Build Thread TEKNO SCT410 2.0 Build

[WickedFog]

Man, for some reason it always feels good to drag the chassis out.

Look at me turning a screw. Why did I take this picture? For this step, place the screw in the hole. Insert your hex driver into the hex socket, and turn clockwise while applying downward pressure Front bulkhead bolted on.

Nice, unique, proprietary standoffs

Bulkhead brace in.

Bellcrank installed.

Time to tie it all together.

You can really feel the strength of this design as the parts start getting bolted on.

Attaching hardware for the steering links. This is OEM Tekno hardware, because for some stupid reason nobody makes a 12.9 grade M3 x 18 buttonhead screw.

After a couple minutes with the steering link rod sticking up there pinched between my fingers, doing pretend power slides with the steering while making engine revving and tire screaching noises, I snapped a pic for you animals. Vroom vroom errrrt!

From there, it is onto the front bumper mount, and the front end is complete.

 

[WickedFog]

Electronics time!

First up is the motor mount.

Make sure to use loctite for any screws going into metal. I see people putting way too much loctite on their fasteners. All you need is a drop.

This big plastic piece attached here was designed by an engineer that was just tossing lines in the CAD program and completely forgot what he was designing it seems. As far as I can tell, this is simply a wire guide. Considering it takes 3 screws, and 3 machine processes to not only drill the motor mount, but also the chassis plate in two places - welcome to the most overly engineered, and costly wire guide in the RC world folks

It hurts seeing this in the box, all pretty and new. Will explain later.

At this point, things are tranquil, and moving along. No drama here.

Then, I went to install the servo in this ridiculous contraption. These bosses were too big for the holes in the servo mounting tabs to fit over. Unless I was supposed to use a hammer in this step? Not to mention the servo wire was nearly sheared off because someone decided to not put enough clearance for the servo wire to go in. But I got it in there. The problem was after realizing the servo would not fit over these stupid bosses, I had to pull it back out. It was the scariest thing to watch the servo wire pull out, dragging though what was essentially a shear point in this part.

So off they went.

Then, I took my rotary tool and cut some relief where the servo cable exits the mount. I mean, the manual CLEARLY shows Tekin electronics being installed in this kit. Did the engineer not even test the fitment?

This has been by far the nicest RC kit I've built to date, but this whole assembly here was pretty damned frustrating to say the least. To have to do not one, but two modifications with a grinder to mount a servo is just plain stupid, and really, really bad engineering.

Rant over.

Time to mount the ESC. I replaced the included stainless screws supplied with the ESC (come on now Tekin) with some steel ones. These were originally 6mm, but I dropped down to 4mm because they were plenty long enough, and I'm always scared of running into the PCB inside the ESC.

Got the chassis side bolted in, and ESC secured. The excitement is building, and I really wanted to get the motor installed, but at this point I realized I had been in that chair a bit too long. So a smoke break came here, along with a couple hour visit with my recliner.

 

[Littlemotor]

Time for the bellcrank.
View attachment 224363

See picture of spring behind this. Something didntlook right bere, but @Littlemotor, who has become my tech support for this build, asdured me it was. And I think this spring was originally used on the Ford Pinto, but Ford realized the Pinto wasn't heavy enough for such a spring.
View attachment 224364

So after realizing that my socket set doesn't have a 17mm socket in it, I faced the realization that I was either going to have to wait til I could get a 17mm wrench, or do this the hard way. I have always taken pride in the fact I could hold up a concrete block with just two fingers and my thumb. But that was in my youth. Trying to compress this ridiculously strong spring, and thread on a super fine thread nut was a bit tougher than that, but after about 6 attempts reversing the nut to find the lead in thread, only to lose my strength, I decided to mark the lead thread location without the spring and try again. After the most intense stuggle I have ever faced in RC (arthritis in both hands and fingers) I got the nut started.

After letting the feeling come back into my fingers, I bear gripped this byatch and threaded it all the way tight, then bscked it off two turns per the manual.
View attachment 224365
You know what's funny? I could have designed and printed a suitable 17mm wrench for this

Upgraded bushings thanks to Littlemoter's experience here seeing a potential weak point and ordering me a set.
View attachment 224366

♫ ♬ ♭ Lets get together and feel all right ♫ ♬ ♭
View attachment 224367

Bearing to install is all that was left, then it's time to remove the chassis from the plastic!
View attachment 224368

Looking killer!! You are Smoking my old asss over here.. So glad to see ya hard at it, and having fun with this one bro!! Gonna be a nasty one here very soon!!

 

[CertifiedMike]

At least you were smart enough to catch it before you decapitated the servo!!!
This is looking GREAT!!!

 

[WickedFog]

Great build . Sometime, when you get around to it, please let me know if the rod ends tighten when you pull on the turnbuckle adjust tool when looking from behind. I'm just curious of the threads/marking on Klinik's turnbuckles. Stock Tekno turnbuckles (every 1/10 & 1/8 scale platform) are backwards compared to every turnbuckle I've ever built when placing the marking to the left.

