Need Help Mechanical double lid lifter

[cybertron]

Tyroman

Forget the hand crank do not want it.


What I want is this mecchanism to work by lifting one side by hand as the opposite side is being assisted by the lifter as stated, but some way to use one motor on the lifter if I choose to.
As dictated in the mechanical mechannism base on nvn mechanise and your revised tandem rack and gear mechanism to be attached to my tubular lifter.

The motor will lift the weight of one side of the lids,as the side with the motor lifts the smaller sq tube the opposite side will be assisted by being attached to the opposite smaller tube. I want only one motor in the system not two, this is the purpose for the lifter to assist in lifting the opposite side.either with or without a motor. But still i want it to work both ways.The doors are only 20lbs.

Yes the motor must be rated to lift that 20lbs. If this is what you imply. It sounds to me that you'll using two motors. Are you. I want to use only one motor.


As for off -limits
Yes no part of the mechanism may be located within the Articulation limits of the short square tubes. As you indicated in pink area in the most recent 3d image.

Nothing can extend below the long sq tube. because the long sq tube will be screw down to the top of the plywood base this is clarified in edit end-on view 3d image.

There's a limit to my mechanical ability to some extend, this is why I came here for help.



Your last question;
"Can this mechanism be make to work by hand as i wanted in this thread plus a motor as an option."
Yes. The pinion gear could be splined or keyed to the motor shaft (with the motor mounted on-axis with the pinion) or the motor could be equipped with a separate gear which engages teeth on one of the racks at a right angle (perpendicular). (With the worm-drive, the motor would be mounted and connected on-axis with the worm shaft at the end opposite the hand crank.)

TYROMAN:
Please show me in a 3d image how this can be applied without using a hand crank but can be lifted by hand and with a single motor as implyed.

 

[tyroman]

cybertron,

If your wood base set-up is as you describe it (and can not be modified), then we are back to the Structure Limits shown in the sketch at post #21 (except for the obvious limitation on structure within the articulation path of the short tubes).

This leaves us with about 1-1/2 inch for the height of the Rack & Pinion mechanism (1" up from plywood to top of the long 1" tube plus 1/2" above the long 1" tube). This is because the "working end" of the higher pivoting linkage bar (where it connects to the short 1" tube) must always be higher that the point where it connects to the rack, otherwise, the mechanism would not allow the lid to be completely closed.

To understand this, you need to construct the cardboard mock-up I suggested earlier.

Please see the attached sketch to understand the following;

View A is what I understand from your most recent sketch, which allows only 1-1/2" height for the Rack & Pinion mechanism.
View B allows 2" height for the Rack & Pinion mechanism if the 1/2" plywood can be installed as shown.
View C allows 2-3/4" height for the Rack & Pinion mechanism if the 1/2" plywood and the 3/4" base can be installed as shown.

The more space that can be made for the mechanism, the more options you have on off-the-shelf hardware that can be made to work. You do not want to limit yourself any more than absolutely necessary... Also, the more space available, the more robust (stronger) the components can become.

 

[cybertron]

Tyroman

Enclosed in your 3d image and A as what i have to work with.

Endclose is a new 3d image I drew too explain the area i have to work with do to the structure to the wall and where the square tubing must be attach to the floor of the 1/2 inch plywood base.

This long sq 18'' tube, I might beable to attach a 1'' wide piece of plywood 18'' long under the tube about 3/4'' inch thick. would this help. can the plate be attach to the plywood base.
If this can't work then what can be done for the mechanism to work.

also how much more can the plate extend above the short sq tubing without interfering with the opening and closing of the two doors.

 

[cybertron]

tyroman

Have you seen my latest post

 

[tyroman]

cybertron,

To aid you in your understanding of machines, I recommend the article found here:

http://en.wikipedia.org/wiki/Simple_machine

Your posts #51 and #53 reveal several points which make your project more difficult...

1. The doors weigh twenty pounds.
2. The mechanism and its motor must fit in a space 2" wide by 18" long.
3. The mechanism can be no taller than 1-1/2"

The weight of the doors is a problem because the mechanism will have very little mechanical advantage. This is because the linkages will be attached to the short square tubes relatively close to the hinges. To lift twenty pounds without bending, the mechanism will need to be stronger than dimensions may allow.

The 2" by 18" footprint for the mechanism and its motor is a problem because the motor will have to be very small to fit in a space less than 2" wide. A small motor which might fit will probably not have the power needed to open the doors. The 18" restriction will prevent a larger motor being mounted off one end of the mechanism (as I previously described for the Worm Drive alternative...).

The 1-1/2" height limitation on the mechanism is a problem because it forces you to use a very small rack and pinion assembly, which (if one can even be found) will probably not have the structural strength to do the job without bending (or stripping gears).

