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91
I just found a program at geargenerator.com that looks like it could be used to model the entire gear train of a clock.  You can add ad many gears as you like.  All the parameters for each gear can be specified including which gears are on the same axle and which other gear it connects to.  It also animates the rotation at any speed you like.  The only thing missing is the escapement.

Steve

Here is a model of my clock design gear train using geargenerator.com.  Hopefully, the link will come through.  It includes all the parameters for 10 gears.

http://geargenerator.com/#60,60,60,10,1,9,40356.23543000015,10,1,10,1,10,20,0,0,0,50,5,10,20,-45,1,1,10,1,10,20,-90,2,0,50,5,10,20,0,3,1,12,1.2,10,20,0,4,0,48,4.8,10,20,-120,5,1,12,1.2,10,20,0,6,0,48,4.8,10,20,-90,7,1,15,1.5,10,20,0,8,0,45,4.5,10,20,-90,0,0,2,-2292

Gear 0 is attached to the 18 tooth escapement.  It rotates once every 36 seconds with a 1 meter pendulum.
Gears 0 to 1 have a 5:1 ratio, so gear 1 and 2 rotate once every 3 minutes.
Gears 2 to 3 have a 5:1 ratio, so gear 3 and 4 rotate once every 15 minutes.
Gears 4 to 5 have a 4:1 ratio, so gear 5 and 6 rotate once per hour.  This drives the minute hand.
Gears 6 to 7 have a 4:1 ratio, so gear 7 and 8 rotate once per 4 hours.
Gears 8 to 9 have a 3:1 ratio, so gear 9 rotates once per 12 hours.  This drives the hour hand and would be placed over the axle for gear 5.  The diagram shows it below to keep the diagram uncluttered.

Steve
92
That is the same way I created gears in TurboCad.  There are a few gear profile generators out there.  I used the version from woodgears to generate the basic profile, then imported the image to TurboCad and re-generated half of a tooth to array into a full gear.  This created a cleaner profile.  The original output from woodgears was made with thousands of tiny line segments.  I simplified each tooth into a few basic arcs.  Each tooth is going to be sanded, so the profile only needs to be reasonably close to a perfect involute or cycloid shape.

I just found a program at geargenerator.com that looks like it could be used to model the entire gear train of a clock.  You can add ad many gears as you like.  All the parameters for each gear can be specified including which gears are on the same axle and which other gear it connects to.  It also animates the rotation at any speed you like.  The only thing missing is the escapement.

Steve
93
General Discussion / Re: Inertia
« Last post by steve323 on March 10, 2016, 09:03:09 AM »
Clock designs have always fascinated me.  I had a wind up alarm clock as a kid and used to take it apart just to figure out how it worked.  I have a few books describing clock design and construction.  Most are reprints originally written in the 1800s and early 1900s.  They all describe the same concepts because all clocks are operating on the same basic principles.

I like many of Clayton's designs.  If you spend the time to make the clock by hand, then it should look unusual.  I wouldn't want someone to look at one of my clocks and think that they could buy a similar looking clock at Walmart for $50.

Steve
94
I would agree.  This learning why and how and what goes into a clock (to me) is hard.  There are days I'm discouraged and just kind of let it sit.  Then there's days when I have an "Uh Ha" moment and it's thrilling.  So... Maybe someday I'll get this all figured out and get something that actually keeps time build and working.  I plan to make the Woodline clock this spring and summer once it warms up.  I have a feeling that will shed a lot of light on the entire process and help me better understand the big picture. 

Now the DXF files I've been posting is experiments I am doing with AutoCAD.  I can create a tooth I like and then use a command called "array".  I tell it how many time to repeat the shape around what radius and it draws it.  So if I can find a winning tooth shape and the proper tooth count I'll be able to create them fairly quickly. 
95
General Discussion / Re: Inertia
« Last post by KKC on March 10, 2016, 06:42:54 AM »
In Clayton's PDf he discusses the length of the pendulum and how everything is then calculated from that.  So according to him determine the length of pendulum and move to calculating the gear ratios from that.  Now in his example he is leading me through the building of a simple I think it was 3 or 4 wheel clock.  The example he's using is a one second swing of the pendulum.  I get that.  He then goes on to explain that 60 tooth wheel and the 8 tooth pinion as well as the 64 tooth wheel and the 8 tooth pinion.  But I haven't absorbed how he went about getting those numbers.  I like how you explain it.  But I'm going to have to study it a little and play with the numbers till it makes since and I'm a little more automatic with it.  I get the 30 tooth escapement.  60 seconds. 30 teeth. hits the pallet twice.  That's easy...

Thanks for the explanation though.  On the first read it seems much easier to understand than Clayton's way.  I'll keep you posted...
96
General Discussion / Re: CNC Questions
« Last post by KKC on March 10, 2016, 06:32:58 AM »

You may have agreed to a licensing agreement that prevents you from profiting from your use of AutoCAD.  :)  It would be really hard for them to prosecute though.  Kind of like it would be hard for Clayton to find out if you are selling clocks of his design at your local gallery.  He lives in Hawaii, so I imagine he retired there and is probably just looking to help support his hobby of making clocks.

