The Beall Clock Forum

General => The Grasshopper escapement => Topic started by: jrbeall on September 04, 2005, 08:42:46 AM

Title: The Grasshopper Escapement revealed
Post by: jrbeall on September 04, 2005, 08:42:46 AM
OK,  now it is available.  Here is the place to go to get everything you need to know about designing your very own grasshopper escapement.  This monoghaph is 18 pages of PDF file.  I scanned it in yesterday and uploaded it to my server.  http://www.bealltool.com/pdfs/Grasshopper0001.pdf

This paper was given to me many years ago by John Economacky of Bridge City Tools.  It has served me well.  I don't know when it was written but I do know that Mr Aydlett is no longer living.  I hope you will find it as useful as I have.
Title: I almost started dancing
Post by: JayRay_Hughes on September 04, 2005, 06:59:29 PM
Downloaded it, read it. Need to read it again, but that definitely will simplify the process for me. Answered some questions I hadn’t asked yet and I think some I had. I need to sit down and do some CAD work and see if it all works out. Also, CAD work helps me get it.

I will see if I can get the math stuff in Excel, and post for everybody to use. This may take me a little bit.
Title: Where were you when I needed you?
Post by: rabbit on September 24, 2005, 01:27:53 PM
Where were you when I needed you?
I designed and built my first grasshopper several years ago. (It and five subsequent g'hoppers are running flawlessly still.)
I had looked EVERYWHERE for information and found pitifully litle useful technical data with which to design an escape mechanism. So, knowing how it worked, and from photograhs of existing examples, I "reverse engineered" my own adaptation. Miraculously, it worked quite well. (I know now how forgiving even a poorly-designed grasshopper is!) My second and subsequent models were further refinements, based on what I'd learned.
This article is excellent! It would have saved me years of trial-and-error. To my surprise, I've gone back and analyzed my previous designs, and by #2 I'd arrived at the correct geometry!
One funny point is the need for the long pallet nibs as a safety against accidental run-down. I experienced this fate on the first model when rewinding about the second time. After destroying an escape wheel, I improvised my own version of a "safety", and by #3 arrived at the long nib solution.
So my advice to anyone wanting/willing to tackle this design: this article is the way to go. There are a lot of subtle variations and techniques that can be derived from other examples, but the explanations and calculations for the geometry are right-on.
Title: The Grasshopper escapement
Post by: Helmut Reinhardt on November 08, 2005, 12:36:52 PM
I thought I died and gone to heaven when I saw your Bow 2 operate. It took me back to 1994 when I saw Jim Borden's works on display at the NAWCC HQ in Columbia, PA. Function and beauty taken to their highest level. After reading about John (Longitude) Harrison in the late 1970's, I joined NAWCC in 1980, hoping to find a dimensioned drawing of the Grasshopper somewhere in the literature. I soon found the April 1972 issue of the NAWCC BULLETIN (Whole Number 157) which contains the entire article of Guy D. Aydlett's article, "The Anatomy of the Grasshopper". In all the intervening years, I tried to build a working model, but my skills as an amateur wood-crafter so far have failed me. I keep trying.
In NAWCC Bn. #161, Dec. 1972, Aydlett gave some info on other clocks he was building, and in NAWCC Bn. 196, Oct 1978, he wrote about  "A Wooden Works Month Clock", giving tooth counts and other vital dimensions.
Title: The Grasshopper Escapement revealed
Post by: Dave on June 03, 2007, 05:00:00 PM
I have made a smaller version using brass and steel with the info provided, i had great issues with trying to fit a gravity tail on the exit pallet, there was just not enough space, i resorted to fitting a dog leg extension which cured the problem. I have since found that the 90deg layout did not work with my clock, i must have made a mistake with the maths, i cured it by rotating the yoke counter clockwise one tooth space and reset the controller arms, the clock works fine now, Dave
Title: The Grasshopper escapement
Post by: Rick from Manchester on June 05, 2007, 02:15:58 PM
Here's a Grasshopper Escapement video I found http://www.youtube.com/watch?v=rluQpoV8638

And...

