Got some questions while planning a rig...

I've got a couple of questions... But first, a few things to get out of the way.

What games will the sim be for?
1. Rally racing sims (RSRBR, Dirt Rally)
2. Track racing sims (Assetto Corsa)
3. Space sims (Star Citizen)
And pretty much no flight sims (Happy to be recommended something that I might find engaging).

Who will use it?
Primarily myself (65kg), but potentially the whole family (45kg to 90kg)

Budget?
Under AUD$1500. I have a Fanatec Porsche GT3 wheel and CSR pedals, but nothing else. I'm also not a welder, builder, electrician, etc. I figure i'll have a few failed attempts and wasted materials along the way.

Decisions made so far.
1. It will be 2DOF seat shaker with wheels and pedals on gimbal. My monitor will not be fixed to it.
2. The 'tutorial' 2DOF with truck wiper design seems tried and tested. If it's good enough for this forum, it's good enough for me.
3. Will probably use SMC3 for Arduino and motomonster for control as it seems easy enough to follow. And if I ever decide to go 3DOF, it's already there.

Decisions not made (and hoping for advice).
1. It seems like 2DOF is all that's really needed to fool our senses for a racing sim. Is there any one particular angle or force that would really make a noticeable difference for racing sims? Heave for all the jumps we get in rally? Sway for the sliding around corners (or would yaw be better)? I'm guessing not significant enough to increase build complexity for a first project.

2. The seat will be balanced on the u-joint for myself. Given that I'll have someone 140% my weight potentially using it, i'm assuming the balance will be off and the motors would need to work harder. Would the 20:1 20Nm motors have enough holding torque for this? Or should I go 50:1 / 60:1? Given that I want to simulate racing sims, what's the lowest RPM that would be acceptable? 100RPM? (or do people have a novel way to re-balance a seat for each person?) I know this is related to the design of the rig, let's just assume the motors are driving rods connected to shoulder height at the back of the seat.

3. Range of pitch and roll. Is 8% pitch & roll enough? too much? I don't want to go nuts. I want just enough to trick my senses. I will be first in line to get an Oculus Rift or Vive when they (their consumer versions anyway) go on sale. I want immersion, but I also don't want to move too much to mess the head tracking. I saw that mounting the tracking camera on the rig didn't work too well.

4. Where'd you guys get those funky cut to order bits of steel? Or should a person of my limited ability just buy a playseat and be over with it?

Its not difficult to build a sim, take some time
Use JRKS and save yourself programming hassle.
I only have basic hand tools, cheap grinder, cheap welder. Hand wood saw.
Where are you in Sydney @Trackpad ?
Dave.

EDIT, I am 85 kg and my shoulder mount seat mover shifted 135+ kg with 25:1 boxes no problem
Desk Racer with 25:1 moves 120kg no problem

Awesome. Thanks guys. I'm all for keeping things as simple as possible. I gravitated towards the ard since I was a programmer in a past career, but having read through some of the setup guides, the JRK it seems a lot simpler.

Okay, updated decisions made.
1. It will be 2DOF seat shaker with wheels and pedals on gimbal. My monitor will not be fixed to it.
2. Design will follow the 'tutorial' 2DOF with truck wiper design.
3. Will use Pololu JRK 12v12 USB motor controllers with feedback.
4. Will use Motion Dynamics 12v 25:1 worm drive motors.

Questions:
1. I see people using funky PSUs from servers. But given that these are 12v 16amp motors and the JRKs are 12v 12amp (max 30), Can I use a car battery charger that can output 12v 24amps and use a battery to help prop up spikes? Do these motors go anywhere near using the full 16 amps? (sorry if these are stupid questions... I've got no idea about these)
2. Also, found this diagram /community/attachments/lever-for-jrk-setup-jpg.13758/that I'm just gonna use for the angles. I've also read elsewhere that the desired angle from the shoulder mount to the motor should be 15 degrees back and out. If that's the case, should I set the centre for the lever 15 degrees upwards and inwards so that it's at 90 degrees to the rod when the seat is level?

Also, thanks for the heads up. Have started shopping around for fabricators around Sydney. Found one just around the corner. Also found a couple of aluminium profile suppliers not too far away.

