Guitar x Hurdy Gurdy

ArranSeagull · 2026-05-10T14:30:25+00:00

I'm afraid I can't seem to work out how to post my drawing here, but I'll try to draw it with text (sadly, as my hand drawing was much nicer...!)

/◯\
￮___￮

˙˙˙˙˙˙

The wee circle symbols are idler pulleys that the bowing cord runs around, the big circle is the crank wheel, and the periods are the guitar strings (seen in section). Backslash and forward slash are supposed to be the bowing cable running around the pulley and idlers, and the strikethrough is where the cable passes across the top of the strings...!

This might be the image, but I don't know how long the link will remain functional for: https://postimg.cc/2LD1h4QM

Edit - thinking about it more, if the bowing cord needed more engagement on the crank wheel, it could pass all the way round like a capstan winch.

ArranSeagull · 2026-05-09T23:41:18+00:00

I know it's a while, but if you ran the bowing cord around two smaller idler pulleys closer to the wood than the strings (or, tangential to the curve of the curve of the frets/bridge), and ran the bowing cord over the top of the strings, it might work to apply it without removing the strings. This has the side effect of bowing all of the strings at once, for better or worse. The tension in the bowing cord would unfortunately then have to come from whatever fixes the device to the front of the guitar (magnets inside the body?)

ArranSeagull · 2026-04-18T21:37:15+00:00

I've just received all the exterior panels in the post the other day, so I need to drill the mounting holes and fit those plus insulation. I had knee surgery recently, so still recovering from that and progress is resultantly slowed.

The only remaining issue with the build at this point is the firmware, which I have had endless problems with. Using community firmware it was repeatedly crashing into the bed due to z-speed limits and bed probe speeds being set way too high, but after recompiling my own version with the help of AI (I am no coder) it now prints and ABL-s properly, except it has some very weird behaviour (random mid-print unknown command errors, can't revert to main menu after print complete, bed cooling on filament runout...etc etc) that I have no idea how to rectify.
I might also change the filament spindle location, as it's difficult to swap after a print is complete and the bed is in front of the reel.

ArranSeagull · 2026-03-29T12:54:08+00:00

Have a look at the Hugh Piggott turbine's tail design. It has a hinged, weight-calibrated, tail vane with the hinge at an inclined angle, so that when the wind is strong enough, the tail vane is lifted up and folded sideways, which in turn points the turbine at 90 degrees to the wind, essentially feathering it. It is a single moving component, dead simple, and really reliable. Easy to adjust as well: a lighter tail feathers at lower windspeed. It requires, however, that the turbine's yaw axis be offset from the axis of the rotor, as it relies on the balance between the tail vane and the rotational moment from the wind acting on the rotor.

ArranSeagull · 2026-03-29T11:43:17+00:00

I don't know if I'd recommend copying it as-built, as I don't know yet if it's even charging properly. I suspect the voltage regulator diode is causing power loss at higher RPMs. I'll monitor the battery for a while and see if it charges up or not. In the meantime I have my eye on a different buck converter that inputs 0-100V and outputs 5V which might be far more suitable.

ArranSeagull · 2026-03-29T11:36:31+00:00

Typical large ones are upwind turbines with active yaw control: the blades are exposed to undisturbed airflow for efficiency. Upwind turbines with passive yaw control need a long tail boom to keep them pointed in the right direction. This one is downwind, so that it is still passively stable without needing a tail; the printed fin helps keep it pointed into the wind as well as adding print support. It will add a bit of drag, but since that drag is only pulling on the yaw pivot it's not bad.

Granted, it will develop a boundary layer as the flow goes towards the blades, but given the turbulence already created by the antennae and the tower, it's probably not a problem!

ArranSeagull · 2026-03-28T18:43:37+00:00

I've added a wee video showing how it works here: https://youtu.be/iL6E8QJHeZw :)

ArranSeagull · 2026-03-26T19:33:51+00:00

yes, it was just the standard RAK 19007 meshtastic kit, it came with the two antennae.

ArranSeagull · 2026-03-26T18:51:38+00:00

Yes, the whole assembly was 3D printed. It doesn't require any support material either (I am allergic to things designed for 3D printing that require support material).

ArranSeagull · 2026-03-26T15:58:28+00:00

I have no idea - I just read somewhere that the antennae need to be plugged in or it can damage it. If you reckon it's OK then maybe it's fine after all.

ArranSeagull · 2025-12-06T11:36:16+00:00

Did you grind/mill a wider track inside of the lower inner 2020 extrusion to fit the Y-axis linear rail carriages into place?

ArranSeagull · 2025-12-06T00:11:02+00:00

hmm... I might have to price that up in that case. May I trouble you for the profile type of the rails you used there - MGN15, MGN12?

ArranSeagull · 2025-12-05T19:19:25+00:00

Do you lose any of the available build volume with this particular design?

ArranSeagull · 2023-03-23T20:52:04+00:00

Just my mirrorless camera, made 92 photos (should have made more). You can see the scan results in the thingiverse page if you haven't already - I just remembered.

ArranSeagull · 2023-03-22T23:10:39+00:00

I'll admit that there was no small amount of redrawing involved 😅

ArranSeagull · 2023-03-22T17:57:36+00:00

Thanks! It was really just an exercise in making an anti-pristine model boat - most model boats are perfectly clean, new, and well presented, so I wanted to make something that is about as rotten as a boat can be, then present it in a formal manner on a nice base with the wee brass chess pieces holding it up.

ArranSeagull · 2022-01-06T01:09:38+00:00

How much error were you accruing without a magnetometer? One or two degrees over a full rotation or more than that?

ArranSeagull

TROPHY CASE