Harrison inspired sea clock with dual balance grasshopper - if you don't mind Meccano http://www.youtube.com/watch?v=z-Gl66PoShE  Someone needs to do this in wood!
Title: Re: The Grasshopper escapement
Post by: Dave on June 06, 2007, 01:57:08 PM
Quote from: "Rick from Manchester"
Here's a Grasshopper Escapement video I found http://www.youtube.com/watch?v=rluQpoV8638

And...

Harrison inspired sea clock with dual balance grasshopper - if you don't mind Meccano http://www.youtube.com/watch?v=z-Gl66PoShE  Someone needs to do this in wood!

Hi Rick, i hope to post 2 vids of my grasshoppers on youtube in the coming weeks, just have to wait while my son finds some time to work his camera. I plan to post my experimental clock as well, warts and all, its rough cut at the moment but the whole clock is just an experiment to see if the maths work, as stated earlier, i got the maths wrong but pulled the project back because i have over 20 years with this escapement and could correct the faults on a practical level. These sort of problems only strengthen my admiration for Harrison who made this escapement from scratch, how he came up with the idea will never be known, Dave
Title: The Grasshopper escapement
Post by: Rick from Manchester on June 07, 2007, 04:22:24 PM
Dave,

Excellent! We can't wait to see your clocks in motion, please let us know the moment you get them up there.  Video opens up a whole new dimension.

Rick.
Title: The Grasshopper Escapement revealed
Post by: Dave on June 11, 2007, 01:42:35 PM
Hi Rick, well i have tried 4 times to upload to youtube without success, i tried this morning and was told that the forum was processing the information or something like that, i decided tonight to delete the vid and was told that there was nothing to delete!!! I have tried again and will see what happens, computers, you just have to love them, Dave
Title: The Grasshopper Escapement revealed
Post by: Dave on June 13, 2007, 02:54:43 AM
Its up and running on youtube, not the best clip in the world but will do for now, its not as loud in person though otherwise it would be moved to the hallway, type in grasshopper escapement to view, Dave
Title: The Grasshopper Escapement revealed
Post by: jrbeall on June 13, 2007, 10:04:05 AM
One of those grasshopper escapement, with a double escape wheel is from Smiths plans.  He has a shop manual for building that clock which is very good.  Looks like a lot of people are interested in grasshoppers.
Title: The Grasshopper Escapement revealed
Post by: Dave on June 13, 2007, 12:47:11 PM
I used to have one of Bill Smiths designed grasshoppers in my shop window in the mid 80s, always a crowd puller. I have found over the years that his escapement design is excellent and will run a first try if made to the specs, it also lends itself to scalling up or down on the calculator which is good news for a designer. I have placed my experimental clock on youtube which uses the information given on this forum by Mr Beall, many thanks, Dave
Title: The Grasshopper escapement
Post by: Rick from Manchester on June 14, 2007, 02:14:23 PM
Dave,

WOW -- Your grasshopper is extraordinary delicate - beautiful work.

Seeing your videos http://www.youtube.com/watch?v=lDJvzg3J1mM has made my day -- well worth the wait!

I think I remember seeing still photos of your regulator few years back (2003? -- don't remember which site), while it was still under construction.

Keep up the good work.

Rick.
Title: The Grasshopper Escapement revealed
Post by: Dave on June 15, 2007, 12:44:23 PM
Hi Rick, thanks for the kind words, much appreciated, i used my own camera for these but hope to post better/clearer images with my sons camera, my first try at the experimental clock clip was a laugh, an ice cream van started blaring out music in the next street so had to be deleted, the next one has the resident blackbird in full song. You might have seen the pics of my clock on my own website, i had to give it up due to health probs but i still manage to potter around the workshop some days, regards Dave
Title: Re: The Grasshopper Escapement revealed
Post by: Dave on July 18, 2007, 01:25:49 PM
Hi Rick, just thought you might like to know, my experimental H1 clock is now on youtube, i am no good with links so type in experimental H1 will take you there. You will see the rough treatment that i give to the clock and it still runs, after all Harrison designed this for sea use, regards Dave
Title: Re: The Grasshopper Escapement revealed
Post by: Rick from Manchester on July 20, 2007, 02:49:41 AM
Dave,

