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When inspiration hits...

jhitesma

Some guy in the desert
Mentor
#1
So last night in mmeyer's "If i were hypothetically bit by the mini quad craze......." I found myself wondering. What happens when you get bit again while in the middle of collecting parts to build one?

I've not very secretly been gathering up parts to do a test build for Twitchity on his quad. I even jumped in and designed a power distribution board that we're waiting on while my parts show up. Then yesterday I got the call that the owner of the warp I've been kenneling is back in town and his KISS esc's showed up. Bad news - the warp is going home to it's owner after I perform one last set of upgrades on it. Good news - I get the BS12a's coming off of it and that means I've got all of the parts I need to put a quad in the air on hand!

But the first test PDB boards for Twitchity won't be here until later this week, and then he has to cut my frame and ship it to me. So my real build won't be starting for probably another week. And with all these bits sitting here it's got me thinking...all I really need right so I don't go miniquadless when the warp goes home is a frame.

Flight test taught me how to deal with this problem ... time to return to my parts bin and use what I have on hand. Leftovers from my ultra budget build!:

10596912_10152198447066805_1633453837_o.jpg

Hmm, looks like it could work. Initial tests with the kitchen scale are looking promising.

Bit more work and suddenly it's looking like something that may fly:

10590796_10152199282721805_1640710804_o.jpg

It's a little porky. That's still without power wiring or ESC's. But with a lot of extra motor wire (I'm going to leave them long for now since I won't be cutting them to size until I move all this gear to the Twitchity frame in a week or so, this is only a temporary copter but I'm already starting to grow attached to it and with MRM having the 1806 motors so cheap in the US I may find myself building another one of these if it flies at all decently.)

Motor mounting is one other issue I need to deal with still, I plan on doing it similar to how Chad did on the HandyCopter for Make only since the 1806 motors don't come with a mounting cross but happen to have two mounting holes that line up perfectely next to a 1/2" wood boom I'll just cut some straps to go under the boom and mount the motors directly to the boom that way. I have to find some suitably long screws though which may not be possible locally. LHS is closed today but maybe I can stop in tomorrow and see if they have anything, don't think the big box hardware stores will have anything that small! If that fails I may look into some kind of mount that extends off the end...just not sure what I'd use yet. I was going to pick up some polycarbonate to use for the top/bottom plates to see if it would help shave any weight (but would look cool and probably be stronger if not.) May try fashioning something out of that if I go that route.

The afromini I plan on using on the Twitchity build isn't here yet so this seemed like a good opportunity to document putting together an arduino pro mini+mpu-6050+A7105 build since a few people have been asking for more info on this route. I have all the parts on hand so why not! Maybe I can even fit it inside the frame this time....

Got a lot to do today and then it's ESC upgrade time for the warp and a little flying session afterwards. So I won't be making more progress on this until this evening. I am taking a lot of photos and even trying to do a few time lapses with the mobius on the build (though the first timelapses didn't go well, bad aim on the first missed most of the action and in the second my wife tossed her "delicates" laundry into the background. This morning I kept meaning to set up the camera but was in a rush to use the little time I had available to build this much and share it.)
 

jhitesma

Some guy in the desert
Mentor
#2
Before I forget them. Few things off the top of my head that should be done to shed weight on this hog.

Aluminum hardware. I'll post the details a little later, but the steel screws I had on hand are heavy. And the washers just make it worse. Switching to aluminum hardware would shave enough weight to be worth doing. I just don't have the bits on hand.

The promini and mpu together weight about 3-4g my scale couldn't decide. So let's call it 3.5g and be happy.

I have a Naze32 and Flip Pro on hand both of which would potentially fit inside on this build. But it would be tight and the Naze is fried and the Flip Pro has a bunch of big heavy pins on it that would have to come off. Either could be mounted topside Warpstyle though. With 1/2" of space between the top and bottom I hate to only use that for wiring harness (and I have a few ideas on the wiring harness I may try.) I weighed them both just since I know people like to use them and the pins make them easier to wire up. The Naze32 was 9g and the FlipPro was 8g.

The promini and mpu will gain a bit of weight when I wire them together, but not a whole lot. Loosing the pins on the Naze or FlipPro would get them in the right zone and make them possible to fit inside.

