Speedy's Sport 3.2 Hot Wheels Homage

[speedy_w_beans 4272]

Onward and upward...

I measured quite a few features on wheels tonight.  Below are some notes; maybe these will be helpful to someone else someday.  I do think I have a little more insight about touring car wheel offset now, though. When someone talks about a +0 mm offset or a +3 mm offset, it's always been kind of a mystery to me what that really means in terms of wheel dimensions.  I knew that more offset meant "wider," but that was about it.  For reference I measured a Tamiya 24mm wide touring car wheel, and as it turns out, if you take the mounting face located 17 mm from the back face of the wheel, then subtract the typical 5 mm thick mounting hex, that aligns the centerline of the wheel with the back of the mounting hex on the axle stub.  So a +3 mm offset wheel would move the centerline of the wheel 3 mm outboard, adding track width.

Anyhow, my intention for measuring all these wheels was to design an adapter that goes from the RJ speed axle hubs to the standard touring car wheel, and with +0 mm offset wheels, set an overall width of 200 mm.  There might come a day I want to run TC wheels on this pan chassis.  For now, though, once I have adapters appropriate for TC wheels, it's possible to design a F1 wheel with a 12 mm hex so the tires with the thicker sidewalls can be used.

Here's the adapter.  It's very similar to a RM01 adapter.  There's internal clearance for the thrust bearing, nut, and axle end.  There's a M4x12 cap head screw installed from the inside to expose about 8 mm of threads for a wheel and flange nut.  I'm thinking I'll add a few drops of CA glue to the screw before I install it; that way it won't loosen when I go to tighten the wheel nut later.  The hub flanges on the axle measure 125.1 mm currently.  With the adapter height set to 30.5 mm, two of them added to the axle creates a 125.1 + 30.5 + 30.5 = 186.1 mm width between the outer faces of the 12 mm hexes.  From there any 0 offset touring car wheels that are installed will add another 7 + 7 = 14 mm of width, so the total will come out to 200.1 mm.  I may add another 1 mm offset to each F1 wheel, and the rubber actually sticks out another 0.8 mm, so the width may end up 203.7 mm, which is close to the 203 mm I measure when the foam tires are installed.

Here's another view with the adapter transparent.  You can see the internal features this way.  There's about 2 mm of clearance between the M4 cap screw and the end of the axle.  The internal clearances have some margin, but there's also plenty of material throughout the whole adapter.  I don't expect an adapter to crack in half and lose a wheel while driving...

It's probably time to fire up the printer and make a few of these for testing.  Next up will be the rear wheels.

[speedy_w_beans 4272]

While the printer is making the first axle adapter, I put together a model for the rear wheels using the F1 barrel profile but the touring car hex position.

The face of the wheel is designed so when the F1 tire is installed, the extra sidewall leaves enough lip exposed to match the wall thickness of the center hole.  There's enough tire sidewall now that I think I can cut a red circular stripe in vinyl and mimic the stripe on the original Hot Wheels car.

So now it's going to take some time to print the other adapter and both wheels; hopefully the next time I post there will be some real pictures to show...

[speedy_w_beans 4272]

The axle adapters are done.  The width is 186 mm from hex to hex, just like I wanted, and they spin true.  Wheels are being printed now.

[ACCEL 2014]

🍕 🥨 🍰

can't seem to find my popcorn

[speedy_w_beans 4272]

I did print a rear wheel last week but wasn't happy with the result.  Whatever, there's a V2 on the horizon.

In the meantime I worked on some battery trays.  The chassis kit only supplied some large zip ties for holding a NiCd/NiMH pack longitudinally in the middle of the chassis.  Rectangular hard case LiPos covered those zip tie holes, and the location of the steering servo and lack of clearance from the upper suspension rod meant it was nearly impossible to install or remove a battery without disassembling part of the chassis.  Anyhow, this setup probably worked for carpet racing, old tech batteries, and peak charging between heats.  But for bashing around I wanted something easier to deal with.

I kept struggling with how to adapt smaller and thinner batteries to the center of the chassis, and then inspiration hit when I considered swapping the battery and electronics mounting locations.  Instead of mounting a battery in the center of the chassis and surrounding it with electronics, why not put the electronics in the center of the chassis and surround them with batteries?  The chassis has spare body post holes to leverage, so I quickly modeled a simple battery tray that accepts saddle pack cells.  Interior dimensions are 70 mm x 47 mm, and it holds my saddle pack cells almost perfectly.