Also, you must have been hanging out with Jared Wiggins and his progressive slop induced sway bar clinic.

Sorry it took so long to get back to you on this Rusty. The links definitely shorten when you pull the wrench towards the rear.

 

[WickedFog]

At least you were smart enough to catch it before you decapitated the servo!!!
This is looking GREAT!!!

Tekin is sending me an invoice for a new top cover. They said with shipping it will likely be about $24. Not as bad as I thought it would be.

 

[TeknoJ]

I would really like to borrow that truck for about a weekend when you finish building it.....it's just a little science project I have going.

 

[WickedFog]

So what happened with the servo was in the bottom of the Tekin servo horn, there is a slotted counterbore that appears to be meant to run a cap screw through, just like the Tekno manual calls for with the stock horn. This would make for a very secure mount for the steering link, especially if you loctite the screw in and put a locknut on top as I have here.

I had previously installed the horn, intending on just screwing down into the top with a buttonhead loctited in, just like I did on our Ryft build. But I remembered how weak that was when the Ryft ripped that screw right out of the Tekin horn, because there is only a couple millimeter of threads left in the horn due to the counterbore on the underside if the horn. So I thought it would be best to run it up through the bottom this time. So I checked the clearance by sliding the buttonhead screw under the installed horn, and sure enough, it had room for the head to be underneath it.

So I removed the horn and realized thet buttonhead wouldn't fit in the the counterbore in there. So I stuck a cap screw in there and it looked like it would clear the servo, and appeared to be what was meant to be used. But after reinstalling the horn, I forgot to look under the horn to make sure I still had clearance with the change to a cap screw. And sure enough, when I fired up the Rx to test everything and set my endpoints, it gouged the hell out of the top of the servo. Yup, that hurt pretty bad. I am still pissed off about it today.

The solution... grind the head of the screw down. Now, I wouldn't try this with 10.9 grade hardware. But with 12.9 grade stuff, you can get by with having a shallower hex socket, as long as you have good tools.

The ideal solution... buy low profile cap screws.

They have the same outside diameter as a standard cap screw, but a shorter head, and they have a smaller hex in them to account for the loss in height of the head. They are precisely for conditions like this, where a buttonhead is too big in diameter, and a regular cap screw head is too tall.

I'll get some more pics of this when I get the new servo top cover. That may be on next month's order though.

 

[WickedFog]

So here's a pic of the damage. I can't look

 

[Littlemotor]

So here's a pic of the damage. I can't look
View attachment 224805

This is why we can’t have anything nice!!

You’ve got a plan, Stan… Gooooooosefraba…

 

[TeknoJ]

So here's a pic of the damage. I can't look
View attachment 224805

Ah shoot, look at it as a weight shaver

 

[TeknoJ]

So here's a pic of the damage. I can't look
View attachment 224805

You are also a machinist man; you can fix this. No Big D

 

[Littlemotor]

Ah shoot, look at it as a weight shaver

If you didn’t MEAN to say “shaver”, that was EPIC right there.. And if ya DID mean to, then @Chubaka would be proud.. Either way…..
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[TeknoJ]

If you didn’t MEAN to say “shaver”, that was EPIC right there.. And if ya DID mean to, then @Chubaka would be proud.. Either way…..
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View attachment 224810

It was a toss up between that and saver, shaver felt more applicable.

 

[WickedFog]

So let me get back on track here, back to this dramatic crime story, back before Stanley Servo's traumatic incident. And I apologize for getting a bit too involved in the build, and forgot to get some pics. But the motor went in next. Pretty straightforward. 5 bolts from underneath. 3 of which went into the aluminum motor mount with loctite.

Next up was assembling Steering Mclinkage. An innocent bystander in this woeful tale.

From there, it was the beginning of Mr Servo's demise, and the inevitable mutilation that insued. The suspect: Tekin the "Crowbar". A dastardly villain from the Dumb Engineering crime syndicate, along with his henchman, Caphead the Mutilator (The aluminum spacer here is to raise the bellcrank side of the link a bit. Without it the angle of the link downward really bothered me).

The scene of the crime. Just moments before Mr. Servo became the victim of this brutal attack by Caphead the Mutilator. Here you see the spacer on its perch, another innocent bystander who is now in witness protection.

The stage is set. All Caphead needs now is for the signal from Servo Von Testor to set his evil plan into motion.

Multiple cameras caught the perpetrator in action.

Then... Servo Von Testor gave the signal.

1500 pulses of modulation width was sent just before a blood curdling scream let out across the RC neighborhood - ArrRrRgGhHhHHh!!

The wound was merely superficial, but the pain will never go away. Caphead was later hunted down and cornered by Mr Milwaukee, and quickly decapitated with EXTREME prejudice. The scene was too gruesome for public viewing. Mr. Servo will be on the waiting list now for a new face transplant. But for now, he has survived the attack.

Oh, @DavidB1126 - here is the process for twisted cables.

Wrap your cable around your 2.5 or 3mm Dynamite driver. Make sure the cable doesn't flip over or overlap itself.

