Building a Proper Motion Seat Base For SCN5's

There has been much confusion about the proper design for a SCN5 motion seat base. Some have experienced actuator damage as a result of misconfiguration. This post is an attempt to help those who will be building their own motion bases to avoid costly mistakes. These are the lessons learned while developing the SimXperience Universal Motion Kit. Since I offer a 1 year warranty on the actuators, I need to try to ensure that DIY users configure their seats correctly to avoid warranty claims!

The test objective for Universal Motion Kit is to provide users up to 260lbs with good quality motion and actuator safety while using 150mm actuators.

It is important to recognize that their are a variety of critical factors and that they all need to be combined correctly to produce a good feel and increase the life of your actuators.

-Seat tilt on the seat base
-Distance of rear actuator bar from pivot
-Width of top-side actuator bar
-Type of pivot
-Location of pivot
-Dampening mechanisms

Important minimum dimensions
30.50 outer dimension from bottom-side ball-joint to ball-joint.
11.25 outer dimension from top-side ball-joint to ball-joint
28.50 from center of pivot to center of rear bar.

Tips
-Use rubber bump stops
-Generally speaking, the pivot should be located directly under your butthole.
-Test your design with the test sliders INCREMENTALLY (I posted a tutorial here a year or so ago with a video on this)
-My actuators are mounted inline!! If yours are offset (like in a Frex design) then you should compensate for this. .50 inches is the difference between success and actuator failure.
-The Frex design is NOT sufficient for 150mm actuators. It failed every test on my test platform with 150mm actuators.

I will update this post with pictures when I have time.


Reference Pictures





Happy building!

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Re: Building a Proper Motion Base For SCN5's

Thanks Bernard for clearing things up!

I will need to do a lot of work if i want to match your design. first thing i will do is adjust the pivot-centre to rear bar. will it help also to make the lenght longer between the bottom of the mounted actuators like you did? maybe its smarter for me to make a separate bar for just mounting the bottom of the actuators on. it would save me a lot of work! (i can mount a new bar on the floor because my sim doesn't need to be moved.)
Where do i get those 'Rubber Bump Stops'?

BTW: My english is not very good for technical stuff...sorry

Regards,

Rob

Re: Building a Proper Motion Base For SCN5's

There are many benefits from a feel perspective to having the mounting bar in the rear as well. I stumbled upon this quite by accident, and was very pleased with amount of realism it added to momentum shifts and changes in direction. It makes the motion more fluid as it would be in a real car.

The rubber bump stops are easy to make. I simply buy a strip of rubber, cut it, and then drill it with a drill press.

Re: Building a Proper Motion Base For SCN5's

Regarding the rubber bump stopps: I've made my own modification - squashballs ! I drilled a hole a little bit out of the center of the squashball, pushed the lift rod through and countered it with a big washer on the upper side. So everytime the lift rod moves down, the squashball absorbs the last mm of the movement. Must take a picture when I'm with my sim the next time !

Originally I wanted to get such a rubber to cut thos bump stopps by myself, but unfortunately I haven't found them at the local stores here... If someone here has this material left, I'd like to buy it from you...

Re: Building a Proper Motion Base For SCN5's

Bernard, I hope I'm allowed to put our European dimension data behind yours ;D :

I'm looking forward to seeing the related pictures - it's always easier to have something visualized.

Thanks again :thbup: !

Re: Building a Proper Motion Base For SCN5's

Thanks for the conversion mate! i needed that

BTW i am using 100mm actuators, does that make a difference?

Re: Building a Proper Motion Base For SCN5's

Bernard, why ? What is the difference between these three SCN5-mounting-versions:

• SCN5 mounted on the actuator arms, facing to the seat back (= Frex style)
• SCN5 mounted on the actuator arms on the back side (= my actual style)
• SCN5 mounted facing each other (= your actual design)

I've tried version 1 and 2 and I didn't notice any difference in the kind of motion or in the behaviour of my SCN5 !

Next question is, whether it is still needed to use lateral stabilizers if there is a cardan mounted (not a rubber pivot).
I only had them mounted to avoid torsion in the beginning when I used a rubber pivot. But now I have disassembled them, 'cause I switched to a strong cardan pivot.

Re: Building a Proper Motion Base For SCN5's

I don't understand why you put rubber bumps stops? I don't know what is the goal of this. I think it could be dangerous for the actuator...

Bernard use a 150mm actuator because his actuators are fix at the top of the seat (Like frex) and he wants 2 Thinks
- good sensation
- less effort for actuators
but if the actuator are fix at the bottom of the seat like prosimu Bernard could use 100mm and reduce the dimension of his simulator.

