Removing play from Y carriage?  

Re: Removing play from Y carriage?

As a noob that just completed the build. I did have some calibration issues and noticed that when i thought that one of the z-offset adjusters needed pushing down i could actually push the carriage down a little. I guess for me it has a very small amount of play such that the force from my finger is probably more than the weight of any part i would ever print. So i let it be. From the experience with support, if you have significant play and cant take some pics and measurements they could prob help.

Re: Removing play from Y carriage?

The most likely cause of lateral play in the Y carriage is that the bearings have not been sufficiently tightened with the cable ties.

However, the nature of linear bearings and manufacture tolerances will mean that there is bound to be a certain amount of lateral movement.

Personally I have not found that this lateral movement has any effect on print quality.

Peter

Re: Removing play from Y carriage?

I seriously doubt that the bearings cable ties are too loose, since I snapped several before I learned exactly how much force I could apply when assembling the carriage. Part of the problem is in the basic design, which magnifies cumulative tolerance issues like this.

Re the print quality, I haven't had the printer long enough nor do I have a sufficient sample size (I only have 1 printer) to determine if the symptom is significant. The items I have printed have all been at .200 mm layer resolution in either PLA or ABS, so a certain amount of layer visibility is expected. However, the fact that the carriage exhibits measurable backlash in both Z-axis and X-axis causes me to wonder if a good print at .050 or even .100 mm layer resolution is even possible. In addition, the printer makes a horribly loud rattle whenever the carriage is moved quickly in opposite directions along the Y-axis (carriage rails), which tends to reinforce the opinion that the compound backlash is an issue while printing. 'Cherry-picking' a set of bearings is probably the easiest thing to try first ; replacing the carriage frame with something that allows a 4-bearing mount would be the next step.

Re: Removing play from Y carriage?

Mark

When you say back and forth do you mean North and South (backward and forward) as you look directly at the Y bed. Or do you mean slight twist West or East (left or right) Check cable ties are fully tight, but also if the Y belt is tight enough. It should ping when plucked.

Your reply above you are talking about different axis X and Z I am confused. My printer is totally dialled in and gives some of the best prints I have ever had. I have several different 3D printers. Including at Ultimaker 2+ The genuine Prusa I3 is as good and in some aspects better. I mean it.

Using Joseph Prusa's Slic3r 1.75mm profile settings from the support page. Wonderful.

Re: Removing play from Y carriage?

Mark

The rattle means you need to tighten up a little the stepper motor mounts, the Y stepper was noisy on my printer, got rid of it by tightening up the nuts either side of the mount rail and the bolts into the plastic. They say do not over tighten in case you spilt the plastic, I feel you need to tighten things up a bit more overall. You may have been a little too loose 🙂

Re: Removing play from Y carriage?

Nigel,
The most play is rotational around the z-axis. Now that I think about it a little more, I should have stated that I have excessive XY play around the Z-axis: if I hold on to one corner of the bed and move it diagonally in the horizontal plane, the bed will twist as if there was a pivot point in the middle of the bed.

Re the tightening, it would be a first if things were too loose - my normal error is applying excessive torque that causes breakage. The rattle is being caused by the slop in the bearings. All of my belts 'twang', so that isn't the issue. I'll go ahead and check the mechanical joints, but I'm betting that if I cherry pick a set of three bearings from the group of 12 I just ordered, I can eliminate most of the issues I'm seeing, including that horrible rattling on sudden Y-axis changes of direction.

Re: Removing play from Y carriage?

Mark

Personally I don't believe you will find any difference when you replace the bearings. There are thousands of these printers out there and since I joined these forums, I believe you are the first person to complain about this issue.

The strange thing here is that you are complaining about something that has not given you a problem. You say there is no evidence of an issue at layer height of 0.2mm and that you haven't tried a print at 50 micron. Best thing to do is to print the 50 micron tree frog from the SD card to see what happens; if it is no good, then complain.

I am totally with Nigel on this; I have 2 printers and the Prusa is by far the best in both speed and quality terms.

Peter

Re: Removing play from Y carriage?

Mark

The 50uM TreeFrog was perfect on my Prusa. You cannot see the layers without a magnifying glass. You are confusing me with what is your genuine issue, and if you really have one.

Mark , Post some photos of your prints, that will help.

Bearing slop is not the issue I feel. I have used the same bearings in 3 different 3D printer builds, and have had no issues. Is your bed level. Follow Peter's tips and slack off the Y plate locknuts and only tighten when the Y plate is up to an ABS preheat ie 100 degC. oops update you maybe need to add some blue painters tape too, under corners, according to a post I saw from Peter, and or flip your glass plate. Oh well. I know what I am doing. My glass plate I guess as provided was level 🙂 or I had a better way.

