DIY Moon Phase Dial

[Gina]

Practical progress on this project is currently delayed while I get a 3D printer working properly - the little UP Plus 2 is in a seriously sorry state in its "death throws".  Maybe I should apologise for the anthropomorphism - or maybe not

[Gina]

Moon globe and shaft.

[Gina]

I've now just about got my Pilot 3D printer working well enough for printing "real" parts and should soon be producing parts for the moon clock.  Here's a test run of the box that contains the "works" - stepper motor and Arduino control unit.  I printed this overnight and it took 3h 40m.  It's a rigid box with 4mm walls which I think could be made thinner having made a test print.  Overall dimensions - 130mm x 90mm x 40mm.

[ChrisLX200]

Having aquired a little Wanhao 4S printer yesterday I'm taking a keener interest in watching these projects :-)  I have yet to get my head around SketchUp, but Simplify3D is very easy to use. I'm just in the process of making all the normal mistakes one can possibly make learning how to get the thing to work (e.g., it took me half an hour to prise my first print off the print bed!).  Anyway, I need to make some stuff and wanted to ask if you design all the gears etc., yourself or do you download and modify templates?

ChrisH

[Gina]

Welcome to the 3D gang Chris   Yes, getting it to work, prising print off bed...  been there, done that, got the T shirt

I design all the gears myself and use the Involute Gear add-on for SketchUp to produce the models with all the properly shaped teeth etc.  SketchUp is "mega" very powerful and capable software but takes a lot of getting the hang of.  To help with this I bought SketchUp for Dummies from Amazon.  I found that very helpful as there were things covered that would be very difficult to find by searching the web.  That was back in the times of version 8.  I've also tried OpenSCAD but couldn't make any sense of it

[ChrisLX200]

I'm going to need something like that SketchUp for Dummies book I think :-)  Is this the full version or the 'free' version you can use these add-ons with?

This is the little printer I bought, and the first few prints I tried in tasteful pink (excluding the disasters of course...!)

ChrisH

[Gina]

Nice prints - it's working well

I have the free version of SketchUp.  It's SketchUp Make 2016.

[Gina]

Having got the little UP printer working again for a while I have printed some more gears.

Minute wheel and shaft.

Clock gear train (including hour wheel and shaft).

[Gina]

Having printed stepper motor drive gears of 32 and 30 teeth I have concluded that a little gearing down would be preferable so I'm going for 16 teeth on the motor gear and 30 on the seconds shaft.  Using mod 2 size teeth this gves 16mm and 30mm for the pitch radii and therefore 46mm between centres.  I will be designing a new box as a result.  In fact now that I have the Pilot printer working and a print bed size of 200mm square as opposed to the UP of 130mm square I have a much larger print size capability.  This means I can design the one unit to hold all the axles and pivots for the pauls rather than just the clock axles.  The stepper motor will now use 128 steps for each second rather than 64.

[ChrisLX200]

Gina are you using PLA or ABS for this? (or other...)

ChrisH

[Gina]

Gina are you using PLA or ABS for this? (or other...)

ChrisH

ABS.

[Gina]

Printed a motor box overnight just to hold the clock gear train so that I can plan the overall arrangement.  I'm thinking of a 300mm square clock face using clear acrylic sheet (that's roughly a foot square for our more traditional readers )  The moon globe will be on top of that on a short "stalk". 

Here is a photo of some of the parts arranged roughly on the table with tape measure to show scale and an overlay square added to show the acrylic square front.  The white box will not be present in that form in the final clock.

[Gina]

Done a bit more - framework for gears etc. plus a couple more gears.

[Pan Euro]

That looks like a lot of printer time Gina.

[ChrisLX200]

Looks a bit more like a clock mechanism now Gina!

I've spent a bit of time today learning how to make gears in SketchUp, not easy without a manual. Just printing a couple of test gears now (I really will have to get another colour than that pink...).

ChrisH

[Gina]

Yes, it coming along   If you have any specific questions about SketchUp I'll be happy to answer them if I can

[Gina]

That looks like a lot of printer time Gina.

Yes, a fair bit   Most of the parts are half an hour to an hour and there's quite a lot of them.

