Black Beauty

As mentioned before: among other projects, I’m currently in process of printing a Mendel.

Thanks to the heated build platform in my MakerBot I’m able to print in ABS without rafts. That not only saves a great deal of time and plastic, it also eases the process of cleaning up the parts after printing significantly.

I print all parts with an infill density of 30% (.3). The black ABS is extruded at 225°C, flow rate 243 and feed rate 28mm/s.

So far,  I had no problems with printing any of the parts. Even the larger ones (like x-carriage-lower_1off or x-carriage-upper_1off) printed out nicely without warping.

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Due to the absence of rafts the amount of wasted plastic is amazingly low so far.

Actually, the only two failed prints were caused by “external” problems, i.e. filament jams outside the MakerBot. I really need a good solution for putting the filament on spools as soon as possible…

Of course, there were minor problems like bad manual homing of the extruder head and such things, but these problems are usually noticeable during printing the first layer of an object. Early aborting one of these bad prints doesn’t waste much plastic nor time.

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A week ago I received the metal parts of my future Mendel. I ordered them -except the ball bearings- from the German branch of the company mentioned by the RepRap project in the Mendel assembly data sheet. Because of the much lower price, I ordered the ball bearings from another company (e.g. 624 bearing @ .78€+tax instead of 1.15€ + tax).

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I bought all bolts, nuts and washers from a local bolt-nuts-and-washers-dealer nearby (… always support your local dealers, right?)

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Besides printing Mendel parts on my MakerBot (about 80% completed so far), there’s some other stuff to do:

  1. trimming the bars and studding to the correct length
  2. somehow creating the “thick sheet” parts without a laser cutter (which I unfortunately don’t have any access to)

Lucky me: my brother owns an organ builder workshop (actually founded by my father), only a 1.5 hours driving time away. So why not doing a nice visit before Christmas…

Having access to the workshop’s machines made it much easier to do the trimming of the rods.

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I created the “thick sheet” parts out of plywood. With help of a scroll saw I was also able to cut the weird shaped “y-chassis” piece.

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I had problems with the long slot holes in the “motherboard-plate” and “stepper-plate”. I tried to machine them with a router, but I couldn’t get them nice and straight. Eventually I figured that most of these slots are only needed to universally mount arbitrary PCBs to the plates. So in absence of a laser cutter or a CNC router it’s probably the easiest way to skip the long slot holes completely and just drill the holes needed for the PCBs you’re actually mounting to the plates…

Concering the “y-chassis”: I wish there would be a way to use a more or less rectangular shape for the actual thick sheet part and rather print the funny shaped parts. Something like this:

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That way, it would be much more easy to create all thick sheet parts with common tools like a circular saw and/or jig saw. That’s already true for all other thick sheet parts.

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Today I ordered the last missing pieces for the Mendel: The stepper motors and the electronics kit.

I ordered these parts not from MakerBot, but from an electronics internet store located in Germany. Considering the (rather high) international shipping costs at the MakerBot store, plus the potential tax and customs fee (if the package doesn’t slip through customs), the parts are about the same price when ordered from a domestic distributor. The electronics kit was (and is, again) out of stock in the MakerBot store anyway.

So far, the costs for my Mendel are (plus VAT):

Bearings 52,80 €
Fastener 32,62 €
Bar/Studding/Belts 69,10 €
Electronics + Motors 171,41 €
325,93 €

Not yet counting the ABS for printing parts and some minor other stuff (power supply etc.).

However, it looks like I’m still in the £309,33 (about 344,13€) range, the Mendel-m4-assembly-data-sheet declares.

Assuming the printing of the remaining Mendel parts doesn’t take more time as expected, I should be able to finish my Mendel by end of the week. I’ll let you know…

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