Arcol blog Just another RepRap weblog

4Jan/10Off

Mendel build progress — day 4 (updated)

It was a long, useful but first and foremost exhaustive day.
Here is the final result of the building:

In a nutshell I finished everything except mounting the motors, cutting to size the belts and all the sheets.
I haven't received yet the motors, hopefully I will this week.

I started the day by mounting the frame. Here are some 360 degree veiw pictures of the assembled frame:

After I mounted the y-bar-clamps:

Then I wanted mount the z bars, and I discovered the printed model has a flaw:

As you can see two holes are missing from the z-leadscrew-base. Here is an extensive forum thread about it.

And thats also the beauty of opensource. The broken part is already fixed, I only need to download it the new version from the svn and print the new one. For a quick and easy fix, I simply drilled the required holes.

For correctly setting the distances of the frame's threaded rods a setting jigs is essential. It is not important the distance between two corners is 247mm or 249 mm, however it is really important that the distances are identical between all corners. For this a home-made jigs is ideal. Here is a picture of mine:

As you can see, there is only two additional part (M8 big washers) required. The black threaded rod is the z threaded rod. It is long enough to check all distances.

The next step was to cut to length the bars. I bought the best available quality from the 8mm rod. That is, I bought linear shaft. It's a 8mm diameter rod for linear bearings, it is really tough.
So my goal was to have the least scraps at the end. So I optimized the cutting in inkscape.
Here is the result picture:

So from 5x2m length bars I can cut for 4 Mendel kit!

At the end of the day an another bug surfaced:

The lowest point of Mendel are not the four frame-vertex parts. The gears are lower and also all the z bearings too!

In the mean time I will put some books under the machine. This bug is yet to fix in the svn.

UPDATE: It was not a bug in the model, but in my building process. Here is a blog post how to correctly put it together.

Hope it was a useful blogpost for all of you.

Comments (6) Trackbacks (1)
  1. Where did you get that black rod from?

  2. I bought directly from a hungarian nuts and bolts factory.

    I only know it has a quality of “10.9″ and not zinc plated as the rest of it.

    Other then that it costs 5-6 times more then the BZP threaded rod.

    Im really sorry, that didnt write the blog text yet, I try to do today.

  3. Looking good! I think the clearance problems are because your Z axis lead screw bases are upside down – look at the photo on this page:

    http://objects.reprap.org/wiki/Mendel_frameW

    Wade

  4. your z leadscrew bases, motor bracket and idler are upside down ;)

    see photos on my blog for example

  5. Thank you for you comments! And also on the forum thread too:
    http://dev.forums.reprap.org/read.php?14,32211

    I try to dismount and re-mount the frame today. I also bought plastic sheets today. And the motors will arrive later this week or the next week. Looks like everything is putting together, and I can surprise the world with something interesting;-)

  6. I don’t know… my brackets are on the right way, and I have the same problem… not nearly as much, but the Z still extends below the frame. I”ve just been using beercaps under the frame vertexs ;)