Basic CMF3, ver. 1.1 / 1236-Cc2

[CMF3]

As some of you might have seen on FB or in the OWH Retro Racing SCRRA forum, I decided to build a chassis that is basically a stripped down version of my more recent all-wire chassis designs. The idea was to make a car with no minimum weight consideration that could be used on the BPR Gerding King track. It was going to be simple, just a front assembly (including front axle uprights and guide tongue) with side “pans”, a rear motor box / axle assembly (including lateral static pans in front of the rear tires, as seen on the 1229’s and 1233’s), and direct main rails holding them together. Nothing fancy.

For me, building in this style so long, this is a really simple chassis build. However, I’m aware even this “simple” design and construction will still look “complex” to those who don’t… which is pretty much everyone else. Still, if I’m going to do this, it is the perfect opportunity to post the build sequence; with any luck, hopefully y’all can see the basic construction elements and processes (and maybe even get a little better insight into the more intricate chassis I put up here).

The final result, designated 1236-Cc2, came out looking like this:












Kind of sparse looking… as it should be…

I knocked this frame out in a day… Granted, I’ve had a little practice hand-bending piano wire with my needle-nosed pliers.

All framing wire is 0.039”… You can get all the details in the build sequence photos and captions. Since it is a “-Cc” design, wheelbase is 3.875”, RAX-GPC is 4.875” (with resulting guide lead of 1.00”). The roller as pictured weighed in at 52.1 grams, so my guess was the RTR car should be about 87 - 88 grams…

And that is why I have pretty much no use for it... And that is why I sent it out to Nesta to take up to BPR for all the kids there to play with it. They’ve only been racing these things forever, so who better to thrash this thing out. Initial report sounded like it’s okay. Cool!

Any of you BPR guys who have given this thing some laps, please feel free to put up any comments you might have from your observations, whether good, bad or indifferent, as all info is good info to me. Thanks!

Addendum:
I built this chassis before the “CanAm Plus class” announcement, so this “Left Coast” chassis may have some application in “Right Coast” racing as well… Not that it really matters… I had already doodled out the next couple chassis in this design progression… just for fun…

Right now I’m thinking a 0.032” wire framed version of this chassis might be fun…

Rick

[CMF3]

I need to apologize to those few guys out there that would use my chassis layout drawings to help them figure out where all these wires on my chassis were going. I’ve gotten lazy, and most design layouts now consist of just a few lines to define certain aspects of the chassis geometry… I’ve built enough of these things I already know how all the wires fit in… Sorry.

All wire is 0.039” diameter, unless otherwise noted.

Pictures 1 & 2: The 4-bend front spanning wire is fashioned, assuring it is flat; the ends are trimmed to size.






Picture 3: The 4-bend front spanning wire is taped in place; a small piece of 0.047” wire is soldered on the forward side of the medial length of the spanning wire.

Note: This 0.047” wire allows for an upward tilt of the guide tongue when it’s installed.




Pictures 4 & 5: For stiffening, a second 2-bend wire is formed to fit against its three medial lengths of the front spanning wire; the wires are soldered together.






Pictures 6, 7 & 8: The 7/32” D x 1.40” L rear axle tube is jigged into place.

Note: Each main rail consists of 3 wires each.
The first main rail 2-bend (with rear axle upright bend) wire is soldered to the rear axle and front spanning wire.








Pictures 9 & 10: Two 1-bend wires are formed to define the outside of the rear static pan framing, leaving gaps at the ends sufficient for another wire to fit; these wires are not soldered at this time.

Note: Picture 10 shows the 0.024” wires used as spacing for the points of these wires at the chassis edge.

[CMF3]

Pictures 11 & 12: The second main rail 1-bend wire is shaped to lie adjacent to the forward length of the first main rail wire and the backside of the forward length of the static pan wires; it is tack-soldered in place.






Pictures 13 & 14: A 1-bend wire (with rear axle upright bend) is tack-soldered to the front side of the rear length of each static pan wire and to the rear axle tube.






