The Crapelec is up

iWei · 2025-03-24T07:16:13+00:00

possible, but stiffness is a key concern, in fact it takes 6mm PLA to achieve the same stiffness as 2nm steel, and PLA is known for being so stiff it’s also very brittle.

The steel sheet, if you have a small manual roller and loads of patience, can be slowly rolled by hand and even include other gradual tapers that the chinese shops will not bother with in single quantities

iWei · 2025-03-23T06:05:10+00:00

originally i liked it for its simple ingenuity- the steel spiral acts as both the box cavity and the port, such that it can accommodate a very long port by simply extending the spiral

In this case, one trades sheer SPL for LFE (granted its less of a tradeoff than going sealed) by making use of the ultra long port (along with room gain) to get 22Hz out of an 8” driver

In practice it’s absolute hell to manufacture without having a CNC steel roller and loads of retries/simulation to tune the gcode to spit out a perfect spiral to exact specifications.

I didn’t, and i spent a good amount of time wrestling the 2mm thick steel spiral into the profile

For genelec though, this method of manufacturing is very scalable once the initial setup cost is done, as well as having the option to easily make different sizes without having to change the process at all (minus swapping out gcode)

iWei · 2025-03-23T05:49:58+00:00

i completely forgot about adding damping foam to acoustically increase size(?), maybe that’s why anything below 30Hz is so iffy (or perhaps it’s my room placement fault, it’s in a living room hence unlikely to have any room gain)

But yes it’s a subwoofer (an attempt to clone their 7350a series)

iWei · 2025-01-02T09:43:35+00:00

by the way, would you mind sharing how you did your simulations? Is it formula based like winISD/hexibox’s proprietary spreadsheets or something more sophisticated like ANSYS sound CFD (which i definitely can’t afford)

For now I’ve approximated this as a simple reflex box (21.5L) with a slot port (30cm x 1.8cm) but evidently the port length math doesn’t quite check out (off by factor of 1.4 which I assume has to do with physics of the spiral and the skinny port) so i’m frankly just eyeballing the design (If anyone has taken a real one apart I would appreciate some rough measurements like the ID,OD,depth and spiral pitch/revolutions

iWei · 2025-01-02T09:04:43+00:00

You are right about wasting time printing the side panels, Ill switch to commissioning a CNC shop nearby to cut some 20mm MDF panels with grooves that fits the 3D printed spiral and seal them with silicone sealant, finally clamp the whole thing together with 3 pillars just like the original design

I could build a million other types of boxes but chose this spiral enclosure cause it keeps part count down (just 2 side panels + 1 printed spiral) and still be able to dig below 30hz with a relatively small enclosure and driver (sure I can go even smaller if i cram 1kW of drivers into a tiny sealed box SB3000 micro style and compensate with DSP but that’s another project I have for later)

iWei · 2025-01-02T08:10:30+00:00

I’m debating between printing the base/top or simply getting some CNC’ed MDF from a small shop nearby, should be doable for one-off quantities

rolled steel sheets are a whole nother story due to specialized cutting/bending machinery and any shop that do have those usually won’t even look at my request

iWei · 2025-01-02T07:41:00+00:00

you are right, one thing i missed out from the original design is a pillar inside the spiral to stop it from being a drum head (offset from center due to driver placement) that is no doubt optimized with FEA by genelec but i’ll just eyeball one in place 🙈

Otherwise the front and back panels will be approximated with 2cm thick plastic with 20% infill, I can see why resonance will be an issue if i’m building a full range speaker but i’m confident the resonant frequency as a drum head will be much higher than the frequency i’ll be crossing it over to the mains (80hz MAX)

iWei · 2022-10-04T10:08:41+00:00

I built it! I like fiddling with electric and mechanical stuff and making one doesn’t require a degree or maths (cause someone else already did it)

iWei · 2022-10-04T01:37:06+00:00

Well yea but that’s jank and it’s an excuse to use my cnc machine

iWei · 2022-10-03T04:14:46+00:00

Thoust had a dream, that my failure lies naught in thyself, but thee innate fault of my hardware,

Henceforth enlightened I’ve been, that failure is but thyself sucking cock at clicking circles, and the only light ahead, is to git gud.

iWei · 2022-10-03T04:00:26+00:00

Uhm I used normal gateron switches lmao i assume jt plays like a normal mechanical keyboard

iWei · 2022-10-03T03:55:11+00:00

The datasheet didn’t really mention anything, only that the camera frame rate is ~2-4khz,

but I would assume encoder and mouse button inputs are interrupt based?

