Wanna help the newbie?

I decided that since no one was seemed like they were going to give me a Thing-o-Matic for Christmas I'd make my own -- the only problem is that I have no idea what I'm doing. I'm currently making a to-do list and looking at sources for the boards I'll need, but I hope to scavenge most of the parts. Any tips or advice you think I should have?

First off, prepare to be so frustrated that you might like to smash your printer and/or PC into a pile of dust. This will really test your patience - especially if you choose the no-kit rout. It took me 6 months to get my Tech zone Mendel in working order.

For a custom built rig, you have a lot of options. For instance, you could buy laser cut wood from Makerbot and source the rest of the hardware yourself or try making a Mendel with a conveyor enhanced build plate.

I suggest starting by researching your available options. Get an idea of how complex the build will be and compare that with what you are willing/able to tackle. Try to think about the physics and layout of your initial designs. Identify the pitfalls. For instance, a conveyor on a mendel will be tricky because you don't really get space for the extra rollers, motor, and gears. You would have to change the build plate design to give you more clearance.

Once you narrow your focus on one or two design paths, try to match the technical specifications of other 3D printers. (IE track down motors that have the same toque and amp draw). Then you can start putting together a bill of materials and weight the cost of your remaining design paths. It doesn't have to be 100% complete - just enough to give you an idea what each option will cost.

As far as suppliers, back when I got my stepper motors, Altronics had the lowest prices on high-torque steppers. They recently raised their prices, so maybe this isn't true any more. It is a bit archaic to search through, but they should have two or three models that will work.

Well, my basic plan is to build the standard sized and equipped Mendel, the only requirement is that is costs as little as possible. So, I'm looking at each part and trying to find other options or different ways of acquiring them. For instance, stepper motors are in 2D printers and scanners -- if I can find one in a used printer with the right specs, it should work.

On a related note, the bill of materials says that the steppers should be 14 or 17 nema and have at least .03Nm torque. While I've found info on nema 1-13, 14-17 are a little harder to find. What exactly is that requirement saying and how will I know if a stepper has it? I'm also wondering if any of you have any ideas on how to test the torque of a stepper, one of my worries is that these old motors might have lost a little bit of torque over the years.

The strength of your motors will play a major role in the performance of your printer. Going cheap here would be like putting a four cylinder engine in a Corvette. It could cripple an otherwise good build.

Over the last five years or so I have scrapped a lot of obsolete/junk copiers. I pull out circuit boards and whatever else I think might be useful. The motors are almost always too weak to be worth saving. Some of them even had custom built motors that would be far too bulky to adapt into the mendel design. Unless you are able to pin down a specific model that you know has good enough motors, it will save you a lot of aggravation and time to just buy reprap proven motors.

In order to get your motor's specs, you have to get the part number and search for a data sheet. Lin Engineering is pretty good about putting them online, many other manufactures don't seem to do that. If you search the selection at altronics, they will have links to data sheets for most of thier motors.

I think you would be better off sticking with nema 17 size motors, as these are likely to be cheaper and easier to find. I'm using a 4218L-08S-01 on my extruder, but the shaft is too big for reprap standard pulleys. You could plausibly use this on every axis, but you would have to modify the pulleys to fit a bigger shaft. For comparison, here is a spec sheet for the other three motors on my mendel: 4118M-02-07RO.

I went the cheap as possible route. After much research, I found somewhere that sold suitable motors for a nice price. I considered salvaging, but you really need solid, reliable motors for good prints. Don't skimp on these.

As for the rest of the electronics and hardware, check my "wooden mendel" blog

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Wooden Mendel
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