Ideas on keeping a part from slipping

[ssbowtie1]

Hi everyone,

I've been working on a project and have built a simple prototype for a proof of concept. The concept worked, but now I need to find a way to revise it because I have a constraint that the curved frame CANNOT slide. Obviously right now it slides quite a bit, since the aluminum curved frame is just rocking on the aluminum guide, with a small force being exerted on it via the rollers.

I thought about installing a guide that matches the profile of the motion of the frame, but would like to consider other options if available. Also, I cannot use any type of urethane because I cannot have vertical motion due to the urethane material softness.

Attached are a picture of the prototype and the profile motion that think it follows.

http://i54.tinypic.com/29e3i53.jpg

 

[ivymike]

put teeth on it
put a series of pins and slots (like really coarse teeth)
the guide, as you mentioned, may be a curved vertical-ish slot with a follower on the rocking part

 

[MintJulep]

 

[tr1ntx]

Radius the ends of the frame and use rollers to constrain the sliding?

(Or instead of radiusing the frame itself, bolt on radiused "ears".)

I'm assuming you're talking about sliding in the direction aligned with the belts.

P.S. I guess you wouldn't have to use rollers, you could use straight bars that the radiused ends slid along. If you can live with the sliding friction.

 

[asimpson]

A cable, chain or band anchored at one end of curved member and anchored opposite end of fixed rail. This flexible tie follows the curve of moving member and plays out as the curved member rocks.

This only constrains in one direction so a second is required in opposite direction.

Picture a drum rolling on the ground with a rope looped around circumference and running on ground. Fix rope to drum circumference at a point and anchor both ends of rope. Drum is free to roll but cannot slide.

Problem is ties cannot be co-linear and two will induce turning force in rocking member.
Solution: Two ties one side, opposite tie running in between.

 

[rb1957]

what motion do you want the curved frame to have ?

you are the "intelligent designer" so this machine so you can make it do what you want.

is one end fixed ? is there a point of rotation ? a single pin in a hole/slot could work.

how much force would this have to react ?? conditions (heat, ...) ??

maybe a roller at the far end (so there's no free space along the the curved frame, but the end can still move vertically)

maybe both a pin (to contrain a center) and a roller (to giude the motion) ??

 

[dhengr]

This time of year I usually just throw some sand btwn. the slipping parts.