My $300 Prusa Mendel Build

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I’ve set out to build a Prusa Mendel for $300. So far I think I’m doing pretty well. The top part is what I’ve already picked up, and the bottom part is what I have yet to purchase — that’s where I still have some flexibility in cost. The first column is the percentage of total cost for that part. Shipping charges for a group of items from the same supplier are listed with the first item in that group. [Note: This chart has been updated many times as I build, and as because I’m already up and running with my reprap 3D printer, there’s no longer anything left to purchase.]

Where I discovered mistakes, I’ve corrected them. For example, I actually ordered nylock #6 nuts instead of regular ones. In cases like these, I’ve just corrected the prices and pretended like I never incurred the cost of the wrong product.

There’s one important point I’d like to make out here: I was patient, I waited for good deals (and occasionally got exceptional ones), and I arranged some group buys for bulk discounts. Often if you agree to purchase larger quantities of a product, you can secure a discounted rate, and so that’s what I did where I could. You might not find all of the same deals I did, but you may get pretty close if you are patient and work with your suppliers.

I’ve added a table below that breaks out the electronics order, including what I had on hand, what I bought from ebay, and what I didn’t actually need. (Welcome Hack A Day readers!)

Finally, be sure to scroll to the right in the spreadsheet views for important notes or shortcuts on most line items.

Electronics

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20 Comments

    • Thanks, Brett — that’s a good idea. This machine seems pretty darn stable to me. Next I’m going to try to build one for $250 🙂

      • Yeh, I think most of the “prusa stability” issues are in the i1 and i2.. i’ve got an i1 and i HATE the frame.. i3 seems WAY more stable!

  6. Awesome list! Best of luck meeting your goal!

    Been wanting to build one of these for a while but been debating on whether or not to source parts or buy a kit to put together.

    I think I may try and source it now 😀

  8. I appreciate the list! A friend of mine just purchased a makergear prusa mendel kit for around $825. This list is very similar to the one I have been making but I am using the RAMPS board vs the Sanguinololu for the added stepper driver and features. Keep up the great work! I really appreciate someone putting out a great list of parts. Btw you might want to check that PSU you bought from the list with a oscilloscope under load if you have one. I have had issues with poorly made china power supplies before.

    • They’re just plain vanilla zinc-plated for the threaded rods and nuts. So far everything has held up fine. The smooth rod is W1 tool steel.

  11. Hey! Awesome work! I have a few questions though, which I’d really appreciate if you could answer:

    1. Was 3400g/cm torque enough to run the machine at a reasonable speed?
    2. How come you did not require a hotbed?
    3. Why did you choose Greg’s extruder over Wade’s?

    Many thanks!

    • Sure thing — (1) the motor torque is fine for me. I run the drivers cool and the motors just a little warm (but not hot). I still haven’t gotten around to testing the upper limits of the machine, but the typical speeds I use in slic3r are 75 perimeters, 65 small perimeters, 90 infill, 80 solid infill, 50 top solid infill, 60 support material, 70 bridges, and 20 gap fill. Travel is 125. (2) I didn’t start with a heated bed because I was trying to hit the price target. PLA usually sticks well to blue painter’s tape, and that’s how I started. I added the heatbed later, though. (3) Greg’s is an improvement on Wade’s design, and it’s what was provided in the set of RP parts that I purchased. Let me know if you have any other questions!

    • Awesome! The belts are in there — they’re sixth from the end of the “purchased parts” list. I would recommend a smaller belt pitch and machined pulleys nowadays, though. You can get a GT2 belt/pulley kit for about $30, and you’ll have much better quality over the XL belts and printed pulleys.

  13. Hey, was trying to do the same kind of thing of making my own Prusa Mendel i2 for roughly 300$ and I’m getting there, but couple of questions. As far as hardware goes, I noticed you did a lot of SAE parts like the threaded rods and the nuts and bolts for most as well. Did you have to altar the printed parts you used to be able to go with the 6 ft 5/16-18 Threaded Rod? I can’t find a lot of good deals for metric smooth rods and threaded rods, but I can definitely get the threaded rods at Lowes a heck of a lot cheaper and the smooth rods I still can’t find that cheap. Just wanted to see if I could get a some input before I screw up and start mix and matching SAE and Metric parts. Any suggestions would be super awesome since I got printed parts on the way and I want to get the right hardware. Thanks! Sorry if this is a lot of info at one time, but I’m trying to do this on the cheap as allowable and soon as possible!

    • Hi — sorry for the delay here. I’ve been away at a conference. 5/16 is practically equivalent to 8mm, so you shouldn’t have a problem there at all if you’re using that on the frame. I picked up threaded rods at Lowes, too — they had the wrong price listed on the website, and they did a price match — I think $1 for each 3′ section! I get smooth rods and fasteners at McMaster-Carr, which has great prices and low shipping.

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