RE: Failed Y-calibration of a new CoreOne
You test the skew with this. https://www.printables.com/model/1143218-vernier-skew-test
RE: Failed Y-calibration of a new CoreOne
As I look and read about the problems with an inaccurately assembled printer from the manufacturer, it will be necessary to assemble the kit with an exact scale, an accurate machine angle and a precise metal prism with perpendicular walls to compare the inaccurately bent parts. Fortunately, this equipment is located in my workshop. It may also be necessary to print some fixtures for assembly. Well, we'll see when the kit arrives what condition the individual parts will be in.
RE: Failed Y-calibration of a new CoreOne
I'm curious if anyone with this misalignment has taken this bracket entirely off and checked it with a machining square. The assumption is that the because the shim solved the alignment offset, the root cause was a bracket bent a touch past 90 (in MartinF's case). If the bracket can be removed without too much trouble, I would think bending it straight would be preferable to installing shims. This may be more than folks are comfortable doing with on a new printer, but from a metal shop perspective, a fix seems trivial if the part can be removed easily enough.
In my case, since I'll be doing the conversion in 2-3 months, I'll have the pre-assembled parts in hand. I'm also fortunate to have limited access to a machine shop at work (and the welders/machinists who work there) so I'll simply take the brackets there and make any needed adjustments before assembling them. If I didn't have that access, I think I would still try my best to carefully square it up at home in a vice before assembling.
Similarly, regarding the above suggestion to machine a replacement part, once you have the bracket removed for replacement, you might as well nudge the angle into square and reinstall. If the angle is corrected, it seems like it should be a 100% durable fix. No need to machine anything.
I don't have a printer to look at, and the photos above are too close for me to gain full context, so I understand that it may not be as straightforward as it seems.
-J
Yes, I've thought about rebending the brackets too (even before @Rainer brought up the idea with the underlays).
But for getting the brackets off the printer, you would have to remove 7 additional screws per brackets (some of them are not too easily accessible on an already mounted printer) and there is the danger that the belts and idlers not held in place anymore may fall apart.
And once you have removed the brackets, there is the problem that one leg of the bracket has a cutout (you can see it in my close up photos). If you try to bend the bracket you have to make absolutely sure that you get no bending on a different position. And I'm not sure how the powder coating of the bracket would survive the applied forces for bending. You have to make absolutely sure that the surface of the bracket remains flat. Otherwise a secure alignmet will be hard to achieve.
The right bracket of our printer only needed an underlay of 0.07mm.
Even if the underlays don't look good, I think they are the easiest solution to apply.
In addition, measureing the exact angle (on these short, powder coatet legs) may not be as easy as it sounds. The powder coating makes the surface irregular and you may not be able to see small misalignments. Because the surface of the x-carriabe is powder coated too, mounting these two coated surfaces side to side may add some inaccuracy.
RE: Failed Y-calibration of a new CoreOne
As I look and read about the problems with an inaccurately assembled printer from the manufacturer, it will be necessary to assemble the kit with an exact scale, an accurate machine angle and a precise metal prism with perpendicular walls to compare the inaccurately bent parts. Fortunately, this equipment is located in my workshop. It may also be necessary to print some fixtures for assembly. Well, we'll see when the kit arrives what condition the individual parts will be in.
For checking if the brackets you get with your kit are bent accurately, you don't need additional measurement tools. You can mount one bracket first and then pull the x carriage to the front and then check (with loose belts) if there is any gap on the left or right side front stop. If the gap is zero, you can mount the other bracket and check again.
If you detect a gap, you may have to repeat this procedure many times for finding the optimal thickness and placement for the underlays.
But I absolutely hope and expect(!) for Prusa to have solved the issue until the kits are shipped out or clear instructions for checking (and correcting) are provided by them.
RE: Failed Y-calibration of a new CoreOne
Well, if one starts from a kit (complete or MK4S conversion), it would be much quicker to check and correct the bend angles before mounting the brackets. You would not want to repeatedly mount, check, remove, bend, remount, recheck... them. A machinists square is good to have in the workshop anyway. Or, if we really trust the laser-cut CoreXY main frame to be square and if its edges are smooth, use that as a gauge?
RE: Failed Y-calibration of a new CoreOne
Well, if one starts from a kit (complete or MK4S conversion), it would be much quicker to check and correct the bend angles before mounting the brackets. You would not want to repeatedly mount, check, remove, bend, remount, recheck... them. A machinists square is good to have in the workshop anyway. Or, if we really trust the laser-cut CoreXY main frame to be square and if its edges are smooth, use that as a gauge?
Yes, I think I understand. But it may be not too easy to measure any small misalignment on these short, powder coated legs (about 40 and 35mm).
And if you detect a wrong angle, re-bending the brackets may be even more difficult. Both legs (not only one as I've written in a post above) do have cutouts. You would have to be very careful when applying forces to adjust the bending angle for avoiding any unwanted deformation of the brackets and/or scratches on the powder coating. The bending area of the bracket is the most massive section. Not the best situation for getting the bending adjustment you are after.
If you decide to adjust any angle deviation with underlays you can mount the printer and perform the adjustment afterwards in case your printer requires it.
RE: Failed Y-calibration of a new CoreOne
Yes, I think I understand. But it may be not too easy to measure any small misalignment on these short, powder coated legs (about 40 and 35mm).
And if you detect a wrong angle, re-bending the brackets may be even more difficult. Both legs (not only one as I've written in a post above) do have cutouts. You would have to be very careful when applying forces to adjust the bending angle for avoiding any unwanted deformation of the brackets and/or scratches on the powder coating. The bending area of the bracket is the most massive section. Not the best situation for getting the bending adjustment you are after.
