Binding somewhere?

Hi guys (and gals?)... I have an issue... when I first got my machine put together, I had certain issues with it but finally got the solved. Using PLA so my first couple prints wouldn't stick to the substrate... that's not the issue now, we'll have bigger worries than that. Right now, the Z axis is binding big time. How do I know it's binding you ask? Took out the couplers between the lead screw and the steppers... steppers run fine. Lead screws are smooth smooth. Linear bearings glide easily up and down the rod. Put it all together... the steppers chatter an the lead screws don't move. I can assist it by moving one of the lead screws and it moves... but the steppers are struggling. I tried loosening the steppers to see if I could move them to help line them up... it worked! Went to dinner, came back... didn't work. Last night as a last ditch efforts I tried to adjust the coupling again... it worked! Went to bed, got up IT WORKED!! Turned the machine off.. turned it on to show wife...DIDN'T WORK!!! I'm about to throw it out the window... can ANYONE help with this? PLEASE!!!

Using Marlin firmware? The find this line:
#define DEFAULT_MAX_FEEDRATE {300, 300, 5, 25} // (mm/sec)

and change the 5 to 4 or 3.

I don't believe it is Marlin. In otherwords, I can't find that parameter you are talking about anywhere on thee machine. If it IS Marlin, it a customized version just for this machine (I got the machine from GearBest) In Marlin, how would I get to the parameter?

I had the same problem and chased it for a month.

Take the lead screws out completely and try moving it up and down by hand, it should be easy to move up. It should also fall quickly under it's own weight. If it doesn't, there's something causing binding. Doesn't sound like it's the bearings from what you've described. Could also be that the vertical rails aren't perfectly parallel to each other. The bearings may have slid fine by themselves, but when locked into the carriages trying to maintain them parallel and the rails not being, could cause binding. In that case you'd measure the distance between top and bottom and make sure they're parallel, adjust as necessary.

If that's not the issue, I'd say the feed rate is too high, it just can't mechanically do the speed requested of it. That would be adjusted in the firmware, lots of people use Marlin, yours might be different.

If you send M115 command to it from your host software, it'll reply back with the firmware and version, that'll tell you if it's Marlin or something else.

For the machine to work, the firmware would have to have been loaded initially, kit makers usually do it for you. It includes settings similar to that stephenrc posted. Then if you need to change anything, you download the source from them, make your changes, and re-upload it.

You may have 2 courses of action for that
1. Hopefully they've turned on EEPROM, in that case you can just send the following commands to it and it'll adjust them

M503 - That will tell you what the current settings are
M203 Z0.50 - That will set the max feedrate for Z to .5 mm/sec (I've found that even as low as 2 is too fast and binds it, .5 is still 30 mm/min, plenty fast for that axis )
M500 - Saves current settings


If you send M500 and don't get something like "EEPROM settings stored", it probably isn't enabled

2. You'd either have to track down the firmware from the maker, make the changes like stephenrc posted re-upload it or start with a clean version of a firmware and change the settings to make your printer work. Which may be easier if you at least get a report of the current settings with M503

Edited 2 time(s). Last edit at 07/19/2016 01:39PM by FA-MAS.

Hi FA_MAS...
Thanks for the info. After tracking down a terminal program, I did everything you suggested.. even found out (I think) where the manufacturer keepss the master copy of it's firmware! But all to no avail...

I DID notice how ever there is something odd about the X Axis and the Z Axis Lead screws. See I disconnect the lead screws from coupling and lift the Z Axis to disengage the lead screws. When I bring the axis back down to reconnect it, The left lead screw slides right into the coupling.. but the right lead screw misses the hole. In order to get the lead screw into the coupling, you have to apply pressure, to the right and slightly back. THEN it slides in.

Now presuming that this is causing the binding because it's off center, I really wouldn't know how to adjust it to line the coupling up! The Steppers has no play in it's screws, the guide rail has ho play in it either. I have knocked the X axis guide rods about 1/8 of an inch back into the block and there;s been no change in the lead screws position.

Any idea how I can adjust the position of the lead screw?
Thanks again for your help!

Don W.

P.S. I've attached a couple pictures to demonstrate what I'm talking about.

Wierd, it almost looks like the lower motor mount doesn't line up with the top support.

I'd take the top plate off that lower motor mount, the one where the motor screws to.
And line it up with the top support using the smooth rod as a guide. The hole for the lead screw should be exactly in the middle of the motor hole.
If it's not, one of those pieces is wrong.

Edited 2 time(s). Last edit at 07/20/2016 01:31PM by FA-MAS.

Hello Folkes.. I've attached a couple pics illustrating what I have do to try and fix the problem. If anyone can think of some I have missed, Feel free to let me know!

Thanks for your help so far.. It is muchly appreciated!

You can figure out if the X End is bad.

Measure the distance between the smooth rods at the top of the printer
Measure the distance between the smooth rods at the bottom of the printer
They should be equal

Then take the couplers off of the motors so you can see the motor shaft
Measure the distance between the left smooth rod and the center of the motor shaft
Measure the distance between the right smooth rod and the center of the motor shaft
They should be equal

Providing that's all good, then it is probably the X End
You can measure at the X End, the distance between the smooth rod and the center of the lead screw
That should be equal to what you measured on the motor shaft, if not, that X End is wrong

Edit: and the entire assembly's level? If were lower on the right side, at that height, it could cause misalignment below, which could be why it binds too.

Edited 1 time(s). Last edit at 07/22/2016 12:58PM by FA-MAS.

Thanks! I will definitely Try this!

BTW, to all.. GearBest... the folks I bought the machine from... has thrown in the flag. I sent them the files I have attached here and after reading then, apparently they had nothing else to try so They are offering a refund (If I want to send it back to China!) Shows you the extent that I have gone through to try to figure this out.. sigh...