Curved Bronze Bearing upgrade

[kilroyo]

Well I wanted to upgrade my plastic bushings, never liked the flat surface in contact with a round rod. And the bearing upgrade that SeeMeCNC offered might of helped things roll alittle bit better, but in opinion didn't look like it would help with the contact area. I tried printing a few, but my machine does not do good with small circles, they turned out more square than round. Guess that's why I need to fix the bearings. I made up a couple out of bronze and seemed to turn out good. I'll try and make up enough to get an axis done and try it out and see if it helps.
[img]http://xa.yimg.com/kq/groups/80652411/s ... earing.jpg[/img]

[johnoly99]

wow!

[michaellatif]

That's cool. You plan on replacing all axis bearings?

[Dave_Sohlstrom]

I expect you have thought of this. Make double sure that the radius of your profile tool is exactly .125" if it is off say .126" then the point of contact will still be one point on the roller. If .124 then it will not seat and point of contact will be the very edges of the roller.

Looks good

[kilroyo]

There's one issue I ran into , with the angle that the top two on a three stack bearing block touch the rod, one side can come in contact with the other. So I'm gonna make the top two bearings with the side towards it each other not have the curved edge. The bottom one is fine. I using a round carbide 1/4" blank and just putting a cutting edge on it.

[kilroyo]

Well I got some made , and made some changes to the one that go into the top of the Y-shaped bearing holder , those two at the top I took off the curved edge because of the angle they intersect would cause them to hit.
[img]http://xa.yimg.com/kq/groups/80652411/s ... ronze1.jpg[/img]

Decided to redo the X-axis bearings first. I replaced the little shafts with some dowel pins. Everything did seem to go together ok .. I did discover that one of my blue bearing covers got burnt and is all bent, Never realized it until I removed them. Wonder if that might be some of my issue.
Here's a side by side comparison
[img]http://xa.yimg.com/kq/groups/80652411/s ... ronze2.jpg[/img]

[img]http://xa.yimg.com/kq/groups/80652411/s ... ronze3.jpg[/img]

Everything works ok, but not the big performance increase that I thought it was going to be. I havent printed anything yet. But I did discover that I forgot to account for the way these bearings are tightened to the shaft. The screw pushes on the shaft on one side and tilts the bearing. Which kinda defeats my whole purpose. Got a closer look at the bearings and it looks like the bottom one and one of the top ones are rolling, but the other top one isnt engaging. Will work on it again tommorow.

[michaellatif]

Looks nice. I wonder if the bottom bearing would work better being flat and the other two top ones being rounded?
That way you don't have to worry about the set screw causing the bearing to move.

[Polygonhell]

IME the BIG performance upgrade is replacing the idler pulleys, this lets you get the timing bets tight enough to get rid of most of the backlash.
I was also expecting a big change from the plastic rollers when I did the bearing upgrade and although certainly better it wasn't night and day.

[kilroyo]

I worked out a solution, but it involves remove alittle bit of material on the bracket to allow it to move straight when tightening up, and then I would have to add another screw to the other side of the shaft. But the 2 bearing mount there isn't any space to add another screw, so I will probably have to go in from the side with a pointed screw
[img]http://xa.yimg.com/kq/groups/80652411/s ... ze_fix.jpg[/img]

[michaellatif]

IME the BIG performance upgrade is replacing the idler pulleys, this lets you get the timing bets tight enough to get rid of most of the backlash.
I was also expecting a big change from the plastic rollers when I did the bearing upgrade and although certainly better it wasn't night and day.

The plastic bearings were the most of my problems with my H-1, they didn't allow me to tighten down the set screws to get rid of all of the play in the carriage. After replacing the plastic for metal bearings I could tighten down the set screws quite a bit more and have no wiggle in the carriage.

I do agree with you about upgrading the idler bearings, I did that and now I have no backlash in my X or Y axis.

[kilroyo]

Even with the changes I was still having issues, until I discovered what I thought was a 1/4" carbide round was 5/16" and I had already cut new bearings for the Y-axis. Well I already had some 5/16 rod so I got to work on modifying all the brackets so it would fit the 5/16" rod, so I wouldn't have to start back over. After getting done, I think I should of just redid the bearings, but everything is changed now. Just have to finish putting on a couple brackets, but I think one of my kids ran off with them, still searching. Anyways its much more work getting the bearings set right. Before with the plastic ones you just tighten them up and go. Now with these they are very touchy getting them exactly right. Barely too much and they lock up, Not to mention getting the bottom one set up square with the other two. Will try a new print in the morning to see if there is any improvement. I hoping I can print a small circle without it coming out oblonged or square

[michaellatif]

Best of luck Kilroyo, if it doesn't work you can just get some R2ZZ bearings and install those with the brass rods you have. To be honest the carriage bearings were the best upgrade, IMO, to this kit.

BTW, have you tried PTFE lubricant (bicycle chain lube)? A while ago John or Steve mentioned running PTFE lube on the bearings and rolling them to get it worked into the bearing. I did that and I think what has happened is some of the lube has come out and helped with the rolling action on the 6.4mm rods. Maybe this is why I can tighten the set screws on the carriages to nearly full? Something to think about.

[kilroyo]

Well I was able to get everything back together and working, it does seem much more rigid now, and there' no twist. But when trying a test print of some small 1/4 circles, they came out pretty much exactly the same, , sorta square. Hum I guess that was a waste of time ..

[Polygonhell]

Have you done the idler upgrade?
Square circles is usually an indication of backlash, which is usually the X/Y belts having too much play.
They need to be tight enough you get a "bass note" out of them if you pluck them, IME it's impossible to get them tight enough and be able to print with the stock plastic idlers.

[kilroyo]

I dont have ball bearings on my idlers, just the acetal center with the ribbed outer shell. They seem to work really well. I can tighten the belt so much that the see thru plastic bases on the ends start to bow inwards. I got my X-axis working really well now. It looks like when I upgraded to 5/16" rod that the PEEK mount on the extruder was rubbing on the inner sides of the rails. Never thought about that being an issue. I'm very pleased with the way it operates now. But the Y-axis is whole different story. Ive been trying to get it dialed in with no play in it, but that plastic platform flexs and just doesnt seem to want to hold those blocks tight enough for me to get it just right. I might be missing something. Just like I missed the extruder hitting the rails. But it starting to look like I need to go to a more rigid design for the platform. Or maybe just stiffen it up a bit. Could of been all the heat from the heated table warped it some

[kilroyo]

Well I was able to get to fixing the issue I had with my Y-axis ,, was having problems with it binding .Those little screws that hold the bearings blocks to the table just didn't seem to work that well, so I ended up adding some small threaded rod from one block to the other using the pre existing holes and that took care of the issue,, seems to work really well . used 2 pieces on each set.
[img]http://xa.yimg.com/kq/groups/80652411/s ... is_fix.jpg[/img]

[michaellatif]

Looks good, might have to do something like that on mine.

[kilroyo]

Since the X-axis plastic housing was melted and warped , Decided to chuck the whole curved bronze bearings and housings. It just came to be more of a pain than what it was worth with the triangle configeration. Linear Bearings were out of the price range but with the flanged bronze bearings being so cheap werent.

[img]http://xa.yimg.com/kq/groups/80652411/s ... uminum.jpg[/img]