<![CDATA[SoliForum - 3D Printing Community — How to forget about circle problems for ever....]]> 2014-04-03T19:53:09Z PunBB https://www.soliforum.com/topic/4824/how-to-forget-about-circle-problems-for-ever/ <![CDATA[Re: How to forget about circle problems for ever....]]> Not perfectly centered... This will cause the belts to tighten and loosen slightly as the pulley rotates.

]]> https://www.soliforum.com/user/2291/ 2014-04-03T19:53:09Z https://www.soliforum.com/post/53468/#p53468 <![CDATA[Re: How to forget about circle problems for ever....]]> wardjr wrote:
Photog wrote:

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.

What do you mean out of round?

]]> https://www.soliforum.com/user/4167/ 2014-04-03T19:39:28Z https://www.soliforum.com/post/53467/#p53467 <![CDATA[Re: How to forget about circle problems for ever....]]> Photog wrote:

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.

]]> https://www.soliforum.com/user/2291/ 2014-04-03T18:30:37Z https://www.soliforum.com/post/53465/#p53465 <![CDATA[Re: How to forget about circle problems for ever....]]> 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?

]]> https://www.soliforum.com/user/4167/ 2014-04-03T17:25:34Z https://www.soliforum.com/post/53459/#p53459 <![CDATA[Re: How to forget about circle problems for ever....]]> 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.

]]> https://www.soliforum.com/user/4251/ 2014-03-06T23:27:23Z https://www.soliforum.com/post/51579/#p51579 <![CDATA[Re: How to forget about circle problems for ever....]]> "I've determined a procedure to isolate and eliminate the slack"

spill the beans!

]]> https://www.soliforum.com/user/456/ 2014-03-06T17:58:32Z https://www.soliforum.com/post/51536/#p51536 <![CDATA[Re: How to forget about circle problems for ever....]]> I'm going for it..... I finally ran into some parts I need absolute precision.

I'll report back with results.

]]> https://www.soliforum.com/user/1682/ 2014-03-05T13:11:25Z https://www.soliforum.com/post/51470/#p51470 <![CDATA[Re: How to forget about circle problems for ever....]]> 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!

]]> https://www.soliforum.com/user/4251/ 2014-03-01T18:02:07Z https://www.soliforum.com/post/51194/#p51194 <![CDATA[Re: How to forget about circle problems for ever....]]> now that you got your pillow block on maybe recalibrate X and Y and try your circles again.

]]> https://www.soliforum.com/user/2211/ 2014-02-24T01:11:48Z https://www.soliforum.com/post/50687/#p50687 <![CDATA[Re: How to forget about circle problems for ever....]]> 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!

]]> https://www.soliforum.com/user/4251/ 2014-02-22T22:46:32Z https://www.soliforum.com/post/50578/#p50578 <![CDATA[Re: How to forget about circle problems for ever....]]> I used these:
http://www.ebay.com/itm/290864467635?ss … 1439.l2649

They slid on with a mild amount of effort.

]]> https://www.soliforum.com/user/4251/ 2014-02-22T04:49:30Z https://www.soliforum.com/post/50515/#p50515 <![CDATA[Re: How to forget about circle problems for ever....]]> MolecularConcept wrote:

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.

]]> https://www.soliforum.com/user/4167/ 2014-02-22T04:32:29Z https://www.soliforum.com/post/50509/#p50509 <![CDATA[Re: How to forget about circle problems for ever....]]> grease what? there shouldn't be much friction thats why we moved to bearings...

]]> https://www.soliforum.com/user/2211/ 2014-02-22T02:22:01Z https://www.soliforum.com/post/50492/#p50492 <![CDATA[Re: How to forget about circle problems for ever....]]> 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.

]]> https://www.soliforum.com/user/3058/ 2014-02-21T13:48:47Z https://www.soliforum.com/post/50416/#p50416 <![CDATA[Re: How to forget about circle problems for ever....]]> 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. smile

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 big_smile - 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.

]]> https://www.soliforum.com/user/4515/ 2014-02-20T23:04:59Z https://www.soliforum.com/post/50374/#p50374