Re: Building a Proper Motion Base For SCN5's

There is no need for stabilizers if using a universal joint.

Your actuators are still offset no matter how you turn them. My earlier designs were offset as well, but I have remedied this in later designs. Please allow me to illustrate.



The point is that if you are using the dimensions that I have posted, you should consider that this offest actutually changes the dimension. I prefer inline because I use dampeners in my actuator covers and an inline dampener is more effective.

I have also considered more narrow designs such as those employed by Frex and Nima (the origination of the ProSimu style mounting). None of these designs meet my performance criteria. Additionally, both designs tend to hop around on the floor, damaging the floor. This hopping also reduces the quality of motion. A wider base is more stable and when used with a dampending bar and inline dampeners, improves motion quality and eliminates the hopping common to these other designs.

Nima is now redesigning his simulator away from that style. He originally did this to save space and understands that this is not optimal. Please do not copy his design!

I use this simple wooden platform for testing a wide variety of actuator angles, mounting positions and widths. I test each scenario with a 260lb driver load at full actuator speed for 1 hour minimum while measuring actuator temperatures and missed targets (actuator re-targeting due to missed positions, some of you may know this as the famous actuator bleep noise).



My findings posted above are the results of these tests with 150mm actuators. It is correct that a 100mm does not need quite as much angle and can use a slightly smaller footprint. It is however my opinion based on extensive testing that a Frex design and Nima/Promsimu design are less efficient and prone to actuator failures. I have no ill will toward anyone at Frex or ProSimu and I wish them the very best. I would however be very hesitant to offer a 1-year actuator warranty when used in those designs.

To be fair however, I would like to offer this: If anyone can show a video of a ProSimu style simulator with a 260lb occupant pass the test here: (http://www.x-simulator.de/wiki/Testing_ ... _Actuators) with the seat slid all the way forward and another test with the seat slid all the way back, then I would be willing to offer a warranty on actuators used in this manner. I can tell you with certainty that the seat slider will change the pivot enough that there will not be enough leverage to pass this test.

Re: Building a Proper Motion Base For SCN5's

This is great information Berney. Keep it coming .

I have used your methods and can 100% validate that it makes a huge difference. I have had someone weighing over 250 lbs on my sim rig and it performed with no issues. The only thing I do is limit the lateral movements a little more than I would if I were driving since I do not use the 25% limiter (but i do use about 10% inside my profile). I do not recommend anyone not using the limiter unless they fully understand how to optimize their entire configuration to avoid damage.

I have a question about the above rubber blocks that can be used to help protect the actuators. Can this damage the actuators during initialization? I notice that the actuator will try to compress the rubber and it is difficult for them to do so which is desirable when driving but I'm not sure what long term effect this will have on them. Is there any way to calibrate them so that they do not compress that far during initialization?

Re: Building a Proper Motion Base For SCN5's

Thanks for validation Ledfoot.

The rubber blocks are intended for use during initial testing and with the 25% limiters on. Once you have verified that your motion base design passes the test, you can safely remove them. Of course if your motion base does not pass these tests, leave the rubber blocks and 25% limiter in place!

I do not recommend using the rubber blocks with the limiters off unless you are using a VERY soft rubber than can be compressed by the actuators during initialization without significant strain. This of course makes for a fine balance between being compressable and providing some kind of protection.

My rubber blocks are .74 inches.

As a point of reference, my motion bases do not ship with the rubber blocks because the unit is already thoroughly tested. I am 6'3 tall and 230lbs. I have no issues even with my limiters off.

Re: Building a Proper Motion Base For SCN5's

Thanks again for the great info !

I will adjust my actuators like Mike, though i (still) use 100mm actuators. next year i want some 150mm. I won't be using bump stops, i agree that that could hurt the actuator. (i disassembled them three times) It would only put more stress on the scn5. Then again i understand why Bernard is using them

For the time being i will mount the bottom of my actuators on a wooden bar for testing with the tutorial from bernard. And flip the actuators around like Mike did. This way i can quickly adjust the mounting positions.

Regards,

Rob

Re: Building a Proper Motion Base For SCN5's

Did anyone experienced a broken pin with 150mm actuator?
Maybe its just a different material used on 100mm and your rig is fine?
sn4il

Re: Building a Proper Motion Base For SCN5's

The last version of Prosimu is well defined with absorber feet and renforced with big plate steel and i doesn't see any hopping.
Could you indicate where do you see hopping on the last video?

Do you have complete video of your last simulator in order to see the capability of your simulator.