Steve

I'm not sure on AutoCAD's claim on what is designed using their software however I do know that everything you print has a student version watermark on the plans.  So I wouldn't be able to design something in AutoCAD and then print it out and sell because it would have that student watermark.  Not sure that's how they cover it or if it goes deeper than that.  I will have to read the fine print. 

Thanks for pointing that out Steve.
97
General Discussion / Re: CNC Questions
« Last post by steve323 on March 09, 2016, 08:52:24 PM »
Those are the kind of questions I have.  If I was to build my own CNC I'd need to know what to watch out for.  Are there any good kits out there that you know of?

Also... I thought TurboCAD could read DXF files.  It's like a universal format that all CAD platforms can read.  and did you see my post on a free student version of AutoCAD?  I just entered all the information like I was a student at my local community college and I was in.  Just a thought if you'd like a stronger CAD platform.

You may have agreed to a licensing agreement that prevents you from profiting from your use of AutoCAD.  :)  It would be really hard for them to prosecute though.  Kind of like it would be hard for Clayton to find out if you are selling clocks of his design at your local gallery.  He lives in Hawaii, so I imagine he retired there and is probably just looking to help support his hobby of making clocks.

Steve
98
General Discussion / Re: Inertia
« Last post by steve323 on March 09, 2016, 08:47:36 PM »
Hi KKC,

I often lie awake at night thinking about the gear ratios in clocks.  Ultimately, there are only 2 criteria that matter.  The minute hand needs to rotate once per hour and the hour hand needs to rotate every 12 hours.  Both need to rotate in the same direction.  Adding a second hand is an optional 3rd criteria.

The gearing between the minute and hour hands is relatively easy. The divide by 12 ratio is done with gears that divide by 3 and divide by 4.  One easy way to do this is with a 30 tooth gear meshing with a 10 tooth gear for a divide by 3.  The second set of gears uses 32 teeth meshing with 8 teeth for a divide by 4. 

Another set of calculations takes place between the pendulum and the minute hand.  The length of the pendulum determines the overall ratios.  Wooden gear clocks usually have 39" pendulums with a period of 1 second in each direction, or 2 seconds for a complete back and forth swing.  Most clock designs use a 30 tooth escapement.  Pairing a 30 tooth escapement with a 39" pendulum would result in the escapement rotating once every 60 seconds.  It needs to be divided by 60 for the minute hand to rotate once per hour.  The traditional way to do this is a 64:8 set of gears driving a 60:8 set of gears.  The first set has an 8:1 ratio and the second set has a 7.5 ratio.  8 times 7.5 is 60.

There are other ways of achieving the 60 to 1 ratio between the escapement and the minute hand.  5 * 4 * 3 =  60, so you could have a 5:1 ratio, a 4:1 ratio, and a 3:1 ratio in the gears.  The 5:1 ratio could be built using a 50 tooth gear driving a 10 tooth gear, or a 40 tooth gear driving an 8 tooth gear.  The minimum pinion size is usually about 8 teeth.

Steve
99
Hi KKC,

I loaded a dxf viewer on this PC.  Here are my comments.

I like the graceful curves of the 60t center wheel.  The large radius curves on the cutouts look best (to me) for wooden clocks.  They are also easier to cut out and sand.  The diameter of the center hub should be sized to match the size of the pinion that is attached to it.

I prefer the 5 spoke design of the hour wheel instead of the 4 spoke design on the 60t center wheel.  I saw someone else post that odd numbers are more pleasing to them.  I agree.  The only change would be to increase the radius where the arms meet the outer rim.  My thinking is that the size of your router bit should determine the size of the gear teeth.  A 1/8" router bit would be able to cut a 60 tooth wheel with a diameter of around 4-5".  The curves in the spokes should have a radius that can be cut by the same 1/8" router bit.

I am still struggling with escapement designs in my head.  The "shoe" style escapement seems common on wooden clock designs, but looks too delicate (to me) in a wooden clock.  My personal preference is for the "slanted triangle" shape of escapement.  Sorry if I don't know the proper names.


Regarding your other question regarding gear tooth profiles.  I have read that there are many tooth profiles that have only rolling friction when the teeth mesh.  Two styles have become popular.  The cycloidal shape is traditional and has an advantage that it is very tolerant of meshing as the clock wears and the gears move apart slightly.  I was replaced by the involute shape when machines started cutting the gears.  Involute gears are easier to make by machines.  I don't think it matters which one you use.

I like that you are designing your own clock.  To me, this is the most challenging part.

Steve
100
General Discussion / Re: Anyone Selling Their Clocks
« Last post by steve323 on March 09, 2016, 07:52:46 PM »
Set up and adjustment would be the other issue.  Joe Schmoe isn't going to know how to hang and adjust the clock to get it working accurately.

That is a problem with wooden clocks.  People are used to things working without fiddling with them.  Even winding once a week is a hassle to most people after they get used to battery operated clocks that run for 1-2 years on a single battery.  Many of the wooden clocks only last 26 hours.  Some are only 8 hours. 

My hope is for at least 8 day operation for my next design.  I will not have wood pivots.  They may have hidden miniature ball bearings.

Steve
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