SIM builds and Materials USED

For me it was the complete opposite...having seen a lot of designs and having studied user reviews for pros and cons...
...i first decided what i approximately wanted in terms of motion and then went on with the construction.
Of course during initial planing i ensured some margin for tuning (be it different C-C rod dimensions, overkill Psu, 24Volt motors, room for 2PSUs and extra battery etc).

I may be wrong but this is how it works for me:
You first have a "vision" to build something.
Then you roughly estimate whats the minimum and maximum performance of the rig you are building.
Then you calculate what materials and power is needed to achieve that performance.
Then you build your construction.
Then you trim/tune...

And i think this is the way it should be in every construction...Unless you are making a complete copy of a comercial design (that you know it works).

Even in DIY designs you have to have some sort of plan...i mean whats the point in trying to build a 2DOF seat mover with used -and thus worn- 50 watts car wiper motors? or crappy linear actuators?... Or with 2Amp H-bridges? ... Or with a 10Amp PSU?

Every one who has already succesfully built a seat mover knows this doesnt work... I think it would be better if all this info was organised in a tutorial/directive so new builders dont start from scratch. Because DIY is a lot about lowering the cost -as well as the joy of creation-. Having a list of minimum specs should provide a way to decide where the cost can be safely cut and where IT CANT.

Ok, there is lots of info on this site and the rest of the net. But this community is well enough organised and has the experience to provide this sort of info for the basic 2DOF racing rig(seat mover).See it as a way to make simracing more accessible to the average joe.

Just my opinion. I am not trying to force anything. I just say that things would be a lot easier for the average joe if all the "basic" info scattered in pieces all over the net were organised in one place.

Again i am talking only about a basic design of the "humble" 2DOF seat mover which is the easier rig to construct and has the best fun factor plus is the best bang for the buck.

Sorry for the long post.

Plans like a basic 2Dof have benn suggested and it does come down to cost versus perfromance sometimes. Motors like 200 w worm gear and JRK are overall the prefered setup for code hopeless people , like me. But some people like experimenting so they use arduino and wipers. My first rides started with wipers and JRKs. I still use JRK but now use larger faster stronger motors.
Also , some people cannot weld so aluminium profile or PVC can be used instead. @RufusDufus has plans for a MDF seat mover. So thats 4 potential designs.

I consider as basic motion design the "2DOF seat mover" , be it shoulder mount, back mount or front mount or any other sort of mount among the many i ve seen on the net.

It is the seat motion that defines the design as basic, not the position of the motors.

But perhaps i was not as clear as i should have been in my previous post and created some misunderstanding and confusion.

I will continue with this:

My simulator has a maximum -3.5 to +3,5 degree range (eg pitch), that is mechanicaly transmited by means of 100(+/-50) degrees of rotation/travel of my motor.

Would there be any difference in user experience if this "motion range"(-3.5 to +3,5 degrees) was achieved with my design or shoulder mount or front mount as long as the rotation/travel of my motor was kept to a fixed 100(+/-50) degrees?

The answer is there would be no difference at all.

In fact the mounting position would not matter at all as long as the (mehanicaly limited) end result is kept to -3,5 to +3,5 degrees of tilt and the motor rotation limit to 100 degrees.

The power transmission from the motors to the seat will be the same in all cases. The speed of the motion will be the same.The user experience will be the same.

So no matter how you mount the same motors, in order to achieve a specific performance, its the motor specs that play the most crucial part(along with the psu and Hbridge).

This community seems to have a lot of experience in simracing.
So i thought it would be safe for this forum to suggest a guideline of minimum/required specs to construct a simple 2DOF seat mover.These specs will ensure a minimum performance for simracers to try and enjoy.
eg
200watt per motor minimum suggested?
+/-5 degrees of seat tilt minimum suggested?
+/- 100mm of head movement minimum suggested?
5 degrees/sec seat tiltspeed minimum suggested?
100mm/sec head speed movement minimum suggested?


Of course every builder could change these specs according to their personal needs.
... faster(RPM) motors
... motors with more power
etc

...reading the long "essay" that i have writen so far ,i wonder if i probably ask for something that may not be feasible.

