DIY 2DOF Budget Build

Today I got my hands dirty and began the start of my 2DOF frame build.
It won't win any awards for looks but it certainly won't break easily as I usually over engineer my builds.
I scored an old race bucket seat complete with rails from Gumtree, which for you non Aussies is our version of a Craigs List for used crap.
Anyhow it was in reasonable condition and quite adequate for my needs and so that became my start point to build the frame for that to mount on to which I made from 50 mm. RHS steel tube and the pedal mount kick up is just some 25mm. RHS steel tube.

I did not get a chance to finish off the base today as rain set in and I am working outside as my tiny shed is full of other tools and my other build project which is a Pirahna Off road buggy that is nearing completion.
It runs a Honda 954 RR Fireblade engine.

So there is not enough room to swing a cat in my tiny shed.

I have already cut out the pivot mounting plates and bored the holes to suit the cut down Subaru WRX CV joint and shaft which I had lying around.
I did not weld them yet until I can dummy fit the frame to the base and work out the correct balance point.

My motors arrive from Sydney tomorrow from Motion Dynamics https://www.motiondynamics.com.au/worm-drive-motor-12v-24v-200w-180-rpm-20nm-torque.html
I also ordered the 50:1 ratio gearboxes https://www.motiondynamics.com.au/worm-drive-gearbox-to-suit-industrial-motors.html after reading quite a few threads on the subject and I took Noorbeast's lead and went the same way.
So I will be busy making some mounting brackets for the motors and some suitable pivot levers to suit the output shafts.
I also have some 12 mm. heim joints on order so I will machine up some steel bungs and thread them to suit and then plug weld them into some steel tubes which will become the adjustable pivot links.
I also have to weld the steering wheel base plate to an upright from the base when i work out it's final position

Anyhow that is enough for one day, but plenty yet still to be done yet.

Seat frame almost done.


The Bits


Rough layout of seat base

Pivot joint made from Subaru WRX CV Joint Shaft

Pivot ready for trial fit and final welding.

Steering Wheel Mount Base Plate My Cheap as chips race seat

So I did a little bit today on my rig and made the motor mounts and pivot levers.
I have welded the CV pivot plate in-situ to the base and the main seat frame.
I tapped three sets of mounting holes so that I can change the balance point by about 30mm. for and aft if needed
All I need to do now is weld the motor mounts permanently to the base and then pull it apart and clean and paint it while I wait for the electrics to arrive
in the post hopefully this week.

Looking good so far. I am in the process of designing one and sourcing parts. what is the spec of your motors?

The motors are from here in Australia https://www.motiondynamics.com.au/worm-drive-motor-12v-24v-200w-180-rpm-20nm-torque.html
and I opted for the 50:1 ratio gearbox https://www.motiondynamics.com.au/worm-drive-gearbox-to-suit-industrial-motors.html which if in stock come in LH and RH versions
but you can just press out the shaft and reverse it to achieve the same as I had to do as they only RH in stock at the time of ordering.

I did a trial fit of the seat on the frame and found I had to make a couple of adjustments.
One was to raise the wheel by 50mm. as I was hitting my knees which was no good so it had to go up.
The other was my pedals.
I decided to alter the inclination angle by a few degrees and bring them back by 50 mm. as well.
My last fabrication job will be for a monitor mount for the 32" monitor I got instead of the VR Headset as money is a bit tight and I think that VR is
still too new and prices are still pretty steep for my budget.

I hope that my Sabertooth and Arduino Uno arrive tomorrow and possibly the hall sensors as well so that
I can tackle the part I hate the most, the wiring.
I know it is pretty basic stuff but me and electronics just don't get along for some reason but usually with lots of googling
and reading posts on forums I usually manage to get it working.
I have built 4 CNC machines before so you would think I am an old hand at this stuff, but alas no.

Here are few more pics, nothing fancy but it should look a bit better with a coat of paint to cover up my sins and rusty old steel.

I threw some primer coat over the frame and base today and also made the monitor stand so that is about it for the fabrication except for the Hall Effect Pots mounting brackets
which I need to make but I need them to get here first !
My order of my other electronics, the Sabertooth 2x25 and the Arduino Uno R3 arrived today and now all I have to do is figure out how the wire and program the little buggers.
Anyone point me in the right direction for the Uno setup file that I would need for a 2Dof rig.
I will also need to get a setup file for Project Cars 2 for Simtools I think as that is what I have been playing with the most and I prefer it to the others that I have tried so far ?

I got one step closer with my build with a coat of paint to cover up my sins and the almost final assembly of all components.
The only things that are holding me up are the Hall effect Pots for position signal inputs to the board, and finally the correct Arduino breadboard wiring leads
which I never thought to order when i got the Arduino.
Once I get those items I can knock out a couple of mounts for the pots and get the wiring completed and then on to the software part and being a noobie with this particular software I am
naturally a little apprehensive, but I hope my previous building of CNC routers and dealing with that programming interface it might make some sense as I assume it only dealing with steps and directions
for the motors ?
I have christened my 2 Dof Sim as " 2 Blue " in recognition of its country of origin Australia

Looks awesome so far - especially the space-age polycarbonate electronics housing ;D. All kidding aside, that paint makes it look remarkable.

I don't have a ton of experience with the sabertooth drivers, but looking at their documentation, they support an RS232 serial interface. (https://www.dimensionengineering.com/datasheets/Sabertooth2x25.pdf). The only gotcha here is that you'll need a level converter to interface with it as the tooth will be talking 12v and your arduino I believe is TTL(5v). The MAX3232 chip is great for this and cheap (for mine I made a cable and soldered/heatshrinked it inline with a cable). The documentation on that about how to use that interface is refreshingly good!