Like i say in my previous post it's a question of compromise:
If you want, you could move a 330 lbs occupant in your seat without stressing your actuators, it depends
of the angle of your 2 actuators (angle A) and the angle from the pivot (angle B).
If you put angle B to 150°, i think you could move a 400 lbs occupant
But like says Letfoot (and i think the same) if you modified this angle, you have less sensation...

So it's compromise. And Frex, Prosimu, SimXperience could be adjust to anybody.


What is your angle A & B? It would be easier for all (in order to adjust each simulator ) to know this (and it's independant for 100mm or 150mm actuators).

Prosimu said that the slider is used to move the G point, it is very useful if you have several occupants (who want to play on the same simulator one after the other) with different weight 99lbs and 260lbs. These occupants haven't the same G point (huge difference) and with the slider, you could change the G point very quickly. However, the slider never go entirely to forward or backward, it's dangerous to do this.

Re: Building a Proper Motion Base For SCN5's

I am having some videos professionally made. Even though my camera is HD, I do not seem to have the talent to make a professional looking video.

I agree that it is dangerous. In my opinion, it is dangerous to have a slider altogether. This is placing too much confidence in the consumer. I will bet my paycheck that some heavy individual will slide the ProSimu slider completely forward and destroy an actuator. Products should be engineered to avoid costly consumer mistakes, not too allow for the possibility of costly consumer mistakes.


** For those who arent familiar with this, be sure to click the above picture and see the seat slider in action.

Moreover, it serves no purpose that I can see other than to be dangerous. Take the heavy person as an example - he will need to have the seat slider far backward in order for proper leverage to exist when lifting his weight.

The 99lb person has a different problem. The simulator can lift him in any configuration. The issue is that a 99lb person is typically VERY short. If you move the seat slider forward for this person, then it will lift his short legs off of the pedals due to the additional lever. :lol:

So where is the benefit that offsets this danger? Truly, there is no need for this risk of damage.

I have already listed the dimensions needed to achieve the same angles as mine in the posts above. Other have followed these instructions with successful results. Also, you are correct about the angle. The greater it is, the less sensation there is. However, this is where the 150mm actuators make the difference.

:thbup: I see the new pictures now on the ProSimu site. It is good that he has added some weight to help keep the bouncing to a minumum.

Ultimately, I do not mind however ProSimu configures his simulator as long as I do not have to warranty the actuators when used in this fashion. I do not view ProSimu as a competitor, I am simply concerned about our differing methods of calculating risk and the potential for actuator damage. I wish him (and whoever provides his actuators) the very best of luck. The entire point of this thread is to help those who are building a DIY motion base to get better performance and reduce the risks of actuator damage. It is still my advice that DIY builders not follow the path of this design because it can and will result in actuator failure.

Once again, my warranty offer is open if proven via video using the prescribed test method.

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Re: Building a Proper Motion Base For SCN5's

hi
bernard wride:

Nima is now redesigning his simulator away from that style. He originally did this to save space and understands that this is not optimal. Please do not copy his design!
this is right i have make this design only for my place.after playing i must move the sim in other
littel room.if the sim only 2inch more length i dont can move in the other room.for my new sim
i go in a other room.the room has not a big size.i can make my new sim 220cm long,

Re: Building a Proper Motion Base For SCN5's

I have tested and can reiterate that having an adjustable seat is a recipe for disaster. All it takes is the wrong movement while sitting in the seat during initialization and you can damage your actuators. The proper way to achieve adjust ability is to move the entire seat, pivot and actuators at the same time.

....Mike

Re: Building a Proper Motion Base For SCN5's

I don't know what was the quality of your slider, but when you have finished to adjust your seat, the slider is definitively blocked...i can't understand that the seat move during initialization :?
The better way to achieve adjusting is to move pedal, whell, and gear box.

Re: Building a Proper Motion Base For SCN5's

It is certainly a lot easier to achieve adjust ability by moving the pedals and wheel. . But it would be so much nicer to have a moving mechanism that moves the entire seat platform similar to just having a seat slider .

Re: Building a Proper Motion Base For SCN5's

It's dangerous if you never read the manual, like when you put aluminium (or a cat) in your microwave... Or you put your motor of your car in red zone during 5 minutes.... I think people who spend 2000$ read the manual and recommendation :yes:

You know like me that the G point on the simulator move a bit between 2 person, (one at 99lb and another at 260lb) maybe about 2 or 3 cm. So the additional lever is insignifiant.

Right, you have list the dimensions, but in order to calculate the angle, i need the dimension of the actuators arms (without this, it's impossible to calculate the angle A or B).

With this, all the people who have a design with 100mm actuators could do a proper motion base. Thanks