Author Topic: The Grasshopper Escapement revealed  (Read 61495 times)

Rick from Manchester

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Re: The Grasshopper Escapement revealed
« Reply #15 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

Rick

Dave

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Re: The Grasshopper Escapement revealed
« Reply #16 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

Offline BrianC

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Re: The Grasshopper Escapement revealed
« Reply #17 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).
BrianC

Offline millerdlca

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Re: The Grasshopper Escapement revealed
« Reply #18 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

Offline BrianC

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Re: The Grasshopper Escapement revealed
« Reply #19 on: June 06, 2008, 06:28:45 PM »
That's what I thought, except the numbers didn't quite match.

Thanks.

BrianC
BrianC

Offline BrianC

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Re: The Grasshopper Escapement revealed
« Reply #20 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
BrianC

Offline jrbeall

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Re: The Grasshopper Escapement revealed
« Reply #21 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.

Offline BrianC

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Re: The Grasshopper Escapement revealed
« Reply #22 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

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.
BrianC

Dave

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Re: The Grasshopper Escapement revealed
« Reply #23 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

Offline BrianC

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Re: The Grasshopper Escapement revealed
« Reply #24 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
BrianC

Dave

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Re: The Grasshopper Escapement revealed
« Reply #25 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

Offline BrianC

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Re: The Grasshopper Escapement revealed
« Reply #26 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
BrianC

Offline BrianC

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Re: The Grasshopper Escapement revealed
« Reply #27 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

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

BrianC
BrianC

Dave

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Re: The Grasshopper Escapement revealed
« Reply #28 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

Offline BrianC

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Re: The Grasshopper Escapement revealed
« Reply #29 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
BrianC