New build, arduino, motomonster, 2dof

We'll see I guess, I wasn't planning on it at first. But once my son's old enough to enjoy sims then it looks like the way to go.

Hey, the 50:1 crab pot motor the fellow sells is 75-80 RPM rather than the 150-160 RPM of the 25:1, is that fast enough for this application?

http://www.ebay.ca/itm/GEAR-MOTOR-1...483?pt=LH_DefaultDomain_0&hash=item51bed470a3

Edit: Some searching revealed another user asking this question, the 75-80 RPM seems to be the output RPM after gearing not the motor RPM, having not build or used a sim like this before is that fast enough movement? 80 would be 1.3 RPS, or .3 seconds for 90 degrees, seems okay?

yes 50:1 is fine, even with a 40 mm CTC lever, you will still have enough speed.
As you are using an arduino, the SMC3 program would be the better one to get the better performance out of the set up.

how old is he?

Uhh, just over four weeks Like I said, the first iteration will just be for rocking, wave and walking motion simulation with an emphasis on safety : no unsupervised usage, kill switch, time out, physical stops, accelerometer based shut off, rigorous testing, final approval of the safety inspector (wife), open to more suggestions. What I like about this project is that it can be re-purposed any number of times as he grows.

ok, makes sense. go hard then

Yes! Though outside in Canada probably not such a good idea Here's the parts list so far to help with anyone else starting out, about $500 so far.

Parts List

Motors/Linkage

GEAR MOTOR 12 VOLT GREAT FOR SAWMILL/CRAB POT PULL/FEED 75-80RPM 50:1
$100 2x http://www.ebay.ca/itm/GEAR-MOTOR-1...CRAB-POT-PULL-FEED-75-80RPM-50-1/351093944483

Economy 3/8 X 3/8-24 Heim Joint Panhard Bar Kit .058 Bungs
$25 2x http://www.ebay.com/itm/390603056582

1" Universal Joint
$30 1x http://www.princessauto.com/en/detail/1-in-r-x-1-in-r-universal-joint/A-p8087165e

1/2" Keyed Shaft
$23 1x http://www.princessauto.com/en/detail/1-2-in-x-3-ft-keyed-shaft/A-p8079717e
* This shaft did not fit my motors, they came metric accepting a 12mm shaft (the next item). Wait for your motors to arrive so that you can measure before sourcing a shaft.

12mm Shaft
$23 1x http://www.bearingscanada.com/12mm-...-Linear-Motion-p/12-shaft-30-hardened-rod.htm

1/2" Shaft Collars
$2 8x http://www.princessauto.com/en/detail/1-2-in-shaft-collar/A-p3871316e

Electronics/Power

Motor Monster Shield
$88 1x http://www.robotshop.com/ca/en/monster-motor-controller-shield-arduino.html

Arduino Uno
$30 1x http://www.robotshop.com/ca/en/arduino-uno-usb-microcontroller-rev-3.html

Rotation Sensors / Pots 10K
$5 2x http://www.robotshop.com/ca/en/dfrobot-rotation-sensor-v2.html
*These pots rotate 10 times, a single rotation reads as 100 on an analog input of an Arduino, the full 10 rotations reads as 1023

Aluminum Heat Sink 30x30x12mm
$2 2x http://www.robotshop.com/ca/en/aluminum-heat-sink-30x30x12mm.html

321632-501 - HP DL380 G4 Redundant Power Supply DPS600-PB
$25 1x http://www.ebay.com/itm/LOT-OF-2-32...edundant-Power-Supply-DPS600-PB-/301432867447

hey @substatica you could save some (a lot of) money on the bay for Arduino and MotorMonster. Not the original ones, but Chinese copies that I used and did work (before switching to jrks).
My personal suggestion is - if you want to buy the originals: Go for them but also got yourself a couple of Chinese cheap clones. It's what I did and it saved my ass because you're gonna do something stupid (I did and I'm not alone) and burn Ard or MM or even both.
just my two cents.
Davide

Truth is I've already got a variety of Arduinos kicking around, but I bought a new one any way so I'll always have one on hand for quick stuff. I haven't gotten into the clones just yet, I'd hate to add another level of possible problems to the mix, at least for the first build.