I'm going to try using the a7105 module with midilec's code to put MW and a flysky RX on the same promini and have a VERY light electronics package as the a7105 is only 1g. Again, wiring this all up will add some weight. I'll hopefully be tackling that this evening if I'm up for it. If not it will happen later this weekend.

Still not sure what to do about the motor mounts...Have a few ideas including one or two that will use the factory screws. Just not sure which path I want to take. I'm already wishing I had left the arms a little longer to protect the motors in a crash since they're considerably taller than the 2204's and so the motors are a bit more exposed than I'd like on an acro quad.

Time to go tear the BS12's off that warp, I should be able to estimate a full AUW soon and see just how overweight this is.
 

jhitesma

Some guy in the desert
Mentor
#3
Two photos for your consideration:

10596755_10152199628246805_95746857_o.jpg 10612429_10152199691596805_1190077442_o.jpg

It's not entirely fair yet, my ubmq is still missing some motor mounting hardware, some wiring, and velcro for the battery. Though I suspect there's still enough room to shave off enough weight to keep it around this same AUW.

No clue how well it will actually hold up or how well it will actually fly just yet. It will have less power than the warp, but looks like it weigh only 30-40g more when finished. Flying the 40g mobius on the warp didn't change it's handling all that much - though I haven't got to try it at the field where I can do more than just hover around. I think this will actually be a fun little budget quad.

One thought I've had about minimizing repairs is trying to replace the inner arm bolt with a nylon bolt instead so it can shear if the arm is hit. Not sure how well that idea could actually work in practice but I'd like to try it at some point.

The warp is stripped down, just waiting on it's owner and it's KISS's to get here. Guess I'll work on this motor mounting question for a bit...
 

Cyberdactyl

Misfit Multirotor Monkey
#4
No clue how well it will actually hold up or how well it will actually fly just yet.
I'm thinking I'll fly great.

As to the crash resistance, it'll be like all wood quads, the boom will split or crack at the frame. But being so stubby, it should take quite a beating. :cool:
 

jhitesma

Some guy in the desert
Mentor
#5
I'm thinking I'll fly great.

As to the crash resistance, it'll be like all wood quads, the boom will split or crack at the frame. But being so stubby, it should take quite a beating. :cool:
Yeah, that's what I'm thinking. I'm kind of hoping the arms are shot enough and it's light enough that they won't break very often. But I made them 4 individual arms instead of 2 long arms with a half lap specifically so it would be easier to replace them. And I'm really thinking about removing the inner bolt and replacing it with some kind of "fuse" like a nylon bolt or a lolipop stick. Something that will keep the arm from moving in normal situations but when the arm is hit hard it can shear and let the arm fold.

We'll see. It's just an idea that struck me and I'm tossing together :) But it's really growing on me quick.

Just finished swapping the KISS's onto the warp - holy cow are those ESC's amazing. Just the sound the motors make is so much cleaner and quieter now. And the performance....just...wow. Gotta start saving up for a set or two of those!

After dinner I'll be tackling this guy a bit more...made up some motor mounts to try...
 

jhitesma

Some guy in the desert
Mentor
#6
Well, I'm too tired to tackle the wiring tonight. So that's going to have to come later this week.

Before we started playing with the warp I grabbed some scrap aluminum I had laying around and tried banging out a motor mount. They didn't come out quite as nice as I had hoped, but even a cool 100 out in the shade with 55% humidity means I'm not looking to spend much time in the "shop" which is just my not very shaded backyard and I wasn't sure if these would work.

10612118_10152200283021805_519403065_o.jpg

Turns out they won't. The aluminum is too thick and doesn't give enough room for the screw heads. In fact I don't think about any mount of this style would work there's so little space:

10602534_10152200284796805_2073539712_o.jpg

10579206_10152200284881805_2005170466_o.jpg

So back to my original plan of finding longer bolts (looks like 2Mx20 should do the trick. But pay pick up some 2Mx15 just in case if I can find them as well) and using some kind of strap under the arm. I've though about making a hole through the arm so a strap can go in higher up, or carving the arm down thinner. But I think both would compromise strength too much. I put a hole under the motor to clear the shaft - and unlike on my knuckle here I made it go all the way through so I could access the bearings for maintenance without removing the motors.

