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The "Dr. John" Series: Gilded Splinters - Mama Roux


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#1 Duffy

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Posted 08 May 2013 - 04:20 PM

I had some time to build a trio of chassis, & it gave me an opportunity to talk about wire bending. 

I do some pretty weird stuff with my chassis. Lacking years' knowledge in the why of chassis motion and construction, I stopped copying "winning" designs one day and started from scratch - a fully-locked-down .078" sled I dubbed OXCART, from which I could begin to learn to "see" the effect of each element I put into the car - and hopefully it'd be a car durable enough to survive my abysmal driving while I learned.

It pretty much worked. I started to "see" enough that I could start to apply motion in a more informed way; and I also found I was learning what would break in my chassis and what would take a hit, and I started to engineer things based on my version of what I was seeing. (Prof. Fate would talk of these by using the term "my conceits" and I like that a lot. You'll see it used here. Thanx Rocky, for that & so much more.)

 

Okay.

So, two things you see here, right up front: these chassis are damn weird by my neighborhood standards, and I keep saying they're the way they are for two reasons - one, they're meant to both isolate motion and facilitate it in very specific ways, and two (& more important), I just never know where to put a solder joint for fear it'll be in a stress riser and will come loose - so I just bend around the damn things.

The fact is, over nearly two seasons of running these sleds you see here, I've had practically no chassis failures and my cars have shown markedly less twist and tweak after races. Maybe they're taking impacts and inputs and handling them, so they're doing what I set out to try.

Or maybe I'm in some Vanilla Sky dreamscape here and you're all gathered 'round my comatose hulk laughing hysterically at this post. Who can tell.

 

Anyway, I've laid out my basic outline and know where the wires are gonna go & all; I've drawn those lines in pencil on my jig surface - those wash out eventually or I can erase, but they'll last thru this build - and also drawn the layout on graph paper as a guide. This is in a notebook I'll keep from build to build, which also becomes the logbook for that chassis on the facing page of each so I know how & what I did.

The first course of rails (.047" for all) is bent right off that page. As I bend, I'll make a little nesting fixture of pins on my jig and transfer tick marks to that, from which I'll lay out and bend all this course for the whole build - one car, six, the procedure's the same since you have at least one opposite wire in a pair.

 

df75 01.JPG

 

Now, you see the (1) and(2) marks here? The (1) is a referent for a bend on the first course, and then to get the next course I did a double-transfer - pushed the 2nd wire into the corner of the first and marked where that bend should go, then marked that on the jig. Now all the second-course wires get bent the same way.

 

df75 02.JPG

 

Look at how my bending doesn't quite work out. This is actually from a slightly-long nesting length, and I corrected it on the second piece. There's always a need for scrap wires later.

Everything on a chassis should fall into place, never be pulled in and soldered. Fix it now.

 

df75 04.JPG

 

This measure-and-bend procedure gets its own rhythm as you work: your mind & hands learn how and where to set the mark for a bend and you stop thinking about it pretty quickly. By the time I'd laid out the first two courses here I was ready for the three-side bends needed in the axle horns below, and they're the same lay-out/bend/try/correct procedure as in the photo above. Everything you do the first time, you try on a test wire (See "always a need for scrap wire" above) and inside of an evening's work you get the rhythm of it. 

Interestingly, one night's rhythm might change by the next night. Roll with it.

 

df75 05.JPG

 

The most heartbreaking bend in the job is the "bracket guard" portion of the rear bale, which runs around the back and also forms the outstops for the pan assembly later. This rear spacing must be just right, and here's where Dennis Samson's E-voice is ringing in my ears (see "DS n the DSF1" in "Gascarnut's Garage" for the backstory)...

I just guess & test.

Really, I've tried so many "scientific" ways to predict an exact bend, & failed 'em all - heck, just try it, measure, correct & try. That's what scrap wire's for. Look closely at this pic and you see the two hashmarks that tell the story of the "corrected" bend. The next three were perfect.

 

df75 06.JPG

 

The only time I abandoned my Gruber parallel-jaw pliers for this build was in the rest of the rear bale: the two extreme doglegs I just laid out on the aluminum face for repeatablility, & also the bend-past lines so all the angles would repeat. The pic should speak for me.

 

df75 07.JPG

 

Once again, as I worked I made notes of what I'd done, including pertinent dimensions and what parts of my tooling were used. Even if I develop further off these chassis, I can refer to this stuff for what I did here and what relates to the next ones.

 

df75 08.JPG

 

So here's all the "hard" bending done and ready for floating together. (I love how that rear bale is giving us the most perfect Tevye "shrug." and I'm not Jewish.) The rest of the roller's just hanging the pan assembly, and there's no tricks to talk about in that. My thought here's just that anybody hesitating to put more than one bend in a wire (and I know plenty who'll say that's too many, I don't claim Special Knowledge in that) might take courage from this.

