My 3DOF project is born!

For the cylinder-piston I get some steel boxes from steelworks. I get it giving precise mesaurements.

In the following link you can see what I mean for steel boxes.
http://www.fratellifavaro.com/prod_dett ... 2&lang=ita


I pick a 400mm long steel box (4mm thickness) and 40 mm width. I welding it on other 4 steel boxes, these 4 steel boxes are my cylinder pedestal cross shape.

I weld a big spring washer in the cylinder on correct cylinder position (this washer will mantain the down side of the spring)

Later I pick a 300mm long steel box (4mm thickness) a little less width than the cylinder and now I can put (insert)it into the cylinder!
Obvious you need some mechanic grease to let the piston can slide smoothly inside the cylinder.

Later I weld another spring washer on the upper side of the piston (this washer will mantain the upper side of my spring)

Now I weld the universal joint on the up side of the piston washer and in finish I weld my 350mmx350mm (5mm thickness) steel plate on the up side of the universal joint! (this steel plate will mantain the main platform structure with 4 attach points)

In the very finish I can mount my spring on the 2 washer (the distance between the 2 washer MUST to be damn precise following the previous calculations about spring!!!!!!!)
;D


PS. When you will be more ahead with your project you will face to have a damn precision custom spring dude... I lost a lot of time building my 3dof using a not precise spring....

I just measured My Strut. It has exactly 30cms Movement (up and down) so thats great

Also We are desiging it so we can tighten and losen the Spring. (the bottom of the spring will be adjustable so it will be lower or higher)

So this way *hopefully* I wont need to spend any money on a spring, We can just adjust it as we go to get the perfect tension.

Maybe its time to start your own thread on your project ;D

But then you will see I'm just all talk

But, I do like to talk, so I'll start a thread

I never insinuated that you were all talk, just a suggestion to start your own thread, thats all.

oh yeah i know. I didnt mean to say you did. Im the one who thinks im just all talk.

anyway im uploading what I have got because I want everybodys opinion of which direction to head.

Hi Aldoz-

When you have were testing did you break any POT's? As they can only rotate so far I thought you ma yhave gone through a few?
Where did you get the Gea that connects to the pot and the motor?
I get my First Winch Motor today or tomorrow, So I can start exprimenting. One of the hardest things I beleive will be finding the right parts to connec tthe motor to the POTS

Hi Aldoz,

Just reading your posts, you said you have 3 motors that can lift approx 230kgs..

I was just thinking, Do you think it would be possible to make 4 Motors, and remove the middle uni joint?

That'll give you like 300kgs.. platform is only going to be approx 50kgs i think.. and I weigh 90kgs.. so thats still well under 300kgs.

Yes, but how fast would it lift un-aided.
Aldoz put in a spring for a reason.

Hello guys.
Yes, as bsft says the spring have a reason to be here!
Stowaway, 3 winches can lift 230kg, this is correct but only If they are running at 25 amps. If I remember good, bsft is using their jrk at 25 amps without problems (with fan and heatsink) but I am using my jrk at 22.5 amps so the kilograms liftable are so and so 180/190 kg (using obviusly all 3 motors).

But let's speaking about the 25amps full force winch motor:
Without a spring I need a really more powerful and big mechanical components and believe me ,I'd be really scared to try my platform with motors at 25 amps so with full movement speed without a CG pivot with spring....
Sure the motors will be suffering very much (and jrk are too little and too fragile to endure such an effort.

The problem is NOT about if my motor can lift 230 kg but the problem is how my motor will lift these 230 kg??
The answer will be : hey dude.. you are really at limit of your mechanical/electrical configuration...
And if you want to have a stable, efficient, powerful and secure motion system using winches so you MUST use a CG pivot with a spring made ​​perfectly suited to the demands of your configuration.
These are NOT just words.... believe me stowaway.. I have reached such considerations after many many tests...

in my configuration, a fourth winch motor would not be sufficient to avoid using the spring.. and over, in my configuration would also be difficult to insert a fourth motor too... My motor positions are not simmetric (left, right, ahead, behind) so the fourth motor would be over of what I need to make my motion system working correctly.

I am so sorry for my sad english :no: , the matter about the correct motors position deserves a very wide and clear explanation and unfortunately do not think I can explain it all properly :?

But many times I thought about using a fourth motor and always I get the result : better with 3 motors....

I hope you can get a bit of this my answer to understand how many importance have the project and the objectives of your motion system.. from the electronics to the mechanical matter...