Here's the outcome.  The ESC moved to the center of the chassis.  The battery trays tie into the spare rear body post holes, and I used the forward tray tab holes as drill guides to put a few more holes in the chassis plate itself.  The trays are therefore held to the chassis with four screws each.  The horizontal holes in the tabs also have button head fasteners in them, and then I have some hair bands stretched between the fasteners to act as rubber bands to hold the cells in place.  I moved the receiver to the top of the servo, and then cleaned up the wiring with some zip ties.  I'll solder a jumper to go between the saddle packs later.

So, I'm happy with the body posts, battery trays, and axle adapters at this point.  There's more work to do on wheels and headlights.  Plus, I'm thinking about some protection for the pinion and spur so street debris doesn't mangle the gear teeth or invade the ball diff as much.  More to come...

[speedy_w_beans 4272]

Ah, happiness today!  I modified my rear wheel design slightly and changed the orientation of printing, and kicked off the printer mid-morning.  Worked on a bunch of house chores throughout the day, and after dinner I retrieved the wheel and cleared out the support material.  A little bit of filing and sanding, some test fits of the tire, and I proceeded with applying the chrome vinyl wheel face and the red vinyl stripe around the tire.  From 1/64 to 1/10:

The way I did the chrome vinyl was to export the face of the wheel as a SVG (scalable vector graphic) file from FreeCAD and import it into Cricut Design Space to ultimately run the Cricut Maker we have.  That insured the cut vinyl would match the printed wheel.  For the red stripe, I just measured the OD and ID of the tire and picked a diameter in the middle.

I was even more delighted when the wheel's hex mated with the axle adapter almost perfectly.  Grabbing some M4 hex nuts from the stash, it's looking good on the chassis.  There's a little bit of rubber flash on the inside of the tire; I'll clean that up soon.

So, three more wheels to go...  Looks like the printer will be running most of the weekend.  It'll be a real milestone when all four wheels and tires are on the chassis.

[Aerobert 2141]

That's awesome. I love it. I was collecting Hot Wheels for almost 20 years and follow your build with interest. Can't wait to see the finished car.

[speedy_w_beans 4272]

Well, well, well, what do we have here?    While the second rear wheel was printing I reused most of the design for the front wheels.  The main difference between the rear wheels and the front wheels is the front wheels are 5 mm narrower and capture flange bearings instead of a 12 mm hex.  They all printed fine and needed the same filing and sanding to clean them up.  The front flange bearings measured 7.93 mm diameter, and I was able to find a 7.90 mm drill bit in the garage to clean up the bearing holes.  That led to a perfect fit between the bearings and wheels.  I adjusted the chrome vinyl design slightly to make the sticker easier to center, and I reduced the red stripe diameter by 1 mm to make it easier to install as well.

Here they are installed on the chassis.  I lucked out and got the front bearing spacing just right; it's possible to tighten the front lock nut down completely and have the very slightest of friction in the wheel bearing.  Backing the nut off an eighth of a turn leads to a freely coasting wheel with virtually no side-to-side slop.

Looks good still...  I'm really eager to paint the body now, but there's more preparation to do.  Patience...

 

[scollins 154]

Wow, just fantastic! Very much a cool project for sure, recreating a childhood Hot Wheels toy into an R/C car, such an awesome idea and great results Paul!  Mad skillz bro!!

[speedy_w_beans 4272]

OK, last chassis topic, I think...

Pretty much every pan car I've ever run in the street has caught a pebble between the pinion and spur gears.  When that happens, the spur loses the fight and a tooth or two becomes deformed.  The consistent whine of the gears is destroyed with a tick-tick-tick sound each time the spur makes a full rotation.  Plus, it doesn't take long for the exposed ball diff to pick up some grit and make it less smooth than when first built.  So, for this car I want to try a protective cover to see if it will prevent pebbles from falling into the gears.

The first step was to take some measurements of the gears and have those represented.  There's a nice FreeCAD add-on called FCGear that will generate quite a few different types of gears.  In this case we just need some basic involute gears with 48 dp (0.5292 mod) pitch.  The spur has 81 teeth and the pinion has 27 teeth for a FDR of 3:1.

The next step was to create some sort of structure for the cover.  In my mind I wanted to use some of the Lexan scraps from the 962 body to make the front and rear covers; this just gives the Lexan something to mount to.  There's about 2 mm of clearance between the cover and structure and the gears.

The rear axle position acted as a reference point for pretty much everything.  The top two holes are offset by +/- 10 mm.