***

There are some things that could address some of the problems which your most recent posts have uncovered:

1. Lighten the doors to reduce the forces on the mechanism and the power required of the motor.

2. Significantly increase the vertical space available for the mechanism so it can be made larger (therefore; stronger).

3. Increase the 2" by 18" footprint for the mechanism and its motor to allow a larger motor to be installed.

***

I have attached two scaled sketches based on the current limitation to 1-1/2" for the height of the mechanism. As shown, the Pinion can be no larger than about 3/4" diameter and the racks no more than about 3/8" tall. Only the approximate length (3-3/4") is shown for the linkages.

Think about what can be done to change the current "givens" for your project so we can have a better chance to make it work.

 

[cybertron]

Tyroman.


Yes i will read the link that you provided.
Yes the total weight of both doors is appox 20lbs. #51
Yes the mechanism and motor that I use must fit in the 2''x18'' limited space.

These are the givens that i mentioned.And that you pointed out.

What I could do is this.

1.Yes I could use mechanical means to reduce the weight of the doors
with counterweights or springs and this will reduce the Force to torque ratio of the motor that is used. How much weight would I need to drop! 5,10,15lbs.

2. Vertical height could be increase to about 8'' with a plate that could be bolted to the wooden base to hold the rack mechanism as close to the bottom of the 18'' long tube as indicated in my enclosed edit image ''but how would the gear be attached, or would it still be attach to the longer tube or to a plate where the rack would be mounted too, and it must not interfer with the closing and opening of the shorter tubes.

3.Increasing this area the 2'' x 18'' space as you stated, this CANNOT be changed at all.There is no way it could be done.As indicated in image.

4.The large Tube could be lifted up with another piece of wood to about 3/4'' to give it more height from the woodbase if needed.As stated in #53.

5. I wouldn't know how to compensate for both of the linkages length do to the 18'' limit in the 2''x18'' space as indcated in my 3d image.BUT I guess this would change once the height changes with the rack or plate I'm assuming.

I'm getting a surplus GEARmotor that's strong for its size, its about 3'' long total, it was used in a tripod that turned a 40lb telescope AND has 6RPMs which is plently to turn from 0-100dgs in a short period, I THINK it has about 1.08watts of power.
I think it could fit somewhere in that 2''x18'' space so the force vs torque ratio would be covered.

I have no idea which pinion gear to use with the racks for this mechanism and the pitch of the teeth for both. I would need help in choosing them.I have no clue what to use.

So this is what I throught about in changing some of the givens for the mechanism in my project.

Tyroman.
Will these changes work for the mechanism to function properly and for added strength.

 

[tyroman]

cybertron,

Please post a sketch of your project as viewed from above... showing all dimensions and components. Include the two doors and how they will be attached at both ends. Also, please show how the 3" long motor will be installed in a 2" by 18" space. The doors (which are 10 pounds each) must be attached to something besides a single 1x9 tube at one end... please indicate what happens at the other end.

I have attached a sketch to get you started... please edit it and attach it to your next post.

 

[cybertron]

tyroman

The image you have posted is the Plan view. If you looking above.. that's what the plan view will look like as you indicated.

The two doors will be attach with my tubular bar lifter only on one side to lift both doors, this is the reason and purpose for the lifter and mechanism is too lift both doors at the same time.
That lifter will lift and hold more then 200lbs with the right motor.My doors only weight 20lbs total.The motor will hold the mass of both doors at any angle as indicated.

Other end must be clear of all objectsto gain acess to storage entrance.There is nothing else being attached to the other side...thee Lifter, and mechanical weight reduction to the doors would accommodate for the mass of the doors if needed.

All components are indicate for the lifter as preposted,anything else that would need to assist in lifting the door like springs or counterweight and there calculations will be my concern.

As for the motor not fitting in the formention space I will chip out some of the wall if needed to accommodate for the motors placement in that space, But only for the motor.
That (wall) was an old wood burning cooking fireplace from the 1800s that's been closed in with cement.

All electrical and electronics is my concern for the motors operation.

The Mechanism
All dimensions,rack and pinion parts,plate,and motor attachments for the mechanism to be attached e lifter is what i need.


link: Would this help you in choosing the rack and pinion parts.

http://www.mcmaster.com/#racks-and-pinions/=439d3f"

 

[tyroman]

cybertron,

We are not yet at the material selection/purchase stage of your project...

The first thing to do is adjust your design to allow as much vertical space for the mechanism as physically possible (The current 1-1/2 " is far to small). This will involve raising the tubular frame as high as possible above the ground to allow the rack and pinion components to be as large as possible. The highest point of the mechanism must be as far below the short tubes as possible. The mechanism can absolutely NOT extend ABOVE the short tubes. See my full mechanism sketch at post #55, where the linkage from the left rack to the left door slopes upward to the left. This requirement has to do with the Free Body Diagram which will apply for this device and will determine the mechanical advantage of the system of third class levers which the mechanism reduces to. This, in turn, will determine the strength and size of the components and the power of the motor which will work.

The second thing to do is develop the "counterweight" scheme which will (to the extent it reduces the load on the mechanism and motor), have significant impact on what components will work for you.

