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Rotary to Reciprocal motion
5

Rotary to Reciprocal motion

Rotary to Reciprocal motion

(OP)
Does anyone know a mechanical way to convert rotary motion to reciprocal motion withen a confined space?

RE: Rotary to Reciprocal motion

It's called a crankshaft.

RE: Rotary to Reciprocal motion

or sometimes called a crank-slider mechanism...  there's also the rack & pinion.

RE: Rotary to Reciprocal motion

Also of interest is the Scotch Yoke. Many good links by Googling.

0

Best regards,

Matthew Ian Loew
"I don't grow up. In me is the small child of my early days" -- M.C. Escher

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

RE: Rotary to Reciprocal motion

Scotch Yoke, isn't that the same as a Cardan-gear?
http://www.flying-pig.co.uk/mechanisms/pages/cardan.html

Ray Reynolds
"Computers in the future may weigh no more than 1.5 tons."
Popular Mechanics, forecasting the relentless march of science, 1949
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?

RE: Rotary to Reciprocal motion

Ray,

Not the same, but very cool!

Best regards,

Matthew Ian Loew
"I don't grow up. In me is the small child of my early days" -- M.C. Escher

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

RE: Rotary to Reciprocal motion

Ray,

Thanks for that link. Neat pages there. The Reciprocator mechanism brought back some nice memories from university (it was a lab exercise for CAD in SDRC I-DEAS 4!)

0

Best regards,

Matthew Ian Loew
"I don't grow up. In me is the small child of my early days" -- M.C. Escher

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

RE: Rotary to Reciprocal motion

of course, when they say "worm gears are a compact, efficient means of substantially decreasing speed and increasing power" you should take it with a grain of salt (they meant ...increasing torque).

RE: Rotary to Reciprocal motion

Allright, Mloew, out with it!
How are you attaching those fine images?

RE: Rotary to Reciprocal motion

I use much of the TGML functionality. Click on the Process TGML link below and make sure you have the tick-box marked. Please use the preview option before posting to make sure you got it right!

Best regards,

Matthew Ian Loew
"I don't grow up. In me is the small child of my early days" -- M.C. Escher

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

RE: Rotary to Reciprocal motion

(OP)
I should have specified that the rotary motion has to stay constant one direction and the reciprocating stroke length is 5 ft. long.

RE: Rotary to Reciprocal motion

heidt,

That statement does not change anything. The crank-slider, Scotch Yoke, rack-and-pinion, and Cardan-gear mechanisms can all take a constant rotational speed and convert this motion to a stroke of a certain dimension assuming you have room to package the mechanism. All except the rack-and-pinion will have a fundamental relationship requiring the diametric dimension of the joint on the rotating member to be equal to the stroke. The physical package space will always be greater than this. The rack-and-pinion packages much more elegantly.

Best regards,

Matthew Ian Loew
"I don't grow up. In me is the small child of my early days" -- M.C. Escher

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

RE: Rotary to Reciprocal motion

(OP)
Can I do any of these inside a 3 inch pipe.

RE: Rotary to Reciprocal motion

Heidt,

Possibly a rack-and-pinion could be packaged in that space. How is it that you are a mechanical engineering professional and so unaware of these mechanisms?

Best regards,

Matthew Ian Loew
"I don't grow up. In me is the small child of my early days" -- M.C. Escher

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

RE: Rotary to Reciprocal motion

(OP)
We have tried all the basic mechanisms and can't make them fit into our space requirements. New inovative ideas would be appreciated.

RE: Rotary to Reciprocal motion

Have you looked at a level-wind mechanism such as found on a baitcaster fishing reel?

- - -Dennyd

RE: Rotary to Reciprocal motion

Dennyd,

I did some Googling with the keywords level-wind mechanism to learn more about this. Is this really (reely? To be punny about it) just a large reduction worm-gear and sector?

Best regards,

Matthew Ian Loew
"I don't grow up. In me is the small child of my early days" -- M.C. Escher

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

RE: Rotary to Reciprocal motion

how about making internal threads on your pipe, and "corkscrewing" it one way or the other?

RE: Rotary to Reciprocal motion

Matthew,

It has some similarity, but it is actually a special form of a cam and follower.  I've used it before for a design of an ultrasonic probe that gets shoved where you don't want it, but the client chose his own design instead.

Heidt,

Perhaps if you provided more detail about the design goals we'd be able to give better suggestions.

- - -Dennyd

RE: Rotary to Reciprocal motion

3" diameter and a 5ft stroke... sounds like a perfect application for a lead screw/ball screw/ACME screw device.

Ray Reynolds
"Computers in the future may weigh no more than 1.5 tons."
Popular Mechanics, forecasting the relentless march of science, 1949
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?

