# Weston Bye Magnetic Gear Clock



## kvom (Feb 26, 2014)

At Cabin Fever last year I bought the 5 issues of _Digital Machinist_ where this clock's plans were published.  Other than drawing some of the parts in CAD, I didn't do anything until this week, when I decided I needed another project.  I spent the day making the first two parts, the main and secondary frames to which other parts are attached.  I had bought a good-sized sheet of 3/8" 6061 aluminum, so cut out two pieces for the two parts.







The stock for the main frame is 7.5" square and too big for the vise, so I planned to mount it on a well-used fixture plate.  Most of the parts will be either milled CNC or turned manually.  Here's a brief summary of how I'm doing the frame.

First find the center of the stock.  Since this is a 1-off part, setting XY zero at the center is pretty easy.






Next use the same CNC program to drill 1/4" holes in both the stock and the fixture plate.






The stock securely mounted to the fixture plate ready for milling and drilling.






Using a gauge block as a height setter:






The subframe is milled from a 5x3" piece and needs no fixture.  The CAM program provides 3 small "tabs" to keep the part from falling through at the end.  These will be broken and the stubs filed off.






And the two frames at the end of the day's work:






I still need to tap quite a few holes.  I also modified the design very slightly.  The holes where the shafts and bearings are mounted are drawn as .469" diameter.  I plan to use hex-head 2-56 screws which have 1/8" heads.  These would interfere slightly with the assembly (Weston used socket heads), so I reduced the bore diameter to .460".


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## dreeves (Feb 26, 2014)

Looking great.  Welcome to the Weston Bye fan club.  It will be a fun journey.

I got mine running good it took some fine tuning but not she has been running for about a 3 weeks now. I have not noticed it loosing or gaining time yet. 

Dave


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## Path (Feb 27, 2014)

Will be following along to see how it goes ... read the articles with great interest but that build will have wait.

I hope you continue to report the progress on your switcher.

Pat H


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## Engineville (Feb 27, 2014)

I appreciate your posting how youre building your clock  . . .  I learn so much form following such build-projects on HMEM.

One of your post states, CAM program provides 3 small "tabs", were used to fixture part for CNC machining.  Id like to learn more about this type of tab-fixturing if youre willing.  For this type of fixturing to function safely, how thick are the tabs?  What is the width of the tabs?  What CAM software are you using that already has this as a programming feature?

I look forward to your future informative postings.


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## kvom (Feb 27, 2014)

Started on the magnet wheels today. planning to machine both the A and B wheels from the same stock with the same program.  However, had some DOC errors on the A wheel, and screwed up the fix, so only got the B wheel done:






To save time and material, I'll do as many of the brass wheels as I can on the same stock, which I'm cutting from a strip 4" wide that I bought 5-6 years ago.  For variety, the ABCD wheels will have 3, 4, 5, and 6 spokes respectively.


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## kvom (Feb 27, 2014)

Engineville said:


> I appreciate your posting how youre building your clock  . . .  I learn so much form following such build-projects on HMEM.
> 
> One of your post states, CAM program provides 3 small "tabs", were used to fixture part for CNC machining.  Id like to learn more about this type of tab-fixturing if youre willing.  For this type of fixturing to function safely, how thick are the tabs?  What is the width of the tabs?  What CAM software are you using that already has this as a programming feature?
> 
> I look forward to your future informative postings.



I'm using CAMBAM as the CAM program.  For the cutout profile, you specify the number of tabs and the type, and then you can use the mouse to drag them around to where they're needed.

You can specify the height (measured from the target depth of the cut), and the length along the cut line.  The types are triangle, square, and skip.  I always use the triangle, which is created by the tool ramping up and down to create the tab.  Square tabs are formed by rapiding up and then plunging back down, so needs a center-cutting bit.  The skip type is used for laser/plasma cutters and just turn the cutter off and back on.

In the case of the wheel, I used 3 tabs.  The material is ~.13" thick and my DOC is .15", so a height of .1" should leave a tab .08" high on the perimeter.  I filed off most of it and will finish the edge on the lathe later.  I used the default length of .1".


