Mendelise Makerbot gen 3 electronics - please help

Hello All

I am looking at sourcing the components to 'Mendelise' the Gen 3 electronics as received from Makerbot.

I have absolutely *NO* experience in electronics so am a bit confused as to exactly which parts I should get.

The source I am using is PCB_adaptions for Mendel

Since the Makerbot gen 3 electronics set does NOT contain any opto-endstops I need to source those parts as well. For this reason I am using Mouser

Currently I am stuck on which capacitor to select for the Motherboard. The wiki adaptions page states '100uF (107K) Radial-pin Aluminum Electrolytic Capacitor' but this is not enough info for me. I do not know what the (107K) means and also no idea what voltage or tolerance or dimensions I should select...

Can anyone please help point me in the right direction? Here is my current filter selection which still has way too many options. Of course I would like to limit the selection to those they have in stock (not on order...)

Once I have my parts selected I will post the details here for approval and for others with the same problem. (The wiki parts lister lists parts for Makerbot electronics )

107K means that the part is 100,000,000 pf (10 x 10^7 pf), or 100uf, and K specifies +- 10% (See the Capacitor Markings section of the Capacitor entry on Wikipedia). This is a case where the precise value is not very important. A +- 20% part is fine. The mod will probably work reliably even if the capacitor is removed completely (although that is not certain in the face of a SD card being plugged into a powered system). That said, I would add the capacitor.

The capacitor is on the output of the 3.3 regulator, so any voltage >= 3.3 volts is an acceptable voltage rating for the capacitor. A good rule of thumb is to use a voltage rating at least 2x what is expected, so >= 6.6 volts is good.

The least expensive part in your list that is in stock (140-REA101M1ABK0511P) will work fine.

Edited 1 time(s). Last edit at 06/04/2010 05:06PM by madscifi.

Hey madscifi

Thank you very much for your informative reply.

I should have remembered the use of numbers and letters to describe certain components.

I have read about the use and understood it but I never recognised it in the wild. hmm...

Thanks for your help

If you prefer to buy kits, so avoiding the need to source individual components, you can get RepRap Opto Endstop v2.1 kits from ultimachine.com (and very probably from other places too).

Also note that you only need the 3.3V onboard power supply components (the 78L33 regulator and the capacitor) if you will be using the SD card slot; if you will always drive your RepRap directly from a USB-connected host PC, they are unnecessary and can be omitted. The reprap.org 5D firmware for Mendel doesn't recognize/use the SD card slot anyway, as far as I know.

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Jonathan

Hey jmarsden - can you point me to some documentation on the wiki which will specify minimum modifications need doing and how to use them with Mendel?


Also, as promised here is my link specifying the Bits to 'Mendelise' Makerbot gen 3 electronics. Could someone in the know please verify that I will not be wasting money getting this?

A note - I have listed a 16 point breakaway header which covers 8x2 point headers. 1 for the extruder controller, 6 for the motherboard (4 at D, 1 at A and 1 at B as seen on the modified motherboard jpg) and 1 spare in case of breakage.

Thanks

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AgeingHippy
can you point me to some documentation on the wiki which will specify minimum modifications need doing and how to use them with Mendel?

Not really; I doubt any documentation of the minimum mods exists. If you understand the electronics enough to read a schematic, you can check what parts on the board use the 3.3V supply rail easily enough by eye (that's what I did before posting my comment earlier!). If you don't understand the electronics, then it is safest to just follow the instructions.

The mods to go from fully assembled Gen3 boards (from MakerBot) back to the Mendel approach are rather annoying, especially the connector changes (long story -- I argued against using the RJ45 sockets back when those boards were being designed, but Zach was the one doing the board design,,,) but the mods are not complex. You are just removing/swapping a few connectors, adding a link so 5V supply comes from the USB cable, and and (optionally) adding a 3.3V regulator to supply 3.3V to the small part of the electronics that needs a 3.3V supply. That's all.

I suspect you may be trying too hard to understand the RepRap electronics, from a standing start -- when you can't reasonably be expected to learn enough basic electronics in just a few days to understand relatively complex hybrid digital/analogue circuits like these. You should consider starting out learning electronics on much much simpler circuits and systems, if learning electronics is your goal. The Gen3 boards were designed more for ease of production than for use as an electronics tutorial. RepRap as a whole is not set up as an education project in the basics of mechanics, electronics, firmware or Java programming... although you may end up with some skills in all of those things if you dive deeply into every aspect of RepRap and can learn as you go! So if you lack electronics knowledge, for now, relax a bit, trust the existing documentation and just follow it (within reason... it isn't perfect).