Based on the very nice photos you shared, I would think that holding the wide part of the bracket in a vise and gripping the narrow part (gantry side) with an adjustable wrench ("Rollgabelschlüssel") should do the trick. Both tools with smooth, non-knurled jaws of course to avoid damage to the surfaces.
But I will know better when I have the parts in hand... If they still require corrections then. As you wrote earlier, one would very much hope that Prusa fixes this asap in production. On the other hand, if @iftibashir's information is correct, my kit parts may already be sitting on some shelf, crooked as they came, just waiting for the build instructions to be finished. 😉
RE: Failed Y-calibration of a new CoreOne
It took me 15 Minutes to get it to a perfect fit. Since bending anything and losing warranty was no option for me, i took what I had in the drawer and clipped off a few cm of 0.2mm metal strip.
I then put it at the opposite side. To get the right side nearer to the front, you have to put the spacer on the left side. Needed two tries to figure that out. These 0.2mm reduced the distance on the right by ~4mm.
After fastening and tuning the belts i clipped of excess material, did my calibration at 85hz on both sides and voila, thats it.
RE: Failed Y-calibration of a new CoreOne
Happy to hear that we have two successful fixes recorded. Thinking about shim material for those of us who don't have .07mm shims on hand...I wonder if some of that HVAC aluminum foil tape would be adequate. It's thin metal, and could be stacked as needed to get to the desired thickness. It should hold up over time under reasonable compression.
-J
RE: Failed Y-calibration of a new CoreOne
It took me 15 Minutes to get it to a perfect fit. Since bending anything and losing warranty was no option for me, i took what I had in the drawer and clipped off a few cm of 0.2mm metal strip.
I then put it at the opposite side. To get the right side nearer to the front, you have to put the spacer on the left side. Needed two tries to figure that out. These 0.2mm reduced the distance on the right by ~4mm.
After fastening and tuning the belts i clipped of excess material, did my calibration at 85hz on both sides and voila, thats it.
Can you send this to Prusa also. We need to let them know that this is an issue.
RE: Failed Y-calibration of a new CoreOne
Happy to hear that we have two successful fixes recorded. Thinking about shim material for those of us who don't have .07mm shims on hand...I wonder if some of that HVAC aluminum foil tape would be adequate. It's thin metal, and could be stacked as needed to get to the desired thickness. It should hold up over time under reasonable compression.
-J
I'm sure you can get shim stock on Amazon. . That's the "official" name for it.
RE: Failed Y-calibration of a new CoreOne
Don't you think their devs/customer support watch this board? Thats what I would assume/suggest them to do.
RE: Failed Y-calibration of a new CoreOne
To @martinf: My post was just a complaint, nothing more. I have already built several printers "from scratch", so to speak, so I know what I am talking about and I can deal with it. Don't take this post as an insult, you tried, and with the kit it's easier in that I don't have to first disassemble (at the risk of losing the warranty) what someone else has reassembled in a hurry, but I can check and adjust all the parts myself instead of sticking some metal plates somewhere.
RE: Failed Y-calibration of a new CoreOne
Glad to know that fixed it, but I cringe when I see how easily the bracket bends around the shim.
RE: Failed Y-calibration of a new CoreOne
So… for people without the machine shop access… would layers of aluminum foil do the trick?
Mine is off by 2mm.
RE: Failed Y-calibration of a new CoreOne
So… for people without the machine shop access… would layers of aluminum foil do the trick?
Mine is off by 2mm.
I'd order some shim stock, it's relatively cheap.
RE: Failed Y-calibration of a new CoreOne
I can't see why not, as long as it gives you the right increment to hit your correction target. It's similar to the aluminum foil tape I asked about above, just without the adhesive. Give it a try and let us know how it works. If not, Brian's suggestion to order some 'shim stock' from amazon is an option, but that will add another $25 to the cost, where most of us already have aluminum foil in the kitchen.
-J
So… for people without the machine shop access… would layers of aluminum foil do the trick?
Mine is off by 2mm.
RE: Failed Y-calibration of a new CoreOne
[...] I cringe when I see how easily the bracket bends around the shim.
I think the bracket is designed to be bendable with relative ease in that area. The rectangular cutout does not do much as a weight-saving measure, but enables "fine tuning" of the 90° bend. (Not with shims, but by bending the bracket arm before or maybe even after attaching it to the X gantry.)
RE: Failed Y-calibration of a new CoreOne
It took me 15 Minutes to get it to a perfect fit. Since bending anything and losing warranty was no option for me, i took what I had in the drawer and clipped off a few cm of 0.2mm metal strip.
I then put it at the opposite side. To get the right side nearer to the front, you have to put the spacer on the left side. Needed two tries to figure that out. These 0.2mm reduced the distance on the right by ~4mm.
After fastening and tuning the belts i clipped of excess material, did my calibration at 85hz on both sides and voila, thats it.
Glad to hear that you cured the misalignment of your printer too!
From your description I'm not sure if you checked both brackets. I think it's important to do so.
A little example:
You detect a 2mm gap on the right side of your printer. You can get rid of the gap by adjusting the angle of the right bracket with underlays. The gap will be ZERO, but the situation may not be good! You may have introduced static load to the bearings of the y axis.
The right bracket may have been perfectly bent to 90°, but the left bracket may be off. With introducing a 'misalignment' to the good right bracket, you can adjust the 'bad' left bracket by pulling it to a 90° angle but you create static load on the bearings of the y axis. This load may cause additional wear or may even affect print quality.
Therefore I think it's important to check (and correct) the angle of BOTH brackets.
Maybe you've already done so but I think it is important for all future adjustment work.
RE: Failed Y-calibration of a new CoreOne
So… for people without the machine shop access… would layers of aluminum foil do the trick?
Mine is off by 2mm.
Yes, aluminium foil would work great too. And you can fold the foil up to any thickness you need.