Mad at RAMP board

In the process to fix and re-wire the purse i3, I replaced the RAMP board and all 4 motor drives. One small but important thing about the board annoys me the most. On the sockets that the motor goes in, it has a 4-wire connector. and the socket has 4 male pins to receive them, but why the sockets are not keyed? This is a connection mistake that can be easily avoided if the sockets are keyed. Is there a reason why the makers don't use the keyed sockets?

Edited 1 time(s). Last edit at 03/01/2018 09:38AM by rich1812.

I'm pretty sure that this is because stepper motors don't care.

You have to match the pairs. Pair 1 and pair 2 don't electrically connect to each other. The RAMPS motor connector is 1B, 1A, 2A, 2B (Maybe 1 and 2 are the other way around, doesn't matter.) What matters is that the pairs 1 and 2 are distinct, and that polarity A and B are correct relative to each other. Because it is arranged that way, the connector going on "backwards" doesn't affect things, the stepper motor still works.

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MBot3D Printer
MakerBot clone Kit from Amazon
Added heated bed.

Leadscrew self-built printer (in progress)
Duet Wifi, Precision Piezo parts

They do care. I mistakenly plugged in the Extruder motor the wrong way. In the pronterface UI, the extrude button and reverse button were reversed. Also another dumb mistake I made was because the poor lighting in my room, I couldn't see well, I plugged in 3 pins from the motor connecter instead of 4. Thankfully nothing was burned out. All these human errors seem to be easily averted by using keyed socket.

The better electronics boards all use keyed connectors, but RAMPS is a budget board, and a very old design that has had only minor updates - and not any of the ones it most needed.

Edited 1 time(s). Last edit at 03/01/2018 03:13PM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Keyed connectors are more expensive and some stepper come with non keyed plugs. Non-keyed connector can take both, keyed and non-keyed so it's more universal.

Edited 1 time(s). Last edit at 03/01/2018 06:53PM by newbob.

Keys are only required on connectors that will damage something if plugged in wrong.

Stepper plugs can go in either way without damage... so it goes the wrong direction, fix it in firmware or swap the plug around.
It could do with a latch just to stop plugs coming out.

Stepper driver are another issue, these blow up if you put them in backwards, and yet zero keys... this needs to be addressed.

Edited 1 time(s). Last edit at 03/01/2018 09:59PM by Dust.

Yeah what he said, some things seem stupid and sometimes it's because they are, other times it's because you don't yet know why it is done a certain way. Every motor uses different colour wires and so you have maximum flexibility if you can insert the plug either way around. If its the wrong way turn it round. If the motor jiggles but doesn't turn your pairs are not pairs.

I agree with dust that plug in stepper driver boards should have a polarity pin blocked like an old ide hard drive connector so they can only be inserted the right way around. Or some other polarity device. I've killed a ramps/mega and a driver by making this mistake whilst attempting to be quite careful.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

There are a lot of "accidents" can be easily prevented. Human are human, no matter how careful one is. human errors happen. How much is a keyed connector costs vs a non-keyed connector? Probabaly no more then 25 cent U.S. As a consumer, I rather spend 25-cents more than have to buy a $10.00 board if it is fried, not to mention the time lost on waiting to get a new one. That's certainly "good" business for the makers but terrible for the users.

Edited 1 time(s). Last edit at 03/04/2018 11:58AM by rich1812.

There are much worse problems with RAMPS than not using keyed connectors for the stepper motors.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Quote
rich1812
There are a lot of "accidents" can be easily prevented. Human are human, no matter how careful one is. human errors happen. How much is a keyed connector costs vs a non-keyed connector? Probabaly no more then 25 cent U.S. As a consumer, I rather spend 25-cents more than have to buy a $10.00 board if it is fried, not to mention the time lost on waiting to get a new one. That's certainly "good" business for the makers but terrible for the users.

The issue is there is no standard wiring pinout (or colour scheme) for bipolar stepper motors. If there was then we could have keyed connectors as standard and just plug motors in and they would turn and turn in the right direction. Buy a duet board, you get molex keyed connectors, but you have to cut the plug off your motors, crimp the provided crimps on the wires, and arrange the four wires in the plug yourself. After that it works. But you could get that wrong, it doesn't matter if you do no harm will occur.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

Actually, the wire colours for bipolar motors are generally standard: red and blue for one phase, black and green for the other. The 4-pin connectors on 3D printer controllers generally expect the two wires at one end of the connector to be one phase, and the two wires at the other end to be the other phase. So if the 4 wires coming out of the motor have those colours, you can use a standard connection order (I always use red-blue-green-black). The motor may turn the opposite way to the direction you want (that depends not only on the motor but also on your mechanics), but you can change the direction in the firmware configuration.

The problem is that for stepper motors with 6-pin JST connectors on the motor itself, there is no standard pinout on the 6-pin connector. I have stepper motors with pinout A-nc-A-B-nc-B and others with A-nc-B-A-nc-B. If you get a cable along with the stepper motor, then the colours of the wires in the lead ought to match the pinout of the motors. This was true for motors I purchased from E3D recently. But if you buy the motor and the cable separately, they may not match.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Okay so "some" motors follow a scheme, but not all. That's the point I'm making, and the issue here is that the OP is perhaps making a valid point about a lack of standardisation - but since there is not any reliable standard we will have to, in many cases, work from first principles and figure out which are pairs and then wire your plug accordingly.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

Anyway, it takes a few minutes to identify the coils and wiring and it is easier to turn the plug around than to install the printer on the ceiling or a wall if it runs in the opposite direction or even change it in the firmware
Easy to swap the pins on a keyed plug too. No wire cutting needed.

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"A comical prototype doesn't mean a dumb idea is possible" (Thunderf00t)