Author Topic: Radial Vector Tool...  (Read 28211 times)

Offline jltrent

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Radial Vector Tool...
« on: November 16, 2010, 06:02:48 PM »
Have been dabbling on and off with building a wooden geared clock, and along the way crafted a software tool to assist in generating radial vectors (ie, gears, escape wheels, ratchet wheels, snail wheels, etc) for the purpose of cutting the parts on a CNC machine (in particular, the CarveWright / Compucarve).  Based on resources found on this forum, included in the tool among other profiles is the ability to generate the grasshopper escapement per Guy D Aydlett's well written paper, along with cycloidal gears using the module method.

I've been in the software business for many years and don't wish to turn my woodworking hobby into another job, so am offering this software tool as freeware (with all its warts) in the event that others might find it useful.  The core application is written in VB6, and in order to make it easily extensible, the individual radial profiles are generated via VBScript.  [This also permits scrutiny of the mathematical algorithms used to generate the various profiles.]  Currently it will export the rendered profiles in the following formats:  BMP, Adobe Illustrator, and SVG.  In the case of the Adobe Illustrator format, this can be converted into CarveWright / Compucarve Designer files (MPCs).

Note:  The software tool is attached to this post as a ZIP file, and has been scanned with Symantec v11.0.6005.562.  It appears that you must login in order to see and download the ZIP file.

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Sept 2011 (v1.3):  Updated tool, with two primary fixes:

* Incorporated capability to input parameters in either Inches or Millimeters.  Note that the output files (SVG and AI format) all make use of points (ie, 72 points / inch).

* Accommodated the European standard of using the "," as a decimal separator.  (This is determined through the Regional settings of Windows.)

« Last Edit: February 24, 2017, 05:29:57 AM by jltrent »

Offline Ya-Nvr-No

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Re: Radial Vector Tool...
« Reply #1 on: November 20, 2010, 06:23:00 PM »
Nice job, Thanks

Any chance the source is available?

Also:
Have you seen
http://gearotic.com/downloads.html

Offline pcstru

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Re: Radial Vector Tool...
« Reply #2 on: November 28, 2010, 07:32:16 AM »
I've been in the software business for many years and don't wish to turn my woodworking hobby into another job, so am offering this software tool as freeware (with all its warts) in the event that others might find it useful.  

Thank you very much - it looks very useful indeed!

Offline jltrent

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Re: Radial Vector Tool...
« Reply #3 on: December 01, 2010, 04:59:56 PM »
Any chance the source is available?

For the time being, I prefer to keep configuration control of the source code.  If there are any specific techniques that I've employed that you're interested in, please PM me, and I'll point you in the right direction.

Offline pcstru

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Re: Radial Vector Tool...
« Reply #4 on: December 05, 2010, 07:04:07 AM »
Two questions. 1. Is the grasshopper shown with the pendulum dead center? 2. Can anyone suggest settings for a grasshopper which keeps the arc small, the pivot point of the pendulum in line with the escape wheel AND yet still manages to have short legs (i.e. the pendulum pivot isn't 8 inches away from the wheel center?

Oh and again, nice work. Thankyou.

Offline jltrent

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Re: Radial Vector Tool...
« Reply #5 on: December 05, 2010, 09:57:08 AM »

In answer to Q1:  Per the attached JPG, the tool will generate the cut path for the grasshopper escapement, and also provide the wire frame for the critical points and lengths of the pallet arms and pallets.  Although the Pendulum Pivot in the resulting drawing is not dead center (ie, straight above the escape arbor), as I understand it, there's nothing prohibiting one from moving the Pendulum Pivot point anywhere around the escape wheel, as long as the critical lengths and angles are maintained.

In answer to Q2:  There's a couple of parameters that one can adjust to shorten the legs: smaller escape wheel Radius is one quick way to shorten the legs... smaller pallet Span... larger Pendulum Arc.  Or a combination of the three.  Of course, adjusting some of these might bring on other challenges, such as smaller pallet nibs, which will call for more exacting tolerances...

Offline pcstru

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Re: Radial Vector Tool...
« Reply #6 on: December 07, 2010, 01:29:00 PM »
Thank you for the reply. Q1 - what I mean is, is that the configuration of the wireframe with the pendulum hanging straight down, rather than at the extreme of the swing. What I'm trying to work out is where the stops should be. Also for a 3 deg swing, is that 3deg either side of the straight down or 3 deg total arc (1.5 deg each side)?

I didn't realise I could rotate the whole frame - that solves the aesthetic of hanging the pendulum off to the side!

I've played with the params but haven't got anything as compact as I'd like. I guess that's just a downside of the grasshopper although This suggests I could do better, or perhaps use two escape wheels like this or more traditionally this.