Picture 15: The jig is removed. The previously tack-soldered wires are now soldered together, leaving approximately 1.25” of the main rails unsoldered (this space is forward of the motor box and rearward of the mounting point for the front axle uprights).




Picture 16: A 1-bend wire is soldered inside the forward angle of the triangular static pan area.




Picture 17: The first 1-bend lateral-most outer side pan wire is formed but not attached at this time. Note: the forward length is longer than needed and will be trimmed later.




Picture 18: The first front wing assembly wire is a 1-bend wire soldered to the main rail wire where it attaches to the front spanning wire; this wire outlines the rear of the front wheel well.




Picture 19: The second front wing assembly wire is a 2-bend wire soldered to the first wire and forward surface of the front spanning wire; this outlines the front of the front wheel well. (I keep these longer than needed along the front of the chassis for alignment purposes; they are trimmed off at chassis completion.)




Picture 20: A 2-bend wire is soldered to the first two wing assembly wires.

[CMF3]

Picture 21: A 2-bend wire is soldered in to reinforce the first and third wing assembly wires with the front spanning wire.




Picture 22: The first lateral-most outer side pan wire (from Picture 17) is tack-soldered to the first front wing assembly wire, ensuring there is some spacing with the static side pan wires.




Picture 23: The second 1-bend medial-most outer side pan wire is soldered to the rear length of the first wire and the forward length of the adjacent main rail wire.




Picture 24: The third 1-bend outer side pan wire is soldered to the inside of the first wire and the rearward front wheel well wing assembly wire.




Picture 25: The fourth (final) straight outer side pan wire is soldered to the rear and front lateral sides of the third wire.




Pictures 26 & 27: A small 2-bend wire is soldered between the main rails just behind the front spanning wire.






Pictures 28 & 29: Another small 2-bend wire is soldered between the main rails just behind the wire from Pictures 26 & 27.






Picture 30: The third main rail 1-bend wire (with rear axle upright bend) is soldered to medial side of the first main rail wire (starting behind the wire from Pictures 28 & 29) and to the rear axle tube.

[CMF3]

Picture 31: Another view of the completed main rails.




Picture 32: A 1-bend wire is soldered to the medial side of each main rail assembly; these wires define the forward edge of the motor box assembly.




Pictures 33 and 34: A straight wire is soldered to the rear of the wires from Picture 32.






Pictures 35 & 36: The first 1-bend (with rear axle tube upright bend) inner motor box wires are soldered to the rear axle tube and to the rear of the (inner) forward motor box wires.

Note 1: This motor box is sized for FK-type motors; as a matter of spacing, I use a 0.5” wide piece of 0.064” brass flanked on each side by a length of 0.047” wire, for approximately 0.6” spacing.

Note 2: Where the main rails rear axle tube uprights attached to the front of the rear axle tube, the motor box rear axle tube uprights attach to the rear of the rear axle tube.






Pictures 37 & 38: The second 1-bend (with rear axle tube upright bend) inner motor box wires are soldered to the rear axle tube and to the rear of the (outer) forward motor box wires.






Pictures 39 & 40: The 4-bend (2-plane) gear-guard wire is shaped and soldered to the rear portion of the inner motor box wires (approximately ¼” behind where the motor bracket face will be placed).

[CMF3]

Picture 41: The 2-bend rear axle tube spreader wire is soldered atop of the gear-guard and to the ends of the rear axle tube.




Picture 42: The center portion of the rear axle tube is removed. (Also, another view of the gear guard / spreader.)




Picture 43: A small 2-bend 0.032” wire is soldered inside the motor box framing. (Not a very good picture; can also be seen in Pictures 44 and 45.)

Note 1: This wire sets a level surface for the can end of the motor to rest upon when the motor is mounted at an angle, which determines its position forward of the motor bracket face (see Picture 44).




