Author Topic: Jacob's Ladder  (Read 14721 times)

Offline b.lindsey

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Jacob's Ladder
« on: March 10, 2013, 01:32:25 PM »
Despite not having much time lately to work on the Wright Bros. engine, I have still had to be in the shop at work a lot to supervise the project prototypes going on this time of year and wanted a small project I could spend even a few minutes on here and there between answering questions and helping the students. One such project had been in the back of my mind since our engine show last fall...a fellow had build a Jacob's Ladder out of wood with a hand crank and using marbles to "climb" the steps. At the time I thought it could be adapted to metal and scaled down to be run from one of my larger compressed air engines. At the same time, I had always wanted to do something with a Geneva Cam mechanism and this seemed a good application for that, replacing the hand crank in the one i had seen at the show.

The basic design is a series of 10 steps operated by a simple cam from underneath, with the cam driven by the geneva mechanism on one end. I chose to scalel it down to a size using 1/4" steel balls instead of marbles, but think it  could be scaled to even half that size.

I have taken a few pictures along the way, not really a detailed build log but more to show the various aspects of how it works. Those will follow in the posts below.
« Last Edit: March 10, 2013, 02:19:06 PM by b.lindsey »

Offline b.lindsey

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Re: Jacob's Ladder
« Reply #1 on: March 10, 2013, 02:06:27 PM »
First up I cut the blanks for the 1/4" x 1" wide steps overcutting each lengthwise



Then i set the vise to mill the top  angle on each step, still leaving the overall length longer than needed for later trimming the flat bottoms to the exact length for each step




After the top angle and length were machines the steps looked like this, however i realized that I had intended to angle the tallest step in a secondary direction to faciliitate ball return so that one had to be remade.




The tallest step is shown below with both angles cut even though the side to side angle shows up more clearly.




This final picture shows the final step along with the one just preceeding it in the ladder....again the side to sidei angle was intended to help the balls feed into the return hole in the intermediaite side plate.


« Last Edit: March 10, 2013, 02:19:26 PM by b.lindsey »

Offline b.lindsey

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Re: Jacob's Ladder
« Reply #2 on: March 10, 2013, 02:16:57 PM »
With the steps done, I cut and milled to size the two end plates and the back plate and the rough layout looks something like this.



Each of the two end plates were then drilled for the 5-40 screws that would secure the main frame parts together and tapped ...a total of 8 holes per piece, four each on the front and bac side.



The holes in the next picture on the lower half of each end plate were drilled and reamed for the addition of bronze bushings for the 1/8" cam shaft


chuck foster

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Re: Jacob's Ladder
« Reply #3 on: March 10, 2013, 02:34:48 PM »
looking good bill, this little set up should have lots of eye candy  :ThumbsUp:

chuck

Offline b.lindsey

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Re: Jacob's Ladder
« Reply #4 on: March 10, 2013, 02:49:42 PM »
The next task was the intermediate side plate on the near side which finished enclosing the steps but with the addition of two angled holes, one adjacent to the top step at its highest position and the other adjacent to the lowest step at its lowest position...simply providing an exit and reentry point for the balls to recirculate. To get the angle, I figure the required height difference from one end of the plate tot he other and made a riser from a scrap piece of aluminum to raise the elevated end. Since the two holes were at equal angles but reversed directions the other hole was drilled the same way but with the riser block under the opposeite end.



Then the outer sideplate on the near side was machined to size, bolt hole pattern drilled and a trough milled out on the back side to provide a chute for the balls to travel down from the top hole to the bottom in the previously described part. This was roughed out with only the two end machined to a specific depth from the top of the piece to match the hole locations in the intermediate plate.



The vise was then set at the proper anlce to clean up the bottom of the chute as shown in the following picture.


Offline Don1966

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Re: Jacob's Ladder
« Reply #5 on: March 10, 2013, 03:05:52 PM »
Gee! When you put your mind to a project, you don't waste any time Bill. I had just read you first post. I am curious to see this one complete.

Don

Offline b.lindsey

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Re: Jacob's Ladder
« Reply #6 on: March 10, 2013, 03:20:03 PM »
With the main "box" done I turned my attention to the geneva cam mechanism which would drive the cam shaft and lobes raising and lowering the steps in alternating fashion.

The "driver" part of the mechanism was turned on the lathe first



I then transferred it over to the mill to locate and drill/ream a hole for the 1/8" pin for driving the other part of the cam.



This was set aside for a bit to get to the same point on the "driven" half of the mechanism...turning the outer dimension then milling the 4 slots for the driving pin to engage.