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## kvom (Feb 28, 2014)

Nice collection of magnet wheels:


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## weez (Feb 28, 2014)

Excellent work so far.  I will be following along as this is one of the projects on my must do list.


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## Philjoe5 (Feb 28, 2014)

Clocks and clockworks have appealed to me since I was a kid.  This is going to be an interesting project.

Incredible work so far.  I can't imagine (me) doing this on manual machines

Cheers,
Phil


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## Engineville (Mar 1, 2014)

Kvom,

Thank you for post #6 answering my questions on tab fixturing.


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## kvom (Mar 2, 2014)

Next part on the list was the frame spreader that connects the primary and secondary frames.  I turned it from some 1" brass rod; however, since a lot of the turned parts are .75" diameter or smaller I'm not going to waste material by using the 1".  Ordered some .75" rod online.

The mounting holes on each flange need to be aligned, or else the secondary frame will be cockeyed.  Drilling through both in one shot might have worked, but with no way to spot drill the inside of the flange I was concerned about the .096"drill walking.  So I came up with this setup:






After drllling one end, I just flipped the v-block and used the (mirrored) coordinates for the other side.






Screwed it in for a test fit:


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## kvom (Mar 3, 2014)

Machined the "bobbins" on which wire will be coiled to make the 3 electromagnets that drive the gear train.  Used some .75" white acetal rod that I have on hand.  These are just shy of 1" long.


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## dreeves (Mar 3, 2014)

They were fun to make weren't they.  I love the brass parts it her will make for a great looking clock

Dave


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## kvom (Mar 3, 2014)

I'm going to wimp out and have Weston wind the coils, and also buy the circuit board from him.  I'll be mailing the bobbins tomorrow.


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## dreeves (Mar 4, 2014)

Kirk, I did the same thing. Im dont know much about those things and the price was right as well. Wes is a great guy to deal with.

Dave


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## kvom (Mar 5, 2014)

I got my 3/4" brass rod yesterday, and had a little shop time today.  Started the 3 bearing carriers.  After parting and facing to length on the lathe, I needed to drill the same three 2-56 clearance holes in each.  Here's my setup on the Bridgeport:






Then back to the lathe to do the first turning:






I'll be busy elsewhere through the weekend, so nothing more until next week.


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## kvom (Mar 10, 2014)

I did finish the bearing carriers.  I also heard back from Weston that my wound bobbins and circuit board had shipped.  That was the good part.  The bad part is that I received the magnets from United Nuclear, and they don't fit in their holes.  I measured the magnets as .125", and then found that both my 1/8" carbide endmills measure .123.  I have a HSS mill that appears to by on size and should work, but trying to set up to enlarger 150+ holes probably isn't going to fly.  So I'll have to scrap all the magnet wheel done so far and remake with the larger edmill.


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## dreeves (Mar 10, 2014)

That sure does suck. I had the same issue with the first wheel I made. I use a 1/8 end mill but made the holes .127 dia. On all the others. The epoxy filled the extra. 

Dave


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## kvom (Mar 11, 2014)

Started the day by making the 'intermediate hubs'.  These are turned from .75" brass round, and are straightforward.  The only issue was drilling and tapping a 2-56 setscrew hole at a 30-degree angle between two mounting holes.  I used my hex collect block to fixture this.






The finished parts:






Got the wound bobbins and circuit board in the mail:






In the afternoon I decided to save the 4 24-magnet wheels rather than remaking them.  Cut an OD arc in vise soft jaws to hold them, and used the 1/8 endmill to locate one of the magnet holes. before tightening the vise.  However, after using it to enlarge the holes they were still too tight.  So I used a 1/16 EM to interpolate a .127 hole (still a little tight) and finally a .129 hole where the magnets slide in nicely.






Redid and A and B wheels today, and will attack the C and D wheels next time out.  The 5 small wheels I'll just remake.


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## kvom (Mar 13, 2014)

Spent the day making fiddly little brass parts needing multiple trips between the lathe and mill.  I have worked out that certain dimensions are key:

.313" (5/16) is the OD of the smaller ball bearings, so any hole with that diameter gets reamed with the 5/16 oversize reamer.