RE: Rotary to Reciprocal motion

MLoew (anecdotal)
I am sure glad you have two guides on the scotch yoke.  I have some test papers where my father drew the yoke with only one guide.  The note returned with the drawing cautioned him about having two guides (best) or one longer one, not more than 2d of the shaft. He lossed 20 points on the drawing.  He was also advised to study the chapter on the yoke and always consider all the inputs on design.
circa. 1925

RE: Rotary to Reciprocal motion

Maybe the solution is changing the basic concept, why not use an hidraulic piston, you can make it fit inside the 3" diameter tube, you can make it 5' long with no problem and you can adjust speed easily, power will be higher than any mechanical device you can use and you can also use neumatic power if your power need is low, the motor will allways turn the same direction driving the pump/compressor and the only drawback is the whole mess of controls, hoses and devices requiered, but it could be an alternative.

Cheers,

SACEM1

RE: Rotary to Reciprocal motion

Can you use something like a screw jack or ball screw where you turn the screw/shaft to move the follower in a fashion to push a hollow piston.  This would be similar to the worm and pall (fishing reel).  
There is another type of traverse mechanism that uses only a twisted rod and follower.  Turn the rod and follower advances.  
The followers have to be made with a antirotation device.

RE: Rotary to Reciprocal motion

Heidt,

I can see from your profile that you are a new member.  Welcome to the fourm.  However, in order to give you a proper answer, we will need more complete information about your application.  As you can see, members have already devoted a lot of time to posting answers that are all over the map due to the lack of sufficient detail to work with.

Give us the details, and I am sure we can give your problem a real go.

rmw

RE: Rotary to Reciprocal motion

MadMango,
Sorry I missed your post I think this is the way to go if he could reverse the rotary motion.  This brings into play the worm and pall as posted by Dennyd.  We had traverse mechanisms, but the longest I've ever seen is 24".

I'm try to find heidt a picture of the twisted bar.
It is similar to the child’s toy were you push down and the top spins.

RE: Rotary to Reciprocal motion

Heidt,
The 3 inch pipe and 5 foot length would suggest a pair of pulleys with a drive belt / chain.  It would depend if there is an amount of power that you need to transmit, or is it the position that needs to be the function.  Besides the many v-belt and rubber belt products, there is a precision metal belt available, www.belttechologies.com , from a company with laser cutting / welding expertise.  They use precision laser cutting to form pattern of drive holes in metal strip to make belts of almost any length.  A clip weld attached to the belt would provide the linear motion. The 5 foot length would not be a challenge for the metal belt.   You did not mention if there was a liquid inside the 3 inch pipe.  The metal belts are usually stainless steel, but could be of other alloys for corrosion resistance.  The thickness / width of the metal belt would be one of the limiting factors for power transmission.   

RE: Rotary to Reciprocal motion

heidt,
It appears that we assumed that axis of the rotary motion must be perpendicular to the  linear motion.  Is this correct or can the axis be in some other orientation?
Parallel, concentric?
Griffy

RE: Rotary to Reciprocal motion

Descriptions of the push drills (Archemedian spiral) and screwdriver patents can be found here...

http://www.idcomm.com/personal/cfales/intro.htm

I've seen ad copy for an industrial version of the bait casting reel's level wind mechanism.  Seems like the perfect solution for this problem.  Self reversing, compact and fits into the package as described.  Someone else must remember the company name?

RE: Rotary to Reciprocal motion

All screw solutions and its derivatives, be them arquimides screws, twisted rods, helical cut groves, recirculating ball screws and rack & pinnion have the same requierement they have tu turn one way to go to one side and the other way to return, and that is not possible as been stated by HEIDT on the 27th so we have to fit a way of inverting the movement in a simple way with the motor allways turning the same direction.

I am thinking that using a simple or multiple lead screw with its nut turning alternatively one direction or the other by means of a friction disk clutch could do the trick.

Think how a friction press works, it has a central disk wheel that drives the nut and it is propelled by two perpendicular friction disks allways turning the same direction, one on each side of the center disk wheel, they come in contact one or the other with the edge of the center disk wheel and depending on the side that makes contact the ram (screw) goes in or out.

Hope it helped

SACEM1

RE: Rotary to Reciprocal motion

sacem1,

I don't agree.  You can have helical cut grooves where the helix angle reverses at each end.  The helix angle likely must be between 30 and 60 degrees to allow the follower to cross grooves successfully.  I've seen this in application somewhere a long time ago but I can't remember what it was.  Perhaps someone else has seen this?

RE: Rotary to Reciprocal motion

Here is a picture of a traverse mechanism that would turn around if the motion was all in one direction.
The turnaround groove is the essential part of the mechanism.
 
http://www.hoistandwinch.com/ourtech.htm

RE: Rotary to Reciprocal motion

strokersix - a Yankee drill?