Its feasible but even the info you ask for is beyond me.
More detailed members of information here may be able to assist more than me at this time. I am about to go to work so i will not be back on till later today.

LOL, the DIY shops here where I live (and presumably anywhere else) are quite profitable, because people buy everything twice until they succeed


Anyway we have a project gallery and I think, you can "leverage" a design from there for your sim. Some of the projects are well documented. Nobody will moan, if you copy his sim even 1:1
The question though will be, if you want to copy an existing sim 1:1 or if you want to adopt to your gusto or capabilities.

My desk racers have about 17 deg pitch and 7 deg roll angle, rear shoulder mount sim is about 8 deg pitch and roll angle. Once you get a decent profile going, its feels like more.

EDIT
more than 100 people whom have played on my sims find then realistic

I agree that trying to define simplicity or basic design is dependent on many factors and seems difficult.

Can you please explain why a s shoulder mount design is more efficient?

Leverage plain and simple.

yes but that comes with a cost at speed ... and to increase speed you need better motors .. so i dont see any efficiency in that.

Edit : not to mention the reduced angles you end up with with longer leverage.

This is how my design works.


EDIT R2=the distance from u-joint to the green arrow(rose joint mounting point).

Bad idea on design, motors have to work hard to overcome and lift weight.
The higher you get the motors to connect about the centre of gravity or above, rule of thumb is about your belly button, the less difficult the motors have to work.
Shoulder mount is overall the best, then desk racer because of the mounts higher than the bottom of the frame.
People of experience talking here.
However, feel free to build how you like.

You all say that its easier for the motor to work once we increase leverage distance.

I dont disagree with that. I cant. It is a fact.
...in fact this is what i used to multiply my motor torque from 16Nm to 128Nm on the seat...as i explained with the previous design(20cm:2,5cm=8:1 leverage).

But this fact alone doesnt make a design all-around efficient. There are more factors involved than torque alone.

Noone refers to the fact that by increasing the leverage distance you decrease the overall seat deviation from the center position( as well as the seat's angular speed).

I dont doubt anyones experience. I built my sim studying your designs.

Anyway, thank you all for your answers.

@pipis2015 , we have given you PROVEN advice.
You are welcome to build it how you like.

The following info will be given with the purpose to provide some detailed info and bust some "myhts".

A DIY (2dof) motion simulator is usualy built with DC motors coupled to wormgear custom or fixed gearboxes (one example is the car wiper motor)

Some facts about brushed DC motors

Pros
DC motors are generaly cheap to buy
DC motors are safe to power (12v or 24v)
DC motors are easy to control with USB motion controlers with feedback (eg: arduino+hbridge or jrks)

Cons
DC motors require big currents to opperate (typicaly 1Amp under no load up to 30Amps peak max or even more than 100Amps peak max in certain applications)
DC motors will generate noise (Brush arcing) causing electrical magnetic interference (EMI)


Some facts about worm-gearboxes

Pros
Worm gears can give large gear(speed) reductions (eg 1600 motor RPM to 32 gearbox shaft RPM)
Worm gears can generate big amounts of torque (eg 0,6Nm motor torque to 30Nm gearbox shaft torque)
Worm gears opperate under low noise because they work under high ratios (low rotational speed)
Worm gears are easy and cheap to maintain

Cons
Worm gears have an average efficiency of around 65%
Worm gears have a high power loss
Worm gears are not suitable for high speed rotation applications
Worm gears are big sizes due to design limitations


Lets start our example with the 200W 1600rpm 0,6Nm motor @12Volts.
https://www.motiondynamics.com.au/2...nd-1600-3200-rpm-selectable-0.6nm-torque.html



We can fit it with a variety of worm-gearboxes to customize our output
https://www.motiondynamics.com.au/worm-drive-gearbox-to-suit-industrial-motors.html
Remember that these gearboxes have less than 70% efficiency. But for the sake of simplicity we will do the calculations with 100% efficiency


using a 75:1 gearbox we get 21,33rpm idle, 45Nm torque at the gearbox shaft
using a 60:1 gearbox we get 26,67rpm idle, 36Nm torque at the gearbox shaft
using a 50:1 gearbox we get 32rpm idle, 30Nm torque at the gearbox shaft
using a 25:1 gearbox we get 64rpm idle, 15Nm torque at the gearbox shaft
Using a 12,5:1 gearbox we get 128rpm idle, 7,5Nm torque at the gearbox shaft