[Gina]

New design for the cam follower lever etc.  This avoids having a weight attached to the lever - the cam pushes the fork both ways.  I've made use of the intermediate gears axle for the pivot.  Distances are :- 60mm hour shaft to intermediate/pivot and 70mm pivot to paul attachment - so that's not far off the same.  Ratchet tooth widtth = 6mm.  So paul travel wants to be greater than 6mm and less than 12mm.  9mm nominal will be suitable.  Lever motion at fork = 9 x 60 / 70 = 7.7mm.  Allowing for a bit of play the cam wants to give 8mm which is 4mm offset (for a circular cam).

Here is a scale model in SketchUp.

[Gina]

I have a simpler method of stopping the ratchet wheel turning backwards as the drive paul retracrs than a second paul, and that's friction.  A spring on the rachet wheel presses it against a fixed disc underneath it.  This provides enough friction to stop the ratchet wheel and moon globe turning backwards.  This will also stop the moon globe turning through vibration or any other external cause.  There is plenty of power from the cam and hour wheel to overcome this slight extra friction.

[Mav359]

Once again Gina WOW

I think NASA said they need help with a mars landing when you finished this project. Any chance of your own website with all your wonders and how-to's so we can shamlessly copy all of them :-)

[ChrisLX200]

I'm printing something far less useful - a T-Rex skull :-)  Still messing around with the printer basically. I did print some gears but I find that if I use a 'raft' it's a devil of a job to remove that afterwards. Without the raft sometimes the parts don't stick to the bed (I use a glue stick which helps). Some of the prints get a bit 'blobby' sometimes, and I have a roll of black fillament which is useless, it won't seem to print at all, so I ordered some new stuff. There are a lot of unforseen problems running one of these things!

ChrisH

[Gina]

Once again Gina WOW

I think NASA said they need help with a mars landing when you finished this project. Any chance of your own website with all your wonders and how-to's so we can shamlessly copy all of them :-)

Thank you very much Alan   I've already thought of putting my projects on my website - just a matter of getting round to it   I do have a website but I haven't updated it for many years.  ATM it covers my early attempts at getting the Maplin FineOffset weather station working properly and the data with my own software and also help with Ubuntu Linux  from when it was first produced    Told you it was out of date   I have a new design of waether station all DIY and incorporating some of my own ideas.  Ubuntu is now a fully refined distribution of Linux and I've moved on the a fork from that called Mint whgen Ununtu changed in a direction I didn't like.  I've kept my website going and it's just a matter of uploading new pages to it.

[Gina]

I'm printing something far less useful - a T-Rex skull :-)  Still messing around with the printer basically. I did print some gears but I find that if I use a 'raft' it's a devil of a job to remove that afterwards. Without the raft sometimes the parts don't stick to the bed (I use a glue stick which helps). Some of the prints get a bit 'blobby' sometimes, and I have a roll of black fillament which is useless, it won't seem to print at all, so I ordered some new stuff. There are a lot of unforseen problems running one of these things!

ChrisH

Those gears look fine Chris   Can't comment on the skull    Blobby prints seem to be pretty common unfortunately.  And getting prints to stick sufficiently to the bed yet capable of being removed later can also be a problem.  I use diluted PVA glue for my Pilot printer which has a Velleman print bed.  The bigger Titan has a glass print bed which is very good, at least with ABS.  During printing I heat this to between 100°C and 110°C then afterwards let it cool and the print just lifts off once the temperature has got down to around 30-40°C.  The glass does need to be scrupulously clean with no grease such as form fingers.  Acetone is good for removing grease and any ABS from the glass.   IPA is also good for removing grease but not ABS.  Nothing dissolves PLA it seems (but I rarely use PLA).  I don't use a raft with my DIY printers but the UP does and with that it seems to work well.

[Gina]

More progress on this project and more photos to post   I tested the cam and lever plus ratchet and paul to turn the moon globe and it worked fine - I estimate I was getting 8mm movement of the paul giving a free 2mm.

[ChrisLX200]

That's _really_ cool ;-)

ChrisH

I take it the Moon is going to be set in a circular mask - or maybe a hemisphere - so you only see the one face?