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SoliForum - 3D Printing Community → Hacks & Mods → How to forget about circle problems for ever....
I can see a lot more than 2 that could be done...
If you're just modding for moddings sake sure.... Personally I find it more valuable to assess mods on their need and merits once you understand the purpose and tradeoffs in a mod. To be blunt... theres more mods than actual problems these days.
yeah yeah yeah ....lol. just getting started, not going glass because the kapton works fine for me, and the case is next.
Well this has been a total fail.
I couldn't get the bearing holder on the rod. The bearings wouldn't fit the Y rod, either bearings were too small or Y rod too big. I ordered the correct bearings as suggested. I got the bright idea of hammering the bearing holder onto the rod thinking maybe it was on it would slide easier. Well - no. That got the bearings on the rod but I couldn't get them to budge an inch. Nor get them to come back off. I thought maybe if I put the bearings in the vice and yanked the rod I could get it. Nope, all that did was break the printed bearing holder. So then I said screw it, I'll just destroy the bearings to salvage the rod. I cranked my vice on them and crushed apart the bearings, but the inner part of the bearings remained and are still on the rod. In the process I put a huge bend in my Y rod. Now I am down a Y rod, and the bearings. Not happy camper. I ordered a new Y rod 3 weeks ago in case this happened, but it hasn't shipped from Solidoodle yet because of the bad weather which I understand and am fine with. But in the mean time I am not able to print.
Anyone have spare Y rod and can print me the bearing holder and find bearings that fit it and mail it to me? Would be willing to pay you LOL
I dunno where you got your bearings - but - a 6mm bearing is supposed to be 6mm - not 5.8 .
Sounds more like quality issues on teh bearings than anything else...
i had this exact same issue! the 6mm rode was a tad over and the bearings were 5.9 ... i sanded the shit out of the rod and sanded the inside of the bearings a little too finally got it on the rod.
bust out the sandpaper bro and make sure you have a few hours to spare..... and a lot of patience
I dunno where you got your bearings - but - a 6mm bearing is supposed to be 6mm - not 5.8 .
Sounds more like quality issues on teh bearings than anything else...
boca bearings.
i had this exact same issue! the 6mm rode was a tad over and the bearings were 5.9 ... i sanded the shit out of the rod and sanded the inside of the bearings a little too finally got it on the rod.
bust out the sandpaper bro and make sure you have a few hours to spare..... and a lot of patience
so I cut the remains of the bearings off the rod with my dremel. and I tried sanding down the rod with my dremel. Now the rod flops around when I'm printing LOL.
About to try a circle, I'll let you know how it goes.
Do you think I should just get a new rod and get 6.35mm bearings instead of 6mm bearings?? Or do you think that extra space will render the pillow block mod ineffective???
I think you should get 6mm bearings... not 5.8mm ones.... a 6mm bearing is supposed to be 6mm... not 5.9.. The problem here is the quality of the bearings... plain and simple. 6.35mm ones will not work as you will have .35mm of play in it - a bearing is supposed to be a near pneumatic fit...
a 6mm ID bearing should equal 6mm ID... anything else then it is of substandard measurements and should be rejected. Even the dodgiest ones I've gotten from aliexpress have managed to get the ID measurements right.....
believe it or not even though the y rod is flopping around and I have no pillow block stablizer on there it's actually printing just fine. I'm sure the dimensions will be off but it's not too bad as far as roundness goes. however I'm printing a pretty big 5" circle I bet smaller circles will be bad.
i got cheeap bearing from ebay. i made it work... it would have been nice if they would have just slid on though
6.35mm is otherwise known as 1/4 inch in the Imperial measurement system, way too loose for true 6mm rod. Problem is, the rod that came in my SD3 is NOT a true 6MM, depending on where you measure it you get various diameters and none of them are actually 6MM...
^ bingo
Ok, a couple of things here:
(1) Measuring inside diameter of small bearings with calipers will normally result in a slightly-lower-than-actual result, but 5.9 is too low - if you're getting that something's not right there, even if they (calipers or bearings!) are a bit cheap.
(2) Anything other than 'precision ground' rods are normally a touch oversized (in case you want to machine bits of them down to the nominal). SD probably picked something that had a wide-ish tolerance range that worked for them and saved by buying a lot of it.