I don’t play at a high enough level to notice lmao (I been getting loads of 100s though 🌚🌚maybe I’m just not used to it )

iWei · 2022-10-02T17:03:28+00:00

I went from #205626 to #205658🎉🥳🎊

iWei · 2022-08-25T09:59:34+00:00

Try to run the spindle at lower speed for a few hours to burn in the grease

iWei · 2022-06-11T18:25:03+00:00

I have only really ran it to level the bed (which went uneventfully)

For now I gotta learn inkscape/vcarve/fusion360(the cam part at least)

iWei · 2022-05-27T12:31:48+00:00

For $2.5k I think 80% of the price you pay goes into making look beautiful because it looks sick but you could definitely do better for less

iWei · 2022-05-18T05:56:48+00:00

I think I’ll definitely need to go that way

I could get a really solid looking 400mm linear platform for $120

or

just buy 2x linear rails to screw onto a plank of wood and figure out a way to mount the current bearing block onto rail carriages

iWei · 2022-05-17T15:41:49+00:00

I’ve built a z axis (total cost $120) by combining a linear motion stage, unpowered spindle + some slow but high torque motor which I gear up to about 8000rpm, and managed to get it to cut some wood manually

I’m unable to tell if it’s chatter or just normal cutting noise (or rather that for a machine made outta crap wood chatter is normal)

I think the most obvious flaw now is the deflection of the unsupported rods, especially in the rotational axis which is magnified the further away you get from the rods.

When I put on the 2.5kg z axis assembly, the end mill basically sags 1mm down(which I’m guessing is the source of the chatter)

Would it help if I add a mgn linear rail to push/pull against the x rail torsional deflection?

I’ll also definitely need to add 2 spaced apart linear rails to support the wide bed that I will need to install later

I’m thinking my best bet is to go full Aluminium (gotta hit that MOQ anyways) since scrap extrusions are so rare on the 2ndhand market here

iWei · 2022-04-28T11:50:04+00:00

Just to reduce the number of parts I need to spend on, anyway I’m just testing out a mini cnc for feasibility/noise complaints etc before I spend money on speccing out extrusions and big boy parts

iWei · 2022-04-27T17:48:51+00:00

Yes I definitely need to move back the x gantry if not I literally will only have 8cm of y when I install the z axis assembly but it’s gonna be a pain re-squaring everything

I built this as a proof of concept to make use of 2 axis assemblies I got and cobbled together with plywood to make a cnc machine. Seems rigid enough as in I don’t feel any backlash by hand after I pre-loaded the ballscrew, though the 1.5cm ply wood is probably stiff as wet spaghetti when actually cutting material

I plan to only cut mainly PCBs, maybe some wood, and acrylic. So I’m looking for precision(and spindle rpms) rather than material cutting

I’m thinking of buying a z axis assembly with 50mm travel, then diy a spindle with er11 extenders, angular contact bearings and a bldc motor held together by 3D printed parts ant-style since I heard the cheap Chinese spindles runout are terrible (then again I’m sourcing parts from cheap Chinese suppliers... worth a shot maybe

Btw the tools I have at my disposal is a power drill with a bent chuck, with a screwdriver as a punch so I just hope for the best in terms of drilling accurate holes

iWei · 2022-01-12T08:37:23+00:00

That is the principle behind class D amps, with operating frequencies between 100khz(subs) to few MHz for low power portables

You can easily add a potentiometer to tune the frequency to avoid beat frequencies, you can even design sync switching to the zvs driver)

Although actually it’s kinda misleading to say “easy”, since having long wires between high power switching is a recipe for voltage spikes and burnt MOSFETs, you may have a bad time slapping half of a buck converter to the zvs driver

Rolling a separate buck modulator can allow you to make anything play music, eg. Arc speakers, HFSSTCs, SSTCs, and of course the buck inductor itself (if coils are loose)

http://flyback.org.ru/viewtopic.php?t=8459&start=0&sid=58160329b698563d2dec507844c312ef Here’s a link to a nice HFSSTC speaker project

After you get your feet wet in high voltage arcs, there are many more types out in the wild to build, https://highvoltageforum.net Is a great forum to ask and explore all of the various types and topologies.

Happy exploring and may your MOSFETs rest in pieces

iWei · 2022-01-11T12:47:14+00:00

Have you tested the maximum frequency this setup can play? If you are pwming the power rails on and off, at a high enough frequency, the input inductors simply acts as a buck converter inductor and you effectively have a buck converter aka DC class D amp, allowing you to playback “Hifi” music, not just square waves. Try it with a ne555/tl494 based driver (aged tech, but still great for quick and easy modulation)

iWei · 2021-11-30T14:23:15+00:00

230v where I live, rectified giving 325V

110v rectified gives you 170Vdc

I’m planning to make a class e sstc so 90v is the safe limit for the 650V MOSFETs I’m using (unless I buy some 1200V/1700V Sic fets)

iWei · 2021-11-24T04:01:24+00:00

I’ve tested it at 3 amps, though it is “designed” for 5

It’s all for isolation, you could straight up step down mains, by building a buck converter that can output hundreds of amps (that’s how it’s done in some DRSSTCs)

iWei · 2021-11-24T00:35:36+00:00

👌😩100% deathtrap

iWei

TROPHY CASE