Sunday, April 12, 2020

Maker Knife - How the locking mechanism works.

Long ago I promised a "how this works"

Here's how the makerknife locking system works.

Extended, you can see there's a stainless steel sear poking up from the bottom.  When you pull the ring, it pivots down, and releases that sear.



What holds the makerknife shut, is the pin sticking down from the top of the frame in back there.



Saturday, February 8, 2020

3Racing's new cheap car: The Advance S - What's the difference?

So, 3Racing is one of those brands I've ended up liking becuase... well they do the accessory game really well.  I found out they also made complete cars.  Turns out, they have been for a long time. 

Unlike a lot of the big players, they don't just make their flagship car, they make a range of models, from the $110 first car to the $500 car designed to fight toe to toe with TRF, Mugen, Yokomo, ARC... well you get the idea.



The Advance S is their followup for the Sakura XI Sport.  The Sakura XI Sport, has already had at least two editions, and at least one "less than savory" clone.  (The TD10 v2). 


Oh, look, toy cars.  But those aren't nearly as fun as the r/c kind.  Lets open the box.

Like every 3Racing kit I've built, you get a box of lovely bags. 


Of course, we start with bag 1.


Because it's useless, and stupid.  That knife is a makerknife.  And it might just be the best knife I've used.  It's this thing: https://www.kickstarter.com/projects/1496249101/maker-knife-the-edc-pocket-tool-you-want-to-carry/

Check it out, it's related to some of my favorite makers.


We start with the diffs.  Well, a diff, and a spool.  


I can't really tell the difference between the diffs.  There's no flash, and all the parts fit nicely.


Here's the bits that go inside the diff.  I like it when I see the backing washers.  


And they stack up.


And drop in.


The kit comes with 2000 weight oil.  Unlike a lot of kits, the bottles are nicely labeled.  


The gasket goes between these.  The gasket provided feels a bit big, and it needed some ... encouragement to go together.  


And here we go, and assembled differential.  


We've built spools before.  If you want more detail, check out the Sakura XI build.


These manual pages are quite nice.  I'm thankful this isn't the photocopied manual from the MG Evo.


The spur setup is symetrical, which makes the build pretty easy.  However, instead of the typical 3 screws, this setup means you need to undo 6 screws to get to the spur.  .. Changing spurs isn't going to be the fastest on this car.  


Maybe.. I need to check parts prices, it might be worth having a spare set of pulleys and spacers so you can have a ready spur to swap.


Done!


And all of that, was bag 1.  Bag 2, starts the chassis build.


More makerknife porn.  So we start with the arms.  

A bag of arms, that is.



First thing I noticed, was this.  The suspension mounts.  The front and rear mount have just one screw, and importantly, have molded in pins.  They fit TIGHT into the chassis, and don't move at all.  Pinning is a very good way to make strong connections like this.  "I approve".  Also, though they look nearly identical, they are different parts.  


The center suspension mounts are molded.  These are the soft plastic that you'll find... oh.  The car is in two kinds of plastic.  The suspension arms are VERY rigid.  Like they clink when you tap them on things.  The rest of the plastic is pretty soft.  ABS would be my guess.  It's well molded, with little flash.  



Be sure to use that m3 thread forming tap.  I could see this ABS stripping easy if you don't.



The front arms, are a bit of a build.  You need to tap six holes.  There are the two shock mount holes, then the drop screw hole.  The droop screw hole is M4, I "should" have tapped it, but instead I just forced the setscrew through.  The swaybar cups are separate, and bolted in.  


The rear arms, have more holes for the shock and swaybar links.  All of the arms were tight on the pivot pins, so I had to use a 3mm reamer on them.  After reaming, they were slop free and flopped as they should on the chassis.


You'll need something like this, to do the reaming.  Ignore the chassis in the background.


So the arms need a place to go.  In this case, they get mounted to a big FRP plank.  


Ten screws, and various other bits later, we have the arms on the chassis.



That's a really flat thing, and to get into the 3d space we need, so things like motors, servos and batteries can be mounted, we need bulkheads. 

In a neat choice, by 3Racing, the steering components are part of the bulkheads.  In another neat choice, both the front and rear bulkheads are identical! 

So we're going to start on the front.  


They're all a "very soft" plastic.  They grip onto screws well, but while tapping them, they moved around a lot.  


The steering is fully bearing supported.  The stackup of parts is important, to make sure fasteners don't rub on bearings, but the instructions are pretty clear on how to make that happen.  


For one page, there's a whole lot going on there.  The bulkheads go on the chassis, and the diffs drop in.  The instructions aren't completely clear, but you really do need to have the front belt on before you get the front bulkhead screwed down.  



