Building The Magnetic Clock

[George_Race]

First, a small introduction. My name is George and I am located near Albion MI. I have been lurking around here for over a year. I retired from Albion College about 5 years ago. Spent three years building a small airplane. After it was finished I started looking for something else to become involved in. My background is electronics, so building a metal airplane was a completely new and enjoyable experience.
I really enjoyed learning to work with metal so decided to explore the world of CNC parts cutting. I spent several months researching and finally decided to build a small CNC/Router. I started with a basic framework from K2CNC. I purchased the steppers and electronics from Hobby CNC. For software I use AutoCAD, CamBam, and Mach3. Started my first CNC cutting about 3 1/2 years ago, and it has been an enjoyable journey with a steep learning curve since the beginning.
I have designed and built a lot of small parts for experimental airplanes. I enjoy doing anything that is a challenge, leading to something new to learn about working with metal.
I also have a small 7 X 10 metal lathe, and have learned enough about turning metal to successfully build several small air powered single cylinder engines. I don't profess to be any kind of a machinist, but am truly a hobby level builder, learning as I go along.
Here is a link to some mods that I made to my lathe.
http://www.mrrace.com/Mini_Lathe_DROs/

I am totally impressed with Weston's Magnetic Clock and have started to make some of the parts. I will be posting some of my first pictures of that build here, later today.
Any and all comments and suggestions are welcomed,
George

[sasquatch]

Geo, Looking forward to seeing the pics of your'e project.

[George_Race]

After arriving home from N.A.M.E.S., I read all of Weston's articles in both magazines. That is all it took, I was hooked! I decided to draw all the wheels, using CamBam, using Weston's great detail published in his second article, it did not take long to draw each of the many wheels. Using CamBam, I entered all the parameters for the CNC procedure to follow. I generated the GCode for each as I went along. I always run any new GCode in Mach3 to show any items that may need tweaking just a bit to cut properly. Finishing all the drawings, yesterday I decided to start making chips on my home brew CNC/Router. I decided to use holding tabs to keep the pieces from being kicked around the shop. My tabs were set at .020 depth, and .050 wide. Really worked out well, every cut out piece was securely held in place during the cutting operation. The first picture shows how nice the holding tabs worked.


Here is a shot of some of the smaller wheels being cut.


Here the "Great Wheel" is being machined.


And finally, here are the results of the afternoon, that I spent cutting wheels in the shop.
Missing is the steel "Rotor Rim" for piece "L". I did not have a piece of .125 soft steel in stock.


My next project will be to make the broach and finish the three wheels that need the hex center openings.
I guess then it will be time to sit back and await the next issue of the magazine to be published!

Your comments and suggestions are welcome,
George

[DICKEYBIRD]

Beautiful work George!

I need to change into a fly and buzz down to your house next time you sit down for a CAD/CamBam session. I'll sit on yer shoulder and be much the wiser for it...long as you don't flatten me with a fly-swatter!

What were your router bit size/RPM/IPM/DOC settings. Those sure are some nice cuts!

[Weston Bye]

Good work George! Made me proud and a little misty to see my design coming to life in somebody else's hands. Tell me, how much machining time? That question was asked by nearly everyone at NAMES and I honestly didn't have an answer. Even if I had kept track, my time would be different, as I did all my parts manually with the rotary table.

I see that you added your own touch with some extra holes in the "Sherline Limitation" area of the great wheel. Nice!

[Mcgyver]

George, that is nice work - what are you using to go from CAD to G code?
thanks

[Bill in Ky]

Very nice work there George! What about showing some pictures of that plane...

[George_Race]

DickeyBird:
I use pretty close to what GWizard shows for cutting parameters. For this project I use the following for all the cuts in aluminum. As I don't have a really hardy mill, I use spiral cuts, .015 deep per revolution. Mill is 2 flute .09375 diameter carbide end mill. My plunge rate is 5 IPM, my feed rate is 20 IPM. Cutter RPM is between 18K and 20K RPM.
Weston:
The middle size wheels, ABC&D were all about 15 minutes total time.
The Great Wheel was about 40 minutes total time. The smaller wheels were in the area of 3-5 minutes each.
Mcgyver:
I used CamBam for all the drawings and GCode conversion for the wheels. Is a great program and probably one of the best $150 I ever spent. They have a great forum where the author, Andy Payne, is always available. The product has been driven over the past sever years by user request. It is really a great program and does 2.5d as well as 3D. They do have a free trial you can download.
Bill:
I have an album of pictures on my web site. Go there and click on the Projects button at the top of the page. There you can see me building my workshop/hangar, my airplane, and information about our local EAA304 Chapter as well.

Guess that is about it for now guys, really do appreciate all the nice comments on my work so far.

If anyone want them, I would be happy to put the CamBam files on my web site for download. I could post the GCode but they would need to be modified to fit your particular Post Processor so the CamBam files would be best to work from. Of course you will need CamBam to take full advantage of the .cb CamBam Files.

Thanks again for the kind words, more work to come soon.
George

[George_Race]

Today was a real learning experience. My CNC/Router was designed for aluminum. Today was the first time I have ever tried to machine soft steel. I slowed everything down, and took .0015 depth passes. A lot of chatter and really noisy cut. By adjusting the travel speed and the router speed I was able to find an acceptable rate with almost no chatter. I am afraid that cutting steel is something that I probably will never do again. Hopefully Weston does not have any more flat surface machining of steel in the clock design! Took about 45 minutes to cut the 20 holes in the plate. The inner circle cut took about 120 minutes, the outer cut to cut the holes in half, about 3 hours. So anyway, I spent most of the day building one part, but really learned a lot about my setup and this pushed it to it's limits.

Below is a pictures of the 20 holes being milled. I use a 2 flute .155 diameter end mill, and did all the cutting climb. I did some testing before starting the actual cut and that seemed to be the best selection for me. Maybe someone can comment on how, if anyway, I may have been able to do it better.


Anyway, the picture below shows the completed Rotor Rim with the Spoke Plate setting in the opening. I guess my accuracy must be pretty good, as the Spoke Plate will not quite go in. Tomorrow I am going to first try freezing the Spoke Plate and see if it will shrink enough to be pushed into place. If that does not work, I will put the Rotor Rim on a cookie sheet, heat to about 500 degrees and see if it falls together.


Maybe tomorrow I will be able to build the Hex Wrench Broach, that I planned on building today!

Your comments and suggestion are always welcome,
George

[sasquatch]

Nice work Geo, and thanks for posting the interesting pics.