As a comparison,
using a SWF-VALEO 404.458(SW2L) 24Volt truck wiper motor:
http://www.smolka-berlin.de/onlines...cteur_24V_DC__Offre_sp%E9ciale%21%21%21_/4398

74:1 fixed worm-gearbox) we get 48rpm idle, 16Nm torque at the gearbox shaft

Lets see how things change when we fit our rods.
http://www.endmemo.com/physics/rpmlinear.php

All forces are calculated at 90 degrees (sin90=1)
For smaller angles than 90 degrees just multiply with sine of relative angle.
eg for 30 degrees multiply with sin30=0,5

12,5:1 gearbox (128rpm, 7,5Nm) fitted with:
25mm C-C shaft/rod gives 0.3351040m/sec linear speed and 300 Newton force
30mm C-C shaft/rod gives 0.4021248m/sec linear speed and 250 Newton force
35mm C-C shaft/rod gives 0.4691456m/sec linear speed and 214,28 Newton force
40mm C-C shaft/rod gives 0.5361664m/sec linear speed and 187,5 Newton force
45mm C-C shaft/rod gives 0.6031872m/sec linear speed and 166,67 Newton force
50mm C-C shaft/rod gives 0.6702080m/sec linear speed and 150 Newton force
55mm C-C shaft/rod gives 0.7372288m/sec linear speed and 136,36 Newton force
60mm C-C shaft/rod gives 0.8042496m/sec linear speed and 125 Newton force
65mm C-C shaft/rod gives 0.8712704m/sec linear speed and 115,38 Newton force

25:1 gearbox (64rpm, 15Nm) fitted with:
25mm C-C shaft/rod gives 0.1675520m/sec linear speed and 600 Newton force
30mm C-C shaft/rod gives 0.2010624m/sec linear speed and 500 Newton force
35mm C-C shaft/rod gives 0.2345728m/sec linear speed and 428,57 Newton force
40mm C-C shaft/rod gives 0.2680832m/sec linear speed and 375 Newton force
45mm C-C shaft/rod gives 0.3015936m/sec linear speed and 333,33 Newton force
50mm C-C shaft/rod gives 0.3351040m/sec linear speed and 300 Newton force
55mm C-C shaft/rod gives 0.3686144m/sec linear speed and 272,72 Newton force
60mm C-C shaft/rod gives 0.4021248m/sec linear speed and 250 Newton force
65mm C-C shaft/rod gives 0.4356352m/sec linear speed and 230,77 Newton force

50:1 gearbox (32rpm, 30Nm) fitted with:
25mm C-C shaft/rod gives 0.0837760m/sec linear speed and 1200 Newton force
30mm C-C shaft/rod gives 0.1005312m/sec linear speed and 1000 Newton force
35mm C-C shaft/rod gives 0.1172864m/sec linear speed and 857,14 Newton force
40mm C-C shaft/rod gives 0.1340416m/sec linear speed and 750 Newton force
45mm C-C shaft/rod gives 0.1507968m/sec linear speed and 666,66 Newton force
50mm C-C shaft/rod gives 0.1675520m/sec linear speed and 600 Newton force
55mm C-C shaft/rod gives 0.1843072m/sec linear speed and 545,45 Newton force
60mm C-C shaft/rod gives 0.20106240/sec linear speed and 500 Newton force
65mm C-C shaft/rod gives 0.2178176m/sec linear speed and 461,53 Newton force

60:1 gearbox (26,67rpm, 36Nm) fitted with:
25mm C-C shaft/rod gives 0.069822060m/sec linear speed and 1440 Newton force
30mm C-C shaft/rod gives 0.083786472m/sec linear speed and 1200 Newton force
35mm C-C shaft/rod gives 0.097750884m/sec linear speed and 1028,57 Newton force
40mm C-C shaft/rod gives 0.111715296m/sec linear speed and 900 Newton force
45mm C-C shaft/rod gives 0.125679708m/sec linear speed and 800 Newton force
50mm C-C shaft/rod gives 0.139644120m/sec linear speed and 720 Newton force
55mm C-C shaft/rod gives 0.139644120m/sec linear speed and 654,54 Newton force
60mm C-C shaft/rod gives 0.167572944m/sec linear speed and 600 Newton force
65mm C-C shaft/rod gives 0.181537356m/sec linear speed and 553,84 Newton force

