mendel: one less piece of studding

here's how to arrange your studding pieces (incl. jigs) so you only need 8 instead of 9:

1: A, D2 (142mm left)
2: A, D2 (142mm left)
3: C, D1, E (21mm left)
4: C, D1, E (21mm left)
5: C, C, B (42mm left)
6: B, J1 (340mm left)
7: B, B, J2 (26mm left)
8: B, B, J3 (103mm left)

(letters refer to Mendel Assembly Data Sheet)

I came across a few arrangements with some rods having only 6mm left, but the width of my cutting disc would consume that, leaving zero room for error, plus I still used 8 lengths of studding.

I had hoped to find a way to fit all 18 pieces and 3 jigs on 8 pieces of 36" stock. I wrote a genetic algorithm optimizer but got no solutions in less than nine piece of stock.

At least it's a lot better than the Darwin which needed 16 pieces of 36" stock and left lot of scrap.

The 9-bar solution is pretty straightforward:

1: A,A (34mm remaining)
2: B,B,J3 (17mm remaining)
3: B,B (174mm remaining)
4: B,B (174mm remaining)
5: C,C,J1 (36mm remaining)
6: C,C,J2 (92mm remaining)
7: D1,D1 (204mm remaining)
8: D2,D2 (78mm remaining)
9: E,E (254mm remaining)

Just a small, maybe stupid, question.

I have been following these experiments for a little while now.

Are you guys taking into account lost material when they are cut and filed?

Triffid_Hunter Wrote:
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> I came across a few arrangements with some rods
> having only 6mm left, but the width of my cutting
> disc would consume that, leaving zero room for
> error

The bar lengths, except for jigs, do not appear to be critical. I don't think any measurements are taken from the ends and most of the threaded rods can be extended indefinitely without running into anything. The 'B' studs might run into problems if more than a cm or two long because they will start to interfere.

When doing the genetic algorithm optimization I assumed a 2 mm kerf, just to be sure.

I would (and did!) cut the stock a mm or two long and grind to length.

John

I had the Idea that it was simpler to do exactly that initialy with my mendel build making the equilateral triangle out of off the shelf 500mm long studding.

The only problem this threw up for me was the drive belts required need to be a fair bit longer as I am not spending any money building Mendel just using what I have got left over from other builds I had to cut the threaded rod to size else I would not have enough belt for X and Y For Z I will not be using belt but two steppers possibly with some gears left over from the pack of 5 you get when building the original mk1 extruder.

Mendel build part1

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On the build sheet, it shows two rods each for D1 an D2, yet the illustration below it only shows one D1 and one D2, both on the base there. I don't see where the other two are used.

In any case, I made a photo showing how I distributed the studding across 7 rods, since I cut only 1 D1 and 1 D2. If I've messed these up badly let me know, and if anyone knows if there truly are two of each of the D1 an D2, please say! Trying to go off of these illustrations isn't the easiest.

Click on this photo to see it big.. each rod has a label on it.

Yes you need two D1 and two D2, see [objects.reprap.org]

It looks like the diagram in the assembly data sheet is out of date. It shows the motor bracket and idler bracket fused with the z-axis base parts. Looks like they were split off to allow a Makerbot to make them.

It takes 8 lengths of studding to make them all.

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