Sunday, June 21, 2015

Pythagoras Clock part VII (Tick Tock)

Yesterday night I worked with the electronics and a little bit of programing. The Pythagoras mechanism is making tic tock for the first time.

Here is a video of the first tick tock:

I learned a lot of things:
  • I used a simple fade up / fade down routine but the response of the solenoid is not linear with the voltage
  • I need to work on the mechanism:
    • Add weigh to the stopper lever
    • Polish the surface of the escapement wheel’s  teeth in contact with the pull lever as in some positions it get stock when returning
    • polish the arbor of the  escapement wheel and reduce the play as it is too loose in the arbor and some times it touches the third wheel. I placed some washers but I thin I will need to mill a new escapement.
    • Polish the rest of the arbors and teeth of all the wheels
This is a lot of work pending that will be done after I return from my business trip and find some time.

I made some provisional fixes and modified the program non linear analog output to smooth the solenoid action and added some weight to the stopper and the results were promising:

I am very exited with this project this will be a fantastic clock!

Thursday, June 18, 2015

Pythagoras clock part VI (Wheels ready)

Today after work I worked in my garage to finish all the rest of the wheels in the CNC router: The hours wheel, the intermediate wheel. the intermediate pinion.

I also worked a little in the lathe to make the small cannon. I could not wait to see all assembled in the frame and the result is  stunning

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This is a close up of the cannon spacer. Still need to make the hole for the fastener:

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And this is a close up of the Intermediate wheel, the spacer and the intermediate pinion:

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I am really happy that everything fitted perfectly and all the wheel turns with almost no blockage. Anyway I need to disassemble all the clock to make all the wood finishing work and polish all the arbors.

Now I will not be able to go back to my garage for the next 10 days due to business travel.

Next step will be the electrical assemble an testing testing Everything arrived today so the only thing I need is time…

Tuesday, June 16, 2015

Pythagoras clock part V (Center wheel and cannon pinion)

Today I was very busy at work and when I finished I could not disconnect my brain from work so against my plans I went to the garage and made a couple more of wheels.

Now my Pythagoras clock has al the gears to count minutes Smile 


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Tomorrow I will be on the road for business trip but I want to finish all the wheels this week as next week I will be traveling again and wont be able to work in the clock

Monday, June 15, 2015

Pythagoras clock part IV (The third Wheel)

Yesterday I finished the third wheel and the pinion and made some tests of the escapement system using a manual push button.

I am very happy with my .0625” 2 flute bit. I really makes a a good work and at reasonable speed. It would be impossible make these tiny parts without it.

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I also made the spacers and stoppers. I made a jig for my drill press and now I can make a perfect centered hole in wood rods

This is how Pythagoras looks with its 3rd wheel installed:
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I tested the escapement with a 5 VDC power supply and a push button but the solenoid engages really fast and the lever pushes so fast that wheel advances several teeth. I need to modulate the the motion.
I have a test program already written fir the Arduino but I need a power transistor to handle  +1 ampere of the solenoid.

Unfortunately with Radioshack out of business now I need to buy the parts online… I will save a lot as Radioshack was expensive but it was very handy and near home. Now I have to wait a couple of days (thanks to Amazon Prime) to get my parts!

Saturday, June 13, 2015

Pythagoras clock part III

Many things have happened since my last post!
I made the frame 2 times more as I was not very happy with the first one. First the mistake in the holes and second the feed rates and speeds.

Wood is not easy and with end mills bits that in general are not designed for wood there is a lot of trial an errors. Searching in the Internet did not help a lot until a found a very good software with the most important characteristics:
  • Full of data including wood feed and speed calculations
  • Easy to use
  • Inexpensive!
The software is G-Wizard Calculator and I should say that any hobbyist with a CNC should use this software. Since I started to use de G-Wizard No more broken bits and 200% quality and milling speed improvement. I really recommend the G-Wizard!

This is a print screen of the speed/feeds window of this great software:

This is the final frame with the quality and speed I like:
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Below the CNC milling the base:
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The base and the frame  looks really nice!!! In love
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And with the help of the G-Wizard I found the right speed and feed rate for a new .0625” 2 Flute end mill bit to make all these small parts and gears from the escapement  with precision and quality:

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I used one of the bad frames to test the escapement system and it looks beautiful even with the unfinished wood!
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Instead of winding and making a homemade solenoid I bought this one in Amazon. It gives a very professional look to the clock..
This is the link:

Next step is to write the program for the Arduino Nano to activate the solenoid exactly each to seconds. One thing I will use is a pulse modulated output to control the speed for solenoid to make a controlled  engage and disengage. In this way this clock will be both very precise and quiet.

Pythagoras will be a very nice night table clock!

Monday, June 8, 2015

Pythagoras clock part II

Pythagoras is a very small clock and is a big challenge to built it as the wheel teeth and in general all parts are small. Wood is vey unpredictable material when working small cuts in the CNC machine.

First thing I want to build is the frame, the base and all the escapement  mechanism.

Today I worked on the frame. I used a 1/4” 1 flute bit. Speed about 10,000 RPM and a very slow feed rate about 5 feet per minute. As the CNC motors are stepper and not servos if by any chance the wood is so hard that the feed cannot advance you can have cumulative error. I prefer to go slow and avoid problem. One day I will make a servo driven router….

I made a mistake placing the drill bit in the CNC so what I did in order to not lose the work is I filled the wrong holes with a piece of rod and glue. Tomorrow I will open the holes manually.

The frame


Milling the frame:

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Frame ready! Note the size compared with a pen. This will be a night table clock…

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The slot to hold the solenoid was the correct size

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Tomorrow I will work on the base and probably the escape wheel…