woensdag 31 juli 2013

working prototype 1

As said in the previous post I did make some changes to the original design: I used 2 ball bearings, one in the wheel and one in the pendulum, so the would be less friction (but the automated powering possibility is lost) and I could keep costs down (only 2 bearings, 16,80EUR in total, FAG bearing 626Z, metal closure)

This works, although in retrospect the automated powering (lifted weight coming down) would've been very handy.

Some problems I encountered during the build and how I solved them:

I couldn't get my hands on bearings the same size as in the instructables post, so I took the smallest I could find (outer diameter 19mm, FAG 262Z, inner diameter 6mm).

To get the bearings on the axles, I had to grind the axles a little, then heat the bearings (heat gun) and hammer the axles in the bearings on the vise. One of the axles buckled a little, so I had to hammer the axle to the end, then drill a hole (multiple drills) in the axle. Since I couldn't heat only the bearing and hammering the axle with a screw on it only enlarged the diameter (small edge above the bearing), I had to chisel small bits of the axle away. This proved to be a elaborate and very time-consuming disconnecting method, but it worked.

Since the holes in the lasercut file were for different bearings, I had to enlarge them, so I bought a metal&wood 19mm drill bit to put on the vertical drill (NL: "kolomboor"). Of course there was some play to fit the bearings in the wheel and pendulum, but I used some paper tape to center them, which worked and allows me to test the MDF-version with the same axles and bearings as the plexi version.

I noticed that the ends of the wheel (wedge-shaped ends) sometimes had imperfections on them, possibly because the area is too small to adequately dissipate the energy in combination with low suction, so small droplets formed at the ends. I grinded these down gently, which ensured the working (it blocked on some teeth before grinding).

As for future variations, I will definitely change the casing, which turned out to be not very stable and elaborate to take apart. I think making the lower (and possibly upper) side a box (pretty easy on the lasercutter) would greatly improve that. Of course the base will be made wider, perhaps some extra mass there too, ...

The MDF-version works great, but has (as was suspected on instructables) a little more friction. The mixed version (wooden wheel and plexi pendulum) worked as good as the plexi-version, so I think I will continue partly in MDF, to limit costs.

For now, you can find a picture of the plexi, MDFand mixed versions below, and more pictures in the folder on mediafire (http://www.mediafire.com/folder/378b85f40worx/Escapements)
plexi

mixed

MDF


dinsdag 16 juli 2013

first prototypes - lasercutting

Since I found a nice escapement on instructables I planned on making it after my vacation coming week (work resumes the 28th of July).
Nevertheless, I found some time today to visit FabLab-Leuven and start lasercutting the original files and a scaled version (50%) in 4mm plexi and 4mm MDF (which was 1/9th the price of the PMMA-slate ;) ).

The file I cut out is just a nested and scaled version of the original; I'm planning quite a few adaptations, so this is really just a test (does it work?) and then hopefully a base version for manual adaptation (filing/grinding, tape, deliberate gaps and displacement etc), which will be input for my drawn adaptations (this is of course a project for a CAD-course).
The files can be found on http://www.mediafire.com/folder/378b85f40worx/Escapements and other files will be added in the same folder when they are processed/drawn/cut.

If anyone wants to do their own testing on this escapement or any other, please feel free to share via the remarks ;) Other information or experience is very much appreciated too.

Update: I realised I will not be able to make an exact replica of the escapement on instructables due to the American metric system vs the European SI standard: I am now trying to modify the lasercut parts to make them SI-compatible. When it works I will redraw the components and put a complete (SI-compatible) bill of materials online for this first setup.

zondag 14 juli 2013

interessante filmpjes, werkende voorbeelden en meer praktische informatie

Dit deel zal nog wat bijgewerkt worden gaandeweg. Gezien de moeilijkheden om vele filmpjes telkens opnieuw te zoeken en te verwerken in deze post, verwijs ik graag naar mijn youtubemap waarin de meeste filmpjes staan: http://www.youtube.com/playlist?list=PLOVM6TM3c8hLlw0WUPny3BcqEp0_3NIoY

Een voorbeeld op instructables: http://www.instructables.com/id/Laser-cut-Clock-escapement-and-Pendulum/

Een heel interessante site met informatie over het afstellen en bijwerken van houten klokken is http://www.claytonboyer.blogspot.be/. Ook http://www.woodenclocks.co.uk/ en http://lisaboyer.com/Claytonsite/Genesispage1.htm zijn gebaseerd op dezelfde ontwerpen.
Clayton Boyer verkoopt zijn plannen van verscheidene klokmodellen met verscheidene echappementen. Een gewone .dxf-file kost geen 40dollar. Enkele uitwerkingen ervan zijn ook in mijn map op youtube te bekijken.
Het kopen van zo'n ready-made plan (in .dxf, dus te verwerken tot een functioneel 3D-model) is voor mij een mooie back-up: ik ga eerst proberen zelf een echappement werkend te krijgen, vertrekkende vanuit de files die ik kreeg van groepen studenten die dit in eerste zit probeerden maar allemaal faalden op het echappement.
Vanuit een werkend echappement wil ik dan varianten maken in andere materialen en licht afwijkende vormen (tape en vijl bij de hand) zodat ik kan onderzoeken wat wel en niet werkt en waarom.
Indien het te lang zou duren om de echappementen aan te passen tot werkende staat, zal er weinig anders opzitten dan het kopen van zo'n plan en daarop mijn onderzoek te doen, maar dat zien we wel tegen eind deze maand.

maandag 1 juli 2013

inforonde

Zoals aangegeven in mijn ruwe planning ben ik begonnen aan de informatieronde. Hiertoe surf ik rond op internet om verscheidene (goede) bronnen over gelijke onderwerpen te vinden. Zowel algemeen horloge- en klokmaken als echappementen worden opgezocht, alsook enkele pagina's over (de wiskunde van de) slingerbeweging en aanpassingen die compenseren voor temperatuur- en andere verstoringen.
Hieronder wordt een lijst met interessante links weergegeven

Opmerking: de engelstalige wikipedia wordt gecontroleerd op juistheid, dus neem ik deze liever als referentie dan de nederlandstalige. Alle sites werden op 27, 28 en/of 29/6/2013 bekeken.

echappement
http://en.wikipedia.org/wiki/Pendulum_clock#Escapement
http://en.wikipedia.org/wiki/Escapement (!) bespreking voor-en nadelen verscheidene varianten
http://en.wikipedia.org/wiki/Verge_escapement
http://en.wikipedia.org/wiki/Galileo%27s_escapement




Variatiecompensatie
http://en.wikipedia.org/wiki/Gridiron_pendulum
http://en.wikipedia.org/wiki/Balance_spring


andere componenten en gehelen:
http://en.wikipedia.org/wiki/Mainspring
http://en.wikipedia.org/wiki/Barrel_(horology)
http://en.wikipedia.org/wiki/Automatic_watch
http://en.wikipedia.org/wiki/Pendulum_clock
http://en.wikipedia.org/wiki/Pendulum
http://galileo.rice.edu/sci/instruments/pendulum.html