More photos are found on my photostream at Flickr: flickr.com/photos/sbgraber/8351936888/in/photostream/

Please note: my braces, while they look similar to Twelvepro's, were designed independently and were mostly done by the time Twelvepro released their files. The major differences between my braces and their design is:

* mine are 7" wide whereas theirs is only 5" wide
* the Prusa frame is stock with the exception of increasing the hole sizes for M3 screws and adding slots and holes for the brace nut traps and tabs
* one brace supports RAMPS 1.4, RAMBo, and Sanguinololu electronics and the other one (will) support RUMBA and Printrboard in the next git commit
* only two additional parts added to the bill of materials
* ability to use all stock plastic parts from Prusa's git repository
* sized for 6mm double-faced melamine board and 1/4" acrylic
* no laser cut files for z-axis motor mounts and smooth rod
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The goal of this revision is to allow people to use frame material that is less rigid than the 6mm aluminum, which is specified for the Single Sheet Frame Prusa i3 Printer (http://reprap.org/wiki/Prusa_i3#Single_Sheet_Frame) and have it laser cut instead of water jet cut. Laser cutters are more accessible for people either at their local makerspace or at local laser cutting businesses. Laser cut material is also less expensive and people can source different frame colors and materials, such as 5mm birch plywood, 6mm double-faced melamine, and 1/4" acrylic.

To achieve this goal, two angular braces are designed and added to the bill of materials and the stock Prusa i3 Single Sheet Frame is slightly modified to accept these braces. A major goal of this revision is to keep the Prusa i3 frame as stock as possible so that people can continue to print and use Josef Prusa's i3 parts from his Github repository: github.com/josefprusa/Prusa3/tree/jo-final In this release, the frame dimensions were not changed at all. The only additional items added to the i3 bill of materials are the two laser cut braces and six 25mm/1-inch M3/6-32 SAE screws and washers.

This frame was designed for use with 6mm-thick material. Thicknesses less than or greater than 6mm will require the brace tab lengths to be decreased/increased and the square tab-accepting holes in the Prusa i3 frame to be decreased/increased accordingly. I have found that oversizing the tab-accepting holes by 0.2mm works but each laser cutter is slightly different and may require adjustments different than this.

Changed and New Parts
------------------------------

Changes to the stock Prusa i3 frame:

* Screw hole size increased from 2.5mm to 3.5mm to allow for either 3mm or 6-32 SAE screws
* Added square tab holes for braces
* Increased bottom 8mm circular holes to 16mm oblong holes to allow pre-wired motor connectors to fit through
* Moved RAMPS 1.4 mounting holes to the braces
* Added "i3" text to top of frame
* removed two heat sink for extruder motor as wood / acrylic makes for poor heat sink material
* removed y-alignment tool and associated holes in frame as the new braces take care of this

New braces (2) :

* Measure 370mm tall x 178mm wide (7" x 14.6")
* Oblong holes in brace bottom allow for pre-wired motor (and other) connectors to fit through
* Mounting holes for both RAMPS 1.4 and RAMBo one one brace (Sanguinololu and RUMBA holes on the other brace forthtcoming)
* 80mm x 8.8mm slot in bottom ties into the top-back y-axis threaded rod using four washers and nuts and an extended y-axis threaded rod
* Nut traps accept either M3 or 6-32 hardware (Nyloc nuts, 25mm / 1 inch screws)


UPDATES
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2013-01-08: Latest frame version from Josef Prusa makes the following changes:

* Removes three LM8UU y-carriage plastic parts. Y-carriage updated so that LM8UU's mount directly to the underside of the y-carriage using zipties.
* Four ziptie holes are added along the base of the frame for managing wires
* Two rectangular motor mounts are removed
* Removed Printrboard mount holes


How to obtain a laser cut frame
---------------------------------------

I have provided three file types for people to use when laser cutting: dxf, eps, and pdf. Your local makerspace or laser cutting business should be able to utilize one of these three file formats to cut your frame and braces for you.

If you would prefer to purchase one of these frames and associated braces online, I will soon provide these parts on Ebay along with my printed parts, which conform to the latest versions found in the github.com/josefprusa/Prusa3/tree/jo-final/ branch. This way you can source most of what you need from one place: myworld.ebay.com/sbgraber

I worked with the guys at SeeMeCNC during development of this frame revision and they are also providing the frame for purchase from their website: shop.seemecnc.com/ These guys are great to work with and I highly recommend them and their products.


Assembly
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Materials:

* Frame (1)
* Brace (2)
* M3 / 6-32 SAE screw, 25mm / 1-inch long (6)
* M3 / 6-32 SAE washers (6)
* M3 / 6-32 SAE nut / nyloc (6)

Slide the tabbed braces into the frame. Slide a washer onto an M3/6-32 SAE screw and insert the screw into each nut trap hole. Use either a standard or nyloc M3/6-32 SAE nut and screw tight.

Assemble the remainder of the printer per the instructions in Prusa's repository: github.com/josefprusa/Prusa3/blob/master/doc/manual.txt
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Open Source Hardware STL courtesy: thingiverse.com/thing:27097