Remarkable!  Even though it's known that the Harrison sea clock design is meant to keep going under the roughest of external motion, it's amazing to actually see it being demonstrated -- never missed a beat -- that's one tough little sea clock you got there!.  Beautiful design and execution, and a remontoire too -- you really know your Grasshoppers! Thanks for sharing it with us, and keep up the good work, can't wait to see it all fitted out.   If anyone wants to see Dave's experimental H1 clock in action, check it out here http://www.youtube.com/watch?v=nJRa7vZqHJo (http://www.youtube.com/watch?v=nJRa7vZqHJo)

Rick
Title: Re: The Grasshopper Escapement revealed
Post by: Dave on July 20, 2007, 08:23:55 AM
Hi Rick, glad you enjoyed the demo and thanks for supplying the link. They look so delicate but as you have seen they aint, theres a long way to go with the clock and many new parts to make but at least it is running, regards Dave
Title: Re: The Grasshopper Escapement revealed
Post by: BrianC on June 05, 2008, 05:13:20 PM
In Grasshopper0001.pdf, on page 261, the formula for BF is "BF = R1 tangent2 alpha", now I know my math was never good to begin with and it's gotten worse over the years, but, what is tangent2?  I Googled it and didn't get anything that made sense.
Hint for a faster response; I'm working on a stand-alone database that will compute all the variables used in the article, with the article in clean printable electronic form (except for the photographs - but including some of the drawings).
Title: Re: The Grasshopper Escapement revealed
Post by: millerdlca on June 05, 2008, 08:53:01 PM
If you look carefully at the text in the pdf, you'll notice that the 2 is in a smaller font and above the baseline - it is an exponent. The function tan2 alpha is the same as (tan alpha)2.

Dennis
Title: Re: The Grasshopper Escapement revealed
Post by: BrianC on June 06, 2008, 06:28:45 PM
That's what I thought, except the numbers didn't quite match.

Thanks.

BrianC
Title: Re: The Grasshopper Escapement revealed
Post by: BrianC on June 09, 2008, 07:32:02 PM
Ok, I'm happy with the files, now how do I list them here?  I could up-load the zip file to my web space but I'd rather have them reside here, if possible, you never know when you could lose the files if they were stored elsewhere.

jrbeall, would it be possible to have them here?

BrianC
Title: Re: The Grasshopper Escapement revealed
Post by: jrbeall on June 10, 2008, 05:00:23 AM
Brian,  Yes of course we can have them here though I don't know how you want them held.  We may have to ask the web master about that.
Title: Re: The Grasshopper Escapement revealed
Post by: BrianC on June 22, 2008, 03:02:30 PM
Here's a link to a Zip file that contains:

An MDE database that can compute all the formulas in grasshopper0001.pdf - it's stand-alone so you don't need a program to run it.

An Excel 2000 file that does essentially the same thing as the MDE, but also has a (very simple) graph of the escapement.  Note that this may require MS Excel 2000 or newer.

An RTF version of grasshopper0001.pdf - it's not exactly the same but it's close (and I added a few  small bits, too).  You can open this with most word processors and be able to search or modify as you wish.  Some of the drawings are scanned from the PDF and a few were re-drawn (this is where I added a few bits :-[) for better clarity.

A text file describing all the files in the zip.

If you un-Zip them to the same directory then you can open the MDE, XLS and RTF files from inside the MDE and XLS files.

http://home.comcast.net/~brian.slater/Grasshopper/Grasshopper.zip (http://home.comcast.net/~brian.slater/Grasshopper/Grasshopper.zip)

Corrections & comments cheerfully accepted.

BrianC

By-the-by, I'm designing a wooden grasshopper 8 day with double pendulum and (hopefully) will be able to post (or link to) pictures - sometime before 2009 - it's starting to look quite nice IMHOP.
Title: Re: The Grasshopper Escapement revealed
Post by: Dave on June 23, 2008, 03:44:18 AM
Hi Brian, i tried to access your zip file but it didn't work for me (at the moment), probably my lack of computer skills, thanks for posting though. Have you and pic's of your new clock and also any details of the twin pendulum escapement, my sea clock has an escape wheel of 4 inches diameter (60) teeth and the pendulum arbors are 5 1/2 inches apart, i am more than willing to scrap my pallet assembly's and start again if any new information comes along, regards Dave
Title: Re: The Grasshopper Escapement revealed
Post by: BrianC on June 23, 2008, 05:13:58 PM
What part didn't work?  If you're having trouble getting it into your computer, try this - right-click on the link and then select "Save Target As" and save the Zip file to your desktop.  While it's downloading, make sure the "close this dialog box when download completes" box is NOT checked.  When it finishes downloading click on the "Open" button in the dialog window.  Then you should be able to run the included files right from there or un-zip the file to your documents directory.