If this project involved designing an optimal mechanism and selecting the most economical components to do the job (which would then be put into mass production) it would justify the effort to fine-tune the design... however, this is a one-off situation and your best bet is to give yourself the maximum flexibility in component selection and then buy the largest (strongest) components which will fit. You do not want to invest your money in a fine-tuned design and then have it break after 10 cycles.

To help you understand my reference to a Free Body Diagram, I have attached a sketch. To get an idea of what the sketch depicts, try lifting one of the 10 pound doors at a point one inch from the hinge (which is where the linkage will attach). You will have to apply about 40 pounds of force to start the door in motion. Much greater force would need to be applied by the linkage, since most of its force is directed horizontally at the start.

 

[nvn]

cybertron: The attached file illustrates how the mechanism in my post 14 diagram works. (The image is stretched in the y direction for illustrative purposes only.) Study this diagram to see how linkages AB, BC, and CD move, and to see how they operate the right-hand door when you rotate the left-hand door. In this image, I rotate the left-hand door 360 deg, just to make it interesting; but your door will rotate only the first 100 deg, which is included here. You can make the image repeat in your viewer by selecting Play > Repeat, or View > Loop.

 

[Danger]

With no offense intended toward anyone, I think that it's time to put this thing to sleep.
All logical, technologically plausible, approaches have been offered, and OP doesn't accept them. It seems clear to me that he wants something unattainable. Let's just pull the plug. (Unless, of course, someone with BlackOps training, Umbra-Level security clearance with a Q rating, and an alcohol problem cares to offer the ultimate solution... )

 

[cybertron]

Are Those your own words. Or dose he speak for every one else.

And no offense intended.

I do have a very limited experience in Mechanical design>

So My intensions was to come to a forum such as this one to get the Help I would need for my project. Seems to me I been getting that.

I have not refused any such offers or suggestions from anyone on this forum. All help is greatly appericated.But How could I use a suggested idea from anyone if the idea dose not fit my objective or work for me in my project.

If you feel as you speak.
Then I'm greatful for your EXPERTISE that you have contributed to my thread.

 

[cybertron]

nvn

Nice video! I see how this mechanism that you provide in post #14 works and functions do to this video.

I see as the left short tube position opens ''point A'' rotates as it pulls torwards ''point C'' as the right side pushes up on the opposite side to lift the shorter tube on the right side as the process reverse to pull torwards ''point A'' went it closes.

At frist in your #14 post I didn't noticed that linkage rod A is longer then linkage C and how A and C positions are mounted high and low above and below the hinges knuckle to give the leverage to lift each side.

How would you attach a motor to this mechecnism or would you have to modified or change the complete design for this mechanism design to function.

Is there a way to show me this in a video. That if you could.

P>S How did you make that video to have that move like it dose If you can explain.

Thanks.

 

[cybertron]

tyroman

I understand what you are stating in post 58

I could lift up the tube to 3/4'' as stated with another piece and maybe to 1'' BUt 1'' that the maximum do to the low point where the door sits low form the top of the longer 1'' tube.The door thickness is only 3/4'' and 1/2 of that sits inside the entrance hole I will have to add a vertical piece to the top of the shorter tube and bend it to account for the diffrence in height but that's not a problem if I don't go higher then 1'' under the long tube.

So your saying the rack and pinion Can't be higher then the closed shorter tubes if that's the case then the plate mentioned in the last few post dose have to be higher the shorter tubes either. correct!

The counterweight reducer will be a spring in reducing the weight of the doors if that's the case the motor will easily lift the door even through it could lift 40lbs.


As to the 41lbs of force if that's the total force of both doors as you mentioned then a 20lb spring would be use to low the force on the mass which is the door. Correct!

Yes 1'' from the hinge and lifting the 10lb 1'' high will have the greatest force on the mechanism to lift the lid in motion,this is where the spring comes into play by lowering the force on the center point of the door and hinge and its mass so the torque on the motor is lowed. Correct!

As for your sketch this is what i understood. If I'm wrong please explain.

 

[nvn]

cybertron: The mechanism I designed is independent of an optional motor. A motor could assist, but is not required for the post 14 mechanism to work. You could attach a motor anywhere you like, as you see fit, if you wish. I will try to leave that up to you.

 

[cybertron]

nvn

Yes the mechanism designed in post 14 dose require a motor to work; I see that.
I do want to add a motor to that mechanism and it would be attached to point (A)
on the short tube would there be a way to attach a gearmotor from the woodenbase in the space that i have to point (A) so it functions like in post 14, but with a motor.
any further help would be appreicated.

 

[cybertron]

tyroman

I added 1-1/2'' spacer under the longer tube to accommodate for the function and strenght of the rack and pinion. Thats the maximum height allowed. Do to adding that spacer to 1-1/2'' I will have to add a vertical bend piece of tubing to the shorter tube to the door because the door will sit at the lowest point of the 3'' height of the tubing.That not a major problem to change.

 

[nvn]

Would something like this work? Not to scale.

 

[cybertron]

nvn


Thanks for the added motor. I appreciated it.

Can you tell me what is the part outlined in red is, is it a standard complete part i could buy,or 3 separate parts and how is this connected to the tube. I'am assuming that the rods are rounded or flat in your image.


