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Jul 05, 2017, 08:03 AM
"Spark Chaser"
jokeane's Avatar
Build Log

QTrainer build log

This is my first 3D Lab Print build. I choose the QTrainer not because I really need a trainer, but because I think it is likely to be a decent flyer even if it weighs a bit more than a balsa plane in the same size. Another reason is that unlike a scale model, the QTrainer can be made in whatever color scheme appeals to you, so using the 'bare' printed plastic won't be a drawback to the appearance. I also just happened to have some HS-81 servos and a 3542 size motor kicking around.

I own the BF109 and Spitfire models, but I've yet to attempt to print and build them. I saw the QTrainer model appear, and since I was already a 3D Lab Print customer, I was offered a limited time discount ($16 vs. $20).

I used my Original Prusa i3 MK2 printer to print all the parts using the included GCode files. I did edit the GCode to add the 'start' commands specific to the MK2 (autobed leveling, extruder priming blob).

Printing took about a week of real time. I didn't log the exact number of hours, but I did print multiple files per day. Usually 2-4 depending on the file.

I used white PLA included with my Prusa kit, and blue eSUN PLA PRO. The black flex (TPU) is from FoxSmart.
Last edited by jokeane; Jul 05, 2017 at 08:10 AM.
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Jul 05, 2017, 08:08 AM
"Spark Chaser"
jokeane's Avatar

Wing start/stop blobs

One minor issue I found was that printing very hot results in some blobbing (zits) at the start/stop location. I cleaned this up with a knife and a bit of sanding. One benefit of white PLA, is that when sanded, it doesn't change color.
Jul 05, 2017, 08:21 AM
"Spark Chaser"
jokeane's Avatar

Wing Assembly

Building these 3D Lab Print planes is interesting. Sort of halfway between building an ARF balsa or foam plane and a plastic model. Probably the closest analog is building a Multiplex kit. But there are far more parts and part alignment is a bit more of an art with the 3D Lab Print designs.

My printer is setup to really 'smash' down the first layer for good adhesion. This results in a bit of 'elephant foot' on the base of the printed part. I tried to clean this up as much as possible, but my seams still appear much more visible than the 3D Lab Print photos.

Oh well. The finish quality of this plane is going to be more functional than beautiful I think.

Wings go together pretty easily. Most of the parts on the QTrainer have some sort of alignment tabs. I used medium CA (Gorrilla brand) and kicker.
Jul 05, 2017, 09:59 AM
Registered User
rcflyer23's Avatar
Very interested to see how this turns out. I just got an Anet A8 and have been tuning it over the weekend and getting some of the "upgrades" out of the way. I was thinking of starting with the trainer as well. I don't need a trainer either but if it works out it will be good for my 10yr old.
Jul 05, 2017, 11:38 AM
Retired CAD guy
birdofplay's Avatar
Not to feel bad about your printing.
I've had similar issues especially the Alignment/Assys !

I got tired of smash down and Extruder Grind/Complaint so
I just use multiple Skirts and then sand or Dremel them off after assy.

Even with 3 skirts "RIGHT UP NEXT TO THE skin" , ( 0.00 offset)
my two Center sections warped UP at the TE so I am going to try "Welding" in some
material to close the gap.

I've been assembling the Cessna, QT and Spitfire prints and "STILL" have not
mastered a skill or technique for alignment/assy. :<{

A much friendlier connection "standard" needs to be developed. and employed IMHO
Jul 05, 2017, 05:12 PM
"Spark Chaser"
jokeane's Avatar

Fuselage Assembly

Fuselage assembly was very straight forward. A bit more alignment tabbing and thicker / stronger parts make this go together a bit easier than the wing.

I really liked the spring loaded retainer on the battery hatch. Very clever indeed. Plenty of room for a battery. I might forego the little battery platform - to me this seems like it has too little connection to the fuselage for strength when you put in a big 3S 3000 mAH pack.

Motor mount seems reasonably sturdy / thick. My motor only aligns with two of the screw holes, but this should be strong enough since the motor thrust will be pushing against the motor mount.
Jul 05, 2017, 05:14 PM
"Spark Chaser"
jokeane's Avatar

Fuselage and Wing

Pretty happy with things so far!
Jul 05, 2017, 05:39 PM
Registered User
Pretty cool Jim!
Jul 05, 2017, 08:18 PM
"Spark Chaser"
jokeane's Avatar

Tail Assembly

Tail was pretty easy to assemble. CA hinges are as usual a bit of a PITA. I found that they appear to work better if you install a square at a 45 degree angle so you are installing a triangular portion into each side. Apparently the holes must have this shape.

I temporarily installed the rudder pin to help align the horizontal stabilizer, and then screwed it down with 2mm x 20mm screws.

If you want to use z-bends, make sure to install your control rods BEFORE you glue in the control surfaces, since the control horn is built into them and you cannot put in a z-bent wire after the fact. I didn't, so I'll be using dubro mini quick adjust fittings. Not too big of a deal since I like these and use them in many of my builds.
Jul 06, 2017, 04:52 PM
B747-400 First Officer
WJH's Avatar
It reminds me of a "PT Electric". By the way, that little fancy tool is very common in metal working / machining. It's called a deburer. Harbor Freight sells them I believe.
Jul 07, 2017, 07:07 AM
Retired CAD guy
birdofplay's Avatar
After 50 yrs of modeling I bought a supposedly REAL Scalpel at Toledo this last Show.

Yes the Blades are Sharp , but, they break surprisingly easily!

Of course I was using them as a Scraper, sigh ...
Jul 07, 2017, 11:58 AM
Staying away from trees..
markag's Avatar
Subbed to this thread. I'm a few weeks behind you on mine.
Jul 12, 2017, 07:51 PM
Ken's CAD Models
dz1sfb's Avatar
Originally Posted by markag
Subbed to this thread. I'm a few weeks behind you on mine.

Jul 15, 2017, 11:18 AM
"Spark Chaser"
jokeane's Avatar

Installing servos

Installing servos went pretty well. You need extensions for the ailerons, but not for the rudder and elevator. I used Dubro easy links on one end and z-bends on the other. Standard music wire.

I added a little reinforced strapping tape to the bottom of the middle wing seam. I don't want to fold this wing in flight.
Jul 15, 2017, 11:26 AM
"Spark Chaser"
jokeane's Avatar

Landing gear assembly

I decided to try the tricycle gear initially. My friends say it is better for beginners. I'm a bit dubious, since I always fly taildraggers. I'm wondering if it will be steerable on the ground without a steerable nosewheel.

For mounting hardware, you need to supply the self tapping screws to attach the gear to the fuselage. I used some leftover servo mounting screws.

For the wheels, you need 3m x 30mm bolts and 3mm washers and nuts. Remember to use locktite on nuts so you don't loose a wheel in flight.

I also assembled the tailwheel. I reserve the right to switch over to taildragger if I don't like the tricycle handling.

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