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Isaac - a Mendel 3D Printer

What we have done with Isaac is transform the basic Mendel into a machine that can be replicated using CNC machines instead of relying on the slow process of printing one. 

Isaac is a derivative of Mendel with the primary goal of making it easy to produce on 2.5D CNC machines. Isaac is a RepRap/RepStrap hybrid with parts that can be either printed on a Mendel sized 3D printer or a budget sized CNC machine. Once you have one you can print one for your friend either off our design or the original. We have spent a significant amount of time on this design and we hope that our variation will allow cheaper machines to be produced as more and more people offer this kit.


A RepStrap is a printer that is built for the purpose of printing another printer, but is generally made out of non-printed parts. A RepStrap is generally considered a non-replicating printer.

A RepRap is a printer that can replicate its own parts. Isaac was designed to be printable and machinable, so you can print an Isaac on your Isaac for your friends just as easily as you could print a Mendel. Because of this advantage you can build an Isaac as your RepStrap and not feel like you have to throw it away or replace it with a Mendel. It is a Mendel!

We did say printing an Isaac is as easy as printing a Mendel, but it isn't. It's easier! The Mendel has over 90 pieces that have to be printed, the Isaac has just 53!!!

Customer Shots

Build Documentation

Build documentation along with a BOM is available on our website. The Bill Of Materials (BOM) contains a list of what is included in the kit and a list of the remaining mechanical hardware you'll need.

Want one?

Option 1: Buy an Isaac

If your ready to start building your own Isaac-Mendel then hop on over to our store.

Option 2: Print an Isaac

We have released our complete design of Isaac into the Open Source community under the GPL3 license. You can download the source via the RepRap hosted Isaac website.

Using your favorite 3D printer, simply print the STL files for our Isaac and follow our build documentation!

Option 2: Cut an Isaac

Have your own CNC machine, or know someone who does? Using your favorite CAD package, ours is Alibre Design, generate the 2D or 3D views of the parts and send it to you CNC machine. Cut it out of wood, aluminum, or HDPE and then send us pictures!!!

Isaac's First Print

Changes from the Original

We took great care to minimize overall costs of construction while maintaining the Mendel footprint. We significantly changed a lot of RP parts to make them machinable and yet still printable. We combined lots of parts where applicable, and tried to design things in such a way to make assembly and disassembly easier than the original.

What's Different?

  • Vitamins: We have reduced the number of nuts/bolts/washers/bearings used to minimize costs where possible
  • Rods: Uses less total length of smooth and threaded rods
  • Components: We have reduced the number of machined/printed pieces from 95 to just 45 (19 unique parts)
  • Pulley Size: We could not find pulleys in the diameter of the original, so ours comes with pulleys with 10 grooves instead of 8. The result is slightly less X-Y resolution at 0.005 inches per half.

What's the Same

  • Build platform: Want to buy that cool Mendel heater bed? It'll fit on Isaac!
  • Spacing:Distances between Rods were left alone so that Updates/Upgrades to the original Mendel will apply to Isaac
  • Belt pitch:  Uses same XL pitch belts
  • Metric based (SAE coming soon)
  • Supports same motors as the original

Prototype #2 Printing