Re: Removing play from Y carriage?

Okay, I think we can cut this conversation off at this point.

Peter, please don't misquote what others write and then use that in your responses. I did not state that I saw no problem when printing at .200mm. Nor did I state that I did see problems. What I wrote was that I didn't know enough to determine if what I was seeing in the prints was significant, but that I was willing to make allowances.

The main reason I brought this up in the first place was that - to me - the amount of play in the print bed movement was excessive. I spent a good 10 years in the 80's and 90's designing embedded products for both industrial and machine control systems, and one of many things that experience tells me is that good CNC machines don't thunk, they don't rattle, and you certainly don't hear bearing slap in linear actuators unless they are just about to fail. To me, this is a failure just waiting to happen.

Now, I do understand that there is a huge difference between a $600 hobbyist kit and an industrial grade CNC costing 20 times as much. However, it should be possible to come up with a carriage design with much tighter tolerances that doesn't cost $500+ per axis. Something for me to investigate further to the detriment of my pocketbook, I guess. In the meantime, I do appreciate the time you and others take to help fellow hobbiyists through the startup phase.

Re: Removing play from Y carriage?

Mark

My maybe last comment on your posts.

You state above that you have experience of CNC systems and designing embedded systems.

Your experience and comments on the genuine Prusa I3 build, seem way out of step with others. I suggest that you built your Prusa I3 wrong.
You did not even know your original problem and what axis it was in. And then flipped/flopped when questioned.
Did you use the correct 3 different paired length 8mm rods in the right positions?

I suggest your engineering experience in theoretical and not practical.

Perhaps you should have paid for the ready built genuine Prusa I3.

Nothing clunks when printing on my I3, in fact it is the quietest 3D printer I own.

I suspect you do not even own a genuine Prusa I3 build kit. Show us pictures of your prints and I3 build.

Re: Removing play from Y carriage?

Mmmh, guys, I'm not sure it's a good idea to get upset and angry (or to write in a way that looks like it).

I'm not sure the mechanical constraint of CNC and extrusion printer should be compared, the CNC should firmly maintain the base material while the tool is removing part of it, when the 3D printer is just adding semi fluid material on top of it. The torque applied on the plate is very minimal, if not nul. My understanding of the Prusa design is that the priority is to hold the axis (X and Y principally) to a minimum loose/backlash by design. (my printer is dismantled during my 'geek cave' refurbishment, I cannot check on mine right now).

Yes, there's a lot of adverbial qualifications here, which are not measurable, quantifiable, and that's make hard to have a common understanding.

In order to better understand your issue, and to compare with our printer build, do you have some pictures or video of the loose on your linear bearing ?

Re: Removing play from Y carriage?

My final comment.

Mark.s3 is a troll.

Re: Removing play from Y carriage?

Christophe, you are correct on the interaction. Unfortunately, it seems as if fanboys are endemic to this hobby.

I've attached a zip of video clip with sound, so you can hear the suspect thunk in action. The webboard wouldn't allow me to attach the video directly, so you'll have to download and unzip the MP4 file to view it. An example of a 'finished item' using this printer can be found on facebook at https://www.facebook.com/groups/KingsOfWarWashingtonState/permalink/520619651477510/ - one of the reasons I purchased the prusa kit was because I got tired of waiting for a couple of kickstarter projects to ship, and building from kit is almost always a good idea when entering an enthusiast technology.

Re: Removing play from Y carriage?

Cute - no warning that the attachment is too large.

(Edit) Uploaded to Vimeo instead - should make things easier to access.
https://vimeo.com/165254525

Re: Removing play from Y carriage?

Result 🙂

Brought you out of the woodwork , but not the issue/issues you complain about shown in your video.

I lied about being my last comment. My bad 🙂

You did not show the final quality and result of your print.

Re: Removing play from Y carriage?

Nigel, I have no idea what you are babbling about, since you hit the killfile after your latest round of creative writing. Please do us both a favor and add my account name to your own killfile so we can both adhere to the Palainian Prime Directive of Ignore and Be Ignored.

Re: Removing play from Y carriage?

Mark

The Prime Directive? I will never interfere with aliens!

Re: Removing play from Y carriage?

Nigel

Mark is definitely not a troll. He is just someone who doesn't know how to ask for help. I do appreciate your posts here, but I would ask you to be a little more patient when dealing with new users of this printer.

Mark

May I suggest that you now leave this thread and start a new thread for further issues you may have. When posting, please try to find a manner which will neither irritate nor upset other (more experienced) users. Ans please remove that (silly) photo 😉

Thanks

Peter

Re: Removing play from Y carriage?

Peter,

Sorry. You are right. I totally apologise. I will leave here for a while. I'm still getting brilliant prints with my Prusa I3.