In finish I would to tell you all that this morning I received the new higly custom spring!!! :yes: . So tomorrow I will build and mount the new cylinder/piston system!!! :brows:
The moment of truth has arrived for me and 3 or 5 days and I will know if all my work and calculations was correct...
My project is near to the finish test... so stay tuned, soon I will post some vids! :rofl:

cool thanks for your resposne I was never actaully going to make it without the spring , but i was just curious.

Against your advice and probably my better judgement I have ordered a pneumatic spring. I ended up going that way because the custom spring shop said my requirements were not plausable, I didnt push the fact or try and work with them as I thought I would just try the pneumatic spring first.. if it doesnt work I can add a spring it it later.

also a pneumatic spring only cost me $95 brand new which includes delivery.

Hello Aldoz, if the jrks and motors run well at 25 amps max current, then you can stay that way.
Purely for reference, I run mine at 34 amps max current and set profiles to suit, then I set the jrk at unlimited current after that.
I am running heatsinks and fans on them, yes they do get hot, yes I am pushing them ridiculously hard. I found my motors need LOTS of current to get real good motion, as they are a copy of a golf buggy motor.
I figure my current draw is some where between 28-32 amps mostly with bigger spikes up to 38 amps ,but that would be for a fraction of a second.
The only reason I blew my jrks AGAIN recently is that I accidently applied the 12 volts wrong polarity for a brief half a second. The jrks are protected against this but NOT when the usb cable is in the pc first. Lucky thing I did not take out the pc as well.
So, if you wish to run higher current, you can do so, but always at a risk, although mine did just fine before my stupid mistake.
:

Hi bsft! I am really sad about your little dead jrk very unlucky situation.
About the max current so currently are you using unlimited max current? (so 0,000 in the max current tab).
And are you getting your jrk hot but how many hot? and what is the average time duration of your tests?
10 min? 20? This is really important. I am thinking to how to use a liquid cooling system (if it was cheap).

mmm I am really scared about to use pneumatic spring but I will wait to see your results! could also fit in and be a good thing because I spent 196€ for my spring and to obtain a more cheapest price is really hard. Asked so and so 10 spring companies and the price of my custom spring is always near to 200€ for all companies quotes. :tape:

but it would just be worst case scenario is my simulator will only be 2 DOF and I wont use the up and down movement until I buy a spring??

Aldoz, I have only run the jrks playing dirt 3 for 3 hours and there are breaks in between each race so the jrks would cool a bit, and that was after the family was a sleep and I was able to game till 3 am. Otherwise I have not the time to give them a few hours run on , say, GTR evo. Most of my game time is 5 mins race - 15 mins dealing with kids, 5 mins race, 125 mins dealing with kids - you get the picture.
The jrks heatsink is HOT to touch , but even on a warm summer day, the jrk does not stop. I am told they have a high thermal cut out.
I found with my motors to get back shuddering motion I had to set the profiles at 34 amps max, then set it to 0.000 unlimited. The jrks still work fine.
I know I am pushing them beyond all reasonable limits as it is.
You can run the jrks to 30 amps if you like at give it a whirl. Mine did NOT fail from high current, just a reverse polarity plug. I since had color coded all plugs so it will not happen again.
Good luck with jrk abuse!
David.

My jrks do get really hot without a fan, but with the fan running they don't get hot at all. It's a very quiet fan as well. I planned to measure the temps with and without the fan yesterday but couldn't find my IR-gauge.

What max current do you run them at and how hard is the motion for the profiles?

winch motors move more weight than my motors, so they would be able to work less hard.
I could set my motors at 25 amps, but the motion is no better than wipers

I have them set to 25 A now. I used to run 0 before I discovered the gear wear, which is a little more powerful. Without the fan the JRK for pitch get hot just holding the sim centered since it's a little front heavy (and has to be). Yeah the winches are slow and strong, but not very powerful. I wonder what the stall current is. I hope I get the bearings and plastic I need to tighten them up soon. My sim probably loads the motors very differently from yours, as mine wants to return to a center position.

Thats true, sims are different builds are require different set ups. I tend o stick with 2 dof, unit joint under the seat frex.
As for stall current, mine would be fairly high I guess. I know its 16 amps one direction full stick, then it takes current to stop and current to change direction, so I must be tossing 32 amps average in them.
I have a fan and jrks with heatsinks in a box. The heatsink is HOT to touch after a while, then again, the motors are too....