Build thread for my 3 dof simulator platform

Okay, the pot was dead, so no wonder it didn't work.

I got the levers from the machinery workshop CTC = 40mm and 60mm



Early SMC3 and motor wiring


The only thing that I didn't get to work as I wanted (after the fact that I soldered very badly the pot and MMs didn't run both ways as I had a bad connection there also)
was that my pots are turning 9,5 turns for the whole 1024 steps and that make it quite difficult to get a good feedback for the motor. That means roughly 100 steps for a turn and if I plan to use 90 degrees of motion for the motor thats only 25 steps that the pot is going to use.

Are those pots feasible at all or should I go with 180 degree pots or something like that?
Thanks!
I already ordered some other pots, as I though that i'll need some spare.

I didn't try all my motors but the one I tried worked really well only downside was that it makes quite much noise, but then again it's quite powerful.

you can always use gears to take advantage of the full travel of your pots :

Is it possible to run SMC3 + simtools with 10 turn pot but only use 100 degrees for full movement? (kind of scaling the 1023 steps to 30 steps?)
I do get that the resolution is much worse and using gears it would be much better, but it seems that finding correct gears is not that easy.

I dont really get how potentiometers are scaled in SMC3, as max limit is clipping the movement, but if the movement is only 100 degrees and full range is 1023, then maxlimit should be 25?
Well I guess I have to fiddle more with SMC3 when I get the next chance.

If I would go with 1 turn pots, should I still use gears? (as the movement is of course less than 180 degrees)

Thank you guys!

You have to take advantage of the full travel of your pots to get maximum resolution and sensitivity.

You can also get away with using 3/4 of the pots resolution(180 degrees out of 250 degrees which is the usuable max travel of common 270 degree pots).

Anything below is worth considering using gears.

Do you have a access or a friend that has access to a 3D printer? You can do wonders with gearing with one of those.

@bruce stephen made is own potentiometer gearing for his rig.

Thanks!
We have 3d printer in our public library, but I realized that plastic gears are easy to find from ebay.
I'll try those.

Had some spare time and soldered all the MMs, PSUs and pots.
Tried every component individually and everything seems to work.
Next step for electronics is to solder the multiple cables/jumpers that connect all the MMs and arduino. Then try to make everything work simultaneously.
The PSU cables are too long and I haven't built the box for all the MMs and arduino. Planning to put them in a MDF box that has a fan on the top and ventilation holes around.

Note to self: do not try to work the motors with levers and full power while they are not fixed to a place. Almost rammed the lever to a PSU when a motor jumped.
My motors arent that fast (around 50RPM), but they do pack a punch.


I did put the heat sinks to MMs after I verified that they did work individually.

I hope that I will have time on coming weeks to plan and build the mechanical side of the sim:
Still need to do before I can start actual stress tests etc:
- finish the wiring (connect all the MMs to arduino and shorten too long wires)
- calculate distance from bottom plywood to upper one and make spring supports accordingly
- Buy, measure and build the connections (M10 threaded rod and ball/heim joints) from levers to plywood
- build the ventilation box for MMs
- buy and fix the corner irons for motors
- plan and make the anti-twist/movement system to block sway and surge (if not done there may be possibility that the forces may drop the sim from its springs even if springs are properly attached)
-This will most likely consist of fork joints, ball/heim joints and M10 threaded rods

Optional but will do at some point:
- Change to 1 turn pots (and as soon as I get the gears that I ordered change back to the 10 turn pots with 12,5:1 gears).
- Removable HOTAS supports
- Integrate USB hub
- Polishing the looks (using router to round edges and make lifting points, put some textile on the rough surfaces, make some cable management, etc, etc)
- Build support for HTC Vive basestation

You might look into using an old ATX power supply enclosure for the arduino and MMs. They have their own fan and of course are metal rather than wood just in case worse comes to worse.

everything looks good and sturdy: motors, levers... good job!

please insert thulbnails images instead of spoilers, it is easier to read and nicer to look at!
yours

Thanks!
I changed the spoilers to thumbnails, and it makes sense
It's better now.

Something went very wrong
As I wired everything up there seemed to be no problem:
- Pots were working and arduino got info from pots.

but as I started giving the motors juice something happened:
- first only one motor turned and it turned only to one direction and only full speed or nothing. Suddenly the MM of that motor bursted with some smoke.
- I removed that one from the circuit and tried next MMs, same thing both were running only to one direction and max power even if I tried to lower the power from SMC3.
- I did recheck all the connections and as I tried again both of them bursted (not simultaneously but in quick succession).
Yesterday I did try each component by itself with the wiring of the first moto monster that bursted and every MM+motor combination. All of those worked.
Now when I hooked everything up together they just got destroyed.
I had heat sinks and a fan for them all.

It looked like I would have shorted them one by one, but only thing that changed from yesterday was that I tried them all at once.
Could the 5V and GNDs have something to do with this? As they are the only wires that are connecting all the MMs.
Below you will find the connections:

I dont have a photo from the connections that I used as I took them off as soon as I realized what was going on.

EDIT: I checked the MMs, one is giving something out but not working correctly and making the PSUs do weird noises. Two others are completely destroyed. Luckily I ordered spares some weeks ago, they should arrive soon.
This is just really annoying as I thought that I was going safely by checking that everything works
Could it be that I may have damaged the MMs as I fixed them on a MDF-sheet with screws? Those screws were exactly the size of the mounting hole.

Okay,
I got the spare MMs and ordered 3 one turn pots.
Now all MMs and motors are working but 2/3 pots I got either got burned while soldering or were DOA anyways.
I was careful while soldering them so I didn't expect them to die that easily. One terminal of two pots apparently got fried.
Either I'll just get some new 1 turn pots (or go for hall effect ones) or just wait for the gears to come so that I can get my 10 turn pots to work.

Got some proper sized corner braces and installed the motors.

I would advise caution, those L brackets are going to bend with any sort of heavy load. Are you planning on having a center post or something?

Thanks for the advice. Do you have any suggestions what kind of brackets I should use?
Those are 2,5mm thick.
What do you mean by center post? I'm planning on using springs instead of uni-joint.

I would use angle iron if I were you. Center post meaning like you said some sort of damper or spring to give your motors some upward force on return

yes, like @shannonb1 said, you need to reinforce the L plate like this to get rigidity

Thanks for the input.
I'll look into reinforcing the L-plates. (I tried to get them moving by shaking the motors as hard as I could and the movement was minimal (1mm perhaps).)
Other option could be dropping the motors one hole down (~3cm) which would give more rigidity, but would limit mechanically the movement of the motor lever, but I believe that I could still get at least 90° movement for the lever, perhaps more. In a motor runaway situation that could damage the whole system.

About the lever, or more precisely the rod connecting the lever to the platform:
- I have fork joints and ball joints

fork joint: ball joint:


- Are there any benefits using heim/rose joints over those that I already have?

I was testing a bit and having ball joint at the both ends of the rod makes (of course) the platform very unstable (with out any stabilizers).

I will put there anti-twist system (fork joint + M10 rod + ball joint + bracket with 10mm high and around 4cm longsliding room for the ball joint; this will enable movement to two directions (vertical and horizontal) but restrict the depth movement) which will stabilize the platform, but I was wondering if fork joints (or rod endings that wont have ball joint, don't know what those are called, eye bolts?) would be better choice for the lever end of the rod than ball joints. The platform end has to be ball joint.
Fork joint would stabilize the sideways movement but it would also restrict the lever movement. In a motor runaway situation that could damage the whole system.

Ball joints are smoother and make less noise.

1 mm x length of levers = big gap -> loss of effects and inaccuracy of information -> less immersion