 

df75 09.JPG

 


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#2 Tex

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Posted 08 May 2013 - 05:57 PM

Good lookin' center-sections, Duf!

 

I remember scratchbuilding; one o' these days I'll give it a go again.


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#3 MSwiss

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Posted 08 May 2013 - 06:15 PM

Good info.

 

Great work.


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#4 TSR

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Posted 08 May 2013 - 06:18 PM

Duff-boy,

You are a freak.

 

Welcome to our club!  :laugh2: 



#5 Pablo

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Posted 08 May 2013 - 07:43 PM

I like the figurine, Duffmaster :)


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#6 Half Fast

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Posted 08 May 2013 - 07:47 PM

Photo #4 looks like a slot car M C Escher Painting

 

What wire size is used in the finished chassis?

 

Cheers


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#7 Rick

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Posted 08 May 2013 - 07:56 PM

Very nice Duffy................


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#8 SlotStox#53

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Posted 08 May 2013 - 08:23 PM

Excellent work Duffy, looks like the chassis underneath your lucky13 proxy entry.. :)

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#9 Dominator

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Posted 08 May 2013 - 08:47 PM

Fantastic!


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#10 Duffy

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Posted 08 May 2013 - 08:52 PM

I like the figurine, Duffmaster :)

 

...It's a Netsuke, Pablo-san!! That jibe never gets old, do it?!!

 

What wire size is used in the finished chassis?

 

I mentioned in there somewhere (I should write less) - .047" in the rails, the rear bale is .063"

 

..looks like the chassis underneath your lucky13 proxy entry..

 

Only in the angularity - that chassis is a wild concoction done up by Wrick Moore, a REAL Wirebender and a fella who's spent a lot longer parsing out the vagaries of chassis motion & applying solutions than I ever may.

 

 

 

Duff-boy,

You are a freak.

 

Welcome to our club!  :laugh2:

 

Do we get cookies?

 

 

Duf


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#11 TSR

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Posted 08 May 2013 - 09:03 PM

Sure thing, comes with your $25.00 membership fee.  :)



#12 Duffy

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Posted 09 May 2013 - 08:31 PM

This concept might be useful to some. Once you've conquered your Fear Of Plying once & for all, you start to see what you might do to make your builds easier.

 

A little Positive Visualization over the task you see pictured here, and I came up with the Duffy Magic Fingers - their sole purpose, to keep the Duffy Plain Ol' Fingers from getting unnecessarily burned to a crisp.

 

df75 11.JPG

 

We don't need step-by-step here, right? You get the idea? You can take a minute and bend up just about any holder in this fashion that you'd need, & then throw it in the Jig Bits tray for future rummaging and/or modification to a new task.

The idea is to just provide a gentle spring tension in the holder - cabinet benchwork jargon is "dog" - & that's all, just enough that you can get your iron & solder next to the spot without a fourth and fifth hand.

 

Remember, I'm the guy who ran out of grips one time (actually two times) and quickly popped the flux brush into my mouth for just a sec while - what's that awful sensation spreading across my lips?...so I need stuff like this. Maybe you're skilled, and can manage. Good for you.

 

Duf

 


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#13 MrWeiler

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Posted 09 May 2013 - 09:17 PM

Yeah Duf, flux is kinda tasty no?
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#14 Duffy

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Posted 10 May 2013 - 08:32 PM

Speaking of dogs (and btw, yah Weiler it's an acquired taste!), here's the actual "Bench Dog" concept applied in micro style:

 

df75 12.JPG

 

See, you need a teeny finger (one that won't burn when it gets hot, one not-YOURS) to hold something in place for just a bit; grab some small wire and bend one up.

Lying in front of the application is the actual dog: the kinky lower section shoves into a hole in the jig plate, & it's sprung just enough that it stays in there and forms a "push" point for the dogleg bend  holding the workpiece. You find a handy anchor hole, bend up the dog, then tweak the last little curve to provide the pressure where you need it.

Get it?

 

Oooo, but what if you accidentally solder the dog to the workpiece too? Okay, let the whole assembly cool & harden. then touch iron to the small wire of the dog and pop it off. No disaster no foul.

 

My Dad was a cabinetmaker, and was always working up quick fixtures to do this or that in his everyday work. That prollem-solving mindset carried over into my own pursuits, but in a funny way I've noticed a re-awakening of the techniques just in the last few days, & have been applying it to this build in a way I hadn't to slot cars, up to now. Strange.

 

Duf


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#15 Rick

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Posted 10 May 2013 - 08:47 PM

I have seen Duffys "dogs" before that he uses and quite ingenious. Funny thing is, someone asked me to make him some Steube Clamps last week. So a made a few. If you view the Stuebe build video, you will see them in action and also another good way to keep a hold on things.

