I wanted to show how I measured the hole locations on the Y-axis. Two reasons, to do this is: to see if the drive nut is inline with the threaded rod or if you are modding for bronze bushing. Since the PP is cnc cut, I will use the side plates for the reference locations. See the 1st diagram. I mainly did these measurements because I wanted to replace the pex tubes with bronze bushing. So the top rod hole centers are lined up in the diagram. It's confusing why this matters, so I will include the sketchup file of the diagram for people to explore. My method of installing bushings is moving only the bottom rod hole. The diagram shows, I have to move the bottom hole down 1/16". The nut for my PP, I found is 1/16" too low for bushing. This brings us back to the diagram having the top holes centered. Well for pex tubes the rods are not centered. So the whole y-axis shifts down another 1/32". So the nut is 3/32" too low if using the original pex tubes. The other pictures are how I measured the nut location. It's not easy because, it's not in the same plane. I use a plum bob.

btw, I just reintalled winxp on my compter and was looking for a free, small/unbloated program instead of photoshop. I really just want to be able to crop, merge pics together and add text. I found a nice one called, "Paint.net", which actually looks like it does most of what photoshop does. And it seemed easier to use. Used it for the 1st time for this post. Another program, I like is called "PIXresizer". If I just need to resize a picture to post, this is what I use.






Attached files Bushings Y Dimensions.skp (107.1 KB)Â

 

Man, all my pics got deleted from that first post, when I was editing and then when back to the last page instead of pushing summit. So I am reupping them now. Anyways I found a mistake and edited the post. And modified the sketchup file. So if you downloaded it before, get it again.

The problem is that sketch up seems to ignore dimensions when they get a certain tiny size. Seems 1/32" approaches this. Anyways, I corrected a 1/16" dimension, which is much closer to 1/32". Now sure, but it seems everything smaller than 1/16" is measured as 1/16"? I documented it in the new sketchup file with some text. It's unchanged in the diagram pic. I'm too lazy and it doesn't matter much there.

-Kwok

<addition> OK so I added all the pics back and guess what, the old ones are now back. Ok, deleted them. Fixed. Either it really happened or I am just crazy. :ugeek:

 

Thanks rcav8r and 3DMON. I set the precision to 1/64" and my problem is solved.

rjarois, you are right about the level and the plum bob. It wasn't that much off level, but I level it. It looks like the hole is closer to where it should be. The error was halved, so I get 1/32" low now instead of 1/16". If there was room for a square, I think that would have worked better. Anyways, people can try it out and devise their own method, if they are curious enough to mess with it.

-Kwok

 

What if you mounted the gantry on the 1/2" rods only (no threaded rod yet), then stretched a string from the motor shaft through the left side-panel hole. That would eliminate inaccuracies in measuring, marking and leveling, right?

 

Dorsal,

Sure that would be another way of checking, if the nut lines up. I just started that diagram to find out how much I needed to move the bottom rod hole for bronze bushings. And it kind of progressed from there. Besides, it though to do if you haven't glued your case together, yet. :roll:

-Kwok

 

Yep, mine was glued together already, too. There is now a 7/16 diameter hole out the left side panel, and the end of the Acme screw is flush with the outermost panel. I still might add a bronze bushing over there someday, but until / unless I get my SmoothStepper board, I'm just wasting time anyway.