So parts are rolling in like waves on the shore, I tested these rotation sensor pots I got, I wasn't quite sure what they would read as they can rotate about 10 times. Turns out each full rotation reads about 100 on the Arduino, so for a quarter rotation I can only get about 25 levels of granularity as opposed to the 250 a single rotation pot would allow -- does this seem like a problem to folks? I assume this would be a problem with ready made software, or would the calibration allow for this?

couple suggestion's if i may,

The U joints at Princess are Junk imo, Tonnes of slop in them and Not suitable for what we want. Check out a wreck yard and pick up a driveshaft. Might be harder to work with but it what we need and can be had just as cheap if you haggle with the Junk dealer.

Rod ends I Highly suggest This Particular Style,

http://www.aliexpress.com/item/4pcs...ight-hand-tie-rod-end-bearing/1559309095.html


Nicer Hall effect pots can be had from DigiKey.ca for a little more than your looking at, But will be Better units in the end. Also Highly suggest you use Some flex couplers to keep the pots safe, With your motor's you'll need a 1/2" Threaded rod axle and for that here's the coupler's you would need.

http://www.aliexpress.com/item/5pcs...12mm-Flexible-Coupling-6-35mm/1949151312.html

http://www.ebay.com/itm/1Pcs-BR-6-3...=BI_Heavy_Equipment_Parts&hash=item2a4578d8de


Heatsinks look a little big, Im assuming you are cutting them down to size ? Ensure to Flat sand them after, I find a lot of heatsinks aren't actually very "flat" and can benefit from a 400-800g wet sand prior to mounting to the JRK's. PSU's look good, I highly suggest the fan mod as well.

Unfortunate about the u-joint, I guess I'll see when it arrives. The heat syncs are cheap, I'll trim them down however they need to be and see what fits.

I probably will pick up some different pots, from DigiKey eventually -- they're easy enough to swap out, for now I've got these rotation sensor pots and a bunch of other pots laying around to get started. I found a place locally that has the flexible coupling, hopefully they have the size I need, I've been trying to avoid ordering anything from China.

As for the winding ball joints, the heim joints I referenced came in, they look great and have the option of either welding a bolt to a pipe and connecting that way or by welding the pipe right to the joint, not sure what the advantage would be of the ones which you referenced, thoughts?

This seem like a big enough heat sync for the motor monster? Should I put one over the caps as well as the chips?

I'm new to DC motors, I purchased a 1/2" shaft from princess auto and the crab pot motor page says that it's has a through hole and it's diameter is 1/2", but the shaft is too big to fit.

Could someone whose used these crab pot motors outline the shaft they used and how it's affixed to the motor? I see holes laterally through the shaft space in the motors, but they're not threaded, are these generally for bolts? pins?

Also I didn't realize that the Motor Monster only allows for one power source, the HP power supplies I got are 575W max, seems like one may be enough to power both 180W motors anyway.

If you got the PGsaw motor's from Canada that look like mine and many other's, The 1/2 Threaded rod will be Tight at first, You want it that way tho, Keep's thing's as centered as possible. I suggest taking a hammer and tapping your 5-6" length's of threaded rod through the hole, It should go. The only time i encountered the smaller shaft (12mm) was on the Blatantly different style gear boxes i used on my 2nd rig.

Yes The small holes are for a coder pin or you can what ever you want to use to key the axle to the Shaft.

Hrm, I'll have another look see when I get home and check with some calipers, maybe it's the paint, but yeah it'd be super tight if it goes in.

Dont insert it on the side with the Holes, There will be a small amount of flashing or shi* the factory didn't clean up after drilling and will somewhat prevent you from getting the axle through, Insert the other side and tap it through with a hammer, If you have a dremel tool you can hit those 2 little holes and ensure they are nice and flush with the rear of the gear axle.