Ha is there a way to make a video out of this image.

that last video was nice. I keep watching it. how was it made.

 

[nvn]

I now revised the attached file in post 68; see the revised file. The linkage bars in the post 68 diagram are flat bars, not round rods. The purple sleeve (cup) is a separate part. It is a solid square bar, then you tap a blind hole along its centerline. The bottom of the cup has a rectangular hole, through which you insert linkage bar HB. Linkage bar HB must be free to slide to the left. I.e., linkage bar HB is not rigidly connected to the purple sleeve at H. I don't know if "linear motion" equipment manufacturers, etc., might have something like the purple sleeve you could buy. You will need to research all available parts and manufacturers on-line. If not available, then you can hire someone to machine some parts. No problem.

 

[tyroman]

nvn,

That is a great animation! How did you make it? Can you give me the name of the software or a link?

If he can live with your design, it would be MUCH better than the rack and pinion system I devised. It is much simpler and could be easily motorized by making the B-C link a rack and connecting his gear motor through a right angle drive to a pinion meshed with the rack.

cybertron,

I'm confused... My understanding of the Structure Limits which you had shown in your sketch at post #53 are shown in PINK on the sketch attached below. Please edit this sketch to correct any errors I have made. Also, please confirm that the doors weigh 10 pounds each, for a total of 20 pounds.

Your latest sketch appears to allow the mechanism to be up to 3" high, is this true?

Now, for the question of how much force the motor and mechanism will need to deliver:

Look again at the sketch I attached to post #59. The force necessary to start opening one of the doors with the mechanism is represented by the arrow labled "total force on linkage". You will see that it is much longer than the line representing ~41 pounds. I have not calculated that force (it will depend on the final configuration of the mechanism and the size of the angle "theta" shown on the sketch), but I would expect it to be in the range of 100 pounds.

Since the motor will be moving BOTH doors at the same time, it will need to deliver twice the force; or about 200 pounds. Any spring or counterbalance system should be set up to make the effective weight of the doors as small as possible.

 

[cybertron]

tyroman.

I will try and made both mechanisms to see which would work best for my project.

I don't know what you mean or indicating about post 53.

The doors do weight 10lbs each for a total of 20lbs. I did not install them they were already inplace.

How do i know each door weights 10lbs, I weighted both doors with a scale' and off there hinges and on there hinges.

These doors are made with 2peices of solid wood 1/2'' thick for both doors this wood is not the kind of wood you can buy at any home improvement store this wood is solid plank boards that they would of used 60+years ago before they had plywood as we do today.There in great condition i just planed each side down 1/16 of inch to get the original grain of the wood back so I could stain them.

tyroman:you did mention in post i think 55 or 56 if I can increase the height of the tubing this will increase the strenght and function of the rack and pinion system.So this is what i did to compensate for that in my last post.

Yes. its ture, I did increase the height of the tube with a 1-1/2'' spacer under the tube, so i looked closer at the doors how they sit and it wouldn't be a problem to do this, but I CANNOT go any higher then 1-1/2'' on the spacer.I will have to accommodate for that height with a vertical bend piece of tubing to attach to the doors since the doors will sit 3'' below the top of the shorter tubes but this is not a big fix or problem to change.

The Gearmotor I'm getting has a high torque ratio do to its very low RPMs AND GEARBOX it can lift 40lbs - 60lbs as i been told, even if I didn't use any springs this motor could lift both doors i would think. But that's not good on the motor.And you want to use half what the motor can lift so 30lbs would be right.
So by using one or two springs on each door will bring the mass of each door weight down to about 0.5lbs or 0lbs I'm thinging two 20lb holding springs would work.if not one larger spring.

tyroman:
How do you get 100lbs to 200lbs on the rack and pinion mechanism the motor is applying the force and the springs that's lifting the doors the rack and pinion is there to guide the door in the lifting. Mostly all the force I would think is placed on the motor when lifting the two door up. Please explain I'm trying to understand this.

NVN.

As I and tyroman stated what program did you use for that video was it Windows Movie Maker or some other program can you please name the software or a link to that program as tyroman suggested.

 

[cybertron]

I now revised the attached file in post 68; see the revised file. The linkage bars in the post 68 diagram are flat bars, not round rods. The purple sleeve (cup) is a separate part. It is a solid square bar, then you tap a blind hole along its centerline. The bottom of the cup has a rectangular hole, through which you insert linkage bar HB. Linkage bar HB must be free to slide to the left. I.e., linkage bar HB is not rigidly connected to the purple sleeve at H. I don't know if "linear motion" equipment manufacturers, etc., might have something like the purple sleeve you could buy. You will need to research all available parts and manufacturers on-line. If not available, then you can hire someone to machine some parts. No problem.

nvn. As for getting any kind of part customed machined would not be an option do to a small amount i want to construct this for. Is there any standard part you can implement in the mechanism design that would be easier to find. off the self of any hardware home improvement store. at the bottom of the revised drawing don't understand the part please explain. thank you.