Picture 44: The modified motor bracket (JK-D3F122) is positioned so the motor will be angled such that the shaft of the motor will be perpendicular with the rear axle while keeping the front of the motor flush with the bottom plane of the chassis, and soldered into place; this allows for a better gear mesh than with an offset, or “hypoid”, motor mounting gear mesh, while keeping the mass of the motor as low as possible.




Picture 45: A short wire is soldered atop each side of the motor box; this helps to cradle the motor and affords easier points to solder the motor in place.

Note: Of interest, the motor bracket in this arrangement is functionally optional (unless required by the rule set being used), since the motor can be soldered in without it.




Picture 46: A piece of 0.025” brass plate is tinned and soldered atop the front spanning wire assembly, the adjacent main rail wires, and the small wires from Pictures 26 – 29.




Picture 47: The guide tongue (Slick 7 S7-25) is tinned and then soldered in place atop the brass plate.




Picture 48: The 4-bend (2-plane) forward front axle (FAX) upright is soldered into place.




Picture 49: The 4-bend (2-plane) rearward front axle (FAX) upright is soldered into place.

[CMF3]

Picture 50: Side view of the FAX uprights in place.

Note: The spanning FAX uprights add lateral strength to the chassis; they are also angled away from perpendiculars for greater strength; the spanning uprights also make axle setting/changing very easy.




Picture 51: The outer perimeter side pan movement restrictor box (1/8” square brass tube approx. 0.35” length) is soldered to the main framing just forward of the triangular static pan framing.




Picture 52: A 2-bend piece of 0.055” wire is soldered to each of the outer side pans so they extend into the movement restrictor box; they should sit level within and just make contact with the inner medial side of the square brass tube.




Picture 53: A 1-bend wire is soldered to the medial wires of the side “pans” and along the forward face of the 0.055” restrictor wire.




Picture 54: A 1-bend wire is soldered to the lateral wires of the side “pans” and along the rearward face of the 0.055” restrictor wire.




Picture 55: The 1/16” round brass rear body pin mount tubes (with 1/16” collars) are soldered atop the side pan restrictor wires.




Picture 56: A small piece of wire is soldered just behind the front wheel wells.




Picture 57: The 1/16” round brass middle body pin mount tubes (with 1/16” collars) are soldered atop the wires from Picture 56 and the rear FAX upright wires.




Picture 58: A small 1-bend wire is soldered to the forward angled faces of the front spanning assembly.

Note: The forward angled portion of this wire acts as a stop for the guide; the rear portion of this wire is a mounting point for the front pin tubes.




Picture 59: (Not pictured - A small piece of wire is soldered atop the lateral edge of the front wings.)
The 1/16” round brass front body pin mount tubes (with 1/16” collars) are soldered atop the wires from Picture 58 and the wires at the lateral edge of the front wings.




Picture 60: Two pieces of 0.010” brass sheet are cut to fit the triangular static pan framing sections, and soldered in place.




Done! Just add runny-bits and it’s ready to go…

[CMF3]

Now, c’mon… That was pretty easy, right?

Rick

[D.Z.]

Your a true mad scientists. Lol. I love your work.

[CMF3]

Mad? They think I'm MAD! Some day I'll rule the world, and we'll see who thinks who is mad then...

HAHAHAHAHAHAHAHAHAHA!!!!!!!

On second thought, nah, too lazy for all that world-ruling stuff... Just play with toy cars... Yeah, that'll do just fine...

My mental-amplifier's volume dial starts at "11"... I have no use for those lower numbers...

[fl_slotter]

Mr. Brain,

So, you're ready to take over the world? I can see that!

I'm quite impressed to see just how much wire you are now saving. Has it gone on to the EPA protected species?

Get back to taking over the world.

When you get some spare time, we need to visit this track to see how your chassis works on a flat track!

[CMF3]

Marty, I don't know that I'm quite up for the long drive from FL to Maine right now... but running on Lou's old UK Black does make it real tempting... Hmmmmmmm...

