Wiring for a Prusa i3 - gauge choice

Hello,

I'm completely new to 3d printing, and plan to build a Prusa i3 as my first printer. I notice however that while there is a nice wiring diagram for connecting the RAMPS board to everything on the printer, there is no real mention of what wire gauges to use: it's also not in the bill of materials.

Incidentally, I'm new to electronics in general, so I can't just guess what gauge I need to use, and I don't have a wire selection to choose from: I'll need to buy everything, and I'd like to get it right the first time. So at the risk of asking an obvious question, may I request that someone suggest what gauge wires need to be used for what connection?

What I know so far from scattered forum posts (please correct me if I'm wrong):
The thermistors for the hotend and heatbed typically use 24 gauge wire.
Heatbed typically uses 18-16 gauge.
Power to hotend resistor uses 22 gauge.
Extending the motors, if necessary, takes 22 gauge wire.

I was thinking to buy a few 10 ft rolls of stranded 24, 22, and either 16 or 18 gauge wire. Will this be enough to complete all connections? Also, is there some sort of connector kit I need to get to connect the wires to the boards?

This would really help me finally get started on this! If anyone has any other helpful advice for a complete novice (cable management, general hints, etc.), I'd appreciate hearing your wisdom. Thanks for reading,
Sincerely,

Edited 1 time(s). Last edit at 08/19/2014 04:05AM by anvoice.

Id suggest doing a search on ebay for "ramps wiring kit" Probably wont have everything you need, but the plugs are pre terminated, so saves alot of hassle. oh and they are cheap.

Thanks, that does seem like a simple option.

I think the main problem is exactly what you mentioned: it probably doesn't have everything, so I might have to buy extra wire anyway. It also doesn't list the gauges of wire. For soldering, I'd have to cut the connectors off (so why am I paying for them?). Wouldn't it make more sense to get, say, lengths of wire of gauge 18, 22, and 24, and some 2,3, and 4 pin housing?

well the one i got was all small guage, good for end stops, motor sensors. some of them were only terminated on one end, which plugs into the board, other end is free to solder onto switch etc. You would still need to get bigger wire for the heaters though.

Thanks, I'll look into the kits, though I think the motors and endstops I'm getting have fairly long wires anyway. The RAMPS - arduino connection would probably be facilitated though.

Since I don't know what gauge I'll get with those and I'll definitely need 24 gauge (thermistor) and around 18 gauge (heatbed) I think I'll get some of each from ebay so I can make those. If I'm missing anything, please let me know.

ebay rgb cable for motorsm thermistr etc, for heated bed 1.5mm speaker cable works for me

Thanks for the feedback.

I was worried that there might be some stringent specifications for wire size, but that doesn't seem to be the case. I got some 18 gauge and 24 gauge wire from ebay, I'll just use the 18 for the heated bed and 24 for everything else.

Quote
anvoice
Thanks for the feedback.

I was worried that there might be some stringent specifications for wire size, but that doesn't seem to be the case. I got some 18 gauge and 24 gauge wire from ebay, I'll just use the 18 for the heated bed and 24 for everything else.

You should be fine with that. The heavy gauge wire is needed where the amperage draw is high. The heated bed is number 1 on that list. The hot ends are next, but they don't draw near as much current.

Ohms law is your friend here. It says that current is voltage divided by resistance. Your Voltage is probably 12v, and for the heated bed, resistance is just a couple of ohms. Do the division and you get 6 or more amps. The amperage then dictates the wire gauge. Do some googling and you should find the answers.