My double-pendulum is, I think, not quite what you think - it's a non-driven pendulum that will swing the opposite of the driven one and thereby reduce the (Newtons third law) movement of the clock frame.  For this wall clock it'll be more of a decoration, but at one time was used to increase accuracy - you wouldn't believe some the things they did to get better accuracy on pendulum clocks.

BrianC
Title: Re: The Grasshopper Escapement revealed
Post by: Dave on June 28, 2008, 12:36:42 PM
I should have said that i did download your file but i was unable to access the right hand columns for some reason, i will try your suggestion and see if things improve. How do you feel about taking on Harrison's chordal pitch gearing, i have 2 pdf files but don't have the maths skills to get to the information, Dave
Title: Re: The Grasshopper Escapement revealed
Post by: BrianC on June 28, 2008, 02:33:26 PM
If it is the MDE, the two right-hand columns on the first row are read-only as they are computed from the other figures.  You should be able to access them for cut-and-paste purposes, but they are not modifiable.   :-[ Sorry, I didn't remember to format them the same as the ones below, I'll have to fix that.

 BrianC
Title: Re: The Grasshopper Escapement revealed
Post by: BrianC on June 29, 2008, 04:19:20 PM
I've updated the MDE file, although the address is still the same so you'll want to download it again:
http://home.comcast.net/~brian.slater/Grasshopper/Grasshopper.zip (http://home.comcast.net/~brian.slater/Grasshopper/Grasshopper.zip)

Harrison's chordal pitch gearing?  More math?  Arrrrrgh, no, please, no, not that.  Seriously, this seriously exceeded what little math I can remember.  After all, 1 + 1 = 10, yes? 

Bi the way, the clock I mentioned, well the design is almost finished.  Thinking out side the box, although it's based(2) on the grasshopper, I saw no reason to have either of the pallet arms horizontal and made both of them vertical - from underneath.  Here's a sketch of it, the colors are just so I could see the different parts not what it will look like:
http://home.comcast.net/~brian.slater/Grasshopper/Grasshopper Clock.jpg (http://home.comcast.net/~brian.slater/Grasshopper/Grasshopper Clock.jpg)

BrianC
Title: Re: The Grasshopper Escapement revealed
Post by: Dave on June 30, 2008, 12:14:52 PM
Thanks for your help Brian. I see your clock frame is based around the Fleur De Lis?? a nice design, i look forward to seeing some pics of the beast. I have a couple of metal projects to finish then onto my first wooden clock, i have always liked the contrast between Mahogany/Walnut and brass, so i will have to design something with these elements in mind, regards Dave
Title: Re: The Grasshopper Escapement revealed
Post by: BrianC on July 19, 2008, 08:50:44 AM
I've updated all the files in my grasshppper.zip file:
The MDE and the XLS now contain all the variables and formulas in the article.  Also, I found that I had left out the pendulum arc formula; that has now been rectified and both files now include testing to see if your desired arc matches and suggestions on how to make it match if it doesn't.
The XLS file has an accurate graphic of the escapement that can be used to layout the pivot plate.
The RTF has been replaced with a MS Word 2000 Doc file, sorry, the RTF version was just too big.
The photos taken from the PDF file have been replaced with images scanned from the ORIGINAL!  Yep, I found the original :) at The American Clock and Watch Museum, Bristol, CT and MORE, I believe the models used in the article are there - at least they look just like them - sadly they are gathering dust in the upstairs storage area with many other beautiful items.

The address is the same:

http://home.comcast.net/~brian.slater/Grasshopper/Grasshopper.zip (http://home.comcast.net/~brian.slater/Grasshopper/Grasshopper.zip)