Unless anyone else has any better ideas on mounting. I think a motor plate would be too weak for this style of quad. Want to find something common and easy...if it could work with the stock motor bolts all the better. But it's got to be solid. Hmmm....ideas ideas...
 

Twitchity

Senior Member
#7
This sounds like to me someone is a little impatient ;) Your ways with electronics amazes me and I'll be following this closely to see how it is done. I'm lucky to get the wires connected to my Naze right, let alone make my own flight controller.
 

jhitesma

Some guy in the desert
Mentor
#8
This sounds like to me someone is a little impatient ;) Your ways with electronics amazes me and I'll be following this closely to see how it is done. I'm lucky to get the wires connected to my Naze right, let alone make my own flight controller.
Not impatient...just "inspired" ;) That photo of your early build may have played a roll though :D

My afromini32 came in last night. Ordered it Aug 4th from TimeCop in Japan and arrived today 7 days later - not too shabby at all!

And it's as wondrously tiny as I had hoped:
10599852_10152201391641805_312857172_o.jpg

Official weight is 1.75g - TC's scale is more accurate than mine :) Add in a 1g spektrum sat and I've got a nice <3g electronics package here :D

10473977_10152201392891805_404315672_o.jpg

It feels even smaller than it looks. The PCB is super thin and there's nothing to this little guy. I'm still going to try and wire up a promini+mpu-6050+a7105 setup to show how it can be done. But since this is so tiny and will fit inside so well I'm thinking it wins for this build :D Those KISS ESC's are even smaller but anything that makes a 2204 motor look huge you know is tiny! Compare to the M3 bolt/nut if that helps you get your size bearings.


Unfortunately my lunchtime trip to the LHS for some motor mounting bolts didn't go too well :( Closest thing they had was some m2 self tapping screws that were way too short :( They weren't too upset about not having what I needed either, looked more annoyed that I wanted something they didn't stock than willing to help me find some. I knew it was a bad sign when the first employee asked me what it was for - having to find parts by application when I just want screws is never a good sign. Checked our local fastenall store and they do carry some M2x20 screws but don't have any at our local store. Two more places I can but they're a long shot on something this small. May just have to mailorder which means more delays getting this in the air...so back to thinking about other motor mounting options...
 

jhitesma

Some guy in the desert
Mentor
#10
I don't know if this is something you'd consider, but Amazon has them $4.39 with prime shipping... You'll have plenty of left overs too... http://www.amazon.com/Stainless-Mac..._indust_3?ie=UTF8&refRID=0XR9QXCB46CGZJY3V1X6
Ordered them as you were sharing that :D

Still wish I could find some here in town today...I'd have this thing in the air tonight...but if I have to wait until Wednesday I guess that's not too bad. Will still give me a few days before the Twitchity frame is ready :D

Guess I can work on the bottom parts of the mounts tonight and get everything else ready to go...

But yeah...assuming they are the correct threads I'll have plenty to share if anyone else needs some :D
 
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Cyberdactyl

Misfit Multirotor Monkey
#11
Talking about inspiration. . . have you ever heard of building a multirotor out of Kydex? After seeing the TBS video of the streamlined hex got me thinking of a main frame built entirely from the heat-formed material. It's extremely rugged. pretty much unbreakable. About as light as CF for a given thickness. Not very stiff compared to CF or G10 but could be shape molded and engineered with strengthening ridges to incorporate adequate stiffness.

I'm finishing up my mini-quad at the moment, so any "inspiration" would have to wait, just curious if it's ever been attempted.
 

jhitesma

Some guy in the desert
Mentor
#12
I haven't seen it, but that doesn't mean it hasn't been tried.

With proper technique it could be a good option it sounds like. CF being used in sheets really is inefficient, but doing custom molded CF frames to really take advantage of the material would be ridiculously expensive. But I'm sure we'll see it soon.

I think molded frames are sorely overlooked. I'd really like to try a polakium to see how his molding looks in person and how it holds up. For the price they look like they could be a lot of fun.
 