I'm assuming the hall effect sensors are for feedback from the output shaft/assembly on the reduction drive, at which point it's incorporating some code for that and the communication with the drive on the Uno (along with a bit of math for position, which given your background in CNC stuff won't be tough)

Thanks for the compliment mate !
My space-age polycarbonate electronics housing was courtesy of the local $2 shop and it it fills the job and houses the gear and it fits in with the whole DIY theme of " 2 Blue ".
As for the rest of the comment relating to the electronics you lost me straight away, although I think I can relate to the RS232 serial interface part as that is what Mach3 control software uses mainly although I think that they have come out of the dark ages and now support some USB breakout boards.
NFI what a level converter is ? Does a ladder count
I will have to sit down and read the whole tutorial to try and make some sense of all the jibberish.

maybe like a ladder, or step stool for that matter. 'Logic level converter' is the proper name and it allows signal communication across voltages that aren't the same. Given the Sabertooth works in 12v (RS232), the arduino, which works in 5v(TTL) would not be happy if you hooked it up directly to the sabertooth's ports. So the logic level converter takes the 5v signals coming from the uno and ups them to 12v, while also taking the 12v from the sabertooth and dropping them down to 5v. So yeah, it's like a ladder but for the electrical pixies.

My head hurts

And no wonder. @A Ro I assume meant well but its complete rubbish so just ignore it. Sabertooth micro is 5v so connects directly to arduino 5v.
If you want to connect your 2x25 to Describe software however you need a usb to ttl converter (12 to 5v). A converter is built into the arduino already and is why you can use it with your computers 12v rs232.

Thanks very much BlazinH for your reply.
Like you said he meant well and didn't know any different which is why ask so many annoying questions which could probably be learned if I read reams of posts
but when sparkies get together they speak a different language which I don't know but a few words.
I am taking your advice and adding a 12V 18Ah SLA battery along with the single 12V 30A 350W power supply.
Thanks for the help and advice ,
Deane.

congratulations, very nice frame and its essential compactness!
a curiosity, the lever is not too close? Can the engines move without suffering?
Hello Marco

Thanks for the comments MarcoMade,
I t was built on the fly and the plan was in my head and I just copied from what I saw other have done in their various configurations.
I guesstimate that the lever should reach about 40 degrees of travel before hitting the frame and I can extend that slightly by moving the pivot point along the lever.
I have four holes, the first one from the motor shaft is approximately 40mm. then 60,80,& 100mm. where it is set now.
There are four corresponding pivot points on the frame, so I can play with points of leverage etc and if necessary I can always cut a little off off or remake the whole arm
and make it go out past the base, then there will be no problem .
All of that is just theory at the moment until I get the electrics sorted out and moving, then the fine tuning starts I guess.

Wow, great progress and looking good, really good!

Initially I was thinking the same thing as MarcoMade, about the motor levers possibly hitting the bottom frame and doing some motor damage, but it sounds like you’ve got several options available to remedy if need be.
Gotta have that buffer in case of a runaway motor.

This may be one of the quickest builds ever, and without cutting any corners!
Can’t wait to see Blue 2 in motion.
Get a bottle of Champagne ready!

of course! you did a great job. no DIY work is perfect on the first try. then there are all the changes in work that we love to do. good continuation, I will follow with interest the developments

Thanks guys for the compliments.

I take after my old man who used to build from scratch model steam trains and other types of engines, both steam and petrol powered.
He was retired and in a steam loco club and he had the nickname of "The Flash" as he would produce a new train in about 18 months, where others with less knowledge and equipment would take up to 10 years of part time work to get on the track.

My old man on the other hand would spend all day out in his shed 7 days a week so he had the advantage of that plus 50 years as a fitter and turner.
I am no where near his level, maybe 2%, but when I decide to do something, I plan, then attack it full on until completion, so my motion simulator is proceeding along those lines.

My usual hold ups are always getting parts and materials as I live in rural Australia, so for me to go and get some steel for my frame it is a 120 km. round trip and everything you order online always takes so long to get here.
The price you pay for that is rewarded with the peace and quiet of the country and not the madness of suburbia.

Now back to the length of my motor's levers.
I based the length on a comment that Noorbeast made about the efficiency of a lever past 40% of it travel was pretty much wasted, so I allowed the 40% and by my guesstimation they should just clear.
I suppose as a safety measure I could implement a couple of micro-switches that would trip if it reached the over travel limit, much the same as a CNC has axis limit switches.
In theory I thought was the job of the potentiometers to send position signals back to the controller ?
For my first test I will take off the levers and observe the motor shaft positions and movements, then try it with the levers if I deem it safe.

Anyhow for something different, This real D.I.Y. this pic is of the last engine that my old man made from scratch at age 86 just before he died from cancer.
He made every part except for the ignition points which were Mazda RX7 points. So every part you can see and can't see inside were all made using a manual lathe and old school manual milling machine.
The manifolds were all sand cast from aluminium.
The propeller was made from timber laminates hand formed and contoured.
He even made the spark plugs, which blew me away.
It was a fully functional, running engine based on the original World War One blueprints of the Bentley Radial Rotary 9 Cylinder Engine that was used by the English R.A.F for a short period in Sopwith Pup trainer fighter planes.

I hope you appreciate his true talents and what a true craftsman can create by D.I.Y.

uaooh!
I do not think you need a limit switch, (maybe some strong mechanical stops).
in fact smc3 if you use this firmware, it has its own electric braking that can be set as desired.
if your problem is the potenziomentri that break if they go over tot degrees, then you just need to build contactless pots. if you have the 3D printer I can post you my stl that work for months, obviously you have to adapt to your engines, my engines are very large (80A 12v).
if you want to have a look. you can not find everything but it's a good base for 180 degrees pot
Marco

congratulations for the wonderful art work of art! incredible skill and competence