Keep the cable snugly pulled and push it all down to the end of the driver, or towards the handle. Whichever gets the cable all barber poled.

From there it is simply a matter of sliding your hex driver out.

 

[Littlemotor]

So let me get back on track here, back to this dramatic crime story, back before Stanley Servo's traumatic incident. And I apologize for getting a bit too involved in the build, and forgot to get some pics. But the motor went in next. Pretty straightforward. 5 bolts from underneath. 3 of which went into the aluminum motor mount with loctite.
View attachment 224807

Next up was assembling Steering Mclinkage. An innocent bystander in this woeful tale.
View attachment 224812

From there, it was the beginning of Mr Servo's demise, and the inevitable mutilation that insued. The suspect: Tekin the "Crowbar". A dastardly villain from the Dumb Engineering crime syndicate, along with his henchman, Caphead the Mutilator (The aluminum spacer here is to raise the bellcrank side of the link a bit. Without it the angle of the link downward really bothered me).
View attachment 224811

The scene of the crime. Just moments before Mr. Servo became the victim of this brutal attack by Caphead the Mutilator. Here you see the spacer on its perch, another innocent bystander who is now in witness protection.
View attachment 224830

The stage is set. All Caphead needs now is for the signal from Servo Von Testor to set his evil plan into motion.
View attachment 224814

Multiple cameras caught the perpetrator in action.
View attachment 224815

Then... Servo Von Testor gave the signal. 1500 pulses of modulation width was sent just before a blood curdling scream let out across the RC neighborhood - ArrRrRgGhHhHHh!!
View attachment 224827

The wound was merely superficial, but the pain will never go away. Caphead was later hunted down and cornered by Mr Milwaukee, and quickly decapitated with EXTREME prejudice. The scene was too gruesome for public viewing. Mr. Servo will be on the waiting list now for a new face transplant. But for now, he has survived the attack.

Oh, @DavidB1126 - here is the process for twisted cables.

Wrap your cable around your 2.5 or 3mm Dynamite driver. Make sure the cable doesn't flip over or overlap itself.
View attachment 224816

Keep the cable snugly pulled and push it all down to the end of the driver, or towards the handle. Whichever gets the cable all barber poled.
View attachment 224817

From there it is simply a matter of sliding your hex driver out.
View attachment 224818

Best read on the entire forum right there!!!

 

[WickedFog]

Best read on the entire forum right there!!!

Why thanks. It helped to turn such a tragedy into a comedic crime story

 

[Littlemotor]

Why thanks. It helped to turn such a tragedy into a comedic crime story

It worked man-I was on the edge of my seat!!

 

[WickedFog]

Here's the part where I got busy and forgot to take more pictures

The battery tray and receiver were installed, then it was time to install the center diff and mount along with the driveshaft. Make sure to put the o-ring in the forward outdrive cup of the center diff.

Then install the pinion. The 4300 kv motor along with a 16t pinion is recommended in the manual for large tracks. Make sure to use loctite here, but leave the pinion just loose enough to slide it on the motor shaft.

You have to install the left side cover (one on top) to hold the center diff in location.

From there, you need to line the pinion up with the spur and tighten the set screw. My UV light was handy, so that's what I used.

After that's taken care of, it's time to finish installing the top cover. I handle bolt installations like in the next pic with every assembly I do, kinda like you do head bolts on an engine, wheel lugs, etc. Regardless if it really matters or not. I can absolutely verify this does make a pretty huge difference when installing fixtures in machining. You can see it on a test indicator sweeping tooling ball locations.

Since the spur cover is what locates the spur, I tighten it first. Then the pinion cover. But I don't take any of them all the way down. I take them down in stages. Bolts just lightly snug on the first pass through the pattern. Then give each a slight turn on the next pass, a little more the next pass, etc. I made 5 passes through this assembly before making one more pass to check that all were tight.

Top covers done.

This is actually the part of the build I installed the switch. Fortunately I have an inventory of just about every screw size used in this hobby. So I broke out my M2.5 screws and selected a proper length screw, which was a 6mm.

Switch bolted in.

 

[Littlemotor]

Looking good man!!

Everyone does things differently, but a lot of times yielding the same result. If it’s lights, it’s a star pattern, or criss-cross. Anything else, and I start in the center, and work my way in a spiral to the outermost fasteners. Either way, it’s three passes until desired torque, bolt stretch, or whatever it calls for.

Also it’s tough to make out-but LOOKED like your switch has “ON” facing the rear of the vehicle. If that’s the case, I’d strongly recommend that ya yank the screws, and rotate it 180deg. If running a mechanical switch (I always delete mine prior to install to eliminate a possible failure point), you always want “ON” facing forward. This way in the event of a crash, or hard hit, lawn dart, etc., the vehicle doesn’t turn off. Seen it happen about a gazillion times. If I misread what looked to be “ON” just outside the metal bezel, and it’s facing toward tue front, obviously disregard.

You’re moving right along man!! Looking absolutely tremendous!! Get you some dammiit ice cream fella!!