If you're going to be ordering from an online electronics component supplier anyway, one 78L33 regulator and one 100uF capacitor won't change your total Mendel build cost significantly. If leaving them off means you can avoid placing the order and get started right now, because you have the other stuff lying around your garage/workshop, or because you then don't have to learn about capacitor voltage ratings etc., then it could be worth leaving them out.

Once you have the Gen3 electronics working, if you feel it would be useful to others, do go ahead and document your exact parts list and (if you wish) the "minimum" parts list needed for the board adaptation work, on the relevant wiki page, so other Reprappers can learn from your experience. It's 100% fine to go ahead and improve our documentation like that.

Your Mouser parts list looks sane to me (I've not read the details of every part on it). A few things I noticed:

(1) Do you really not have any old PC hardware with jumpers you can use, instead of buying a jumper for $0.12 ? I have so many little screws and jumpers and old PCs here I'd not even think about buying jumpers

(2) No opto endstop boards or parts to build them. Save on shiping, order as much as possible in one order from one supplier.

(3) Interconnecting wiring is also absent; do you already have the appropriate cables to connect your boards to each other and to the extruder and steppers? If not, will you purchase those locally? Again, it's not usually economical to order the parts one week and the wires the next... order everything at one time to save on shipping costs.

(4) Power supply and connectors and wiring for it -- if you 100% follow Adrian's power wiring for the original Mendel, you will want to make a little veroboard for 12V power, use mating XLR connectors on both the power supply and on the Mendel, and use a bit of 'chocolate block' to distribute that 12V to all the boards. So theoretically, unless you have those or plan to purchase them locally, you'll need a 12V PSU, the XLR connectors, a bit of veroboard, and some chocolate block and appropriate wire to get 12V to each board.

You could easily argue that (2) (3) and (4) have nothing to do with modifying the boards you purchased, and you would be correct. But, if you are ordering stuff online, you will want to think the endstops and wiring stuff through *before* placing your order with Mouser.

As to how the electronics are used in Mendel... well, they are a major subsystem, a very significant part *of* the Mendel design. Adrian's wiring video on YouTube talks through how they connect together, what sort of documentation are you looking for beyond that and the schematics? There is no "IKEA"-style step-by-step instruction book for Reprap construction, it's all a matter of whatever us volunteers together can create. If a few good tech writers join the RepRap community, and create us a really good manual later, that would be wonderful. For now, the wiki, and asking questions in your local RUG, these forums, and in IRC, is what we have to work with (and, importantly, the wiki content is what we need to to improve and add to as we go).

Apologies for the long post

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Jonathan

Hey Jonathan

Thanks for your reply. Not to worry about the long post. I much prefer an informative post over a brief one

Yes, I do intend to order as much as I can from one source, in this case Mouser. Postage is about £12!! I have only exposed my 'Mendelise makerbot electronics' project list for a sanity check by the community..

As for the endstops, I think the parts for 6 comes to about 12 pounds and I will be making them on stripboard as getting the printed PCB will require a delivery from somewhere else. Unfortunately I did not get them from Makerbot when I had the chance

Wires and connectors will also be included in my mouser order if I can but the PSU will need to be sourced locally. Perhaps I will be able to cannibalise my girlfriends old PC...

I do sometimes feel I am asking elementary questions but then remember that the only stupid question is the one that is not asked

so - expect many stupid questions in this forum as time goes on.

Cheers
Charles

You only need three endstops for Mendel, i.e. the zero positions. There aren't any attachment points for limits and they are totally unnecessary.

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[www.hydraraptor.blogspot.com]

Thanks for that Chris

Maybe I will only get the goods for 3 end stops.

Do you or anyone else have an opinion on whether 90 degree or vertical headers are preferred?

Cheers

No I don't know, I am actually using micro switches on my Mendel fastened on with P clips. It's a much simpler solution. [hydraraptor.blogspot.com]

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[www.hydraraptor.blogspot.com]