Is this part right?

Hi all,

I have got my Prusa v1 working and I'm using it to print parts for another printer a Prusa V2.

One of the first parts I printed was the Y bearing holder in the attached file (the file is y-bushing.stl from the prusa i2 repository).

My slight concern is that although the dimensions of the stl seem to match the dimensions of the part (by 0.2mm or so at least), the LM8UU bearing is not a snug fit - there's about a mm or so gap.

Can someone just put my mind at rest by confirming that it's right (or not right)? I'm worried I have some kind of weird scaling issue with the printer that won't become apparent until I've printed the rest of the parts

You should compare the dimensions of the STL with the result. You may have a calibration problem. Or, it is possible that the bearing or the part is just a misfit... Most LM8UU bearings are 24mm long.

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-David

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Well, I measured the STL file using a program I found (can't remember the name) and compared it with the dimensions of the parts using a digi caliper, and it's pretty close, I think the printed part is actually .2mm smaller.

Also my bearing is pretty close to 24mm.

So that was my question - has anyone had any experience with this part? Is it just supposed to be like that?

Can anyone recommend some alternative Y-axis bearing holders for the i2 that are a better fit, if so?

Cheers

These work great for me (I'm using an i3, but the bed plate should have the same 30mm hole spacing) and hold the bearings without the need for cable ties.

---

-David

Find me online at:
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LinkedIn
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Check out my FolgerTech Prusa i3 (plexi) at MindRealm.net

There are 2 types of lm8uu bearings european and asian.
The european are lm8eu
Im pretty sure one is slightly longer than the other.

I specifically ordered the european so i knew exactly which spec i had and ive found them a bit tight in most holders ive printed.
Maybe you have the asia made ones?

Gordon

I have the LM8UU, which are the asian ones and are 24mm long.

I definitely used the files from the "metric-prusa-lm8uu" directory and they are definitely 25.5mm long and not 24. (This is measuring from the inside faces of the bearing holder in the stl file itself, not the print.)

I measured the files in the "metric-prusa-lme8uu" directory and they are the same.

I even tried running the "generate-metric-prusa-lm8uu.sh" batch file but it still generates the bearing holders at 25.5mm long. I have no idea why it's doing this.

I've looked at the source, especially "bushing.scad" and can see where it's supposed to select the correct size in the code but it just doesn't seem to be doing it.

The Y bearing holders weren't a problem as in the end we just printed some alternative ones from thingiverse, but we need to do the X carriage and Z ends soon so if anyone knows why it's doing that it would be really helpful.

Edited 2 time(s). Last edit at 02/22/2015 10:21AM by TBJ.

Double post, but perhaps the i2 is a horribly out of date machine now and we shouldn't be trying to print it at all...

I just like it because there are no laser cut parts required... if we want a rigid, fast machine should we be making an i2 or should we just forget about it and build an i3?

Cheers.

Theres nothing wrong with the i2.
I built one from scratch as my first machine sourcing parts from all over.
It would cost less than £300 to reproduce.
I now get as good prints as ready built machines over £2000 pounds.
In fact had a chance to compare my printed parts to an ultimaker 2 recently and the were as good if not a bit better.
But i have spent time in improving and tuning it over time.

The only limitation ive found is build height. Im limited to about 8cm due to direct drive stepper motor getting in the way.
And if i want multiple nozzles for multiple colour printing it would seriously restrict my xy print area.

But for a first machine its more than good enough.

Gordon

That's what I thought. I like the I2 because at least you can print the majority of the frame parts yourself.

Just wish I could find out why the bearing holders are mis-sized on github.