This picture, you can't take, if you're doing the job right.  The "anti rotation" metal shafts can't be in place, if you're putting the front belt on. But here are the two bulkheads.  They really are the same, front and rear.  There's 7 holes that need tapping on each bulkhead.  28 total.  (Just emphasizing how much you need that tap. )


And the bulkheads on the chassis.  That's the motor mount on the left there.  One of the few aluminum parts of this build.  


The motor mount has plenty of clearance to the chassis.  This means the chassis has more symmetrical flex.  In theory, this helps make the car more consistent on track.  I believe it, but I can't say I have experience that defines it.  Thankfully, most of my experience has been with cars that already had this in mind!  


Motor mount and center pully from the top.  


Diffs, center pully, and belts all installed.  It looks like a car now.  And.. I have something to fidget with.  *spins pulley*


Next up, we need to hold all those parts in place.  The diffs are held in place with the bulkhead caps and shock towers.  



The shock towers, also have the anti twist columns like the bulkheads do.  They too are symetrical like the bulkheads themselves.  Low parts count is good for manufacturing, and for chassis predictability.  ... and spares.  


There's a lot of book for these two parts.  


Because of how soft the plastics are, getting them bolted on isn't the most straightforward task.  Just get one bolt lined up at a time, and don't cinch it all down until all 8 screws are started.


Same goes for the top deck.  It takes a little bit of fiddling to get it to fit in through the front belt. 

It was at this point, I installed the m1.6 screws that hold the diffs in their tension setting, and the center shaft in place.  


Bag 5.  Swaybars.  


Here's the front setup.  They're bearing supported, which is really nice.  They're essentially slop free.  And have no friction to their movement.  


And the rear bars.


So... from the swaybars, we need to get in on the knuckles.  There's nothing special about them, but we'll cover them in a moment anyway.  


The car comes with a very nice toolset.  A bunch of socket wrenches, turnbuckle wrench, and a pair of pliars that are designed to hold ball cups, and turnbuckles without hurting anything.  


Here's the set of tools.  You need to build the plairs.


Here's the front knuckles on the car.  


Just admiring them a bit.  The only thing to keep in mind when building them, is make sure you have the top-hats on right.  


OK, maybe there is something to talk about.  This car comes with brass compression spacers for the knuckles.  So when you tighten the wheels up, you aren't stressing the bearings.  These are brass.. a nice touch.  


Ok, everything but the turnbuckles are in place.  This is where the process slows down a lot.  


That little plastic case, is critical here.  As is laying out the bits.  I build all my cars so "pulling back" on the turnbuckle shortens the turnbuckle.  Also, this kit has special outboard turnbuckle endds, to provide more clearance for wheels.  



That little plastic case, is the container for my left hand thread forming tap.  The layout of parts here, is so I tapped the right ones.  


And here we go, all the bits installed.  


Looking at the knuckles you can see the open top ball ends at the wheel ends of the turnbuckles.  That.. mostly completes the chassis.  


The shocks are a bit of a disapointment.  They're ultra shorty, but unlike the Sakura XI, they have plastic caps, and only single seals.  


The shock shafts come first.  


Eclips, then pistons.  


O-rings go in the shock bodies.  


O-ring installed.


The shaft guide.  


The shock seal cap.  


Here's the completed shock body.


Putting the spring perch is slightly tricky.  Thankfully there's no o-rings in these, but you still need to take great care not to cross thread them.  I highly recommend turning them backwards until you hear the "click" of the first thread, then you can screw it on.


All the sub-assemblies ready to go.  


350 weight oil.  Most companies can't be bothered to label theirs.  


Shafts, in bodies, with shock ends on.  


Don't do this.  Wait to install the springs until they're filled. 


They really are tiny shocks.  


But filling them goes the same.  


And the shocks snap on. I think they're leaking.  That may require some better shaft seals...  I really hope I don't need new shocks.  


So, all of the accessories need to go on.  Steering servo mount, battery mount.  What's nice about this kit, is the battery mount is complete.  And doesn't need a strap or battery tape.  The steering servo mount is also completely floating, so it doesn't add any tweak or stiffness to the chassis.  


I threw the wheels on, body mounts, and bumper.  Take a good look.  






I'm quite pleased with this kit.  Lets cover the high points:
  • LCG shocks.
  • Symmetrical design.
  • Floating steering servo.
  • A good tool kit.
  • Bearing supported swaybars.
  • Complete battery restraint package.
The low points... 
  • All plastic shocks.
  • Seems quite flexy.
  • Shocks leak.
Next is to take it to the track, see how it compares to the Sakura XI ver.Nu.