ERE Repair Cafe Mastermind Group

[jacob]

This was a triumph. I now have the right size flange coupling. Thanks amazon for dropping it off w/o ringing the doorbell once again.

So far this has been an exercise in buying correct/compatible parts.
RS550 motor: https://www.ebay.com/itm/155198531351
Motor controller: https://www.amazon.com/dp/B071NQ5G71
Coupling: https://www.amazon.com/dp/B08333PNZQ (3.17mm, not 3mm ARGH)(*)
Power supply: 18V/1A adapter from an LED floor lamp

Next step:
Figure out how to make a propeller.
Acquire 5 gal buckets and pressure fit couplings.

(*) Forensics: I first ordered a 3mm coupling. The reasoning was that while my $2 plastic caliper showed the shaft being 3mm+, 3.17mm sounded like an odd number compared to 3mm. Usually when it coming to pegs and round holes, wood is forgiving but metal is not. So part of the confusion was also an ID vs OD concern. I was worried that 3.17 might be too loose. However, given how 3.17 fits fine, I realized that 3.17 is pretty much the same as 1/8". I briefly considered trying to drill out my 3mm coupling, but I figured the potential for catastrophe would be high using a drill press.

[jacob]

The general ambition, project, and time-allocation level of our MMG is way lower than this (I think?) https://youtu.be/hMAvbu9OzwI?t=1372 but the attitude of learning remains (I hope!). Incidentally, if you're into DIY robots, Fielding's entire channel is great! I goes all the way back from the early start of making his own jigs and powertools, then building garage sized CNC machines, and now making [industrial] robots. A great example of a self-directed learning curve. (Also if you watch the whole youtube link, there are some holistic systems-design insights ala "you can never change just one thing" around the 35m mark which are generalizable.)

Posted for potential inspiration.

Next meeting this Thursday using google meets.

[AxelHeyst]

Oh that is an amazing channel. I don't have any desire to build a robot (ironically, since my dad was an industrial robotics engineer), but I think my ambitions for a Mojave sunken greenhouse with aquaculture and an evap-loss only recirculating water system might come close.

Since it's neither smoke season nor allergy season anymore, motivation for my hepa-filter projects has been flatlined. That said, I've got a couple projects worthy of the group:
.Serenity's power system is having issues - under a moderate load the battery voltage drops rapidly and my inverter does a low-voltage shutdown. I suspect two battery cells are kerput, but I need to verify that my solar charge controller is doing what it's supposed to be doing. Learning opportunity here is to dive into the weeds of MPPT charging algorithms, and how to diagnose if it's an SCC issue or an AGM battery issue.
.The seismic retrofit of my studio. I'm installing some gusset plates between the girders and posts, but I need to learn a bit of seismic engineering principles to decide how to properly brace the structure, including from shear uplift forces. Preliminary digging into how they brace mobile homes reveals that... every earthquake, they update the building codes because a bunch of homes slide off their foundations, crush the utility connections, and start a fire. So I need to come up with something better than code.
.The next phase of my neighbor's PV system upgrade is to design and install a DIY panel ground-mount system that can handle the winds we get around here.

[jacob]

We ran out of repair projects and got busy with other things, so the Repair Cafe has been shut down.

We may restart in the future. Please post below if there's interest.

[jacob]

Mission accomplished. I built a filter. (See viewtopic.php?p=279224#p279224 ). The key was another thread that mentioned the existence of "inline duct fans". This was both a cheaper and more effective solution than trying to built the system out of "fundamentals", a common weakness from "thinking like a physicist".

[jacob]

Aside from repairing random stuff, we also have a jointly themed project in which we all build a "motorized filtration device" of sorts. This can be anything as long as it involves a motor (which could be human powered) or a filter or both.

