Odd circle test results (Page 10 of 24)

Constructive criticism would be trying my and wardjr's ideas and seeing if they work. These ideas to recap so far are:

1. make sure the rods are glued down;
2. ensure your case is square;
3. remove the stock pillow block;
4. design a part to make 3 points of contact on the rod that fits the stock carriage, and
5. chop the belts and try an open-loop design. the SD4 is the first SD to use a closed-loop belt design and I personally think the holders for the belts stink. this design change was recent so it is likely not thoroughly tested. (SD support confirms the design change is recent).

These are the ideas. I've tried 1-3 , will be skipping 4 because I don't care about making the stock carriage work, but I will try 5 with the stock carriage if I can get my printer up and running, but my Y carriage is pretty janked now.

FYI, cipher0, the reason your x belt was loose is probably because the bottom holder for the pulley is broken or will soon fall off entirely. My X belt did the same thing yours did and when I took it off, the carriage fell apart, so be cautious if you take this belt off again. Don't lose the piece like I did (I took a pic earlier but dropped the piece inside the printer somewhere since lol). There's no ribbing or fillet support on that part, it's a straight up 90 degree angle so failure is guaranteed.

4. chop the belts and try an open-loop design. the SD4 is the first SD to use a closed-loop belt design

yes forgot that. belts can stretch too due to moisture etc even

Because they won't. I said in an earlier post that I would also design a part to attach to the carriage and secure the belts with. I'll try this out if I can get up and running and no one else will. I'll need a few extra M3 bolts and a nut so I'll need to get out to the hardware store first.

The closed loop design is not present on any other Solidoodle model except recent SD4s. They only went to this design in the last few months according to SD support.

You wanted a fundamental difference. There it is. I have to get some sleep so I can go to work tomorrow, but if I can get my printer going with this messed up pulley, I should be able to design this in about an hour and only a couple of iterations. It would attach to the existing screw hole for the existing clamp and extend a little beyond the carriage with a screw hole. All you need is a washer, M3 bolt and a nut. Our printers are filled with them, I might even just take one off a fan.

I'll also need a hole punch. Darn it.

jagowilson, good luck with your tests.

However I asked this question, you said SD3 prints perfect circles. I said I've only seen wardjr's print perfect circles but his Solidoodle is modded. is there another example which I maybe missed? Thanks. Theres one SD3 phoio on fb but its not clear.

Wardjr, by this do you mean you can't twist the carriage on that printer but still get our artifacts? A bit hard to tell from that picture because of shadow, etc. What kind of carriages does it have?
Thanks for taking the time to help us.

I only beta tested the Solidoodles site never any hardware.  As far a my printer the second (black circles) where on a pretty much stock SD3 at least as far as the carriage and belts go.  The circles where pretty darn good for no bearings or pillow block.  So what I was saying is I couldn't twist that right carriage.  I also like jagowilsons idea that the closed belt could be slipping through its keeper.

Show off

Yes other than how the belts attach it's the same.

I got some m3 screws, washers, nuts and Zip ties so if my printer works I will do my best to test the belt theory tonight.

Anyone have any suggestions for what to use to punch a hole in my belts ?

Yes, my SD4 uses the closed belt design too.

Note: It appeared I just needed to tighten the bolt under my extruder carriage on the x-axis to increase the tension on the belt.  Through all the belt tensioning of the y-axis, I completely disregarded the effects it would have on the, already under tension, x-axis belt.  This is fixed now but it didn't fix my circles (as expected).

Tension in the room is high (get it? *wink *wink).  I was just teasing Wardjr since he was so professional with his earlier comments of reminding us how Solidoodle's team has to make financial decisions which possibly impacted performance of their product.

We are all friends here on the same mission.  Let's stay focused.

I look forward to this video.

So i got to thinking about this and decided to dig through my boxes of old parts and this is what I came up with.

Now the important thing here is I can grab this by the left and right carriages and try to twist and nothing budges.
It would break something if I twisted any harder.  So even if this doesn't remedy your guys issue it is still an issue.
You can see the epoxy on the end of the rods that squished out during assembly.  I have vast experience with composites and I can assure you that it is indeed epoxy.  I am surprised at how rigid this is there isn't even the slightest motion when trying to twist it.

Hope this helps.

Yeah but at this point you have broke a bunch of other stuff so don't be so quick to judge

also i noticed this morning before I left that if you tug on the bottom of the belts... they have some play. enough play that if the belt tension isn't just right you can make the carriage go crooked on the Y rods. the right side is the only side with any noticeable play however.