 

[nvn]

On linux, you can use octave, gnuplot, and ffmpeg. I don't know the details of how it works, since I didn't set it up; and I wouldn't have time to go into that. I don't know if it works on Windows or Macintosh.

cybertron, you will be the one who needs to do most of the on-line research to locate off-the-shelf parts, unless someone else here happens to find some parts for you. Also, I think there are individual machinists who will do small jobs. So don't give up before you have tried to contact them.

 

[cybertron]

On linux, you can use octave, gnuplot, and ffmpeg. I don't know the details of how it works, since I didn't set it up; and I wouldn't have time to go into that. I don't know if it works on Windows or Macintosh.

cybertron, you will be the one who needs to do most of the on-line research to locate off-the-shelf parts, unless someone else here happens to find some parts for you. Also, I think there are individual machinists who will do small jobs. So don't give up before you have tried to contact them.

I throught you might of had some other standard part for that part that will be connected to the flate stock that i could get at an hardware store. And yes i will be doing the on-line rearching which I have been doing. But the part that connects to the bar is i think a custom made part that will properly be hard to locate.Yes i will contact some machinists in my area but I do know a one item custom part can get expensive to forge.

No I'm not going to give up?

As for the flate bar what do you think i would need in size and thickness because you didn't state this.
I did find some on-line Alumimum or steel, sizes 1'',1/2,3/4'' 5/8'' wide and for the thickness 0.05'' 3/16'' or 1/8''.what would be the way to go. As for connecting the bar together, I do have some ideas.

In post 68 in the drawing what is that part in the low bottom right.please explain.

What is a program I can use for Windows like the one in the video, I don't use Mac which i think those programs work in.

 

[cybertron]

Another alternative if your current project is over budget, is an inverse trans-axle. The motor is placed at the bottom center, attached to it is a parallel gear (at 0dg.) A second gear placed perpendicular to the right of the first gear. The main gear turns counter clockwise. The second gear turns a screw, where a third one (gear and screw) is placed parallel (facing the opposite direction). Both screws turn the same direction perpendicular to the motor or drive shaft, to form the main axle. Attached to each axle is a cable that pulls each door open or closed, both at the same rate and in equal and opposite directions. To be more specific the two main axels are attached, such that the counter clockwise drive rotates both axles clockwise, pulling the doors open.

This might not work do to the space that the motor must be place in.
Can you show a 3d drawing of this alternative option.

All suggestions, ideas, and help is greatly appreciated. thank you.

 

[nvn]

As for the flat bar, what do you think I would need in size and thickness? ... In your post 68 drawing, what is that part in the lower, right-hand corner? I don't understand the part. Please explain.

cybertron: Don't worry about sizes just yet. You are not ready to select stock sizes. The view shown in the lower, right-hand corner of my post 68 diagram is a bottom view of the linkage bars shown above it in the side view. This gives you two views (side view and bottom view) of the connection at point B. All of my parts (in the post 68 and post 14 diagrams) are inside the square tubes, except for a portion of linkage bar AB, which passes through slots in the long and short square tubes, as stated in post 39. The motor in post 68 is also outside. Unlabeled views on a drawing are called orthographic views[/color] (orthographic projections).

 

[tyroman]

cybertron,

In your post #72 you say;

"I don't know what you mean or indicating about post 53."

Here is what I mean...
In your post #53 you attached a sketch titled;
"End on view area to work.png 1.PNG"
On that sketch you have the following notes;
"This area is what I have to work with."
Next to that note is a long line with arrows at each end. It is labled;
"18" long space is length of the 18" tube".
Another shorter line with arrows at each end is labled;
" 2" space"

Also look at your post #56 where you say;
"Yes the mechanism and motor that I use must fit in the 2''x18'' limited space."

Now look at the "Plan view B.PNG" sketch I attached to my post #71. The only space on that sketch which is not PINK is the 2"x18" space between the mechanism and the wall. What I need you to do is either confirm or correct my understanding that no part of the mechanism or motor can be in the PINK space shown on "Plan view B.PNG" attached to my post #71.

 

[nvn]

The image I posted in post 60 was grossly simplified, because it has the pins (points A and D) collinear with the hinge and square tube face. In reality, these two pins are offset from the square tube face. Now that I am taking a quick look at the actual configuration, with accurate dimensions and accurate pin offsets, I am currently unable to get both doors to open to the same angle at the same time using the post 14 design. If there is a solution that makes both doors open at the same rate and to the same angle, I have not been able to find it, in a matter of minutes, using the asymmetric post 14 concept.

I am starting to think we may be required to use a symmetric design.

 

[cybertron]

cybertron,

In your post #72 you say;

"I don't know what you mean or indicating about post 53."

Here is what I mean...
In your post #53 you attached a sketch titled;
"End on view area to work.png 1.PNG"
On that sketch you have the following notes;
"This area is what I have to work with."
Next to that note is a long line with arrows at each end. It is labled;
"18" long space is length of the 18" tube".
Another shorter line with arrows at each end is labled;
" 2" space"

Also look at your post #56 where you say;
"Yes the mechanism and motor that I use must fit in the 2''x18'' limited space."

