Questions - Help - 3DOF AC Platform IT Begins -

Hum, the force is not that "constant"
it would be great to have units on this curbs! as the beginning rises very much!

Please can you tell me what kind of spring shape/design can give the "constant" force? I haven't found it in the given link

Hi Speedy, yobuddy, ALL,

My gosh, the facts and ideas you have. Can you just "imagine" all of us physically getting together - it would either be a "fist-fight" or "great" things would happen....probably the latter.

May I suggest We regroup /rethink my use of a compression spring?

1. This platform will be used about 95% of the time by myself - so the weights I have given for the top platform, measurements, etc. are accurate, in order to purchase the best spring configuration possible.
2. My one grandson, Jon Lawrence, is 4 years of age - and as long as he is with his "Pop", even in my lap on a "static" platform, he will be happy - and for many years to come. He will not
pay attention too or recognize that the motion is different when only he is on it, or when both he and I are on it together. I will be the one to notice AND I can live with that, vs. making
changes that have no relevance to him.
3. I am definitely going with a spring, it's just WITH YOUR HELP, getting the right one.
Going to "assume" the constant pitch closed and ground end type spring.
4. I just do not want to reinvent the platform etc. for my young grandsons' 5% use....just not feasible "for me".

With that said gentlemen, all of your ideas, facts, and help "have not been in vain". As stated earlier, this is "our AC platform" to show both us and others as to what CAN be done. Yes, I'm building it to "our" specs....
as I would have built an albatross on my own. FOR THIS, I THANK EACH AND EVERYONE OF YOU!

To move on this, I have attached two sites that offer a "Compression Spring Calculator". This is an FYI as I don't expect you all to do all the work. Prior to ordering a spring, I must fabricate the
Spline Pipe / Spline Coupler so that I can double-check my measurements again. At this point, I will take your information given to me, talk to a spring manufacturer, AND post here to get your
thoughts before I order.
http://www.planetspring.com/pages/compression-spring-calculator-coil-calculator.php
http://www.springsfast.com/custom-compression-springs.php

OK - asking - does this make "sense" and sound like an acceptable plan???

Thanks to all and please have a blessed day!

Tom

Wow Tom, that's what I've been missing ... online spring calculator ... I'm really impressed ... Where are you @prilad ? ... the spring seems to be a big surprise here ? I feel like it's something that have more to discover and should open a separate thread for it ... and to be more professional simulator forum ...






@RaceRay ... Can we find an online sketching site to be integrated here so we can present our ideas faster and easier ? I have many things to add ... but not in English ... Are GIF's Enabled ?

Thanks to you Mr.\ Tom ... All of us sure will meet in Heaven ... every one here is giving his best thoughts/questions ...

Hey Speedy & Guys,
YOU MEAN I HAVE "FINALLY" BEEN ABLE TO ACTUALLY CONTRIBUTE SOMETHING WORTHWHILE HERE?????????????INSTEAD OF ALWAYS CRYING FOR HELP......????????????????

Fellows, I've had the above two sites bookmarked for over a year.....I played around with the calculator, but at that point in time, had nothing to work with and it was WAY over my intelligence.

AFTER watching the attached videos, I now know more about springs than I have in my entire 66 years on this earth. One things for sure, they can and are a complicated thing!

Speedy, glad it's of help to you AND all of us here. Never know when we're going to need it.

Thanks so much fellows - for everything you have and are doing to help this ol' fellow. MUCH appreciated.

Have a blessed one,

Tom

Yes Tom that's how we grow as a community not like a few still hanging here stealing other ideas for their commercial purposes, shame on them.

Hello eaorobbie,
I firmly believe that 90% of humans are "takers" and the other 10% are givers. We have some fine "givers" here, thank goodness. Makes it a pleasure to work with them all.
(My bold, red, statement at beginning of previous reply - well, I felt ashamed that I hadn't given something "worthwhile" (IMHO) back for all I've received.)

Thanks and have a blessed one.

Tom

yobuddy,
Thanks so very much for your kind words. I am one of the "givers", not takers.....just felt like I was not giving enough back.
Appreciate it.
Tom

Tom please don't be modest ... you're a big intellectual man already with a high contribution score ...
For us it's only a matter of explaining a point or two and the ball will go back to your play field and I know that you'll score professionally ...
Actually I like the speed of learning that you're doing till now ... and don't worry about giving back any thing right now ... just keep focused and keep moving forward .

A very big thanks in advance to you and every one adding a step forward in the way of information perfection that lightens your brain when dark cornered or help is needed .

Sorry for late answer @RacingMat ... as you can see the flat portion of the blue curve gives a near perfect leveled constant force from the spring to the load ... regardless the deflection=distance of the load while moving above the spring up and down ...

In the following video a test is performed as per the above part2 video ... pressing on a spring above a scale for a certain distance L1 the scale marks 5.xx then increases the pressure and the spring contracts to L2 and the readings on the scale is 10.xx ... that test represent a positive gradient constant force compression spring " the green curve".

Speedy,
Thank you so much for you kind and encouraging words. I will "earn" my keep...no doubt about it.
More to come tomorrow or Thursday on the "Build" Portion of this thread...just been puny and under the weather as they say here in USA.
Have a blessed one,
Tom

hey why don you use a ps2 golf game controller and just wire up there pot it works on a cable system called game track its a fighting and golf game simulator with two cables
Gametrak try ebay or amazon they work well no broken pots just need set up you values they have 6 ft cable to each pot that is geared down so if you over shoot values will go back to zero i did post about these before look at my posts there some pictures thanks hope this helps i will be using mine for 3 dof
helicopter sim with some driving thrown in

Hey fireflyone,
Thanks for you reply and suggestion.
I have already purchased the pots, "Contactless", infinite turn.............and from what I understand, there is either in firmware or the Sim Software, a safety to prevent over-run. I'm not at that point yet,
so I "may" be wrong on this. Been under the weather since last Saturday, and with all the coughing and drugs, "me" just don't know much.
Thanks so much,
Have a blessed one,
Tom

I guess I'm the first to see this post that has time to reply! Just to inform you Tom, there is no 100% safety to prevent over-run I know of except to install limit switches that will physically cut off the power so the motor(s) can no longer function. In firmware/software you can program in tests to make sure the pots are within range and to continually check to see if you are getting a change in your pots resistance when your motor should also be moving. But if you have a malfunction with your motion or motor controller, there is no guarantee it will shut down the motors. From my experience anyway, once you have your system up and running smoothly, limit switches are not a 100% necessity. However, before this point comes, they can be very helpful in preventing damage (wasted time and money) while you are getting everything worked out. But even though you may be able to get by without limit switch's once your system is tuned, it is always much safer to have them over not having them! So you may want to consider what it would take to install some. Get yourself well friend!

Hi BlazinH,
Hope you're doing well my friend.

Thanks so much for your information and I "stand corrected"....

When I post pics (in near future) of my crankarms, gearshaft with pot attached, you will see IF the motor or motors go crazy, for whatever reason, the crankarms, rods and rod-ends will NOT interfere/or/damage pot.
These pots I purchased are 180 degrees, but they will turn continuously without damage, which is a good thing. I will have a master "Kill Button" on the top platform, by my right side, so if I do encounter "craziness", I can hit one button and stop it all.

Thanks again for you continuing to "educate me"....I could take a test on what I have learned from all of you, and probably pass it with flying colors. My retention and attention of detail are still functioning pretty good.....(that's about all though - other than I can still weld pretty good.)

Stay in touch friend.
Have a blessed one,

Tom

We are all kids at heart Tom no matter our age we enjoy our toys too much still.
The day we stop learning is the day we walk into heaven.
Back on subject.

I like the idea of limit switches to stop the craziness but do use a emerg stop switch on my 12v builds, wont build one without one.

Thanks eaorobbie,
The day I walk into heaven, God is going to get tired of ALL the questions I have - then the real learning begins!

Tom

Long live all of you ...

I believe in that too ... I'm always asking God for his help and support ... So let me ask him for more [God help us all ] .

back to topic ... I'm using a limit switch to put a maximum and minimum moving limits ... Since I'm using a VFD with AC motor like Tom will ... I want to add an important point :

killing the power for the VFD will take about FULL ONE SECOND to STOP/STALL the motor ... due to the charged capacitors inside VFD ... that will not for fill an emergency stop ...

Since I don't have an external control panel for the VFD to access the stop button ...

I used the motor direction wires ... "2 wires "coming from the controller to make a reverse direction condition if the motor is OFF the working aria ... VFD can stop/reverse direction of motor in 0.02 second ... that's a good thing for OFF limit emergency ... So if motor crank arm exceeds it's working area it is reversed by the VFD to motor speed and power ... I will make you a simple wiring diagram for that and post it ...

Until we find some easy to use sketching program or any online at least 2D drawing tools ... please some one post a link here ... and to wait for a better weather ... lets take a year walking like turtles for a 10' target ...

Hi Speedy,
Here's a free program for drawing, computation etc. @terry wells listed this way back on page 2 of this thread - I downloaded it but could not get it to install properly.
http://www.sketchup.com/download

MORE great information: I had no idea that the internal capacitors of the VFD's existed - little less take two seconds to stop an "out of control" motion sim.
Had no idea about what can be done with the controller. This is great to KNOW and that you have a workable plan/diagram - "me thinks" that stopping and reversing in 0.02 seconds is
fast enough.

Thanks so much for the info and a probable solution for an "Emergency Stop".

Have a blessed one,
Tom

here with paint ...