(3) Pushing a 6.000mm ID bearing half way down a 6.000mm OD precision ground rod will be nigh impossible at the best of times, so you may not even want a perfect fit here...
(4) Forcing bearings on/off things never helps, but is often fun...
To deal with the rough rod, I'd suggest using a way-oversized bearing (e.g. 10mm ID) for the middle one, and a printed/otherwise plastic sleeve between it and the rod. The plastic sleeve is flexible, so should be pretty easy to push down the rod even if it's a bit out of shape (printing tolerance aside...), and then the bearing can press onto this. Once assembled, it would work a bit like bicycle wheel spokes and be surprisingly stiff, especially for the forces likely involved here. When I get mine I'll have a crack at doing it this way and let you know the results properly, in the interim anyone else is free to try of course. 
Much as I don't like imperial things, and love the innate beauty of a good bit of 'well-engineered' as opposed to 'hacked together,' the 6.35mm bearing idea is not so terrible 
- the bend is always in one direction (towards the y motor belt), so it would just sit tangent in there once tensioned up. Even if it was loose, this would at least guarantee the largest movement of the y pulley rod in the y-axis direction would be +/- 0.175mm at the bearing, which by the time you work out the leverage (bending displacement to be accurate, but CBF integrating that many times) would be a whole bunch less at the y-pulleys (which is what translates directly into backlash in the print) which I suppose is a lot better than without anything - depends how you define 'too much', as always.
Dremel + diamond grinder bit + needle nose + Bearing = fit lol. i was angry about that too, 15 bucks for the damn bearing. but it works. just grind slowly, i took slightly too much off on one side, so the bearing wobbles a little on the one before installed. but once the pillow block in on and screwed down, nothing moves! and don't forget the grease once everything is on.
grease what? there shouldn't be much friction thats why we moved to bearings...
grease what? there shouldn't be much friction thats why we moved to bearings...
probably grease to get the bearings to slide onto the rod.
I used these:
http://www.ebay.com/itm/290864467635?ss … 1439.l2649
They slid on with a mild amount of effort.
I'm still trying to get decent circles. I've added the pillowblock bearing mod, ensured everything is lubed with lithium grease, and checked belt tension and alignment. Although my other calibration prints come out very good, my 25mm discs are slightly elongated in the left-rear to right-front axis (approximately 10 o'clock to 4 o'clock for other pilot types out there!).
I've attached a photo to show my problem. (Disregard the slight under-extrusion...this is my crappy filament from Kbell Engineering...I don't feel like recalibrating every few feet, and I'm okay with wasting it while I sort out my problems.)
Any suggestions from the Jedi Council would be appreciated!
now that you got your pillow block on maybe recalibrate X and Y and try your circles again.
I figured out that I still had some slack remaining in my X and Y belts. I've determined a procedure to isolate and eliminate the slack, and I now have nearly-perfect circles! At at 35mm diameter, I'm only off by .06mm...which I consider very good. In addition, the 'smoothness' of the circular arc is quite good.
I understand why printing circles gets people so irritated!
I'm going for it..... I finally ran into some parts I need absolute precision.
I'll report back with results.
"I've determined a procedure to isolate and eliminate the slack"
spill the beans!
Ok, I had posted this in another parallel thread:
I am finally closing in on getting my SD4 to print perfect circles, and here's what I found:
I printed and installed the pillowblock bearing mod on my Y-rod; I don't think it is necessary on a SD4 (I didn't notice any difference), but it certainly can't hurt, especially if you're going to really crank up the tension on your belts.
Your photo indicates to me that you have some slack in your X and Y belts. (I had similar-looking circles, but my boxes and other geometric shapes came out fine) I kept reading posts on here, that said to tighten the belts, but not specifically where or how. I finally figured it out on my own.
Start with your X belt, the one that moves the extruder left and right. Using the Manual Control tab of RH, use the arrows to position the extruder in the center of the build plate. Now use the arrows to move the extruder left and right the maximum single step (50mm if I recall) while watching the belts. As the extruder moves and stops, any slack that's present will accumulate in the 'return' side of the belt. When you command the extruder to move the opposite direction, look for a shudder (like the twang of a guitar string) in the belt (the former 'return' side that is now the 'tractor' side). That 'twang' is slack that needs to be eliminated by tightening the belt's hex screw at the bottom left rear of the extruder. Make small adjustments to the screw, and repeat the process until the shudder is gone.