Now look at the "Plan view B.PNG" sketch I attached to my post #71. The only space on that sketch which is not PINK is the 2"x18" space between the mechanism and the wall. What I need you to do is either confirm or correct my understanding that no part of the mechanism or motor can be in the PINK space shown on "Plan view B.PNG" attached to my post #71.

The 2''x18'' is the area that's left where I must place the motor and where the rack & pinion mechanism will be placed and attach to the long tube.My tubular lifter is in the that space already.
My post in 53 is showing you indicated by the arrows that the 2''x18'' is the space where the motor and the rack & pinion mechanism will be placed in. The lifter is in that space too but what's left is an area of 2''x18''

Right! There should be NO pink area from the tubular lifter to the wall this is where the motor,rack&pinion mechanism and the lifter. In post 71 you have the lifter tube hindden in the pink area. which it shouldn't be.

If you can Picture two leaf style cellar doors that open from hortizonal to vertical there should be nothing blocking that area to enter.

 

[cybertron]

tyroman

I edit post 71 to show you what the top view would look like if you were looking down at the two door.

As you can see you have the tubular lifter than the mechanism then the left-over space which would now be 1-1/4'' from the mechanism to the wall.

As stated in post 53 and 80.

The pink area ENDS where the tube lifter begins.As indicated in edit image.

 

[tyroman]

nvn,

I think it is less important to cybertron that the doors move "exactly" in unison than it is that the motion of the mechanism begins with both doors at 0 degrees and ends with them in a 90 to 100 degree position... can you find a way to position the A and D connections and adjust the length of links A-B, B-C and C-D to make this work? Perhaps have the A and/or D connection(s) made at a "crank" attached to the short tubes (see attached "nvn's links.PNG" sketch).

Also, since cybertron's earlier clarification that the mechanism does not have to be "inside" the long tube and that the long tube will be installed "with a 1-1/2'' spacer under the tube", there is more vertical room to position your mechanism if you attach it to the side of the long tube rather than inside.

Mounting the motor as you have described (off the end of the long tube) may be unacceptable to cybertron (based on the 2"x18" work space)... but I think this can be solved with your design if the motor is connected to a right-angle drive
see:
http://www.torquetrans.com/right-angle-gear-boxes/miniature-right-angle-drive.htm
http://www.torquetrans.com/right-angle-gear-boxes/images/ra202_figure_1.jpg
or bevel gear:
http://www.qtcgears.com/KHK/newgears/KHK230.html

which is then connected to a pinion mounted on the side of the long tube. The pinion would mesh with teeth on the edge of your link B-C (which would be made from a rack of appropriate length). See sketch "door-mechanism-05 (with motor).png" attached. This would also be the way to motorize the double rack and pinion design if that is the way cybertron decides to go.

Again, I believe your design will be stronger and simpler than the double rack and pinion design... if we can make yours work.

 

[nvn]

tyroman: I tried about ten different ways, so far, and could not get both doors to end in the range 90 to 100 deg. But I will continue trying all of your new suggestions (or any others you may think of) over the next several days, to see if I finally get lucky and find a combination that works. I'll let you know as soon as (if) I find something that works.

 

[cybertron]

tyroman

I just want to know if the two doors don't open in unison how would both doors open exactly at 90 and 100dgs. And close at the same time at 0dgs.

If one door starts to open,then the other door follows 20dgs behind how would both doors
reach 90 0r 100dgs exactly. I would think one would be at 90 the other door would stop at 70dgs or less. That would be unacceptable.

Now if both doors start opening from 0dgs in unison both doors will stop exactly at 90 0r 100dgs went motor stops at that angle.This is how they must open. If they don't one door could block the entrance at a predetermine angle and that's not good.

They must open in unison to close in unison so either door does not block the entrance do to the small foot print of the opening.

 

[cybertron]

tyroman


In post you also showed nvn in the first image how the door are attached to the short tubes,They are not attached there.

The two doors sit at the 1-1/2'' spacer level sits. I did not indicate at all that the doors would sit on top of the shorter tubes nothing can go on top of the shorther tubes,But There will be a bend piece of metal that will be attached to the top of the shorter tubes bend at a 90dg angle then 3'' down then bend at another 90dg angle then attached to both doors. I stated this in my post in 67. The two doors sit at the wooden base level,not on top of the shorter tubes.I showed you in post 82 how the tube would look from a top view. Because the two doors sit at the woodenbase level or floor level. I did state in post 67 that a piece of bend metal will accommodate for the 3'' heigth difference do to where the two doors sit. They do not sit on top of the shorter tubes.

 

[nvn]

I have not been able to get both doors to end anywhere near the range 90 to 100 deg using the asymmetric post 14 concept. Therefore, as mentioned in post 80, I am starting to think you may be required to use a symmetric design.

 

[cybertron]

I have not been able to get both doors to end anywhere near the range 90 to 100 deg using the asymmetric post 14 concept. Therefore, as mentioned in post 80, I am starting to think you may be required to use a symmetric design.

