Greg's Batch 4 build, maintenance, repairs, upgrades

Finally getting started on my batch 4 assembly. Thought I’d record the process. I’m following the video but it’s awkward to stop it at a specific image and rewind, re-listen. I’m going to take pictures and write detailed descriptions.
Step 1. Legs

Sorry for the poor image. I’ll try to improve them going forward. I decided to start taking pics after I’d assembled one leg. A couple of things I’ll note here after building the legs:

  1. Your work area needs to be really well lit. All the black bolts, and black standoffs, and black parts, and black carbon fiber make it really hard to see small details. It also makes it hard to capture with a cell phone.
  2. Nothing needs to be ‘persuaded’ to fit. It might need some fiddling. The tolerances are very tight but also very accurate. If something doesn’t fit and the part is symmetrical try flipping it over. I’m test fitting a lot before bolting things together.
  3. I’m using a small screwdriver handle with that Allen wrench. The end of it spins so you can turn the bolt while pressing forward. It also helps to keep the wrench straight on bolt head.
  4. Refreshment should be in one of these ice mugs so it stays cold while your attention is on the assembly.

Right! Parts collected for the task at hand. Bolts and standoffs sorted out.

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The lower hoop blocks. For batch 4 they’re in halves and they are not symmetrical. The shoulder is narrower on one side. The narrow shoulder needs to be toward the side where that bolt hole is closest.

This is WRONG.

This is correct!

Notice the scrape marks on the part in that last pic. This is from multiple test fitting. These parts are snug but i did not do any sanding to make them fit easier. I pushed in one half, then removed it. A tiny bit of material scrapped away. I pushed in the other half, removed it. Pushed the first one in again, then added the second one. Took them both out (because one was flipped wrong per the first picture). After repeating the process for both ends of both pairs things were snapping together and seating well.

Assemble leg.
Sorry for the blurry pic. I promise this was not the result of the … er… refreshment.

Screwed standoffs to the side I fit the hoop block into. This is the outside leg half. The one without the extra notches as noted on the video. The correct standoffs are the same length as the thick part of the hoop block. When I pushed the inside leg half over that block everything lined up perfectly.

It’s still a good idea to make sure all the bolts are threaded - not cross threaded - before tightening anything down. There is not much wiggle room here but there doesn’t need to be. Tight, accurate.

Speaking of tight…how tight is tight? I don’t know. This is the first time I’ve worked with carbon fiber parts. With that little screwdriver handle I’m not getting much torque on them. Also I tightened the whole thing in at least three trips up and down each side of each leg. 1, Snug them all, 2, tighten them all a bit, 3, tighten them all a bit more, 4, make sure they’re all tight. I’ve not used any thread locker on these bolts. Should I? Seems vibration will be minimal, checking them will be easy. Preflight?

Note: be sure to make a left and right leg!

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I used threadlocker blue/medium for all screws…(I think Paul recommended this)

Just for fun I used washers. Don’t forget to put something for the net strapping on the legs - I used some universal rings / needs longer screws as well. If you use the Apco harness you can put the lower quick straps between the standoffs…

I recommend as well the 3d printed endstop from GliderPilot!

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Paul’s video shows thread locker (blue locktite) as a requirement but during the assembly he does not mention nor show where he’s using it. Everywhere? I guess it’s not like it should ever require disassembly except to replace/repair a part damaged in a crash. Going back and thread locking everything can only cost me time. Having a loose bolt go through a prop?!!?!

I see you used the outside two of the three holes at the bottom of the leg support plates. Per the video I used the center one only. Thoughts here anyone?

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Putting the lower plates on the legs. What should we call this piece? Pelvis? I flipped and switched the two plates to get the best possible snap down over the legs at the front side. The result was one side snapping down nice and flush and the other side hanging up over the center tab of the inside leg half. In the picture below you can see the slight gap there.

Chamfered the edges of that tab with a file, and also shaved the slot with a utility knife, just enough until it snapped together. Note that the leg outsides are already chamfered. They came that way.

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Doesn’t matter - I used the two outside lower holes because the Apco Split Harness has 4 lower fixing points.
Apco split harness on OpenPPG

For the plates I used a rubber hammer gently and they fit in snug!


Completing the legs.
Bolted all the standoffs to other side of the pelvis.

It dropped in place perfectly without any fiddling. Threaded all the bolts and tightened them down. Like the legs I went over them in a pattern 3 or 4 times pretty much torqued as much as I could comfortably get with that little screwdriver handle.

To mount that lower, center hoop piece I needed to first fit both ends over the 3D printed mounting blocks. i.e. Fit one end then pull it off. Fit the other end then remove it. Go back to the first end and it fit a touch looser allowing me to slip the other end in.

Voila. I’ve since mounted the lower leg hinge blocks. Pretty straightforward.

Goose necks
Skipping ahead a bit I assembled the swing arms. Gathered the bits and laid out to ensure I make a right and a left!

