Length of the wires for the reccomended springs

[Michael Thonfors]

Hello Cody or anyone else who might know the answer.

I need to know the length of the wires used in the design of the second arm..  (springplug to springplug) The book doesn't tell the length what i could find. :/

Has anyone tried to hard solder the wires to something instead of crimping?

[michael carolan]

Michael..You really are blazing a trail at the moment on all fronts..its great to see. I think it says in the book cables are 8 inches / 200mm long.I've been looking for a thread here somewhere which described a better cable retention method....I think it was a ball that you threaded the cable through and a collet but I cant find it now. I'll keep looking
Mike

[Michael Thonfors]

Ah! found it.   well hidden.. hehe. how much does that get between the springplugs then. hmmm...

i cant get ahold of such crimp balls for the moment and i think hardsoldering is a good option.

[michael carolan]

Michael,
This is what I meant
http://www.wrca.com/wra_singleshank20664.html
but I know you're not gonna want to wait for them :)As far as I know both Jake and Wade have built Codys arm as per book you could pm them about how much cable is inside..I suppose it depends a lot on spring length and plug length...tricky one that to get right straight off..
Mike

[Michael Thonfors]

I guess that the springs should reach the adjustment screws without needing to be stretched?

[Jake Danilchik]

Michael,

I hope this picture I threw together will help you determine the length of the cables for your arm, unfortunately I think it will only provide a rough guide at best.   (  note : you will notice the cable lenghts are of unequal length when you look at my pictures....  I am unsure why it ended up that way... but I vaguely remember running out of cable crimps... ).   anyway...

So here are the totals for one arm segment :

36.2 cm of cable (not counting any end crimps ... etc)
17 cm of active spring ( when not tensioned ) 
This leaves me with 3.8 cm of postive initial tension adjustment screw travel left.
This is for a sled of 14 pounds ( 6.35 kilograms ).   
Also note that I have springs that have very light intial tension rating.. so I have to pretension quite a bit.  You might not need to do this and will  end up with more adjustment screw travel than I have.

P.s.  If you haven't already considered this , you might use heavier springs in the "bicept" segment to handle the added weight it has to carry compared to the "forearm" segment.  You can see that I bought two different springs ( purchased from century spring ~ see picture for part #'s ).   Of course mine are very light compared to most since I am testing my rig with a light camera until I finish my spring covers.

Man, I love what you did with your "arm".   Keep it going Michael, you are the object of everyones envy !

cheers,

Jake

[Michael Thonfors]

Thanx A LOT for those pictures!  now im on track again

[Mike Mann]

Jake,

     I see you used springs that are longer with a smaller OD than the plans called for.  My sled should weigh around the same as yours.  I was wondering how they feel to you.  I picked up the ones called for in the plans and they are so stiff.  I placed 35lbs on one and hung it from a hook and it just barely opened the spring up.  Also agree with you about Michael's arm.  It just looks fantastic.  I thought about trying to go that route, but I think I'll just use some plastic in some spots to pretty it up.

Thanks,

Mike Mann

[Jake Danilchik]

Mike (Mann),

I wouldn't presume to have a definitive answer for you but if I were to do it over again I would use a bit heavier springs (than I did).   Mainly for the ability to add weight ( batteries, lcd screen, or a larger camera , but also because I think I have these maxed out ( any more spring deflection and they may fail ).    Also, even though I bought longer springs than suggested in the plans they are effectively the same length ( I screwed the spring plugs in as you can see to increase the spring rate )  I am satisifed with the result and therefore haven't done much experimentation to see if I can optimize the spring rate vs intial tension.
Making those spring plugs is quite a difficult job ( although Michael Thonfors makes it look easy ) so make sure you choose your springs wisely. One thing I should mention is that I used 1/16"th cable instead of the 3/32"(?)  that Cody's plans call for.   I mostly did this because I knew my sled weight was low but also because  the id of the spring I chose was smaller.  This doesn't leave much room for error when drilling the holes through the spring plugs for the cable to pass through.      The devil is in the details !
Goodluck !

cheers,

Jake

[Mike Mann]

Thanks for the reply Jake.  I didn't even notice how you moved the spring plugs deeper in until you mentioned it.  I really need to sit back and study the dynamics of this whole stabilization thing a whole lot more.  It gets kind of old using the old trial and error method (costly as well).  And where did all these Michaels come from?  Thanks again.

Mike Mann

[Michael Thonfors]

i used 3mm wires.  a bit larger then suggested. the holes where not so hard to drill. used 3,2mm holes if i remember right. and then i used some stainless tube and chrimped on the wire  ends and made a hard solder too..  made a simple breakingtest.. put the wire end(with the crimped and soldered end) up in a gap in a big metall shelf and tied the other end of wire to a vagon, a piece over the ground then me and a friend stood in the vagon and jumped. nothing broke..  probably a couple of hundred kilos of load there..  My springs is adjusted to nearly minimum tension ot rhe sled is to high. but i use a quite light camera (1,5 kg)