 

Stuebe Clamp.JPG


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#16 Duffy

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Posted 10 May 2013 - 09:32 PM

Good one Rikky.

Yah, I got a few too, and one day I'll make up some more of the standard slotted aluminum bar clamps you supply - but in diff'nt lengths. (Y'oughta offer an assortment!) And this and that and and and - 

But the oher thing is, when you're rummaging in your box for just the right hold-down (and I always gotta include The Pablo Caveat: "They're not clamps, they're PERSUADERS!"...) and it's ten at night and you don't got a drill press right there...wire is your friend and you can bend up exactly what you need at the moment. All it takes is a little positive visualization.

 

I was just gonnna go into a pipedream (and I don't smoke, and anyway where the heck does the term originate?) about wanting to have a grid of #10-32 holes along the edge of my jig as well, for persuader anchors when it comes time for pan placement - the center T-slot works fine for everything else - but then I remembered, that's exactly the moment I recalled the bench-dog app in the first place! Never mind, stop the (drill)presses.

 

Duf


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#17 Rick

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Posted 10 May 2013 - 10:00 PM

That's the time your teeth and a chopstick come into play, and that way you can get a real good wiff of that Stay Clean flux aroma. hahahahahah. Can you picture Robin coming into your work area, viewing this, shaking her head and walking out without saying a word........................hahahaha


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#18 Duffy

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Posted 10 May 2013 - 10:06 PM

It's happened.


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#19 Duffy

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Posted 13 May 2013 - 10:34 PM

Now, remember, this flexybendywiry thing is intended to allow for some forgiveness in an impact as well as a consolidating of possible stress risers, since I really don't know where to risk putting a possibly-fragile solder joint...

But it seems to've also given me a pretty forgiving axle carrier. Here's how I've evolved it:

 

df75 13.JPG

 

In order to make a simple procedure out of a fairly fussy bend of a complex front axle stanchion, I just bend up a generic yoke of sorta yea-width, and then mark off a ballpark height for the second bend, the one that lays along the rear-pointing horns on the sled.

 

df75 14.JPG

 

The the fussiness of this bracket is made unfussy by tweaking the height using the back-angle bend, and the width by bending the splay this way and that. Once the long rail engages the axle along its centlerline, I'm in there.

 

df75 15.JPG

 

The backside leg's even easier: it's an upright that then bends around and engages the side of the sled horns.

 

df75 16.JPG

 

Here you see the front bracket soldered in, and the rear legs poised to be dragged in & engaged -

 

df75 17.JPG

 

- Like this. You see me dragging the upright in to engage my jig axle and keep it flat to my jig plane.

The kink down there on the jig plane is shorter than the nesting length inside the sled horns, so you can pretty much make them as long as they turn out. The real limitation for both bracket elements is to leave enough length along that axle to fix some wheel collars to. Do the math.

 

df75 18.jpg

 

The whole point of this elaborate gafozzle is to create a "torsion" mount for the front axle; it's hung on a semi-sprung bracket, which in turn is hung on these rear-pointing horns that are hung on the two legs that splay out from the narrow joint of wires under the guide tongue. It creates five separate elements that can flex separately & in concert in a stress input, and hopefully absorb that input instead of breaking something.

So far, it seems to be working. I do not bind the axle with wire when soldering, and in two years of using this weird mount I have not had a single failure. That don't in NO way mean it won't happen - "All Engineering is a race to see what fails first" - it just means it works so far.

 

Duf


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#20 Pablo

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Posted 14 May 2013 - 06:22 AM

Cool, Duffy :D


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#21 Tex

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Posted 14 May 2013 - 07:04 AM

JFC, dood! The More Wricky influence is just dripping from your new work. Bravo!


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#22 SlotStox#53

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Posted 14 May 2013 - 09:36 AM

Superb idea and design Duffy !

#23 Duffy

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Posted 10 June 2013 - 03:27 PM

Somebody asked for the capper on this sled - it's appeared in the chassis gallery here (first on 10/7/2012, post #1107 on pg.37), but I'll add a shot to this thread.

 

Duffy 71-72 Gilded SplintersSM.jpg

 

Duf


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#24 TSR

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Posted 10 June 2013 - 04:44 PM

Duffster,

Before I even have the nerve or the energy to advise you to get a life or to meet me on the mountain to escape the coming sunami  (whichever comes first), how much do those things weigh, please?  :)



#25 Duffy

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Posted 10 June 2013 - 04:56 PM

51 on the sled in the rear, & I think 55 in front - we have a 100gr. minimum in Can-Am & 110 in Coupe. Actually I was kinda hoping I'd find a life washed up on the beach after the tsunami. Sorta double my pleasure.

 

Duf


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