I'm wondering whether it would be better if everybody built exactly the same project or the group even just made one single project. I've seen the latter work out well in the "machiningSphere" on youtube, where different machinists build different parts of the same widget. The former would make it easier to make progress. The original approach in the quote above had I working on the same topic but in different directions. This meant that the group was only able to provide maybe-try-level suggestions instead of very specific "use this component available from ..."

[AxelHeyst]

Both ideas sound appealing to me. The latter would provide motivation to not slack because others are counting on you for the group goal.

I also wonder if this is a good MMG to move either mostly or entirely onto the forum/clearnet? People can 'join' when The Project is something that appeals to them/their skills/their needs and they can skip when the project isn't that relevant? We simply might not have had enough people in the first group for critical mass.

(As an aside: now that I've seen your filter, I want to build approximately the same thing only smaller.)

[jacob]

I finally feel confident that I can build a CNC router + I have something to use it for.

My aim is to make this particular one: https://www.instructables.com/Homebuilt ... ased-GRBL/ ... using wood for all the components including the 3D printed ones. I want to hook it up to a dedicated Raspberry pi.

In the spirit of much increased synergy from making the same project, I invite people who are interested in making the same router to join me. It would be most helpful to be competent in at least one of the many skill components required. For example, given my background in mechanical clocks, I'm certain I can make all the wood+metal structures. OTOH, I know nothing about CNC programming.

To reiterate, the group strategy is to make the same widget. This will make it a lot easier to help each other. I would, for example, be able to make wood brackets for those who don't have access/skill to a scroll saw or a 3D printer, but this will only work if we're all making the same thing.

[AxelHeyst]

I am very interested. Wouldn't be able to start until January of February. I'd like to make it one of my Skillathon blocks. If it works out maybe those interested could pick the same time chunk?

[sodatrain]

I've kinda wanted a CNC machine for s while so the topic is interesting! My interest came from wanting to cut up and build plywood furniture - so my interest was mostly in setups that could handle a whole (or at least half) sheets of plywood. Also, the pace at which things move at here in Guatemala combined with materials sourcing/transportation challenges, I could never keep up if the plan was to do it ballpark at the same time or on some monthly cadence.

I'm ecited to find this thread, tho!

[jacob]

@sodatrain - This is a small desktop-sized model using nema17 motors, so likely only suitable for engraving and cutting thin material. Not for metal and probably not 3/4" plywood either although that's just a guess. The benefit of building a small unit is that it is cheaper and takes up less space. Unless you're doing mass fabrication, why not just use a jigsaw? Plywood furniture doesn't require precision or intricate curves.

I would also expect sourcing parts or tools to build parts, etc. would make it hard to block off a month. Likely this will take a few months where parts and tools aren't easily available.

[sodatrain]

However, tools often serve as a replacement for skill rather than as an extension of skill and therefore the size of the toolbox may be inversely proportional to the user's skill level. Hence, tool inventory tends to initially grow (learning process) until it's eventually reduced as skills replace tools.
https://aeon.co/essays/we-live-in-a-one ... a-polymath

Woooow - what a great article! Fascinating read about the value of leaning, how it impacts our brain function, how that impacts our health as we age etc. I've sent it around to several people already. Thank you for sharing it! Polymathics is such a great idea.

[sodatrain]

@sodatrain - This is a small desktop-sized model using nema17 motors, so likely only suitable for engraving and cutting thin material. Not for metal and probably not 3/4" plywood either although that's just a guess. The benefit of building a small unit is that it is cheaper and takes up less space. Unless you're doing mass fabrication, why not just use a jigsaw? Plywood furniture doesn't require precision or intricate curves.

Yeah I saw the size/scale. I guess those desires of mine predate my ERE phase. You are right - it would be totally unnecessary for me now. It was to compensate for my low skill levels and to allow for increased production volume. I was originally thinking of trying to sell some products.

Re tools - I'm starting to build a little studio space (11'x12') with lumber that is pretty freshly cut and actual 2"x6" not nominally sided) with a jigsaw and a sawzall because that is what I have!