Offline jltrent

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Re: Radial Vector Tool...
« Reply #7 on: December 07, 2010, 08:17:52 PM »
From my limited grasshopper experience, the Entry, Exit, and Pendulum Pivot Points are of course fixed relative to each other, but at the Pendulum Pivot point, the Pallet Crank Arms and Pendulum are adjustable relative to each other.  In other words, view the grasshopper and pendulum as separate components, but on the same arbor at the Pendulum Pivot point, with both components adjustable on the arbor to provide for a balanced Entry and Exit Pallet action.  Once satisfied with the balance, the Pallet Crank Arms and Pendulum are then fixed in place on the arbor.  This is how I designed and adjusted my first grasshopper.  (It was a prototype "vertical gear stack" clock that I never finished, but could get to run for a few hours.)  The pallet stops, of course, were attached to the Pallet Crank Arms, yet adjustable relative to the Pallet Arms.  (Refer to Guy Aydlett's paper for the terminology.)

On the clock I'm working on now, I'm attempting to combine the grasshopper and pendulum all in a single component, which in effect (I believe) is a compound pendulum.  This is forcing the need for adjustable counter balances on the pendulum to permit the adjustment of the balance between the Entry and Exit Pallet action.  (Ie, I shift weights around to get the compound pendulum to lean a little further to the left or right which alters the balance between the Entry and Exit Pallets.)  This is still "work in progress", and time will tell whether this will ultimately function, although I feel confident it will once I lengthen the pendulum.

As to the pendulum arc, by my calculations (based on Guy Aydlett's paper posted in the Grasshopper section), it represents half the swing.  Ie, a 3 deg pendulum arc will swing a total of 6 deg.  That being said, in practice I haven't measured this on my initial grasshopper to confirm this, and at the moment, don't have ready access to do so...
« Last Edit: December 07, 2010, 08:22:44 PM by jltrent »

Offline pcstru

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Re: Radial Vector Tool...
« Reply #8 on: January 30, 2011, 10:54:54 AM »
http://www.youtube.com/watch?v=sH2BXEamxwk

First ticks of a grasshopper escapement based clock. Grasshopper and gear geometry from the radial vector tool supplied by jltrent (beginning of the thread).

Seems to work well. Again, many thanks.

Offline jltrent

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Re: Radial Vector Tool...
« Reply #9 on: February 10, 2011, 07:12:10 PM »
Glad to hear that the tool worked out for you, and that you were able to figure out what I was trying to convey in my previous post!  The grasshopper you designed has nice clean lines, and an overall pleasing appearance.  Noticed you posted another video of a working prototype of the entire clock.  Looks good!


Offline pcstru

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Re: Radial Vector Tool...
« Reply #10 on: February 19, 2011, 09:55:19 AM »
Final ... very very nearly finished clock.





@jltrent - for your radial vector tool - is there any chance you could increase the number of teeth you can specify in a gear? I'd like to try a clock with a huge gear.
« Last Edit: February 19, 2011, 09:59:20 AM by pcstru »

Offline jltrent

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Re: Radial Vector Tool...
« Reply #11 on: February 19, 2011, 03:56:07 PM »

Nice clock!  The oak frame really gives it that finished look.  Nice accents at the top, and with the pendulum too...

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With respect to increasing the number of teeth specified in a gear, all the VB scripts are editable.  Simply go to the "RadialScripts" folder, and open up the "Wheel and Pinion via Module Method.ws" file in Notepad.  Look for the following line:

        validate = (16 <= Nw and Nw <= 128)

Simply change the upper limit of 128 to whatever you desire.  (I now notice that I inadvertently throw the following error if you've specified too many wheel teeth, "invalid Number of Pinion Teeth", when I should actually have indicated "invalid number of Wheel Teeth".)  Save the file, and then restart "Radial Vector Generator v1.2.exe".

As a test, I just upped the limit to 400 myself, and generated a pinion-wheel pair of 20-400.  The program sat there and took some time, but generated the pair nonetheless...

Offline pcstru

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Re: Radial Vector Tool...
« Reply #12 on: February 20, 2011, 07:57:32 AM »
Worked a treat. Thanks.

Dave

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Re: Radial Vector Tool...
« Reply #13 on: February 20, 2011, 11:52:46 AM »
Sorry to be the bearer of bad news but the layout is wrong, the long pallet should be vertical to the wheel teeth, have a look at Mr Beales bow clock and see what the layout should look like, regards Dave

Offline pcstru

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Re: Radial Vector Tool...
« Reply #14 on: February 21, 2011, 02:09:19 AM »
Sorry to be the bearer of bad news but the layout is wrong, the long pallet should be vertical to the wheel teeth, have a look at Mr Beales bow clock and see what the layout should look like, regards Dave

Why? Effectively the whole escapement has just been rotated so the fulcrum (is that the right word?) is in line with the rest of the arbour centres. I don't really see what would necessitate the long pallet to be vertical, it's pushed into the wheel by the stop so no gravity issues and ... well, it works.