Hi, does anyone know if these 4 screws should be tight or loose? I stated getting bad prints so tired to level bed couldn't get it to level and i was hearing a noise everytime the bed moved. Took the plate off to find all 4 screws extremely loose.
Loose enough so that the bed can move in X-Y as necessary for any Z-Screw wobble. If they're tight then binding may occur.
Loose enough so that the bed can move in X-Y as necessary for any Z-Screw wobble. If they're tight then binding may occur.
Ok becasue they where so loose and my print quality went to crap!! So i did tighten them but octive.com and now you are saying they shouldnt be too tight. So guess im going to back them down again and see how it goes. With the printer off i turned the Z- screw by hand to see if it was hard to move but it wasn't moved very nice.
This issue happened also to me and it was causing bad prints and strange noises...
Then I tightened the 4 screws and now every print is ok.
This is the ballscrew nut, right? If the 4 screws aren`t tightened down, the ballscrew nut would have freeplay in the vertical direction, giving inaccurate z movement. In other words, if there is eg. a clearance of 0.1mm due to lack of tightening the screws, the ballscrew would move need the same distance (to take up the slack) before the platform would start to move. You could also lift the platform by hand and feel the slack. This is a precision CNC machine, so it doesn't sound right.
The 4 screws should, in my opinion, be tightened down. If there is supposed to be slack so the ballscrew would cope with misalignment in the XY direction, then that would be a badly designed and toleranced CNC machine.
Yes it is. I feel the same way. My other printer is tight. Octive told me not to tighten these screws. But when I can move the metal frame the bed sits on with my hand that don’t seem right. I hand tightened them for now. Wanted to see what people think. Is the screws tight on your printer?
Regardless of what opinions you might have, the engineering staff has commented numerous times that the screws are supposed to be loose. I personally have not disassembled it to take a look, but I would assume that the design allows for tight z tolerance while allowing x-y play.
Edit: This is not to say that they aren’t TOO loose. If you have z axis free play snug them up just enough to eliminate it, but the screws should still not be fully tightened when you’re done.
Yep that’s just what I did snugged them up. Still makes no sense to me that they shouldn’t be tight. But oh well.
Since ‘snugginging’ is relative, I’d advise caution. Did you make sure to check for binding along the whole axis after tightening the screws?
Ok first I tightened them I turned off machine and moved the screw by hand. It turned very easy and no binding. Then people said not to tighten down. So losseed them but not so much that there was play like there was went they where really loose.
Loose screws in any design, specially when there is vibration, is bad engineering. They are just waiting to come loose. Bolts/screws should have a preload. If XY movement should be taken into account, then it should be solved by design, not by some loose screws. If these screws are recommended to be loose, it`s not by sound design, it`s a bodge to remedy out of tolerance parts.
Loose screws in any design, specially when there is vibration, is bad engineering. They are just waiting to come loose. Bolts/screws should have a preload. If XY movement should be taken into account, then it should be solved by design, not by some loose screws. If these screws are recommended to be loose, it`s not by sound design, it`s a bodge to remedy out of tolerance parts.
Well yes and no. They really aren’t at risk of coming loose since, well, they already are. And since they have lock nuts and aren’t under load, they’re not really at any risk of getting looser.
I get what you’re saying about “bad engineering,” but I’d have to disagree. You want screws to be loaded because that’s what you’re used to, but that doesn’t have to be the case. Engineers have to optimize the design for the set parameters, and these often include cost. They probably could have spent hundreds of hours and thousands of dollars to develop a “perfect” design, and then spend God-knows-what to set up tooling for their fancy new part (or avoid all of this by using EXTREMELY expensive high precision ball screws), or they could use a 10 dollar off-the-shelf component with loose screws that would work just as well. Personally I’d call that grade-A engineering; it performs the intended role to the specifications set as simply as possible.
Oh there is a chance to them to become more loose. Mine did to the point I could hear something vibrating so bad I knew something was loose
Did it become that loose or was it that way to begin with? Unless you checked beforehand there really isn’t a way to know. And anyways, if you’re worried about it a little thread locker will make sure that it won’t happen again.
Last night you caught me on my way out the office so when I saw this issue come up in our system my generic answer was to not tighten the 4 screws down but to try and leave them snug but not to tight. I may not have related that to well and I did not have the time to go into why the design is like this.
In any event, you are back up and running which is all that matters.
-Michael
I noticed print quality go down so went to level bed when doing that I heard a weird noise. Found the 4 screws all loose. They have lock nuts on them. So I think they don’t come to tight from factory.
The point here, regarding design, is to avoid possible reliability issues. Obviously the issue here is that the screws come loose, so if the design is such that the XY is supposed to move due to loose screws, it`s not good. The screws need to be tightened down by the factory operator, and I suspect (don't know of course) it is left to the assembly guy to estimate when the screw is "about right". If he uses calibrate torque tools, different story. But this is China, so he might not.....
You have a few potential problems with design, besides that the screws work loose.
1. If the screws are too loose, there will be vertical free play with associated accuracy problems in Z direction.
2. There are free holes in the ballscrew nut flange (the holes that the 4 screws go through), so if the screws are loose, the nut will rotate in its free hole till it stops on the screw, again causing accuracy problems.
Calling this "grade A-engineering" is not my choice of words.
Just checked my machine, it`s a week old. 3 screws were loose, about 0.5 mm clearance under their head. They are free to rotate and wobble around, doing absolutely nothing.
The last screw is tight, can't rotate it with my fingers anyway. I am less than impressed with this.
Just checked my machine, it`s a week old. 3 screws were loose, about 0.5 mm clearance under their head. They are free to rotate and wobble around, doing absolutely nothing.
The last screw is tight, can't rotate it with my fingers anyway. I am less than impressed with this.
Yeah, amazing how such an "unimpressive" machine produces better results than any other FDM printer in its class. Terrible, terrible design.
Yep it is amazing. But left 3 loose and one hand tight