Once you have the shudder removed, loosen the set screws of the sprockets, and run the extruder left and right by hand to even out the tension throughout the three belt segments (upper long segment between sprockets, and the left and right segments between the extruder and sprockets. You want to remove any slack, have even tension throughout the belt, but not overtighten (which may cause your X stepper motor to stall). It may take a few attempts to get it right.
If you do this first, the bulges in your prints should move from their present orientation of 10 o'clock - 4 o'clock to 12 o'clock - 6 o'clock. This will indicate that the remaining slack is in your Y-axis belt. You are on the right track.
Use the same procedure to eliminate the slack in your Y axis belts, starting with the left one. Move the extruder forward and back with RH, and observe the belts for slack. I recall that there is a screw front and back for adjustment. The added complexity of Y-axis is that you need to tune two belts, and they need to be of similar tension and aligned (not keeping the extruder assembly crooked) for everything to work properly.
To summarize belt tension: If the bulges are 10-4 o'clock, both belts are loose. If the bulges are 9-3 o'clock, it's your X axis. If the bulges are 12-6 o'clock, it's your Y axis. (the reason both belts will cause a 10-4 and not a 2-8 is because Slic3r runs circles counterclockwise).
This was beginning to frustrate me, especially since my other prints were turning out so well. My circles aren't quite perfect yet, but I'm very close! A few more tweaks, and they'll be perfect.
I hope this saves you some butt-pain.
By doing this, I can print a 35mm circle that's within .06mm of being perfectly round. As soon as I get a chance, I'll try some more adjustments to see if I can improve on that. I think that if I can get a 100mm circle within .05mm, I'd be quite happy.
Just got the pillow block installed last night!
I had to use my dremel to grind out the inside of the bearings for they would fit on the Y rod. I also got a new Y rod to insure my old one wasn't bent. I slid the pillow block onto the rod in the position and drilled the holes for the screws. Fastened it to case with M3 bolts and nuts. Hoping that when I screwed down the pillow block it wasn't pulling on the rod.
.
Per instructions, I then tightened the Y drive belt down as hard as possible per instructions.
I tried 3 circles as a test, diameters 10mm, 30mm, and 60mm. I've noticed:
- The 10mm circle came out with flattened edges on 2 opposing sides (noting there's still a problem in one of the axis).
- The 30mm and 60mm ones seem to be fine though, they look very circular to my eyes.
- Layer adhesion seems to be better, I am getting more solid walls now for some reason?
- But unfortunately now I am getting a really obvious seam that runs up the circle (I made the circles tall, like a tube/cylinder shape) maybe unrelated, but never noticed this before.
- The solid infill seems to fill in better now and more solid.
So overall I'm seeing a benefit but still want to get the other issues fixed. Any ideas? Your thoughts?
Just got the pillow block installed last night!
I had to use my dremel to grind out the inside of the bearings for they would fit on the Y rod. I also got a new Y rod to insure my old one wasn't bent. I slid the pillow block onto the rod in the position and drilled the holes for the screws. Fastened it to case with M3 bolts and nuts. Hoping that when I screwed down the pillow block it wasn't pulling on the rod.
.
Per instructions, I then tightened the Y drive belt down as hard as possible per instructions.I tried 3 circles as a test, diameters 10mm, 30mm, and 60mm. I've noticed:
- The 10mm circle came out with flattened edges on 2 opposing sides (noting there's still a problem in one of the axis).
- The 30mm and 60mm ones seem to be fine though, they look very circular to my eyes.
- Layer adhesion seems to be better, I am getting more solid walls now for some reason?
- But unfortunately now I am getting a really obvious seam that runs up the circle (I made the circles tall, like a tube/cylinder shape) maybe unrelated, but never noticed this before.
- The solid infill seems to fill in better now and more solid.So overall I'm seeing a benefit but still want to get the other issues fixed. Any ideas? Your thoughts?
That seam is probably caused by the not having random start points checked. No that things are more precise the start point is going to be more obvious. You could also try increasing the retract on layer change amount or speed.
As far as your circles go loosen the belt a bit just to test you may have a pulley out of round or your grinding of the bearing may be out of round.
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