Mk 3 Y-Axis Rod Mounting Redesigned
I have redesigned the Y-Axis rod mountings to get rid of the cable tie fixing, and also ensure that the Y rods are exactly in the correct position. A potential problem with the stock mount is that debris or scrap plastic can stop the rod seating fully in the clip in slot, thus leaving it out of position. My version eliminates that possibility and looks a lot tidier IMHO.
If you are interested it is here - https://www.thingiverse.com/thing:2942265
Re: Mk 3 Y-Axis Rod Mounting Redesigned
Looks good, I will give it a go. Why not correct the hole size instead of reaming it out with an 8mm bit?
Re: Mk 3 Y-Axis Rod Mounting Redesigned
Does it change bed position? Is it required to re-calibration? - I suppose so, but want to be sure.
Re: Mk 3 Y-Axis Rod Mounting Redesigned
Looks good, I will give it a go. Why not correct the hole size instead of reaming it out with an 8mm bit?
A reamed hole will always be more accurate than a printed one. Prusa do this before assembly of parts that hold the 8mm rods.
Re: Mk 3 Y-Axis Rod Mounting Redesigned
Does it change bed position? Is it required to re-calibration? - I suppose so, but want to be sure.
There has to be some change of position even if only due to the fixing bolts being in a slightly different place in the frame after re-tightening. I recalibrated, I would imagine it is best to.
Re: Mk 3 Y-Axis Rod Mounting Redesigned
I've put these in but haven't had a chance to recalibrate and print anything yet (have been on holidays).
I'm really intrigued by them. I'd like to explore why a reamed hole is better than a printed one. Bearing in mind I happily used a drill to ream out the ones printed for your design, I notice there is almost no way to do so without doing so at some sort of angle.
In my mind at least, the only way to accurately ream the hole so that the hole is straight and not at an angle (even a tiny angle) would be to use a drill press. I don't have access to one.
Rather than resort to using industrial machinery, wouldn't it be easier to enlarge the hole slightly to compensate for the filament shrinking to get a diameter that wouldn't need reaming in the first place?
Additionally, looking at your thing, it is pretty much the same as the original piece, but with the filament covering the top of the rod (instead of having a zip tie). What gets me thinking is why didn't Prusa just design it like this? Why have it open with a zip tie in the first place? What is the benefit? I guess it could be cost - at the scale they are making printers I imagine it would amount to a roll of filament every x thousand printers.
Re: Mk 3 Y-Axis Rod Mounting Redesigned
All this is only my take on things really. I have never seen a printed hole that is as accurate as one that has had a drill bit through it to clean it up.
You are right about the drill press but I don't have one here either. You are also right about the possibility of angle but with the hole being very close to size and the drill only being driven by hand then the bit os going to follow the hole IMO, it is not going to start drilling an angled hole.
I believe my method to be more accurate than printing the hole larger. All that will do it to give you the same inaccuracies as the smaller hole but magnified and introduce the possibility of the rod being loose or offset.
Not sure why Prusa stays with the cable ties really. I've been running my modified ones since I designed them and I have not yet found a downside to them. We shall see!