.375" is the OD of the larger ball bearings, so holes get reamed oversize.

.188" (3/16) is the diameter of the large shaft and the ID of the large bearing.  Need to check fit on the bearings.  I intend to make these large shafts from separate pieces held together with loctite.  This is because cutting a long thing shaft with precise constant diameter on my lathe is hard to do, and because I have brass rod of the proper diameter in stock.

.125" (1/8 )is the diameter of the small shafts and the ID of the small bearing.  Again check fit.

It's hard for me to determine how critical any of the plan dimensions are from the drawings.  I suspect I'll find out when I get enough parts made to start assembling.  I am going to use loctite anywhere a press fit is specified.


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## kvom (Mar 14, 2014)

Here's where I am with the brass parts:







I have a few more to go, and then it's on to the steel rotor, the aluminum wheel too big for brass, and the chapter ring.  Then it's time to try to put it together.

I recently acquired a vibratory finisher, and intend to try to polish the brass wheels with it.  Have to buy some walnut shells for that.


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## Path (Mar 14, 2014)

Nice workmanship .

I remember reading about the clock and hoping that someone would take it on ... 

Very interested on how the vibrator finisher works ... can you show 
us before and after pictures?

Thanks,

Pat H


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## Philjoe5 (Mar 14, 2014)

What Pat said.  Really interesting project.  Thanks for the update

Cheers,
Phil


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## Engineville (Mar 14, 2014)

kvom,

Thank you for your post #21.   Specifically, the showing of tabs to fixture five parts for CNC milling from a plate.  It is good for me to see that this technique really works.

Some years ago I saw this fixturing method used to make a model engine flywheel from an aluminum plate;
http://www.cartertools.com/modengfly.html

This past year I took a course on CNC milling at a local community college.  The lab assistant never had heard of tab fixturing and would not allow me to use it.  I was going to make a base for a Webster engine.
http://www.machinistblog.com/free-plan-webster-engine-works-4-cycle-gas-engine/

My point is I learn from your postings on HMEM what I can not learn in a formal course.

Thanks again, and please keep up the good work.


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## kvom (Mar 14, 2014)

Sometimes fixtures take more thought than the parts.  For the wheel plate I just milled steps in the aluminum jaws I already had mounted on the vise.  That way I didn't have to worry about the endmill doing through the bottom of the work and into the parallels.  12 different tools on that job.  The cutouts with the tabs use ramping rather than plunging to get to depth.  I use a center-cutting endmill but ramping is still easier on the tool.

I have some conical ceramic polishers that I will try out with the vibrator on some scrap pieces.  I tried using them in a tumbler but found I'd have to run it for a week to see any results.  The vibrator is supposed to work much faster,.


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## kvom (Mar 16, 2014)

Today's output was to mill the rotor rim from some 1/4" steel plate.






The brass center will be attached using 5-40 screws.

The plans call for 3/16" thickness, but I'm going to surface grind off a few thou from each side and try the fit before going much thinner.  The rotor will be gun-blued eventually.


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## dreeves (Mar 17, 2014)

Kirk. I made mine out of 1/4 stock with no issues.  Parts are looking great. 

Dave


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## kvom (Mar 17, 2014)

Dave,

How did you secure the circuit board within the base?  The 4 corner holes in the board seem to be 1/16" diameter, too small for 2-56 screws.


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## kvom (Mar 17, 2014)

Made the rotor center section today and attached to the rotor rim with screws:






It seems I could mount it with either side facing the front of the clock:






The 6 pole pieces for the coils are show partially done.  I had them in the vibratory tumbler for 8 hours, but it still didn't remove the mill slag from one side.  I'll just make that the side facing the coils.  The rest will be blued.  Still need to mill and angle in the tops and drill/tap some holes.


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## dreeves (Mar 18, 2014)

Kvom, I just drilled them bigger to fit the 2-56 bolt. I will post a picture of my base tonight. I also put a switch and removable power cord. 

Dave


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## kvom (Mar 20, 2014)

I have enough parts to try some test assembly, so I cobbled together a temporary stand with 2 pieces of steel rod and some plastic.






