Sunday, January 23, 2011

18 day RepRap Marathon

A experiment in self funded exponential replication.
For the next 18 days, it's just going to be me and my RepRap hobby.  It's something I have wanted to do since I first read about RepRap 2 years ago, and finally I have the time to do it (Use it or loose it vacation days, got to love them :) ).  This will be an experiment in how exponential growth works in the real world of RepRap. 

To keep myself honest, I am going do to 1 blog post each day telling about the progress i have made toward my goal, and what I have learned.  It should be interesting considering my pension for doing stupid things and telling the world about it. :)

I go into this project with

1 95% completed Prusa Mendel

1 50% complete set of Prusa RP parts set to SAE fasteners
1 100% at this time operating MB Cupcake (with DC gearmotor, so let's see if it holds out)
1 1 set of the Makergear Stepper extruder kit to replace my DC gearmotor if it dies
2 Set of screws, smooth , and threaded for Imperial Prusa Mendel
1 Set of screws, smooth, and threaded for Metric Prusa Mendel
2 sets of PEEK barriers from Makergear
2 NEMA 17 stepper motors (two different makes, so must me by X & Y)

My goal is to by the end of the 18 days have enough money coming in from RP parts sells, and enough experience with the Prusa Mendel Design that I can reach exponential growth (If only mathematically for a few days).

I am going to set a lofty goal, 6 new printers in 18 days, all funded via selling RP parts online.  I feel I can use what I have already because besides my Cupcake I got 14 months ago, everything else has been paid for by selling RP Parts.

The "Plan" assumes that I will not have the Prusa printing parts until Friday, that the Makerbot holds out for 18 days at a 20+ hour printing pace (We will see), that I will at no point have more than 2 printers functioning at one time, and that I have a quick turn over on the Prusa Mendel RP sets.

To this end all RP parts sold from this project will be only $100 ($50 less than the going rate), so that they go quickly.  All parts will come with a certificate stating how what number replication it is for me, and what machine made it.

My "base" build will be as follows
$50 4 63 oz-inch stepper motors
$220 1 Ramps Electronics and 4 connectors for motors
$165 1 plastruder kit from Makergear, if they are out of stock I will just get 1 more stepper motor and $87 an operators pack and mount
$40 a 20A power supply
$35 12 brass bushings, and 8 foot of .2" xl 1/4 inch wide belting.
$50 Local fastener store all the Tool & threaded rod and fasteners.

So $560 that's the simplest, easiest way to build a Prusa, I could cut that by $200, and likely will if it seems practical, but considering I am going to be printing 20+ hours a day, I might not want to get into complicated soldiering :)

I go into this project with $600 from selling RP parts, so on Monday I will order 1 of everything I need for Prusa2

So for the 18 day run, this is my "plan"
1. Finish partial set, and 1 more for getting ahead on Prusa Mechanicals
All components for 2nd Prusa ordered
2. Sell 1 Prusa Set ($100)Altronics
3. Sell 1 Prusa Set ($100)Ebay Power supply
4. Sell 1 Prusa Set ($100)electronics
5. Sell 1 Prusa Set ($100)belts/bushings
6. Sell 1 Prusa Set ($100)Hot end
All components for 3rd Prusa ordered
7. Sell 1 Prusa Set ($100)Alltronics
8. Sell 1 Prusa Set ($100)Ebay
2nd Printer online
9. Sell 2 Prusa Set ($200)Electronics
10. Sell 2 Prusa Set ($200)belts/bushings/hotend
All componetns for 4th Prusa ordered
11. Sell 2 Prusa Set ($200)Electornics
12. Sell 2 Prusa Set ($200)Motors/Hot End
13. Sell 2 Prusa Set ($200)belts/bushings/powersupply
All components for 5th Prusa ordered
14. Sell 2 Prusa Set ($200)Electronics
15. Sell 2 Prusa Set ($200)Motors/Hot End
16. Sell 2 Prusa Set ($200)belts/bushings/powersupply
All components for 6h Prusa ordered
17. Sell 2 Prusa Set ($200)Electronics
18. Sell 2 Prusa Set ($200)motors/Hot end
All components for 7th Prusa but hot end belts and bushings ordered

That would mean that in 18 days I could supply the world with 27 new Prusa Mendels, and they would return the favor by giving me 6 1/2 back.  of course there are a lot of ways this could not work out.

-My MB loves to eat DC gearmotors, if this happens before I get Prusa1 up and going the Geared Stepper falls into the critical path.
-The parts could not sell, but I think at 1/3 less than the going rate I shouldn't have an issue with that.
-It could take more than a week to get Prusa1 up and going (All I need to do it put the build plate & hot end on, calibrate, and I am good).  Not likely, but with the help of #reprap in IRC I think I will have no issues
-The Great Gremlin, we don’t' talk about him, but Makergear and Prusa designs are mostly Gremlin resistant.

Next post tomorrow evening.  I made Day 1 pretty easy considering I work 14 hour days on the weekend, and those days are hard.  Wish me luck, and if you see me in #RepRap tell me to print faster. :)

Still Extruding


  1. Seems like you forgot to take plastic into account (not a critical part, I know)
    How much ABS do you think is needed for a prusa set?

  2. I have over 14 lb of plastic :) Prusa only 2/3 lb, so I shouldn't run out without a lot of forwarning to pick up some more cheap plastic :)

  3. I think this is a great idea! good luck! (and if you fancy listing on eMAKERshop, please do)

  4. Hi Neil,
    Great plan - hope it goes well for you.
    One Question... Do you plan on printing or buying gear pulleys for the motors?
    I notice these need to be reasonably precise in construction and wondered what you are doing for these.

  5. Plan to try to print them. On my last Prusa I bought a set form Makergear, and they are NICE. He prints them currently on his Up!. I will try self printed on the next, and if I don't like will resort back to paying for them.

    Heck $10 for 2 nice gears is not bad at all

  6. I still have the extra motors you sold me. I am happy to sell them back to you if you end up needing some.

  7. Fantastic idea!!! But... updates please! :)

  8. Good luck! Looking forward to updates :)

  9. Great idea.

    But what happened after Day 1?

    Your videos of your build of your Prusa is one of the things that got me to decide on finally buying a kit to build a RepRap. I ordered a Prusa kit from MakerGear which I expect to receive in about a week and a half.

    -- Don King

  10. Makerbot blew up and some family emergencies. :) But I did manage to finish 4 of them though :)