Cheers

Greg Locock

RE: Rotary to Reciprocal motion

I have a Stanley Yankee Handyman screwdriver - same idea. Funny you don't see them much anymore - used to be very common in the fifties and sixties - developed initially for production lines - but have been supplanted by electric and pneumatic screwdrivers.

RE: Rotary to Reciprocal motion

Yes, Unclesyd's link is what several of us are thinking of... this type of levelwind mechanism self-reverses and could be contained within the cylinder described, IMO.

The follower or shoe rides in a helical groove cut in such a manner as to reverse axial travel at the end of the stroke without changing rotational direction.

The company I referred to earlier was Norco/Flennor.  I may have been mistaken about the self-reversing feature of their product, however.  Still, the product used followers positioned in helical grooves to obtain large linear travels from relatively small rotational input.  Probably worth talking to them...

RE: Rotary to Reciprocal motion

heidt,

The levelwind mechanism I mentioned earlier seems to have gathered some support.  I have one I modeled in SolidWorks several years ago.  It is not to your scale but it could be a good starting point.  The beauty of this mchanism is that it has a constant direction input, a smooth and quick direction reversal, and a (typically) uniform traverse speed.  It is also very compact, but it does involve some geometry that folks aren't familiar either designing or manufacturing.  The link provided by unclesyd should be a good starting point if you are really interested in this mechanism.  A Skotch Yoke or similar mechanism will usually have a sinusoidal output for a constant input.  What do you need?

As others have mentioned, you have a wealth of creative, experienced and willing contributors to this forum and this thread has grown long.  You need to help us help you by giving more specifics of the problem you are trying to solve.

- - -Dennyd

RE: Rotary to Reciprocal motion

Adding to the post by Dennyd the mechanism is quite simple to make but becomes interesting to say the least in the design.  The ones we used had all different traversing profiles, such as slow, speedup, slowdown, pause. All our traverse mechanisms were designed and built in house on a combination tracer and hydraulic milling machine.  In most our mechanisms the worm was case hardened steel, the pall was made of nylon covered steel or bronze, the shoe had bronze bushings, some allowed a small adjustment pall position.  All operated essentially 24/7/365 with very few problems.  

I was checking on the design parameters when I was made aware that the designer, retired in 1990, of all the traverse mechanisms on site, sadly is in a nursing home.  
No one at the site has his design expertise and his files and books were cleaned out because it was deemed he had nothing of value since he was a self taught machine designer and I might add a good one.
  
There should be current information on design as they are still used in some textile industry and as noted in the winch industry in place of fairleads.    

Here is a better picture of different type cams.
Also note that they are called differents names.

http://www.kedacorp.com/cylindrical%20cams.htm

Anecdotal:
The book he used for traverse mechanisms was small with a reddish cover and gold leaf edges on very thin paper pages, it looked like the old Audel Handbooks.

RE: Rotary to Reciprocal motion

I propose we stop all the work until we know how much power has to be used, propelled or what ever with this device as we are all trying to put the tail to a donkey not only blindfolded but without knowing if there is even a donkey around.

Cheers,

SACEM1

I agree with strokersix just wonder if enough power can be transmited with so long a lead on the screw.

RE: Rotary to Reciprocal motion

A roller chain or cable can do a similar action as a rack and pinion. What type of load is being moved?

RE: Rotary to Reciprocal motion

Hi Guys-
New member, first post:
What does the follower of a LevelWind Cam look like?
Can a levelwind work in high speed / High load applications with the right design?
Can a LevelWind Cam be used in low pressure angle desing i.e. <30deg?
Really would love to see a 3D design of a LevelWind and Follower!!

THANKS for All the Help!!

RE: Rotary to Reciprocal motion

Pharoah72,
It called a pawl and has end cut to the radius of curvature of the inside dimensions of the worm or cam.  They can be any length as long as it will pass over a slot without stopping or trying to enter the slot. The width is determined by load and amount of play that is acceptable.

Checkout this website.

http://www.kedacorp.com/cylindrical%20cams.htm

RE: Rotary to Reciprocal motion

Ok, I'm not sure whether my suggestion has a name for it or whether it's mentioned. My suggestion is to use a long threaded rod with the pitch travel you wanted per revolution. Add a coupling at one end so that a motor can be attached directly or through a step down. Next, put a piece of metal with a threaded hole that mates with the rod. Restrict the rotation movement of the metal piece but not linearly.

Regards

RE: Rotary to Reciprocal motion

How about a Geneva machanism? they are simple to make and will do the job. I recently saw one on an automatic pancake making machine. It was great!

RE: Rotary to Reciprocal motion

Isn't a Geneva mechanism more for indexing

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