With that done, the back side was faced off to the final thickness needed.




Offline b.lindsey

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Re: Jacob's Ladder
« Reply #7 on: March 10, 2013, 03:21:07 PM »
Bear with me Don, just taking some time to post everything up.

Bill

Offline b.lindsey

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Re: Jacob's Ladder
« Reply #8 on: March 10, 2013, 03:28:44 PM »
To finish the two parts of the geneva cam, a couple of simple fixtures were needed for the rotary table. These are shown in the next photo, the upper fixture is for the brass "driver" part and the lover one for the "driven" part. The two pins locate the face between the slots for milling a radius in the correct position and the part can then be indexed to each of the four faces that need that radius. The 3/8"-16 SHCS is for securing each fixture to the threaded center hole of my Sherline RT. In the upper fixture a spacer had to be added underneath the part so it's diameter would clear the top of the SHCS.



The next picture shows milling the four sides of the "cross"

« Last Edit: March 10, 2013, 03:31:56 PM by b.lindsey »

Offline Bearcar1

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Re: Jacob's Ladder
« Reply #9 on: March 10, 2013, 03:29:49 PM »
This, is going to be way cool! 8)  I *think* I see where you are going Bill, but am anxious to see the final result anyway. These sorts of Rube Goldberg types of things have always been fascinating to me both in there form and their simplicity. (Although the later can be debated at times  :o )


BC1
Jim

Offline Chris J

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Re: Jacob's Ladder
« Reply #10 on: March 10, 2013, 03:30:20 PM »
Gee! When you put your mind to a project, you don't waste any time Bill. I had just read you first post. I am curious to see this one complete.

Don

I'm curious to know what it is  :facepalm:
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Offline b.lindsey

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Re: Jacob's Ladder
« Reply #11 on: March 10, 2013, 03:35:01 PM »
Thanks guys, I'm getting it posted as fast as i can :)


Offline b.lindsey

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Re: Jacob's Ladder
« Reply #12 on: March 10, 2013, 04:10:56 PM »
A short note here on the geneva cam mechanism. I chose to use one with four index positions, although most any number can be used given shanges tot he sizes and geometries of the driver disk and driven disk. One can imagine that a 12 position cam would have a larger driven disk and a much smaller driver disk.  There is some information and videos one these if you google "geneva cam."  At any rate I chose a 4 index position for two reasons...one to act as a speed reducer....4 revolutions of the driver disk for each 1 revolution of the driven disk...and two, to provide a pause or dwell time at each position, mainly to allow time for the steel balls to exit when the top step reaches it maximum height and again when the lowest step reaches its lowest height to allow balls to re-enter.

OK...that said, it was on to making the lobes for the camshaft that will lift and lower the 10 steps. I cut and faced to a fairly precise length, 10 pieces of 1/2" dia bronze. They were then transferred to a set up in the mill to drill/ream the offset hole in each one as shown



As to assembling them on the camshaft, the first one was loctited onto the shaft and allowed to set. The arrangement is such that each alternating lobe is 180 degrees apart from the next. The second lobe was added then and my caliper jaws used to orient it such that they lined up 180 degrees out of phase.



Once these two were fixed, I could lay the assembly donw on a flat surface and add the remaining ones, butting each up against the next and alternating their ipositions. The final assembly is shown below as it fits inside the main box.


Offline Chris J

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Re: Jacob's Ladder
« Reply #13 on: March 10, 2013, 04:16:20 PM »
Thanks guys, I'm getting it posted as fast as i can :)

It looks fabulous, whatever it is  :)

Great photography, what are you using ?

Chris
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Offline b.lindsey

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Re: Jacob's Ladder
« Reply #14 on: March 10, 2013, 04:45:51 PM »
These last three photos may help show how this will work.  The first and second photos show the cam with the steps installed in the two extreme positions positions. At each position different pairs of steps match up at their top angles allowing the balls to in effect roll downhill to the next step to the right, and at the same time going higher and higher up the ladder as each successive pair of steps match.  At 1" width for each step there can be up to 4 balls across on every other step ascending up the ladder. The final picture shows the geneva cam end though without the intermediate and outer side plates for the ball return arrangement.

I will note here that a little fiddling had to be done to the bottom of the steps to allow enough clearance for them to fall via gravity into the area between the lobes to either side. Likewise, the 1/4" steel balls don't have enough mass to traverse or skip over any mis-match from one step to the next so a little caareful filing had to be done there also just on the highest part of each step's angled top. 