75:1 gearbox (21,33rpm, 45Nm) fitted with:
25mm C-C shaft/rod gives 0.0549780m/sec linear speed and 1800 Newton force
30mm C-C shaft/rod gives 0.0659736m/sec linear speed and 1500 Newton force
35mm C-C shaft/rod gives 0.0769692m/sec linear speed and 1285,71 Newton force
40mm C-C shaft/rod gives 0.0879648m/sec linear speed and 1125 Newton force
45mm C-C shaft/rod gives 0.0989604m/sec linear speed and 1000 Newton force
50mm C-C shaft/rod gives 0.1099560m/sec linear speed and 900 Newton force
55mm C-C shaft/rod gives 0.1209516m/sec linear speed and 818,18 Newton force
60mm C-C shaft/rod gives 0.1319472m/sec linear speed and 750 Newton force
65mm C-C shaft/rod gives 0.1429428m/sec linear speed and 692,30 Newton force

As a comparison,
SWF-VALEO 404.458(SW2L) 24Volt truck wiper motor (48rpm, 16Nm)
25mm C-C shaft/rod gives 0.1256640m/sec linear speed and 640 Newton force
30mm C-C shaft/rod gives 0.1507968m/sec linear speed and 533,33 Newton force
35mm C-C shaft/rod gives 0.1759296m/sec linear speed and 457,14 Newton force
40mm C-C shaft/rod gives 0.2010624m/sec linear speed and 400 Newton force
45mm C-C shaft/rod gives 0.2261952m/sec linear speed and 355,55 Newton force
50mm C-C shaft/rod gives 0.2513280m/sec linear speed and 320 Newton force
55mm C-C shaft/rod gives 0.2764608m/sec linear speed and 290,90 Newton force
60mm C-C shaft/rod gives 0.3015936m/sec linear speed and 266,66 Newton force
65mm C-C shaft/rod gives 0.3267264m/sec linear speed and 264,46 Newton force

Not bad at all for a 35euro part.

The above charts show that whatever we choose to do, there is a tradeoff between speed and torque.


Now you can calculate the force you apply on your simulator.
REMEMBER:
All above forces are calculated at 90 degrees (sin90=1)
For smaller angles than 90 degrees just multiply with sine of relative angle.
eg for 30 degrees multiply with sin30=0,5 (the force is reduced to half)

By multiplying the above force with the distance from the contact point to the center of rotation (radius from pivot point) you can then calculate the torque on the pivot point.

This is important because every build needs different minimum torque values to be able to move the suspended weight as required.

By feeding the values of:
a)linear velocity (calculated above) and
b)distance from the contact point to the center of rotation (radius from pivot point)
to the calculator
http://www.endmemo.com/physics/rpmlinear.php
we can find our simulator RPM
Then from rpm we can calculate both our angular speed in degrees/sec and linear velocity at our head point, so we can see if our simulator meets the desired minimum criteria to provide the experience we want.

Be sure that your force (ie your rod-ends that transmit motion) is on a 90 degree angle (perpedicular) to the radius from the pivot point. If not then you have to calculate only the perpedicuar(to the radius) component of the force (multiply with sinus of angle).

As you understand... the more your angle deviates from being perpedicular to the radius from the pivot point... the less effective it becomes.

Lesson learnt:
The maximum effectiveness of a rotational force is achieved by staying as close as we can to a 90 degree angle between the force and the radius from the pivot point.


This is why it is suggested for shoulder mount designs to have the rods not vertical but at bigger angles.Because if the rods are vertical then the effective rotational force to the simulator is minimized and the stress/fatigue on the parts is maximised.

many thanks to noorbeast for our discussion.

I must have missed something, What 'Myths' are you busting and how is it different to what has been advised? Torque calculation are only one part of the story, let us not forget how Inertia also plays a part in every design.

I am non busting anything.
I just share some facts.