Cyberdactyl

Misfit Multirotor Monkey
#13
I've searched like crazy for ultra thin Kydex. The thinnest I can find is .060" or 1.5mm. That will work, but it would be awesome if 0.8-1mm was avaliable, being that folds and ridges would be necessary, ultimately driving the thickness at locations to 3mm or more using 1.5.
 

jhitesma

Some guy in the desert
Mentor
#15
My Ace is horrible :( Their hours are super restrictive - not open past 2 on Saturdays, closed on Sundays and not open past 5 many weekdays! And they have bins for all the nuts and bolts I need regularly...but they never actually have them stocked and can never say when they might be able to restock :(

I want to like the store because they have that nice small local store feel and I know a few people who work up there. But their inability to keep hardware in stock and unwillingness to restock it topped up with the hours that mean I have to give up a lunch break to go there - or remember to go first thing Saturday morning which is usually flying time...by the time I do resort to going there usually I'm still left empty handed.

Hard to believe when I moved here they were the better of the two hardware stores in town...the other one had more empty shelves than shelves in use and felt like an abandoned store since clerks were no where to be found. That one closed down when HD and Lowes started talking about coming to town after their attempt to stop them from being allowed to build failed. Not a shocker. If they put half the money they put into fighting the big boxes into actually stocking their shelves the community wouldn't have been begging for the big boxes.

Thankfully Amazon is showing my screws as set for delivery today - let's hear it for free prime shipping :D

And last night I made some good progress on the PM+MPU+A7105 setup....actually got it wired up and flashed...only to discover that the MW integrated version needs a 16mhz promini and the only unused one I had on hand was an 8mhz :(


Started working on laying everything out and making sure this will fit...the PM is a bit big but should manage:
10605523_10152202180616805_8370363_o.jpg

Then began wiring it up, first I attached the MPU-6050. This is pretty simple, just matter of connecting 4 wires. I like to use old IDE cables for wiring since they're effectively free (I have piles of them laying around), they're the right size and can clean things up since they're flat ribbon cable. But being monocolor can be hard to keep track of - triple check every connection! And they're fairly thin fragile wires - so it's best to do some liberal hot glue strain relief over connections when you're done.

On MPU -> On ProMini
V+ -> VCC
Gnd -> Gnd
SCL -> A5
SDA -> A4

A5/A4 on the Promini can be a bit hard to find, they're not around the outside edge like the other pins, they're between those pins and the main processor and the labels for them are on the backside (if they're labeled some of the cheap promini's leave off the labels.)

10577996_10152202204836805_238776239_o.jpg

10601983_10152202204696805_434352089_o.jpg

10596756_10152202204491805_1406986570_o.jpg


With those four wires connected you can hookup an FTDI connector, flash MW, run the MW configurator and see things respond. At least you should. I didn't because I was using a 8Mhz arduino instead of a 16mhz...

But I continued on, since I was flashing the RX integrated version of MW I figured maybe the problem was MW wasn't booting because the RX wasn't able to find the A7105.

I tinned up the pads on the A7105 that need to be connected. I don't have my notes handy so I'll have to fill in the actual connections later.

10605515_10152202219006805_2002722805_o.jpg

Six wires later I have a complete FC/RC ready to go!

10589369_10152202230521805_1223825661_o.jpg

10605941_10152202230641805_126651691_o.jpg

I left the wires a little long for now, the RX wires in particular. Even so it came out fairly light! If I had had a 16mhz promini on hand it would even be working :) I could pull the one off my blunt nose versa but it's got full headers installed and I don't feel like pulling them off. So I'm just going to order some replacements and for now continue with hooking up the afromini instead.

I wired up an adapter to go from the 6 pin FTDI adapter to the 4 pin serial header on the afromini, and was able to get the afromini upgraded to the latest baseflight and talking to the configurator in a matter of minutes - can't wait to dig in on wiring that up tonight. And if the motor screws really do arrive tonight...could be a midnight maiden kind of day :D

And I've got some more 16mhz promini's coming from ebay - so I'll still complete a how to on this...just have to wait a few weeks for me to resupply on 16mhz promini's. I could have ordered one from a US seller and had it here quick - but they're a lot more expensive that way ($7 instead of $2.50 and no free shipping) and since I've got the afromini and a flip pro just sitting here...I didn't see any point in tossing away money on fast shipping!

