Wednesday, 28 April 2010

Z axis

Well after a bit of delay, here is the next part of the build. The z axis, although made up of only a few bits, was one of the fiddly-est parts of the build.  Here you can see one of the z axis threaded rods in its bearing assembly.

The underside of the assembly has a cog on that is rotated by the z axis belt, this ensures that both z rods rotated at exactly the same rate. Tightening the belt so that it was tight enough that each step from the stepper motor produced a movement in the z axis but loose enough that the stepper ran smoothly was frankly a pain in the arse. I think a different tensioning mechanism would be beneficial.
However once the z axis is done the only thing remaining is to mount the x axis. But before I do that here are a few pics of the frame so far.

The next step took a while, basically the x axis needed to be fitted. This involved loosening a few bolts, the z axis guide bars, z threaded rods/gear assemblies, sliding the x axis on, screwing the threaded rods into the trapped nuts (in the x axis), tightening everything and fitting the belt. All in all it took quite a while to get it to the point that the x axis was level and z axis would move up and down smoothly and easily. Here are a few shots of it with x axis fitted (if the x axis motor looks the wrong way up then that's because it is! I was testing an idea at the time of the photos).

Since it's rather late I will save the photos of the finished mendel for another day, time for a nice cup of tea. How quintessentially british! 

Friday, 23 April 2010

Frame and a few fixes

Quite a long post today, as I had a fair bit of fixing to do. A few people pointed out that my x-axis wasn't quite right, it turned out I had put the carriage on upside-down. Luckily it was just a case of loosening a few bolts, taking off one end and the carriage and putting them back on the right way round! Here is how it looks now, carriage on the top and x-axis stepper pointing down. 

I also tightened the belt, I had left it loose when test fitting it and forgot to tighten it! Once that was done it was on to fix number 2 or 3 or 4 or something. One of the RP parts that holds one of the bearings for the z-axis was missing some holes, here is the part.

No idea why the holes are missing, it doesn't look like it failed print the holes properly just like it never tried, so never mind. Simple to fix though, pop it into a vice with the other RP clamp part as a guide.

20 seconds of drilling later, and its all fixed.

Now that's done, I can get cracking with the frame. All the nuts are finger tight at the moment as I will check distances/measurements once the frame is in one piece.

Here is the other half of the frame complete, just need to bolt them together now. I did have a bit of trouble getting the threaded rods through some of RP parts, but again it wasn't a big deal I just cleaned up the insides of the holes a bit with a file.

Bolting the two halves together was relatively pain free, the bearing assemblies for the y-axis belt are just loose fitted in the picture below as I hadn't broken out the ruler yet.

Just enough time to finish the frame off by adding the last two threaded rods. And all done, still need to check measurements, but that's for another day.

Here is my jig-stick :) made from a few bits of steel stuck together. I turned the ends down on a lathe to within about 1/10th of a mm of the jig lengths on the reprap wiki so it should be ok.

Finally a shot of my work-area (my carpet), as you can see I'm a tidy person.

And there you have it, I'm getting close to the end of the mechanical build. Now I need to fit the y-axis, attach the x-axis and z-axis, thread belts on and I should be very close to being done.

Wednesday, 21 April 2010


Time to crack on, so up next is the Y-axis. This is basically the "tray" that stuff is printed onto. Of all the parts it was the most annoying/fiddly to assembly, so many washers and bearings at funny angles.  Here you can see the two sets of bearing assemblies that the Y-bars slide through. The two blocks in the middle of the clear acrylic sheet are

belt clamps.

Here is a better view of the bearing assemblies, as you can see all funny angles. Getting all of the bearings to run smoothly and not foul on random bits of plastic was a pain, but once it was all tensioned it ran very smoothly.

The four bolts in the middle hold the purge plate and y-opto flag, but I don't have them yet :(

So that's another piece done, just the z-axis and frame to go!

Tuesday, 20 April 2010


Now the building starts, the wiki recommended starting with the extruder, but I'm missing a few bits (nichrome wire etc) so I decided to start with the x-axis.  I started with the Z-axis bearing (the Z-axis guide bar runs through the two washers in the photo, while one of the threaded drive rods runs through a trapped nut).

I then moved on to the extruder carriage, you can see the extruder stepper mounted here (the black box).

Time for the other Z-bearing assembly, here you can see the top set of 3 bearings that trap the z-axis. The x-axis stepper and drive belt were next to be added.

Et voila! One X-axis fully assembled, the action is very smooth and it's a lot more rigid than I was expecting.

Here you can see the extruder carriage, and how it sits on the supporting rails.

Monday, 19 April 2010

A box appears

It's always nice when a parcel turns up, however I don't remember ordering any bananas...

But what's this? The box is completely lacking in bananas, instead someone has filled it with reprap parts, which is much better!

So many packets and bags, all neatly labeled.  Everything is there and in perfect condition which is impressive considering it came all the way from Hungary.

So now that it's all here time to start building, I'd just like to say thank you to Laszlo again for getting everything printed and shipped to me and for putting up with my constant stream of emails!

Sunday, 18 April 2010


Welcome to AberRap, yet another reprap blog! This blog will follow the construction, operation and hopefully tweaking and improving of a reprap Mendel. 

So what is a reprap Mendel? Well wikipedia says:

"The RepRap Project is an initiative aimed at creating a largely self-replicating machine which can be used for rapid prototyping and manufacturing. A rapid prototyper is a 3D printer that is able to fabricate three dimensional artifacts from a computer-based model.".

The Mendel is the second generation or "new and improved" version of the original Darwin reprap machine, it is less prone to jams and is basically "better, faster and stronger"! I got the mechanical parts (printed parts, studding, bars, nuts/bolts,belts and stepper motors) from Laszlo at If you are interested in making one yourself definitely drop him an email, he's a great guy and really helpful. 

Now that the obligatory introduction is done, on with the build!