I'm not sure how the 1236-Cc2 chassis in this thread would do on a flat track (the 1229's and 1233's did quite well on the LTD down in Fort Myers); I was thinking Gerding King all the way on this chassis. Of course, for S&G's, we could always ask Nesta and the other guys to give it a try on the BPR flat track some time...

Rick

[CMF3]

SoCal legend, and all-around cool slot car guy, Bryan Warmack has been kind enough to take an interest in this 1236-Cc2 contraption of mine and put it through the paces on the BPR Gerding King track. Bryan’s feedback has been priceless and I can’t thank him enough for his time in this regard.

Initial reports were very favorable. The chassis worked well, and was fast… This is a prime example of the theorem, “It is better to be lucky than good”, since as a first attempt to build a chassis for the BPR King it would be most accurate to describe my design process as a WAG.

However, Bryan started putting this thing through some laps. He didn’t think the car could be driven through the turns as hard as it could be. To improve this, Bryan made two changes:

1) Adding lead to the static pans flanking the motor box, and attaching two small pieces of brass with tape just behind the middle body mount pins. This brought the RTR mass of the car to about 92 grams, which in Bryan’s experience is a very suitable weight for the track at BPR.

2) Bryan noticed the chassis exhibited the same characteristics of a previous chassis of his, and determined it had a little too much flex/twist. To improve this, Bryan made a 2-bend 0.039” wire to fit inside the central open chassis space; he soldered it in at the forward aspect of the motor box and to the forward soldered aspects of the original adjacent main rail wires on each side. This basically changed the chassis from 3 wires per side main rails to 4 wires per side main rails. He also adjusted the brass pieces behind the mid pin tubes to keep the car weight around 92 grams.

At this point Bryan reported he was very happy with the chassis, and after an initial race last month, assured me he could get this thing on the podium in the next SCRRA monthly King track race at BPR…

This past Saturday, after qualifying third with a 3.979s lap, Bryan not only put it on the podium, but won with it, and turning a not-too-shabby 337 laps for the race. Cool!

Some pics of the car, with two close-ups of the new 4-wire per side main rail section (for those with real sharp eyes…):













Not surprising, Bryan’s main rail modification was seamless, and fits the chassis perfectly.

So if I were to build another one of these 1236 chassis, I’d make it a 4-wire per side main railer, and maybe add two small 0.010” brass sheet pans behind the mid pin tubes for weight addition tuning…

The question is… Do I build another?

Or, maybe something a bit different…

Who knows…

Rick

[68Deville]

Yes Bryan did a solid race on the King and he delivered a First place win in the A-main.
Congrats to him for a stellar race as well.
Rick dying for a new mouse trap for F1, what do you think about that?
Sick of what we are running at this point!
Thanks for sending me the chassis, so the guys could try it out.



Nesta

[CMF3]

Nesta,

Bryan is da man! I was real happy he got the win. I told him to just hang on to the chassis there; that way we’ll always have it as a “baseline” for comparison to other builds.

I hear the dreaded “6-Pin Technology” might be getting some new converts at BPR, after guys saw Bryan just plow through the wrecks. Of course, it’s all part of my plan to take over the world, one slot car raceway at a time… Drink the 6-Pin Tech kool-ade, kids! (Disclaimer: If the kool-ade makes you see wild streaming colors and hear crazy weird sounds, you drank the wrong kool-ade… or the right kool-ade… depends on your point of view… )

As for F1’s, I have to admit, most of my efforts have merely been all-wire adaptations of some of the designs and principles I was using in my CanAm builds, usually just as an afterthought to see what might be applicable; my last attempt was the A212, which was just the 1229 under an F1 body. And all my F1’s were built with the (expletive omitted) 100-gram minimum weight rule in mind…

Hmmmmm? Maybe I need to do like I did for the 1236 here, and just come up with something with no minimum weight consideration that might work on the BPR King… Now, that’s an interesting thought… Hmmmmm…

In the meantime, I’ve got the 1237 design, that’s been bugging the beejeezers out of me, so I’ll probably have to see if I can build that first…

Rick