The mounting block for the rear motor pod was next.  The top two holes align with the top two holes of the cover structure and are offset from the axle the same way.  The one vertical hole aligns with an existing hole in the top cross brace of the motor pod; the intention is to use a 3 mm fastener to keep it in place.  There's a semicircular cutout to make room for an existing fastener, and the notch in the block captures the vertical plate in the motor pod so the whole mount doesn't rotate at all.  Between the vertical screw and the notch, the block isn't going anywhere.  To figure out the height of the block, I used a height gauge to check the height of the pod cross brace as well as the top of the spur gear, then added offsets as necessary.

With the block and the arches finished, the next goal was to create a cutting template for the Lexan.  The extra cylinders and blocks represent additional cuts besides the outline of the arches.

There's a magic button in the Part workbench that lets you create a 2D projection from any view.  So, by selecting the top view and then using the tool, a basic wire outline of the cutting profile is created.  This is then exported as a SVG file to Inkscape, where the template is copied and mirrored to create an inner Lexan piece in addition to the outer one.  The inner piece gets both cuts for the pinion and axle, but the outer one only gets a cut for the axle.

So I ran the printer last night and made the mounting block and arches, and today after some chores printed the templates, cut them out, and taped them to the Lexan scrap from the body.  After some cutting and using a body reamer to make the holes, it all came together pretty well.

So hopefully this keeps some pebbles out of the gears.  The design is meant to stop most debris from entering the top or sides, but if something does get in, then the bottom is wide open to let it fall out.

Onward with the body, I think..  This should be fun seeing it come together!

[Grastens 2795]

And it has continued to be fun watching this come together - I, for one, am happy to see this fantastic project as the subject of a build thread

[ACCEL 2014]

[speedy_w_beans 4272]

I suspect this is the moment many of you have been waiting for, namely, seeing the body come together!  With my Hot Wheel and calipers in hand, it was time to get to work.

First of all, I want to mention just how incredibly useful it is to have some paper rulers printed and ready for use.  Because of the shape of this body shell, it can be difficult to measure and judge length with a rigid ruler.  With the paper rulers I could follow body contours and get more accurate measurements to use in designing masks.  Also, since the body is still clear it was really nice to cut rulers to size and tape them to the outside of the body, using them as alignment guides while laying down masks and tape on the inside.  Just use a search engine to find "printable rulers," there are quite a few options out there.

Here I was using a cut ruler with some marks to align a mask..

It made aligning a multi-segment stripe much easier.  Here's the main red stripe with a cutout for a yellow '9', as well as window and headlight masks applied.  I took several measurements of the original Hot Wheel using calipers and scaled up the stripe and number trying to keep the proportions the same.  At this stage I used Inkscape to design and Cricut Design Space to do some cuts/joins as well as print to the machine.  The vinyl itself is relatively compliant and handled the cockpit roof without wrinkling.

Here's the start of the purple stripes; if you look at the original Hot Wheel posted earlier the old Porsche logo is painted orange within a purple stripe.  The logo on the Hot Wheel as well as this body is taller than the official logo, but I'm trying to replicate the Hot Wheel as much as possible.  I just found a .SVG of the logo using a web search and imported it directly into the vinyl cutter software.  I set up a rectangle and used the logo to remove parts of the rectangle, and flipped the logo since it's installed from the inside but viewed on the outside.

Everything finished...  I used some tape to finish the purple stripe and then worked on the yellow section at the front and rear of the shell.  Paint sequence will be orange/silver, purple/silver, yellow/silver, red/silver, black, and window tint.  Both Saturday and Sunday are expected to be nice days with 80 degree F temperatures, so I'm going to take my time on this one and try to avoid paint bleeds as much as possible.  My biggest worry are the two vertical fins at the rear of the shell; it's always difficult getting paint into tight spots like those.

Hard to believe it took most of the day to mask this.

I should have some paint pictures by Sunday evening.

[Finnsllc 917]

whole other level bro! wanna be you when i grow up..That is typed with nothing but respect

[Re-Bugged 10138]

The paper ruler idea, very smart 👍🏻

[speedy_w_beans 4272]

Annnnnd, let there be paint!

As expected, the rear fins were a pain to paint.  Even though the main body only took two coats of orange, the fins needed that and a healthy third coat to guarantee coverage in those corners of the shell.  I tend to have a heavy hand when it comes to painting, and knowing that, I tried my best to make the first coat a light one just to seal the masks.  It didn't matter; there were still a few small bleeds into the yellow stripe and one "R" in PORSCHE.  Since I was just using solid colors and no metallics or pearls, from past experience I knew these few bleeds could be corrected by scraping an Xacto blade against the paint to remove it.  The scuffing in the Lexan wouldn't be a problem for the next color.  Note:  This does not work for metallics and pearls; scuffing the shell with a hobby blade will mess with the particle alignment in those paints and it will definitely show later.  Better to use a solvent and some careful wiping to make corrections.