I went the full frame route and I get thrown around plenty on the 25:1 motors as the frame is well balanced for me. (105kg)

I would test the COG when you have done your build with yourself and heaviest player and see how much the COG is thrown out, if it is not heaps you could place your pivot point in the middle ground.

As you would be the lightest person the motors will be just fine even if the COG is set for the heaviest player.

I made a design boo-boo on my full frame in that I built it for Racing Games, but now I am getting back into Flight Sims and when I mount the yoke I have to push my seat back a few clicks on the rails which throws out my COG. Having said that it still works just fine and a Flight Sim will not throw you around as much as a Racing Sim anyway. (I notice you don't really run flight sims anyway) but it's good to know the COG does NOT have to be perfect to still get good movement.

Got a lil excited and ordered:-
2x Hall effect pots (as used by noorbeast in his dx racer compact sim)
2x 12x12 JRKs
But sadly the worm motors are out of stock. Will bide my time for those.

Still doing my research on batts & chargers vs PSUs.

Good to know that COG doesn't have to be perfect. I've been getting some ideas looking through the showcase. I'll have to toss up the costs between getting a fabricator cutting & welding stuff for me (i'm really not handy) vs meccano set aluminium profile.

And woops. I'll get the terminology right one day. Full frame it is.

Hi @Trackpad, you can also use a cheapish static rig and adapt it for motion if your not a welder!

Mike

@Trackpad , how about a PVC frame?
Igonre the big actuators, DC motor would throw it around

@AceOfSpies I've seen a couple of Playseats for $470, so that's kinda my benchmark. If I don't think I can DIY for less than that, then that's what I'll go for. I assume I'll need to set it up on some plywood to support the pedals?

Thanks @noorbeast , I was wondering how some other builders managed to generate those awesome designs and screenshots. Here I am on pencil & paper and trying to remember high school trig and physics. Started the download this morning and hope to play around with it tonight.

@bsft Awesome! hahah. Had no idea that PVC pipe would be strong enough.

I sent you a PM, but PVC, I had to buy from a wholesaler, 50mm PN 18 rating and it cost me $270 for pipe and connectors from memory. I held it together with screws, it was lighter than steel, very sturdy, less mess to put together and painted it would have looked like a round pipe frame.

Got my hands on a u-joint from an old Ford. Rust covered, but it's moving.

Might be a silly question... I've found some LED power supplies that I'm pretty happy with. Am I better off hooking up a 200W power supply per motor? or 1 400w power supply to both? I'm assuming it makes no difference... but just thought I'd confirm.

Will get the heim joints and conical spacers shortly.

But I think that's it for now. Not gonna get anything else until I get the frame, seat and motors sorted (couldn't find any other motors with the same-ish specs, so i'll just wait until they get back in stock).

You will need 500 watts per motor, so what you have is not enough, My LED power supplies are 12v 500 watt units, one per motor.

@Trackpad - where did you get your conical spacers from? I found these a pain to get...

@bsft Whoa... really? 500 watts? Wow... okay. Is this because the worm drives can hit higher than the 30amp peak listed?

@noorbeast I can see why you guys go for the huge 2k+ watt PSUs now. My preference would be to buy new, so will compare the PSUs with the LED power supplies. I do like the idea of not modding though.

@Archie I haven't bought them yet. Still shopping around. This is the ebay store that I've found some in stock so far. http://stores.ebay.com.au/QS-Compon...=12212889&_sid=61394735&_trksid=p4634.c0.m322 They've also go the high-misalignment spacers linked in the FAQ too http://stores.ebay.com.au/QS-Compon...l?_fsub=7&_sid=61394735&_trksid=p4634.c0.m322

As I suspected, US based Ebay seller.
These spacers are like hens teeth in Australia. Even local Kart builder have either never heard of them or can't get them...

Did you see the Postage cost from the US? EEK!

@Trackpad , Ive been running motors like that for about 2-3 years, with JRKs.
They are fine being overdriven.
Motors when under motion run at stall current, not rated. And usually stall is 2.5-3 times the rated. Hence a 200 watt motor being thrashed to 550w in very short bursts.
They usually run at about 28-34 amps continuously under decent motion, and they survive a 45 amp spike for a bit hit just fine. So a 500 watt PSU will be fine as they usually can handle a big grab of current.
You will be surprised just how much thrashing these motor survive.