I finished the poles pieces and screwed two to the frame.  The separation from the rotor looks a bit too much at this point, but without the coil actually mounted I can't be sure.

A friend of mine who is an electronics expert is going to help me get it wired up as soon as I have all the parts on the rotor shaft done.  Seeing the rotor ticking over one blip per second will mean that the rest is just a matter of fitment.

As far as I can tell the only real tolerance requirements are that the magnet wheels are sufficiently close to the one they interact with to impel the proper motion.  The other two main shafts may need some adjustment from the plans to do the adjustment since there is a wheel afixed to the end of each.


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## dreeves (Mar 21, 2014)

KVOM, You are correct that the steel wheel must be as close as you can get it with out hitting the coils. Looking great can't wait to see it ticking.

Dave


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## kvom (Mar 21, 2014)

Bit of progress today.  Wheeled out the surface grinder and ground the rotor on both sides, so it's ready to be blued.  Also ground the 5 small wheels still lodged in the original workpiece as well as the rotor center.  

Then finished drilling the pole pieces and did a fitup on all 3 sets.  The separation from the rotor is about .06", probably too far(?).  Options for getting them closer are either to remake them, or to make the mounting holes in the frame larger.  An option I rejected is to reverse them and redrill/tap the mounting holes slightly lower down, but that would leave the original holes exposed.

I also discovered a non-obvious fact.  The little spacers in the accessory hubs need to be loctited inside the hubs.  Otherwise the wheel assembly and hubs can slide over the bearings and shaft.  The through hole in the spacer should also be drilled larger than .125 to be sure to clear the shaft, otherwise it will rub.


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## kvom (Mar 25, 2014)

After a weekend away from the shop, I made a few parts sufficient to mount the rotor shaft securely. Then attached the coils and pole pieces to the frame.  At this point, I should be able to hook up the circuit board and power supply, and see if the rotor will turn over.  It should turn at 1 RPM, as it drives the second hand directly.






I ordered the N52 magnets for the damper circuit today on eBay, so they should be here by the weekend.  I'm still working on the best way to machine the damper disk, which is 3.9" diameter but onlyt 1/16" thick.

I also decided to try to (try to) make the large magnet wheel from clear acrylic, and the chapter frame from acrylic as well.  I ordered a couple of 12x12x1/8 sheet from McMaster this morning.


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## kvom (Mar 27, 2014)

This morning I made the damper disk for the second time.  My first try was from 1/8" brass that I tried to mill flat to 1/16", but the result was uneven and had a twist.  This version is made from 3/32" aluminum, thicker than in the plans but should be workable.  Disk diameter is 3.9".






In operation the steel fork at the bottom contains 2 neodymium magnets on either side of the disk.  When the rotor turns along with the disk, the magnets generate eddy currents that act as a brake to keep the rotor from overshooting.  I'm waiting for the magnets to show up in the mail, and the damper will be easy to test.  Presently when I spin the rotor it will keep going for several minutes; with the damper in operation it should slow much more quickly.


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## dreeves (Mar 27, 2014)

I made my disk from 1/8 thick and it works great. I just modified the bracket that holds the magnets.  The disk does not have to be solid you can cut holes in it just leave about 3/4 of inch rim.  Sure is looking good cant wait to see it running

Dave


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## kvom (Mar 28, 2014)

I received the neodymium magnets in the mail this morning, and inserted one into the eddy current bracket.  Even without the second one the braking is quite pronounced.  If I give the rotor a good spin it stops within a single revolution.  I'll need to insert the second when the rotor shaft is disassembled; it might not even be needed.


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## kvom (Mar 29, 2014)

Today I took the frame/rotor and PCB to my friend's place, where he soldered push-on terminators to the coil leads and right-angle pins to the PCB.  Then when he tested the recommended JameCo wall-wart, which supposedly output 12V, we found it was giving 18V.  So then it was off to Radio-Shack to get another type.  Back after lunch, we measured 13.5V output, so he soldered on the terminators and hooked everything to the PCB.  With the power attached, we got no movement on the rotor.

