2dof to 3dof DIY Seat mover

Is there any 'play'? Or is the back knob doing it's job for tightening it even more?

I've used a screw before through that small hole and 12mm bolt instead of the pin, but there was always a small amount of 'play' which has irritated me, bolt would be kind of a loose. Once the pots were connected I could see that play in the feedback graph od jrks and motors would jitter, I had to tighten it strong with that back knob like yours.

I've even considered to put some small welding points between the shaft and 12mm bolt to make it really tight, but I didn't in the end. Would that be bad? One-two welding points for making it tight, and than that pin would be there mostly for security, even if it has some play on it it wouldn't matter because bolt is welded and also tightened from the back.

Gear box swapped and considering different mounting positions. Unfortunately got a call from Element14 where i ordered the pots from and despite the web shop showing them as IN Stock, I assumed they were....well....In stock. Apparently not and they are expediting them from the UK due to the screw up. So at least a good week's delay on those.

yep, same here, got to wait a week or so.

the jitter in the jrks could be the pots and the slight play in the gearbox. I know that using pots, be it cheap or expensive, there was jitter. It seems to be have solved since using hall effects now, no jitter.
With the bolt, tighten the crap out of it and put a 5mm grub screw into the motor shaft into the bolt. That holds it very solid.

Motor mounts made with bolts and levers basically done, Screwed up and drilled the Rod end hole too big on the levers so ill just have to remake them. I also Need to get the axle bolt drilled out at the machine shop to ensure it stays true for the Pot mounting.

I went with 10-24 set screws to Key into the axle and also used 1/2 threaded rod vs 12mm bolts. I couldn't find Long enough 12mm bolts that were All thread, so a 3' length of threaded rod was all i had to choose. Yes it was Tight tight to the gearbox, but after pushing its way through a couple times its Super snug but can easily be removed.

looks good, but how long is the centre to centre on the levers? looks a bit long there. recommended overall is 60 mm CTC on 25:1 gearboxes. Any longer and you start to loose torque in return for speed.
I have put 80mm CTC on motors but thats with 60:1 boxes and its now too much throw for the owner, well, thats what he asked for.
I think 45mm CTC calculates to 500mm per second.

that lever in the pic is 65mm, Remembering i want speed Vs torq, what length should i use ?

Here is a handy picture to understand how to setup the Jrk with a lever.


It only uses 76 deg of the pot travel when pot is connected directly to shaft, no issue as the Jrk will create a scaled feedback value and makes min equal to 0 and max equal to 4096 which returns the overal scaleback values to high resolution so no mater the angle you retain the resolution of the motion. Bonus. And being a 150-180 rpm motor you can achieve very fast movements and 80mm at the lever relates to 10 deg of movement in chair.

I stand corrected , Rob uses a 65mm CTC lever so stay with that and follow what he says about setting the feedback range.

So question guys, Had a buddy come over with a Fine tip soldering gun and got my JRK's all wired up. Question tho, the Read out for the JRK wiring basically lists the pot wiring as Ground on the bottom, 5v regulated in the middle and Aux Output and Feedback input for the top 2 pins, Now for ground and 5v, Am i shorting both pins together or can you use just one pin, Also the top 2 pins are listed as an input and output, Are those also being shorted together and connected to the Feedback pin on the Pot ? Just trying to understand how a input and output being shorted works exactly.






Next, When referring to this page and the part about the Pot for adjusting voltage, What wire is what ? there's only 2 wires im working with, Pots have 3 pins.

https://sites.google.com/site/tjinguytech/my-projects/HP47A


here's something i have from all the pics i saved SO.....Knowing pin 3 is 5v but what is pin 9 and what do i hook that up to ? Feedback, If so do i need to run a ground for the pot ?












Also what Awg wire do you suggest for the motor's/JRK's.

Oh also got the power supplies up and running, the fan cut back mod really helps with the noise of the fan on Full speed(all be it wasn't very loud to be honest) Also got a JST pigtail inline ready for a 1kohm pot. Jrk holder's waiting on a fan (speed/style suggestions ?) and some heatsinks.

Ok with the power supply you only need to set them up to produce 12v's and as per the picture on the hook up the 12v+ goes to the VIN on the Jrk and the Gnd from the powersupply needs to got to the GND of the Jrk.

I use 4mm2 wire for connections to Jrk, it pays to keep them to a minuim length too as well as the feed to the motors should be as short as the setup allows if too long you will get voltage drops as the Jrks can draw up to 48amps on motor stall and direction changes.

The Jrk itself has a power regulator on it that will feed the 5v needed to the pot. As in the pot only connects to the Jrk via 5v,FB,Gnd which must be connected to the 5v leg on the pot and Gnd leg on the pot and the FB connected to the wiper on the pot.

