Nearing the "end" of my 2 dof build, a 3D printer has been essential!

Thank you, and yes that's it, and dang...it's in the FAQ already...thanks @noorbeast for FAQ reminder

Thanks @RandomCoder!

@gSeat - There was a more detailed post with temperature measurements but it devolved into an argument over it being overkill, too complex, etc, so I just deleted it for better or worse. The upshot on the cooling was with a six amp (maybe 12 amp - don’t remember) load, without a heat sink at all an IR measurement on the chip was showing around 100 F. Mounted on the Alpine heat sink/fan with the thermally-conductive pad, the temperature only increased three degrees at the hottest point measured on the chip. It’s important to make sure noting sticks down below the bottom surface of the board - don’t want anything to punch through the pad and short to the heat sink.



I’m powering them from the 12 volt connection on the JRK board but that gets its power from the main power supply so it’s from the motor power supplies. I just put polarized headers on the boards and the mating connector on the fan wires. The 12 volt pins are on the white 2-pin connector nearesr the USB connector. Pololu has a pinout on their website and in the manual. It doesn’t have a PWM out for the fans though but the fans are wired for PWM. The end result is the fans run mid speed instead of idle or full speed. I’ve been thinking of adding little PWM boards so the fans only run as much as needed but I haven’t yet. The photo shows the motor and power screw connectors but I yanked those and soldered the high current wires direct to the board with bullet connectors in line so things can be disconnected if necessary.

Thank you @Zed- since you read the docs and relay the info for the layman like me (ill still read them), it's like, why not take advantage of the knowledge and learn via application with all the extra info!

Thinking instead of the big heatsink and fan per JRK, maybe smaller heatsink that covers the board, or at least the critical part of it (because of your quote below), with thermal pad mounted efficiently as you've documented and then push/pull fan box that cools the jrks and the PSUs...thinking...

@Zed - Sorry to ask "mid thread", but the connectors you have used for the JRK's, do you have a link to the supplier?
(So I can get the dimensions and source some locally here in AU)

Mine are header pins and soldered on - I prefer the "quick connect" clips you have used on your JRK's.

EDIT: Found them . I recalled the name once I hit post. "Molex" style... which then led to PCB headers, which then led to Ebay

https://www.ebay.com.au/itm/2-5-10p...-PCB-Header-2Pin-or-3Pin-Connector-Terminals/

@gSeat - if you look close at that image you attached you can see the array of fine holes. The group at the bottom of the photo the way you have it oriented are under the H-bridge and both conduct current and heat. There are other ares of holes under other parts for the same reasons. The area you marked should be fine for a heat sink since it covers the heat generating areas. There aren’t parts that really throw much heat outside that area.

I see where you are going with the offset screws but just a word of caution - if you are taking the heat out through the bottom of the board, you still want a thin thermal pad between the bottom of the board and the heat sink. Mine are 1.0 mm thick. The pad material is also kind of funky - It’s a high W/mK rating silicone-filled pad. You want thin pads of 0.5 or 1.0 mm thick with a rating of probably 7 W/mK rating (edit - or higher) and specified for CPU/GPU use. It gives a little to conform to what it’s pressed up against but not a lot. I used the screws in the JRK mounting holes to provide the clamping force that pulls on the heat sink to sandwich the pad and clamp it between the board and heat sink for good, even, contact, besides just working as mounting screws for the JRK. You want them moderately tight but not extremely so since you can squish and squeeze the pad material. Just something to keep in mind.

My JRKs run cool as cucumbers so maybe it is overkill. But JRKs are also $100 each. I think protecting the investment was worth it for me.

Cracking up at "cool as cucumbers!!!" Thanks for mentioning pad thickness, read you say before, was distracted by thermal tape options, will do!

Since will have an extra heatsink stash, will simply thermal tape a heatsink on the chip itself too...figure why not.

Roger that!

@Archie what post shows the molex connectors with the JRK boards - I didn't see it in this thread? I'd like to take a look too, cheers!

@gSeat - Hey mate, they are not Molex connectors it was just my thought process.

I typed in Molex connectors into Google,
which spiralled to PCB Headers
which in turn lead me to Ebay.

The post that made me think of upgrading my JRK with the quick connect 2-pin and 3-pin is Post #43.
Picture of the JRK with the white connectors

Gotcha, yeah, I went a few times looking for "hard drive molex connectors" but thanks for mentioning the quick connectors, ordering various kinds, another to add to the bunch, building to begin soon!

Thanks @Archie! Hectic week for me so not on so often to answer stuff.

@gSeat - The JRK comes with a pin header strip you can use but it quickly got obvious that some assembly would be done just by feel in the tight quarters of my electronics bay. I pulled the regular pins and replaced them with polarized connectors so there would never be a question on which way things plug together and I could do it just by feel if necessary. Those are just standard 0.1" center holes on the JRKs so any 0.1" spacing connectors should be fine as long as the pins fit in the JRK board holes. If you zoom in on that photo showing the connectors in post #43, you’ll see I did have to clearance the plastic a little to clear components on the board. Easiest to see on the 2 pin connector.

@gSeat - one other thing to consider depending on the kind of fans you get - Avenga76's wind units have a cooling fan for the MonstorMoto that he just powers from the MMs the same as the wind fans. That way the faster he’s running the wind fans and the more current through the MM, the more the MM cooling fan runs too. But it’s just a smal 2-wire, 12 volt DC muffin fan without PWM control or tach. His method works like a champ.

hello i used this system to cool the motomonster, cool under and over with temoconductive paste, the asus heatsink is tightened with original springs so as not to warp over the chips and keep 100% contact, using the 12cm fan of the psu atx, it works well , but in the end I moved to the H bt2s bridges from 43 A, since then no heat problems

Congratulations, I work beautiful.

show this board does not heat anything for your legal project

the motomonster is a great driver, but it is often used beyond its capabilities and also taken clone. suffers from thermal latency, a large thermal energy that can not be quickly dissipated in any way, for me it was too weak 14A and went more and more often in thermal shutdown even if the sink had only 40 *. so I used the 43A b2ts I was already using for the DD steering wheel, and magic huge power made my 2dof station very reactive. if you want news or photos of my drivers H ask well bye. Marco