He used a logic probe on some of the board leads to determine that its output seemed correct, each firing every three seconds.  After a nit of head scratching, we tested the magnetism on the pole pieces and got very weak force.  It turned out I'd used some drill rod for the coils that is only weakly magnetic.

Went home, found some steel rod that attracted the damper magnets strongly, cut to length, and replaced them in the coils.  After hooking it all up and plugging in the power, I got motion of the rotor.  Unfortunately that motion is jerky and mainly in the wrong direction,  So more fettling is needed.  I suspect that the separation between the rotor lugs and the poles is too large, and I'll need to remake the pole pieces.  

Here's a shot of the board and its connectors.


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## dreeves (Mar 30, 2014)

Kirk, I had some issues with the rotor as well. Instead of remaking the 6 steel post I made the holed on the main frame larger so I could adjust the coils to the rotor. I set mine with a business card. When you checked it did you have the other gears attached? 

Dave


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## kvom (Mar 30, 2014)

Just had it with the rotor and the rear wheel.  I may try enlarging the holes.  Today's project is a test for making the large wheel from acrylic.  Going to make an acrylic version of wheel A on a small piece first.

*** some time later ***

Here's wheel A made from 1/8" cast acrylic sheet, using almost identical machining.  No ne of the operations resulted in any chipping of the edges.  I used a 1/4" HSS O-flute mill, a type of cutter recommended to me on another site.  This tool has a single cutting edge and a very wide and long flute.  The 3 inner pockets were machined with this bit.  The outer rim I cut with a 2-flute carbide EM.  This left a sharper burr, but being plastic is not a real issue.  The inner pockets were chamfered, and this too worked well.

The photo shows the brass and plastic versions.






I now feel confident about making the large 7" diameter wheel from acrylic, as well as the chapter ring.


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## kvom (Apr 7, 2014)

Machined the large wheel using a piece of aluminum as the fixture plate.  For support I used a set of 12" vise jaws I got from Monster Jaws, in which I milled steps.







Then made the magnet pockets in brass strips that form the rim.  I had to make these in 3 separate pieces in order to fit 4" wide brass sheet.  The flat head 2-56 socket screws are stainless and thus non-magnetic.  Since the wheel is now effectively 1/4" thick I made the brass hub thicker by 1/8".






Then some test fits.  I discovered that I'd messed up the small wheel that is connected to the large wheel's shaft by countersinking the wrong side, and also not milling a relief groove to clear the bearing.  So that wheel will need to be remade.  I also did remake the bearing carrier as I noticed it was drilled off-center.

The shaft lengths seem to be critical in getting the wheels to be close but not touching.  The two intermediate shafts are easy to adjust, but the shafts that go through the bearing carriers are harder.  I won't really know until I get everything  assembled.


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## kvom (Apr 8, 2014)

Remade wheel H, this time correctly plus the end of the shaft that attaches to it.  I'll wait to make the head of the shaft that clamps the large wheel when I have all the pieces assembled and can check clearance.

Then I mounted a scrap piece of 4x4" acrylic sheet and tested out engraving the numbers that will go on the chapter ring.  Used a 1/16" V-tip engraving bit I bought years ago but haven't ever used.  Looks as if a .005" depth gives the look I want.  It was hard to get a photo, but found this old wood background:






The acrylic bows when clamped in the vise, so I'll need to bolt down the big sheet on the fixture plate and try to it as level as possible to get even line widths.  I might even reset the stock height for each number.

The font is French MT.


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## Swifty (Apr 8, 2014)

Maybe a few strips of double sided tape will help hold the acrylic down, make the strips small as they can be difficult to get off.

Paul.


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## RonGinger (Apr 8, 2014)

Yes, but if the tape is not dead flat and covering the whole area the plastic will bend down between tape strips and with only .005 depth of cut your line width will vary a lot. This is a tough problem- the right way is a nice flat vacuum table, but those are crazy expensive and can take a long time to make.

I have tried a couple kinds of tape with varying success. I do not have a good answer.


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## bb218 (Apr 9, 2014)

Vacuum tables suck


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## kvom (Apr 9, 2014)

I plan to drill and bolt the acrylic sheet to plate of aluminum that is pretty flat.  Using 7 quarter inch screws and washers.  That should keep the stock from bowing much.