Do not connect the pot to anything but the Jrk.

With fans I use standard 120mm pc fans , mine are cheap and a little noisy but like to here that they are working , for a heatsink I use a simple little one for example http://www.jaycar.com.au/productView.asp?ID=HH8580
Just the right size and has thermal tape already on them making them easiy to attach, some use cut down pc heatsinks but you need to work out how to attach them.

Thanks Robbie,

yes the power supplies are all done up and tested, I understand that part of the wiring but...

Am i jumping both Auxiliary Output and Feedback input ? Or Only using the single Feedback Input pin ? Also for 5v and ground, Am i shorting both pins or can I use just One ?

I got some little heat sinks basically the exact size of the chip, i posted pics and a link to the Pdf for the chip with sizes. also I have some Artic Silver aluminum thermal paste to stick em on, Do they need to be actually held on by something ? they wont be moving around at all so I would think the paste would be enough to hold em there...

Ok the wiper as three terminals, on most cheap pots there is a lug to help lock it in a mounting surface, the wiring lug near that is normally the gnd , the wiper is the middle lug and the far end one is the power in lug. So to wire to the Jrk we need to connect as follows:
Jrk Pot
5v Power IN
FB Wiper
GND GND

Do pots on both Jrks.

There is another option and that is to connect the Power In to Aux pin on the Jrk instead of the 5V , but will explain that later use a clip dont solder the wires on directly then it can be changed. It allows for the Jrk to use an error catch if pot fails for some reason it reads the pin and then promotly stops the motor dead until pot is fixed or back in the feedback range. Handy but not needed to get you going , can explain more later.

With the heat sink a elastic band around or 4 small dots of hot glue, I like heat transfer tape , the better the contact the better the cooling. You have you Jrks elevated with an air gap under them too, this is a design bonus as they will dispate twice the heat so should stay nice and cool.

Ok so Use JUST the the Feedback INput pin on the JRK to the feedback on the pot. I have little JST connector's like whats on the power supply to keep all the pins separate So no more soldering on the JRK itself, I can just delete AUX output wire off the connector, but obviously the Ground and the 5v power i can short those 2 pig tails together and connect to the pot.

Can I suggest getting rid of the text for the Aux output on the diagram for our intent purpose. as you can see it caused a little confusion. lol

the pots im getting are listed on the back whats what....but thanks for the tip on the pot, will come in handy when the cheapo 1kohm show up for the PS to determine which pin is which.


Mounting the JRK's like that all came from the pics ive seen of different rigs, Its actually a Battery Cage for a 12v gel cell for a Starter box for Rc Cars. We all run lipo's now so thought it suited the job nicely, plastic part trees were used as the legs, little hot glue, some small 2mm screw's and whamo mounted, with 30mm of height to the base of the fan and the heatsinks are 26mm tall.

Can I use the power supply for the Fan ? then could i get a fancy fan with LED's, if so i could steal a 5v pin off the PS to feed the "low voltage" LED's.....im i thinking right on this ?
this fan in question
http://www.memoryexpress.com/Products/MX26096

3 pin connector so Ground, 12v and 5v....Right ?

Hi Nick!
No problem using the PSU for the fan in addition: it's peanuts consumption.

I am powering my "fancy" LED fans (ok, they are all I had in the spare parts bin) with the PSUs

The LEDs are fed directly off the 12v source for the fans. With resistors I assume in line.

Oh so just hook up the 12v and ground and it will power the LED's itself. Awesome, ill add another pig tail onto the bigger 12v/negative outs, Dont wanna poke into the Small pins in case i break one of the solder bridges.(soldering iron tips on the way for future Small soldering work)

man i love free shipping, Lol
http://www.ebay.ca/itm/10-Solder-Sc...on-/131124981499?ssPageName=ADME:L:OC:CA:3160



Question for dave and Robbie, for the Axle bolt and the pot attachment, How did you guys drill out the Bolt and ensure it stay's 100% TRUE so the Pot isn't damaged when installed. ? I have a buddy with a lathe but its anally set up to do Piston for our RC modding business. http://clockworkracingengines.com/ he's also got a Mill but i question the ability to keep it 100% centered. Im sure i could run to the local machine shop (Anything Custom) but who know's how much they would charge for something like that..... OR just ghetto it and try my best on the drill press ?

i dont think i have an exact lined up hole in the bolt. The shaft in the motor is a tad over 12mm anyway, I find drill as close the centre as you can and fit the pot on a slightly flexible bracket. I have never had a problem with a pot not being 100% lined up.

Awesome..... that's a little re assuring, I was planning on at least getting the bolt chucked up in a lathe to give me an indexing mark on dead center. then i guess the mill could be used to bore the hole and i could just enlarge it to the size i need. Flexible bracket for Pot, Check.

Thanks Again Dave.