After seeing this design I don't want to build mine anymore. I will be looking for someone willing to print out these parts for me.

[www.plansandprojects.com]

Tell me what you guys think of this.

Thanks

Colin

That's Ron Thomps design [www.thingiverse.com] and personally I would stay as far away as possible. The original Prusa design is lacking some rigidity already and just replacing the threaded rods will no improve it in any way. If it had been redesigned and engineered to be strong maybe. Unfortunately all of the Mendel variants have a flaw, have a look from the front you will see it is made up of a square with a rectangle on either side and no triangulation. This forces the metal rods to be all of the structural support to stop it from flexing sideways which does not work very well (it needs added diagonal support). By replacing them with flexible plastic parts you are very unlikely to end up with a usable machine.

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Im going to have to agree with Brad with this, The sells was probably the most rigid mendel variant machine out there without added hardware like cross beams. The prusa alone flexes quite a bit on the frame, just simply putting a finger on the top vertices and pushing you'll see and feel the frame move.

The best is to do what Brad has suggested with the cross brace for the Prusa, not the best looking but it'll get the job done. If you want an even more rigid build I would say the best best is to incorperate some more of the sells back into the prusa (but that would be moving backwards in a sense)

I'll back up sublime/ECSuyu on this too. The prusa is already too flexy (but only a little), and this is going to be even worse.

If you wanna make something exotic, the [mendelmax.com] is probably a better choice, at least it errs in the opposite direction

What I am thinking of doing now instead of this, is taking Ron's out line for the sides and front and cutting them out of Aluminum Plate or Steel on the Waterjet here at work. I know it takes away from the spirit of reprap, I just want a solid machine. I hate dealing with flex in machines.

Colin

I believe even with aluminium/steel plates you'll need to have the frame joints to be at least 3/8"-1/2" thick per section before you will be able to gain the strength from going this route. Thing sheets of both would still rock back and forth from the momentum that gets generated by the X and Y carriage moving. Especially once you start to hit speeds of 80mm/s+.

The flex in the mendel machines doesnt happen much in the Y plan as it's well triangulated. But the X plan (view from the front) needs extra triangulation to allow the machine to not flex under the weight transfer of the X carriage's constant motions.

Eugene

Edited 1 time(s). Last edit at 12/21/2011 02:17PM by ECSuyu.

If you want an aluminium framed machine you have many choices. Most like what you are talking about is the Orca v0.3 [www.mendel-parts.com]

But you also have the choice of Mendel Max as Rantenki mentioned as well as Fablicator.

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