holes opening from 3.6 to 3.2 mm one has to change these three lines:

diff -w x-end-idler.scad x-end-idler_mod.scad
16c16
< translate(v=[0,-19,30.25]) rotate(a=[0,-90,0]) cylinder(h = 80, r=1.8, $fn=30);
---
> translate(v=[0,-19,30.25]) rotate(a=[0,-90,0]) cylinder(h = 80, r=1.6, $fn=30);
64c64
< translate(v=[0,-15.5,30.25]) rotate(a=[0,-90,0]) cylinder(h = 80, r=1.8, $fn=30);
---
> translate(v=[0,-15.5,30.25]) rotate(a=[0,-90,0]) cylinder(h = 80, r=1.6, $fn=30);
119c119
< translate(v=[-8,-15.5,30.25]) rotate(a=[0,-90,0]) cylinder(h = 20, r=1.8, $fn=30);
---
> translate(v=[-8,-15.5,30.25]) rotate(a=[0,-90,0]) cylinder(h = 20, r=1.6, $fn=30);

EDIT2: With these changes the STL is this:x-end-idler_mod.stl.zip

EDIT3: Attention, my changes are solely based on the discussion here - I have not even measured the real diameter of the used screw - so beware before you print!

Your STL looks good. The hole is correct now (3.2) and It has the lip for the bearings that the STEP is missing. I also notice you got the revision stamp. I wonder why those don't show up in the STEP conversions.

You want parts? I got MK3 parts https://www.thingiverse.com/jltx/designs...
Posted : 16/01/2018 5:53 am
stahlfabrik
(@stahlfabrik)
Honorable Member

Thank you for having a look at it!

So I guess I will try to print this then and switch the current part for the new one.

But I will not be able to reassemble the printer within the next 10 days I think - maybe coming weekend but there is so much more to do...

If anyone with a wiggly x belt wants to give this a shot: PLEASE do so!

Posted : 16/01/2018 1:16 pm
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