Ok, So the concept for that propose mechanism in post 14 will not work at all, what was the reasons for not getting the doors to 90dgs,was it the limited space or other factors of the design. And using an optional motor.



As for a symmetic design will this concept work, and will it work in such a small area with the optional motor as mentioned.

 

[nvn]

The main reason the post 14 concept does not work is due to the asymmetric mechanism geometry.

I have not worked on a symmetric design much, myself (except for posts 7 and 10).

 

[cybertron]

Tyroman

Is your mechanism design concept a asymmetric as nvn concept in post 14 or is your concept symmetric as nvn proposes that a symmetric design will be needed.

Will your concept as proposed work also.

 

[cybertron]

What about something like this? Not to scale.

nvn

In this design concept as proposed in post 10 is there a way for this to work in the small limited space that i have and using my motor that's been mentioned in this thread with the concepts that already been stated and suggested by you as well as tyroman suggested with right angle gears and rack parts.Is there any other combinations that you could come up with in this concept that can work in my project do to the limited space and geometryand getting the doors to open and close at 0-90dgs.
In post 67 i increased the height with a 1-1/2'' spacer to compensate for the rack and pinion that tyroman advised,So I have now about 3'' from the wooden base to the top of the shorter tube to give some more height to the area.

I hope you have not given up on me just yet! But i do Apperciate all the time you have given to me on the mechanism design and to this thread.

 

[nvn]

Something might be workable. I might investigate a symmetric version of something somewhat similar to posts 68 and 10.

 

[cybertron]

nvn

OK.That seems knid of interesting meshing post 10 and 68 into in someway.

I looked at the space much closer, if the motor that i will using is placed length wise as indicated in post 82 that will limit the lenghts space from 18'' to 14'' deducting 3'' for the motor that's including the shafts length on the motor, (plus 1/2'') on each side for any variances for adjustment that's tight,So if you keep or place the motor like in post 82 that would be OK ''but, there will only be 14'' left for any placement of a symmetric mechanism concept in that area but you will have the 3'' in height do to the added spacer as indicated in post 67.

Maybe the parts that tyroman suggested could help with the symmetric design where it could fit and will work.

 

[nvn]

I now found a solution using my asymmetric post 14 design concept. The attached video file, below, shows how the mechanism works. Study this file to see how linkage bars AB, BC, and CD move. In this video, I rotate the left-hand door 100 deg, which causes the right-hand door to rotate 101.4 deg. You can make the image repeat in your viewer by selecting Play > Repeat, or View > Loop. The support blocks for linkage bar BC are shown at points E and F in my post 14 diagram.

For the design shown in the attached video, the (x, y) coordinates, in mm, of points A, B, C, and D when the doors are at 0 deg (closed) are A(17.00, 25.40), B(164.83, 0.00), C(414.83, 0.00), D(477.00, 0.00). The coordinate system origin is located on the left-hand end of the long square tube, at the tube longitudinal centerline. The linkage bar lengths (from pin centerpoint to pin centerpoint) can therefore be computed from the above coordinates, and are |AB| = 150.00, |BC| = 250.00, and |CD| = 62.17 mm. The long square tube is 460.00 mm in length.

The drive mechanism for this design is shown in the attached .png file, below. The .png file shows a side view of the mechanism, and a partial bottom view.

See all my previous posts for a detailed description of this design. All of my parts are inside the square tubes, except for a portion of linkage bar AB, which passes through slots in the long and short square tubes, as stated in post 39. The motor is also outside.

Notice in the video, the brown plate at point D interferes with the bottom face of the long square tube. Therefore, you might need to cut a slot in the long square tube if the brown plate interferes, unless a refinement in the exact dimensions (such as adding the hinge thickness, etc.) resolves the problem. The above coordinates currently assume coincident tube faces, as shown in the video. I.e., no allowance is currently given in the above coordinates for hinge thickness, because an exact hinge thickness in mm has not yet been given.

 

[cybertron]

nvn.

Will this design solution work and function as stated, is this the finished design. Can I start asembling the mechanism.

Also I'M not do sure about where these two number indicator at.Please explain!
When the two doors are in the 0deg closed position, on the x y corrdinates for point A these two numbers 17. 00 and 25.40 are placed where on the shorter tube.

As for the flate bar material what do you think i would need in size and thickness because you didn't not state this for in side the tube.

I did find on-line Alumimum flate stock and steel, sizes 1'',1/2,3/4'' 5/8'' wide and for the thickness 0.05'' 3/16'' or 1/8''. what material would be the way to go steel or alumimum.

In post 68 and 94 in the drawing this part in the low bottom right.Please explain.

What is the brown plates dimensions was not mentioned.

I'm assumming the thinkness for the hinges is appox .2'' 0r 1/16'' have not purchased any hinges yet.

 

[nvn]

cybertron: No, the design concept is not finished yet. Let's first try waiting for three or four days to see if tyroman has comments.

 

[cybertron]

cybertron: No, the design concept is not finished yet. Let's first try waiting for three or four days to see if tyroman has comments.

