Need to determine best placement and stroke length of a pneumatic cylinder

AI Thread Summary
The discussion focuses on optimizing the placement and stroke length of pneumatic cylinders for a device designed to tilt a 500-pound load on a 24" x 24" platform. The user is considering using two 2" bore cylinders with an 8.5" stroke but is unsure if this is sufficient for the required tilt angle. Suggestions include mounting the cylinders at a 45-degree angle and potentially using longer stroke cylinders to achieve the desired motion. Concerns are raised about the structural integrity of the uprights and the force calculations needed for effective operation, particularly noting that a cylinder can push harder than it can pull. Overall, careful consideration of geometry, cylinder placement, and force requirements is essential for the successful design of the tilting mechanism.
WilliamHerron
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I'm making a device that will use pneumatic cylinders to tilt a 500# load 20 degrees.
I'm making a device that will tilt a 500# load 20 degrees.

Going to consist of a hinged 24" x 24" platform (that the load sets on).

The platform will tilt to the right(clockwise) according to sketch.

The upright post that the cylinder is attached to could be any length.

The cylinder will retract to lift the platform and load.

What would be the most effective placement of the cylinder?

I currently have a couple 2" bore... 8.5" stroke cylinders... will this be sufficient.. or should I use longer stroke cylinders?Thanks much!
IMG_20221004_125249480.jpg
 
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I feel that my best bet would be to mount the extended cylinder at a 45degree angle...and go with a longer stroke(Not sure how much longer) but, I'm not sure.
 
How long are the cylinders themselves? Obviously, you'll have to ensure the extended and retracted length is going to be in-range.

Is this a Hallowe'en thing? Maybe I'm just primed for the season but I envision a Frankenstein's Monster contraption on a porch. :)
 
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DaveC426913 said:
How long are the cylinders themselves? Obviously, you'll have to ensure the extended and retracted length is going to be in-range.

Is this a Hallowe'en thing? Maybe I'm just primed for the season but I envision a Frankenstein's Monster contraption on a porch. :)

The cylinder is about 14" retracted ..and 22.5" extended.I wish it was that cool..

Hah
 
About right?
1664905977731.png

1664906386219.png
 
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Absolutely!I'm using 2 - 2" bore cylinders.

Is the stroke length long enough to get the ideal starting angle?(your sketch looks a bit better than mine... hah... Whatd you use?)
 
WilliamHerron said:
(your sketch looks a bit better than mine... hah... Whatd you use?)
I just Photoshopped it. It's what I do.
WilliamHerron said:
Is the stroke length long enough to get the ideal starting angle?

I cannot speak to the engineering aspect; that will have to wait for someone qualified to weight in.

But speaking simply to the geometry, anything between 9.9" and 15.9" will do the trick:

Pulled from this online calculator:

https://www.omnicalculator.com/math/triangle-45-45-90
1664906730137.png

1664906774556.png
 
9.9 to 15.9...Are you saying that needs to be the length from the hinge to where the cylinder mounts to platform?
(And, I guess thatd give the 45degree angle)
 
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Question: that upright seems to be the weak component. Are you confident it can be secured to the base sufficiently strong to torque 500 pounds?
 
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  • #10
i am going to have 2 uprights.

2" x 2" tube steel... 3/16" thick walls.
I'll add a bit of reinforcing to the bottom of ONE of the uprights. (I really can't add anything to the left of one of the uprights)

I'm going to tie the 2 uprights together with a couple pieces of 2"x2". probably one at the top.. and one in middle.

Confident?

Nope.

:|
 
  • #12
WilliamHerron said:
9.9 to 15.9...Are you saying that needs to be the length from the hinge to where the cylinder mounts to platform?
(And, I guess thatd give the 45degree angle)
Sorry, no. I have not accounted for the range of the piston. It can't be as small as 9.9". That won't allow for any retraction of the piston.

Practically, the best bet is to go with something just shy of 15.9" so it's at almost max extension when load is flat.
 
  • #14
WilliamHerron said:
Sorry about that. I do not know how to merge posts.
No need to be sorry.
Just saying that you had good progress and advice in that previous one, and that the cylinders seem to be just a continuation.

I would complete a design of the platform and frame prior to the actuator’s location and points of anchoring to it.
Sometimes, what seems possible finds unforeseen conditions mandate by structure and available space.
 
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  • #15
(possibly) important note:

When using an air cylinder to retract, the rod area must be subtracted from the cylinder area in the force calculation (a cylinder can push harder than it can pull). Your cylinder can push 315 LB with 100 PSIG air. The geometry in your/Dave's sketch requires a larger force than that (approx 350 LB) to init motion. I think that the cylinder is going to have to be mounted higher / more horizontal (assuming 100 PSI). If you have higher air pressure, you might be OK - need rod size to calc cylinder force.

Edit: a whole bunch happened real fast while I was typing. This was going to be post #6...
 
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  • #16
Dullard said:
(possibly) important note:

When using an air cylinder to retract, the rod area must be subtracted from the cylinder area in the force calculation (a cylinder can push harder than it can pull). Your cylinder can push 315 LB with 100 PSIG air. The geometry in your/Dave's sketch requires a larger force than that (approx 350 LB) to init motion. I think that the cylinder is going to have to be mounted higher / more horizontal (assuming 100 PSI). If you have higher air pressure, you might be OK - need rod size to calc cylinder force.

Edit: a whole bunch happened real fast while I was typing. This was going to be post #6...

I was thinking that cylinder could PUSH harder than PULL... And my original thought was to have the cylinders under the platformBut, space and ease of maintenance was an issue with that.So... I had to punt... And try something different.I've been told that plant pressure is 100psi.
 
  • #17
WilliamHerron said:
I was thinking that cylinder could PUSH harder than PULL... And my original thought was to have the cylinders under the platformBut, space and ease of maintenance is an issue with that
It could still be constructed to push. if you make good use of the space to the right of the base; it would just be a little more complicated.
1664911320075.png

(For illustrative purposes only. I don't recommend this geometry)
 
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  • #18
What air pressure do you have?
 
  • #19
Dullard said:
What air pressure do you have?
I have been told that plant air is 100psi.
 

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