That said it does work well so far. There are a couple of additions I want to make...a couple of feet for the while thing to sit on and an acrylic top so as to keep everything inside the box. The balls as well as the steps will fall out if turned upside down !! I also want to sand the outside so that all the various plates match up seemlessly just for appearance sake.  I will get it all assembled again this afternoon and try to take a short video.






Offline ScroungerLee

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Re: Jacob's Ladder
« Reply #15 on: March 10, 2013, 04:50:21 PM »
That is looking great.  I particularly like the use of the Geneva crank, it adds even more eye candy.  Looking forward to a video I am!

Lee
Mmmmm.... Shiny!

Offline b.lindsey

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Re: Jacob's Ladder
« Reply #16 on: March 10, 2013, 04:51:18 PM »
Chris, maybe those last pictures will explain is more, at least until I can make a video later today.  As to the camera it is a simple Canon PowerShot SD1200 IS which I have had for a few years now. Its a pocket sized point and shoot which has served me well and takes nice close ups too.

Bill

Offline arnoldb

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Re: Jacob's Ladder
« Reply #17 on: March 10, 2013, 05:36:06 PM »
 ;D Seriously cool project Bill  :ThumbsUp:

I'm looking forward to the rest.

Kind regards, Arnold
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Procrastination is nearly the same, but it precludes machining.
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Re: Jacob's Ladder
« Reply #18 on: March 10, 2013, 06:59:33 PM »
I made one of these in wood a while back, fun but a bit noisy after a while ...  :-X  Been meaning to make a marble pump as well but not got round to it!

Offline zeeprogrammer

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Re: Jacob's Ladder
« Reply #19 on: March 10, 2013, 08:24:25 PM »
I caught this at work today but couldn't see any pictures (good old IT policy). Marked the post as unread so I'd find it as soon as I got home. (Didn't need to. Lots of interest here.)

Looking forward to the video. Very neat project!
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Offline Don1966

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Re: Jacob's Ladder
« Reply #20 on: March 10, 2013, 09:11:11 PM »
OK Bill, I now understand what you are doing. I will be watching for the video. That is just to cool!  :ThumbsUp:

Don

Offline b.lindsey

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Re: Jacob's Ladder
« Reply #21 on: March 10, 2013, 09:58:34 PM »
Working on uploading the video now but youtube is painfully slow !!! Another half hour or so and i should have it :)  Thanks for the interest. Zee...what you doint working on Sunday man? Don't these people know you need family and shop time :)

Bill

Offline b.lindsey

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Re: Jacob's Ladder
« Reply #22 on: March 10, 2013, 10:57:02 PM »
OK, here is the video if I pasted the correct code. Thanks again for the interest everyone.


Offline swilliams

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Re: Jacob's Ladder
« Reply #23 on: March 10, 2013, 11:23:50 PM »
Great project, write up and video Bill.

Steve

Offline b.lindsey

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Re: Jacob's Ladder
« Reply #24 on: March 10, 2013, 11:38:55 PM »
Did the video work Steve? It isnt for me but could be because i am on the phone rather than computerb.

Bill

Offline zeeprogrammer

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Re: Jacob's Ladder
« Reply #25 on: March 10, 2013, 11:52:23 PM »
The video worked great and was well done.
Very neat project Bill.

I had to add it to my list of 'nifty gift ideas'
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Offline Don1966

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Re: Jacob's Ladder
« Reply #26 on: March 10, 2013, 11:52:52 PM »
Awesome Bill! I love it..... A great weekend project. Nice video also.

Don

Offline Walsheng

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Re: Jacob's Ladder
« Reply #27 on: March 10, 2013, 11:55:46 PM »
What an absolutely futile endeavor.
And I love it!  I just put it up high on my build priorities.
Nice job and nice video.

John

Offline Chris J

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Re: Jacob's Ladder
« Reply #28 on: March 11, 2013, 12:28:59 AM »
Great video.

It's an executive toy  :pinkelephant:
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Offline b.lindsey

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Re: Jacob's Ladder
« Reply #29 on: March 11, 2013, 12:41:25 AM »
Well as soon as i make a few correction to the drawings and design the feet for it, I'll be happy to post them in the plans section if anyone wants.
Thanks for all the comments. Needless to say it took more than just this weekend but probably don't have more than 30 hours in it ovreall, so its still a rather small project.

