DIY Moon Phase Dial

[Gina]

Well, I have ball bearings on the two intermediate wheels and the moon drive lever and they are all running true    I've tried running it at fast speed and it runs but makes a lot of clattering.  The gears are not 3D printing accurately enough and the teeth are not coming out concentrically with the centre hole.  This is with the little UP plus 2 printer and I shall have to admit defeat on this printer for anything like precision   Consequently I shall have to put my efforts into fixing the electronics/electrical fault on my Titan printer or finish the upgrade on my Pilot printer.

[Gina]

Taken the clock apart again and replaced the seconds gear with the previous one.  Reassembled and tried running and it's better - running continuously though clattery.  Maybe if I leave it running it will run itself in   The stepper motor is quite happy - just running slightly warm, well below the 80°C rating   Maybe this will do for now and I can get the rest of box made up.  I'll make new gears when I've got a 3D printer working well enough.

[Gina]

Been working on the case.  Sides, top and bottom 6mm plywood cut and glued to the back and each other.

[Gina]

Case pretty much completed and moon housing attached to case.  Inside of moon housing fully lined with velour ultra black flocking.  RGB LED lighting strip glued round the front of the box to lie just behind the frame.  Clock reassembled and box screwed to the frame.  I'll take some photos shortly.

[Gina]

Just one photo for now - I'll take some more tomorrow.  This shows the clock hung on the wall illuminated by my anglepoise desk lamp - the built-in illumination is not connected.  I have a bit more to do before running it.

[Gina]

Some more photos of the case.  One of the back and two of the front showing the moon globe casing from a higher than usual angle.  I plan to either cover or paint the moon globe housing.  Might do a "Blue Peter" on it

[Gina]

All wiring connected up to circuit board.  Clock runs   Backwards   Got a pair of motor wires crossed over - no problem.  Lighting works but it's pink instead of yellow - probably another wiring error   I'll probably tidy up the wiring when I have things right - no point ATM.  NB.  The case is square - photographic distortion is making it look otherwise!

[Gina]

Looking at the Arduino sketch I see why the illumination colour is wrong - I had forgotten that instead of using pins 3, 4 and 5 for RGB, pin 4 doesn't do PWM so I used pins 3, 5 and 6.  I'll go and move the wires...

Later - that's fixed it

[Gina]

Clock running fast forward, moon clock advancing correctly and yellow illumination as set up   I haven't added the blue paper to the inside and this is just with the bare plywood.  I'm not sure the blue paper is necessary - I might try different colour illumination though.

[MarkyD]

Red for night mode and blue for day mode

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Mark

[Gina]

Yes, could do

[Gina]

I've been trying different colours but difficult to tell in full bright daylight.  Yes, it's bright today

[Gina]

No constructional work on this project recently but plenty of thought.  I think the main problem is that the gears etc. are not up to a high enough standard due to problems with my UP Plus 2 3D printer.  Also the main axle needs better support than at present.  With the current parts, the clock will run for a while then stop due to a jam up.

For 3D printing I have a new extruder and X carriage to try with my GinaRep Pilot printer and I'm hoping to produce prints that are as good as the UP Plus 2 use to produce.  Current thinking is that this stands more probability of success than trying to repair the UP.

I think the main axle support arrangement needs redesigning.  There has been a problem with the seconds wheel slipping on the seconds shaft (main axle) and also with the motor gear slipping on the motor shaft which is round without a flat.  Maybe metal hubs with grub screw rather than ABS would be the way to go.  Currently the main (seconds) shaft/axle is supported at the back with a ball bearing but the front relies on a plain hole in the acrylic clock face.

Basically the whole clock needs tighter tolerances and better engineering and I don't think I will get very far until this has been addressed.

For the main (seconds) shaft/axle I think a bearing is wanted in the middle and not rely on the hour shaft running in a plain hole in the clock face panel.  A turned hub for the seconds wheel could run in a ball bearing attached to the case.

Here are some rough sketches to illustrate my point.

1. Main axle (seconds shaft) with ball bearing at the back - LHS of sketch - seconds wheel, minutes wheel and shaft, hour wheel and shaft with moon drive cam.
2. Cross-section of above.
3. New boss for seconds wheel in aluminium with seconds wheel shown in yellow.  This would be a thermal contraction fit onto the hub.  The hub can then be carried by a ball bearing attached to the case panel.

 

[Gina]

Spent a few hours turning a hub for the seconds wheel.  Problem is - it's rubbish   That cheapo Chinese lathe is alright for rough turning jobs but totally useless for anything small and accurate!

[Gina]

Had a look around the net and as I suspected nothing I can afford will do what I want!  What seems clear is that I can't afford engineering as well as astronomy.  At least not any time soon.  A precision lathe costs a similar amount to a decent scope or camera.  But I have an idea or two that could change things.  I don't know if I can get my present lathe any better - the basic problem is lack of rigidity and that seems a fundamental problem.

Having seen the engineering quality of Proxxon machines I think I would quite like one of their lathes.  This one is probably the bottom of the range and very simple with no lead screw or screw cutting facilities but could be good for simple little jobs.

[MarkyD]

I went for one of these a few years back.  Has not let me down and is fairly accurate as far as my eyes can be - my next mission is to convert it to CNC

http://www.chesterhobbystore.com/conquest-lathe-super-3966-p.asp

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Mark

[Gina]

Looks similar to the one I have but clearly better in many ways.  I think that was one of the others I nearly went for.  At the time the Warco version of the Seig 2 looked best but seems I was wrong.  Current price for that lathe is only a bit more than the little Proxxon but it has vastly more facilities.

[Stub Mandrel]

59 minutes ago, Gina said:

Had a look around the net and as I suspected nothing I can afford will do what I want!  What seems clear is that I can't afford engineering as well as astronomy.  At least not any time soon.  A precision lathe costs a similar amount to a decent scope or camera.  But I have an idea or two that could change things.  I don't know if I can get my present lathe any better - the basic problem is lack of rigidity and that seems a fundamental problem.

Having seen the engineering quality of Proxxon machines I think I would quite like one of their lathes.  This one is probably the bottom of the range and very simple with no lead screw or screw cutting facilities but could be good for simple little jobs.

Probably one of the most over-priced lathes on the planet.

[Gina]

You're probably right.

[Stub Mandrel]

Seriously, if you already have a SEIG / Real Bull mini-lathe (IIRC the Warco ones are Real Bull, but they are all developments of the same original design) you should be able to get excellent results if it is set up well.

[Gina]

I have another idea for the seconds wheel and pinion.  Replace the plastic pinion (which turns out to be just 5 prongs anyway) with 5 3mm pegs set into the aluminium hub.  I could make the holes for the pegs with my new micro milling machine.  This should result in a more accurate pinion than the 3D printed version

[Gina]

One of these would make it much easier but I can't afford it this month.

[MarkyD]

That's the one I have just bought for the mill.  It is a nice little unit, solidly built   Haven't used it yet though

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Mark

[Stub Mandrel]

Google 'small rotary table' they are more versatile but don't come with an integral chuck.

[Gina]

Done that as you suggested   Having the chuck sets the Proxxon one above the rest.  OTOH I wonder if I could make one, complete with stepper motor so that i could set a nice accurate angle without having to squint at little vernier scales.  It would be nice to have a chuck though to hold round objects like the boss of the seconds wheel for my moon clock.