OK. I will wait

 

[tyroman]

nvn & cybertron,

My comments will be brief.

Nvn, have you done any calculations to establish the forces which components of the mechanism must withstand? Do you believe that cybertron's motor will be powerful enough? (see my post about the free body diagram).

cybertron, as I understand nvn's design, manual operation and motorized operation of the doors are not independant. In other words, if the doors have been opened by the motor, they can not be closed by hand (distinct from use of a hand crank which you rejected when I suggested the worm-drive design). The motor (or a crank) will have to be used to close them. Are you OK with that?

In general, nvn's design appealed to me when I learned that the doors weigh 10 pounds each. This is because his simpler design had an advantage over the rack and pinion design since it would allow larger (stronger) components within the limited space available (about 3" from bottom to top). However, if his current design is installed inside the 1" square tube, that advantage is lost.

Lastly, for cybertron, I'm confused that you seem OK with the parts of nvn's design which occupy space in the "off-limits" area which you have defined. Neither the motor nor the link attachment point at "D" are within your 2" x 18" work area.

 

[nvn]

tyroman: I have not investigated nor considered motor power in any way. Yes, I did a very preliminary calculation of linkage bar axial force for the post 94 mechanism. Neglecting hinge thickness, neglecting short square tube self weight, neglecting hinge friction and friction at support blocks E and F, and assuming a door weight of 44.48 N, I got a very preliminary maximum linkage bar axial force of 409 N tension, and 332 N compression. These are the maximum axial forces in linkage bars AB, BC, and CD. The maximum axial force in linkage bar HB would be close to 409 + 332 = 741 N tension, neglecting the aforementioned items. In the future, if I have time, I will assume and implement a hinge leaf thickness of 2.10 mm (total hinge thickness, 4.20 mm), which may slightly alter these force values.

 

[cybertron]

tyroman

I assumed that nvn design could be opened by handcrank, hand manually and motor stated in his design as well as with a the motor. If his post 14 revised design cannot be open or closed by hand but only with a motor, if that's the case, is it because the mechanism is on the inside of the long tube or will it work if the mechanism was on the outside of the longer tube or is it the limited space available.The 18''

Also by looking closer at nvn revised 14 design I don't think there would be any room for the motor if the mechanism is located inside the 18'' long tube and that would be the entire length of the tubes space. How would a motor fit and work if the motor was to be inline with the 18'' long tube this would extend that length to 21'' plus, which dose infringe on the off-limited space as you stated tyroman. I do see this.

tyroman Yes i did reject the hand crank. Reason for this was stated in one of the post i posted. Security, Time it takes to open the doors with a handcrank and anoption to use a motor. Now looking closer at the space that's available
18'' in length there's only 2'' in he width for a Handcrank to turn if it sits an the bottom of the woodbase and inline at the end of the long tube.

If nvn can made the mechanism that he revised that's inside the longer tube and includes the motor, But dose not extend the mechanism length into the off-limit space and can made the doors open and close by hand as well with the motor but off-sets the position of the motor to the side of the 18'' long tube, would this work.

If the doors cannot be opend or closed by hand or with a motor independantly then a motor would be used to open and closed the doors.

Tyroman Is there a way to use nvn design on the outside of the long tube and have it open independantly by hand but without a so call handcrank mechanism. I did like what you suggested by using bevel gears to move the bar in nvn design is there a way to still make that work in nvn revised #14 design.

Also. i need a design that dose not use any custom forged parts. All parts must be off the shelf readly available.


The motor that i have can lift 75 in lbs meaning it can lift 75lbs to 80lbs maximum and hold it one inch up from the front of the Box do to the high gear ratio this was stated by the vendor where i purchased the motor from.

Is your rack and pinion design still being work on. I still need a mechanism to construct.

 

[tyroman]

cybertron,

I have attached a sketch made from a snapshot of nvn's first animation and one of his motor drive sketches. Two areas are highlighted with GREEN to indicate the parts of his design which would be in the "off-limits" area, outside of the 2"x18" area you have established.

As I understand your last post, you did not realize that the motor would be in the off-limits area and you now want to know how nvn's mechanism could be motorized differently. What about the other location (at link CD) where the mechanism is "off-limits"? If this is NOT acceptable, then nvn's entire concept may have to be re-thought and the exercise of re-designing its motorization could be wasted effort.

Please consider the above and decide what is acceptable to you.

If you decide that link CD being off-limits is acceptable and still want to know if the motor could be made to work within the 2"x18" area in some way; my answer to that question is a qualified NO. This is because, with the linkage BC INSIDE of the long 1" tube there would be very little room for a gear to be driven by your motor. If nvn can re-design his mechanism to be mounted OUTSIDE of the long 1" tube, then YES the motor might be easily connected. This is up to you and nvn.

Note; CAPs above are for emphasis... not a shout.

PS; in future, I suggest you print out the sketches posted by nvn or me and take the drawing to your nearest auto mechanic or hardware-man so they can help you understand what the sketch is showing.