Oh - the one big gotcha here. The reason I used an 8mhz PM is because they run at 3.3v while the 16mhz ones are speced at 8mhz. But the MPU-6050 and A7105 are 3.3v only parts. So I figured by using the 8mhz PM I'd be able to leverage it's built in 3.3v regulator to power everything off the 5v from a BEC. Switching to a 16mhz PM means the power situation is a little more complicated. The 16mhz PM will run on 3.3v - it's out of spec but it works. But my BEC's don't put out 3.3v! There are 16mhz promini's available with 3.3v regulators - they cost about the same but are a bit trickier to find. That's what I have on order to keep things simple and clean. Without one of those you'd have to use a 5v PM and power it off 3.3v which can be done with a small regulator or if you're really gutsy with a diode to drop the voltage.
 

jhitesma

Some guy in the desert
Mentor
#16
Here's a timelapse of building the arduino based controller outlined above:


My screws for the motors arrived today so I'm working on some mount ideas. I don't really have time to cut up metal straps tonight so I'm trying a layup of 1/8" ply with hotel room key on top not sure if it will be stiff enough or not but it's about the only thing I had on hand I can work without waking my daughter up :D

Fingers crossed...
 

jhitesma

Some guy in the desert
Mentor
#17
Ok, the experimental laminate material made up of 5 minute epoxy a gift card and some 1/8" ply actually turned out better than I expected. it's pretty darn stiff. Definitely stiffer than the bare ply was - but I still planned it with the more flexible direction towards the short side. Hard decision time. I don't want to cut the motor wires too short since I'm going to be moving all this to the Twitchity frame shortly. But they're WAY too long from the factory. Gotta figure out just how much I'll cut down for now and get the ESC's wired. Then figure out what to do about control. My original promini plan is out for a week or two while I wait on a 16mhz promini from China. I have a few other options I'll get into at the end.

Hang on, I tried to remember to take photos even though I forgot to run the time lapse tonight (bummer too, it would have been an interesting build night.)

Oh, I did forget to get photos of making the laminate. It was just an expired discount card from the local football team stuck to a chunk of 1/8" ply with some 5 minute epoxy. Better ply and better epoxy would work a lot better, so would proper prep. This was a quick and ugly test. I gave it about an hour to cure then marked out about 8 motor mount squares, I figure they will get broken and spares will be a good idea.
10602082_10152204097786805_1411706346_o.jpg


The mounting holes on 16mm on center, so I set my calipers and then (ab)used them to mark the wood on a scrap of my laminate.
10600018_10152204097986805_1936006596_o.jpg


I then drilled test holes in the scrap.
10602428_10152204098771805_856342476_o.jpg


I used the scrap with the end of a broken boom from my knuckle quad to test things out - it worked quite well!
10473988_10152204100461805_1619719634_o.jpg

The laminate did start to deform a little bit - but the boom itself deformed more first.
10612010_10152204100916805_1217559821_o.jpg

Slightly shorter bolts would be better, I'm probably going to add some shims. If I tighten these to where I really feel the motors are secure then the screws stick up enough that even though they aren't touching anything the motor feels tighter - so I think they're affecting the magnetic field. 18mm aluminum screws would be perfect. I'm just going to add something else between the boom and the laminate (or make a 3 layer laminate and use that instead.)
10602303_10152204101116805_1043224659_o.jpg

With the method looking like it will work I went ahead and made the actual mounts. I used the scrap pieces to make a little jig for marking the centerline on them:
10614806_10152204103276805_1303048660_o.jpg

Just slide the motor mount in and draw a line. I had actually forgotten to take photos of this and didn't get the jig quite right when I put it back together for photos. So my line is a tiny bit off.
10614982_10152204103066805_1413124284_o.jpg

With center lines on them I took the scrap I used to test and found it's center, then lined it up and used a fine tipped pen to mark the holes. At least on the first one. On the other three I just eyeballed it - worked just as well, this isn't a showpiece copter and these may not work at all. Still it was nice to try and be accurate and consistent for a bit. I still used the test scrap to mount holes and then center punched them before drilling with brad tipped bits to get them as accurate as possible. But I just eyeballed where the set of holes went on the plates overall.
10590820_10152204105196805_1565255158_o.jpg
 

jhitesma

Some guy in the desert
Mentor
#18
I then proceeded to install the motors. Here's how that went:

All the bits for one motor:
10602513_10152204117361805_1332707915_o.jpg

Put the screws through from the plastic side so the plastic can protect the wood a bit:
10599899_10152204117731805_494959359_o.jpg

A metal strap would be stronger and thinner - but I need to take up the thickness anyway and I can't work metal in the house and couldn't find anything suitable that didn't need modifications. So wood plastic laminate won out for the first test:
10612110_10152204117636805_927101615_o.jpg

One at a time put the screws into the motor, they're easy to cross thread so be gentle and go slow. Get both in straight and smooth before you mount it up to help make sure you don't cross thread them:
10602211_10152204118471805_1280039238_o.jpg

When you actually mount the motor this should take a good bit of strength. The laminate will be in a position where the plastic is being pulled and the wood is being compressed so as long as the glue joint was decent (mine wasn't) this should be fairly strong. But I'm limited by the length of my screws how tight I can go more than how much the laminate will take. I'm a bit worried about vibration though. I've never had good luck with loctite on aluminum but I'm worried about these SS bolts in the aluminum, just don't want to destroy the threads in the motor (which is what I've had happen with loctite on aluminum in the past)
10585814_10152204119976805_195157837_o.jpg

Now...how to bring it to life....

First choice was going to be with the promini homebrew multiwii with integrated flysky RX. But with the wrong promini this option is out of the running for now :(
10602045_10152204123771805_273158702_o.jpg

I do have a Flip Pro I've been loaned that would fit. And I could use that with a lemon 6ch RX I have on hand to get something in the air...heck tonight if I really pushed. But it would make an already piggy mini even heavier and would be kind of tough to fit it all in on there - the pins are tall enough it won't fit inside so the FC would have to ride on top and I was really hoping to keep everything inside. If the RX and the FC didn't have pins on them I'd probably give this a go. I don't want to pull the pins off of either so this is not likely to get used.
10605896_10152204123381805_1565580901_o.jpg

Afromini is where I think I'm going. It's just too darn tempting to pass up!
10605489_10152204124481805_1206669271_o.jpg

There's just one problem with the afromini. It will only do PPM input or Serial. So I can't use the lemon 6ch RX I have on hand or any of the other RX's I have on hand. I could use my openLRS RX but I don't trust it anymore and it's kind of big and heavy for this build.

But...the 8mhz promini that can't run multiwii can be used with the A7105 that's already connected to it as a FlySky PPM RX...which is a project I've been meaning to tackle for some time and think I may go play with now. Just a matter of unsoldering the MPU-6050, flashing different firmware and hooking it up to something to give it a try. Dinner sounds more likely though and then bed. Guess what I may be doing at lunch tomorrow :D
 

jhitesma

Some guy in the desert
Mentor
#19
Ok, one more for tonight...I have a flight controller/RX setup functioning! It's not ideal...but it will work:

10576388_10152204261106805_647847512_o.jpg

I can connect it up to Baseflight configurator and confirm that everything is working - TX/RX and the afromini!

Now to wire up the ESC's and figure out where/how to mount all of this in this little guy. Should be a fun project for tomorrow!

Getting the RX working was pretty simple. I just removed the MPU-6050 from earlier, used the latest code from midelic - then jumpered A0-GND to bind, removed it and wired pin 10 to PPM in on the afromini and the power/gnd pins next to PPM on the afromini to RAW and GND on the promini. Let my FTDI power the afromini so I could talk to it...and boom we were up and going!

Biggest problem was remembering to enable PPM mode on the afromini - had me scratching my head for a minute why the LED indicated I was bound but the sliders weren't moving in baseflight :D

Wish I could pull an all nighter and finish this little guy now....
 

Twitchity

Senior Member
#20
Nice build, and the time lapse was fun to watch. I always enjoy seeing how others work since I typically pick up a few things to use while I'm working. I can't wait to see this little quad in the air. That promini has way too many wires for me (not to mention I'd get lost trying to configure it).

Just an update to get you motivated to finish this build asap... The first batch of prototype PDBs should arrive today :) I'll be sure to send you many pictures to torment you as you have to wait longer. G10 should be in tomorrow as well, so hopefully mid next week I'll have the quad ready for shipping.