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## RonGinger (Apr 9, 2014)

Good luck. I have ruined a number of jobs with variation in depth of cut- when you are only .005 deep it does not take much to be noticeable. I recently bought a diamond drag engraver, which i have only used once. It did OK, not as deep as I would have liked but useable. It has the advantage that its depth of cut is spring loaded against the smooth nose of the tool housing.


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## kvom (Apr 9, 2014)

I'll run a DTI over it when I get everything set up to see what kind of variation in surface I get.  In the worst of cases I could reset the top of stock for each number.


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## kvom (Apr 10, 2014)

Started the day trying to drill the mounting holes in the acylic sheet, but I've found that with the 12" aluminum jaws the vise interferes with the mill column on both the bridgeport and the CNC mill in order to get the full 11" Y travel needed to mill the chapter ring.  After some cogitation I think I have a plan that will work.  If it does I'll post the setup later.

Went back to the rotor test; enlarged the holes for mounting the electromagnets and moved the pole pieces closer to the rotor teeth.  Finally I'm able to get the rotor to turn, although it's motion is jerky.  Here's the test run:

[ame]https://www.youtube.com/watch?v=mf7RgXRrV60&feature=youtu.be[/ame]

The rotor wobbles on its axis so I need to investigate and see if getting a flatter rotation will make it smoother.


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## kvom (Apr 14, 2014)

Since I found that mounting the 12x12" sheet for the chapter ring wouldn't work with the vise, I took a different tack.

When I bought the CNC mill in 2009, I got it with the tall column, thinking this would allow me to machine much taller pieces if the need arose.  However, I failed to take into account that the Z travel is the same with either column, and as a result I could not reach the top of the vise jaws with tools even with the spindle all the way down.  My solution for the past 4+ years has been to mount vises on a 6" tall cast iron tilt table.  I was able to use the school's large surface grinder to grind the top of the tilt table, and it's been a quite good solution.

Now, with the vise removed, the top of the tilt table is still too low to machine flat stock fastened to its surface.  My new solution for this was to take 4 steel blocks, all approximately 2" cubes, and use the surface grinder to make 2 sides of each flat and square to the other.  By grinding all 4 blocks at the same time, all ended with the same height, to less than .001".  Then placing these on the mill table and under the tilt table, the mill's spindle nose is less than 2" above the tilt table surface.  This will be close enough to mill the chapter ring.  I'll need to hold the engraving tool in a drill chuck as it's too short to reach still.

Here's a pic of the tilt table and steel cubes on the mill table.  The tilt table surface is flat to within 5 tenths across the X direction, but the back surface is lower by 10 thousands compared to the front.  Not normally a big problem in normal milling, but I'll need to shim the acrylic sheet for the engraving.


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## crueby (Apr 14, 2014)

kvom said:


> I'm able to get the rotor to turn, although it's motion is jerky....



Saw one of these clocks running at the show - I think once you get more of the gears on, the back pressure between them will dampen it quite a bit. The finished one had just a small amount of that wobble/jerkiness - I think it is the nature of the magnets. The large spacing on the first gear allows it to bounce a fair bit, the smaller gears with narrower spacing cuts that down. Any of you ex-science teachers out there should be able to give the technical reason (inverse square law on the distances, something like that? I was a software guy, this is a hardware problem!)


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## kvom (Apr 16, 2014)

I got the fixture plate and acrylic sheet mounted to the table, so started the machining on the chapter ring.  Doing the numbers first while the sheet is relatively flat, I measured the height at each position using a DI compared with the surface at 0,0,0.  I wanted to ensure that the linewidths engraved were the same everywhere, and since the surface height varied by .01", I decided to use a separate machine OP for each variation in height.  Basically, programmed a tool change for each different height, moved the spindle over the next number to be engraved, and set the tool height using a gauge block.