Bill

Offline swilliams

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Re: Jacob's Ladder
« Reply #30 on: March 11, 2013, 12:42:37 AM »
Video worked for me too Bill  :cartwheel:
You're going to start a craze on building these  :Lol:

Steve

Offline b.lindsey

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Re: Jacob's Ladder
« Reply #31 on: March 11, 2013, 12:54:27 AM »
I like John's description...a futile endeavor it is for sure...but it knocked a couple of things off my list of "want to do's" I think the kids will like it at the shows too...it should be relative indestructable and can still be easily turned by hand.

Bill

Offline Bearcar1

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Re: Jacob's Ladder
« Reply #32 on: March 11, 2013, 01:51:42 AM »
That will most assuredly be a huge hit for the kids at shows, Bill. Even some of the adults too, at least the younger-at-heart individuals. Any drawings you do would sure go a long way towards the beginning of building a better mousetrap.  :noidea:


BC1
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Offline Pete49

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Re: Jacob's Ladder
« Reply #33 on: March 11, 2013, 03:11:46 AM »
Great stuff.... everyone needs a time just to be a kid again and this is a fun way to do it.  :ThumbsUp:
Pete
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Online Kim

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Re: Jacob's Ladder
« Reply #34 on: March 11, 2013, 04:01:00 AM »
Bill,
That is such a cool little contraption!  I love it!  I think I'm going to have to build one of those someday too.
Thanks for sharing your work with us!
Kim

Offline vcutajar

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Re: Jacob's Ladder
« Reply #35 on: March 11, 2013, 10:49:27 AM »
Just saw the video.  What a wonderfull toy Bill. :NotWorthy: :NotWorthy:

Apart from making the top cover transparent how about making the side where the balls climb up also transparent so one can see it working from the side and also see the cam.  Just a suggestion.

Vince

Offline b.lindsey

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Re: Jacob's Ladder
« Reply #36 on: March 11, 2013, 10:57:30 AM »
Thanks Vince.  I have thought about a clear back plate for greater visibility just as you mention. It would be easy enough to do since that plate is just rectangular with 8 counterbored holes for the SHCS's that mount it to the two end plates. I may give it a try yet. My only concern is how the clear acrylic or Lexan would wear with the steps riding up and down against it, but only one way to tell and that is  to try it. I suppose even if that was a problem, one could occasionally pull the back plate off and repolish the inner surface.  Acrylic will for sure buff out very nicely as I have tried that before. Thanks for an excellent suggestion!!

Bill

Arbalest

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Re: Jacob's Ladder
« Reply #37 on: March 11, 2013, 11:10:37 AM »
You don't need to enclose it. Most of the others I've seen only had one side but you don't even need that:

<a href="https://www.youtube.com/watch?v=eLh8DtltHK8" target="_blank">http://www.youtube.com/watch?v=eLh8DtltHK8</a>

Offline zeeprogrammer

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Re: Jacob's Ladder
« Reply #38 on: March 11, 2013, 11:16:34 AM »
I was wondering the same about using a clear back as well as the probable wear on it.
How about keeping it clear from just above the ladder? Cut at an angle to follow the stairs?
That would minimize the wear and you could get a good view to the inside.

I thought it would be neat to see the ball return too. But instead of clear plastic...maybe just a slot too small for the ball to pass through but big enough to see the ball pass by?

I just saw Arbalest's post. Also a possibility.

I'm seriously thinking of this as a gift. I'd like to make it smaller though. And I would have it enclosed so the player doesn't have to worry about losing anything. I think Bill, you mentioned plans? I'll be interested.
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Offline Chris J

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Re: Jacob's Ladder
« Reply #39 on: March 11, 2013, 11:19:35 AM »
Thanks Vince.  I have thought about a clear back plate for greater visibility just as you mention. It would be easy enough to do since that plate is just rectangular with 8 counterbored holes for the SHCS's that mount it to the two end plates. I may give it a try yet. My only concern is how the clear acrylic or Lexan would wear with the steps riding up and down against it, but only one way to tell and that is  to try it. I suppose even if that was a problem, one could occasionally pull the back plate off and repolish the inner surface.  Acrylic will for sure buff out very nicely as I have tried that before. Thanks for an excellent suggestion!!

Bill

I wonder if actual glass would be better material than perspex ?
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Arbalest

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Re: Jacob's Ladder
« Reply #40 on: March 11, 2013, 11:25:36 AM »
Here's another.

<a href="https://www.youtube.com/watch?v=5Ip2lbifl2o" target="_blank">http://www.youtube.com/watch?v=5Ip2lbifl2o</a>

Arbalest

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Re: Jacob's Ladder
« Reply #41 on: March 17, 2013, 02:12:19 PM »
Just received this link, one of them includes a stair type lifter.

http://woodgears.ca/marbles/paul.html

 

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