After my second coat of silver I just about freaked out when I found some silver peeking through the orange on one of the fins.  Had I put the paint on too heavily again?  Did the solvent in the silver eat away the orange?  What sticker do I put over that? Meh.  At this point I was so frustrated with the few bleeds and possibly my impatience leading to a bad paint spot that I just went outside and started mowing the yard.

About half way through the yard work I came back in and inspected the shell again and realized there was a silver smear on the outer protective film from one of my fingers.  I started picking at the silver spot on the fin and it was flaking off, so my spirits lifted as we were back to just a few bleeds needing some scuffing.  Peeling back the purple masks, I applied two coats of purple and a coat of silver, and left it to dry more while I finished the yard.  At this point the PORSCHE lettering was starting to stand out more, and I was getting excited about moving on to the next color.

The yellow masks came off next and the bleeds were addressed.  The loose paint particles were captured in a damp paper towel and then it was time to shoot two coats of yellow and a coat of silver.  I had an old can of yellow in the garage and figured it would be nice to use it up instead of starting a new can; there was just enough to make it work.

Off came the red masks and I could smell success on the horizon.  The red itself laid down so nicely, so uniformly, that I didn't even use a second coat.  One coat of silver, and that was that.

Finally the window and headlight masks came off, and I was debating between leaving them clear, painting them with smoke/tint, or painting them with translucent light blue.  In the end I wanted to capture the original feel of the Hot Wheel and went for the translucent light blue; so glad I did.  The only issue I see is the translucent blue isn't perfectly clear; there's a little bit of haze thanks to some humidity we had today.  It's really tough; winter is the perfect time to use translucent paint, but it requires a heated space to do it.  Summer is great for paints overall, but the humidity wreaks havoc with window tint and translucent paints.

It was such a joy to pull the blue protective film off the body and see the true colors finally.  And it was also a joy to put the body right next to my old Hot Wheel from 1974!  I'm looking forward to working on the finishing details next and getting this mounted to the chassis!

 

[ACCEL 2014]

I have made Speedy an appoitment with the CDC he's a very sick man and needs immeditate testing and treatment, his builds are infectious and prone to spread RC fever, causing wallet shrinkage, more parts and pieces than needed, unrest do to modding and building kits that will not discontinue, furthermore as i can contest for myself i believe there will never be a cure.

My doctors perscription reads as follows to help with these symptoms: Take two Choclate Chip Cookies.

[Re-Bugged 10138]

3 hours ago, speedy_w_beans said:

Annnnnd, let there be paint!

 

That’s just to good for words, hats off to you 👍🏻 
I mean the ‘Porsche’ logo..... just look at it...Brilliant 👍🏻

[Aerobert 2141]

That's so awesome. The idea with the paper ruler is brilliant and one of the best ideas I saw in the past. I really love the result and can't wait to see it mounted on the chassis.

[Badcrumble 4203]

Amazing work - the shell, the masks, the 3D printed parts, those wheels and tyres...and that blue looks fine in the photos. I got worried when you got to 'an old can of yellow'. Thanks for the tips on the translucent paint too, I have pink and red I was hoping to try at some point. I will have to try and watch the humidity.

My own Hot Wheels homage was never going to be as complex as this!

What an end result, looking forward to it mounted and those tyres in the arches.

[scollins 154]

Amazing job Paul, really glad to see how well this turned out for you! EXCELLENT

[speedy_w_beans 4272]

Some fun advertising I found on YouTube.  In one of the shots there's a copy of my Porsche going down the track, and in a few other segments I see other cars still in my small collection.  Looking forward to finishing and driving it!

 

[Re-Bugged 10138]

Great vid!! I had some of that track in the Matchbox equivalent, loads of fun making tracks from off the top of the stairs with a loop the loop and ramp at the end somewhere in the middle of the lounge 😁

[Re-Bugged 10138]

On 5/11/2020 at 10:42 AM, ACCEL said:

Any left to pass around buddy as I think we’re building for a grand finale here....😉

[ACCEL 2014]

Ok RE-Bug, i see six tubs, please only take one.

Speed doesn't get any, he'll get butter and salt all over his project.

everyone else can dig in.

Sorry Speedy, not till you'er done and have washed your hands.