All was going well until, with 4 positions to go on the seconds dial, the drill chuck holding the engraving bit decided to open, flinging the bit across the table and snapping its point.  Luckily no damage to the plastic sheet resulted.  So I ordered a carbide 60-degree chamfer bit from McMaster, which will be long enough to hold in a collet, and which will allow me to finish the last engraving.  In the meantime did the two center cutouts and shut the mill down with the spindle at the 0,0 position, so it will be ready when the new bit comes in.


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## RonGinger (Apr 16, 2014)

Nice work. Dont you just hate long jobs like that where you have so many opportunities to screw it up 

Are you going to try to edge light the acrylic sheet? If the letters are deep enough that should really make them pop out.. Maybe a couple LEDs mounted on the bottom edge?


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## kvom (Apr 17, 2014)

While waiting for UPS to deliver my chamfer bit and let me finish the chapter ring, I decided to do a trial assembly of the parts I've completed.  The photo shows everything but one of the intermediate shafts with two wheels.






Found some things to fix,  mainly to remake the center shaft, where the rear part is about 1/8" too long.  The front intermediate wheel also rubs the center portion, so it's diamter can be a couple of thou smaller.  Also need to move the big wheel forward a bit and finish its shaft.

I'm debating whether to try to polish all the brass wheels before I glue the small magnets in their pockets.  In any case, leaving on a 2-week trip on Saturday, so that won't happen before then in any case.


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## kvom (May 3, 2014)

After 10 days away, including a visit to NAMES, time to get back to the clock.  Put it all together for a fit check and discovered two tight spots with clearance issues.  

The front 6 magnet wheel is very tight to the rotor, so dd a bit of filing.






And the front 24-magnet wheel is close to the collar of the center shaft.  Took .04 off the collar to clear.






Then took it all apart for some finishing.  I used a buffing wheel on wheel A to get an idea of how the brass would look polished, but I didn't care for the result.  The brass stock has marks from the rolling mill that would be too hard to polish out, and besides most brass clock movements are not polished.  So I just used some 600-grit paper on the 5 larger wheels to get a matte finish.

Then used some Casswell Perma-Blue to color the steel parts - rotor, damper frame, and the poles.






In most light they look grey rather than blue, but the coloring should prevent rust.

Finally, glued in half the magnets.  All the alternating holes with the same polarity.  The other holes will have the opposite polarity.  That's the job for the next day, followed by reassembly to see if the damn thing will work.






Here's a pic of the chapter ring I finished before leaving on my trip.






As an aside, here's an interesting version I saw at NAMES.  All made from Corian:






Seems any rigid, non-magnetic, machinable material could be used.


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## kvom (May 4, 2014)

Finished gluing in the rest of the magnets and did a test assembly of the gear mechanism to test.  Other than the large wheel, all the others seemed to hook up properly.  The large wheel rim is separated too far from its engagement partner  by about 1/8".  This will be easy to adjust by facing off from its hub to move it closer.  After disassembly, I need to finish up a few things before an actual run test.






1) Loctite the intermediate and minute hand hub to their respective wheels.  They're currently a tight slip fit and can slip under any pressure.

2) Drill the end of the rotor shaft to accommodate attaching the second hand.

3) Machine the relief groove in wheel D, which I overlooked originally.  My CNC mill is down for repairs, so I'll likely use the lathe or the rotab.

I found that the assembly should go like this:

1) Attach the bearing carriers to the frames.

2) Assemble the secondary frame completely but do not attach to the main frame as yet.

3) Assemble the rotor shaft components onto the  main frame - rotor, damper, and magnet wheel.

4) Add front intermediate shaft and wheels to the main frame.

5) Attach secondary frame to main frame.

6) Finally add damper assembly and coils.

I found that using  82 degree flat head screws to attach the three wheels with the hex holes is probably not optimal.  A countersunk socket head works fine, and there is no clearance problems.  The issue with the flat screws is that the theoretical depth of the 2-56 head is .051".  With a 1/16"  hex boss on the shaft and a 1/8" thick wheel, it is quite tricky to get a precise countersink.  Too deep and the wheel is loose, and too shallow the head protrudes.  Since the countersink is on the opposite side from the magnet pockets, a second op is needed on these wheels.  If the countersink is off center, even is the depth is correct, the screw head can cause the wheel to be cocked.


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