The bolts are the largest ones which are the same as for the leg hinges. These all use 5/16 (or metric equivalent?) nylon lock nuts. The bolts stick through the nuts sufficiently.

I tightened them down and the mounting blocks did not move so I backed them off 1/8-1/4 turn just until they spun easily.

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Motor mounts
Assembled the motor mounts. These use the smallest standoffs. Here’s the pattern.

The bolts are basically sitting inside the motor. I applied threadlocker to all the motor mount bolts. If one backs out you’ll probably loose a motor. Also it’s impossible to check/re-torque these. To keep things clean I put a bolt through the plate then applied the threadlocker then spun on a standoff and tightened it. Repeat 4X per mount. Four mounts.

The forward motor mount plates in batch 4 have some extra material removed so it’s much easier to see which way they go. Like this.

Test fitting the motor arm. It fits perfectly.

Motor arms
These use the longest standoffs. The ends where the hoop mounts are different than shown on the video. Figured out it goes together like so.

Note the slight angle formed on the hoop mounts. They should angle inward slightly not outward.

And run into the problem everyone has regarding thread depth in these standoffs. The bolts are 3mm too long.

So I decided to try cutting them down. Nipped the ends of a pair with bolt cutters. Cleaned up the ends with a file and everything came together nicely.


Finishing motor arms.
Second idea. Decided to space the hoop mounts out instead of cutting the bolts.

The bolts fit really tight through these so I drilled them out with a 1/8" bit. Still plenty snug. The bolt heads still fit quite tight into the recesses

Lining up the arm hinges in pairs.

The nuts are metric but a 9/32" wrench worked nice. Tighten, then back out 1/4 turn or so.

An evening’s labour. Getting a blister from the screwdriver handle. :-7

Note that I’ve not added all of the hoop mount blocks. The kit was short on the bolts for them. I’ll have to go by a handful.

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At this stage I coated all moving parts with white lithium grease. This makes them move much smoother, and will prevent wear of the rather soft aluminum and anodization.

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I had the same problem with the kit being short on these longer 45mm M3 bolts. The kit is ALSO short on M3 lock washers which are used when mounting the speed controllers. This was annoying, on both parts. Ordered extras of both from McMaster Car

Center plate.
Applied some hot glue to these sites of the circuit board. The just felt a bit loose, I wanted some strain relief.

Should the kit have two main switches? Mine only had one. There seems to be four corners where the circuit board will bolt down. I choose the lower left corner - or will that be the right corner?

Time to solder the more to the speed controllers. Solder, check, flux, check 35 Watt iron, check…!

LOL no. That wire is way too heavy for my little iron. This should work better. Torch, flame shielding, needle nosed pliers.

First one. Serviceable I think.

One motor connected. Carefully wiped them off and inspected and tried hard to pull them apart. By the time I got to the last set I was getting fast and the connections were looking better too.

All done. Hooked up two controllers each way. Guessing that’ll give me two spinning in each direction.

You really need to invest in a higher watt iron. You will need that later for the main wires anyway.

Hook each arm up to the controller to check the spin direction because the wires could be crossed before coming out of the motor. Mark the direction of each one. If you need to reverse one just swap any two of the three wires.

Paul didn’t include a second switch with batch 4 because it uses higher volts and lower amps. The switch is rated for 300 amps which is what you will get at full throttle. However, the true problem with the switch is when it gets damaged from arcing. Therefore, I highly recommend a pre-charge switch or button to protect the switch from damage. In addition, I prefer two switches so each only has to handle 150 amps.

Here is a link to the pre-charge switch I designed. Scroll up in the thread to get more details about how it works.

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Hey gliderpilot. I was wondering if the batch 4 kit Incorporated your pre-charge switch. I guess I have my answer. I don’t have a 3d printer. How much do you charge for your switches?

Since I’m still waiting for batteries I did two more flights (#s 9 and 10 ) today on a Blackhawk 125. Did my first reverse launch with a motor. Five mins sniffing two stroke fumes waiting for the right wind.:roll_eyes::smirk::nauseated_face:. Still way worth it though :grin:

Definitely I’m not going to assume the motors will be correct without checking them. Just starting out with the best bet.

If you can’t find someone local you can order prints online. That’s a really small print so my price would only be a dollar. The shipping would be a lot more though. If you have other parts you would like me to print to make it more worth my time I’d be happy to help you out. Feel free to PM me.

Ha. Totally slipped my mind that there are local 3d shops. Thank you. I’ll check into it.
Meanwhile… Testing the ESC wiring.
I still don’t have bonkas but I do have a 40 Volt Ryobi lawn mower battery. Temporarily squashed the battery cables together with controller power to alligator clips. Clipped to the battery and… Nothing. :thinking: Ok touched positive clip to check it and zap snap then lights and bleeps :notes::bulb:. Everything checked out. Two motors spinning each way. :grin:.

Dang I’m taking blurry pics again. :confused: