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Top Eliminator '62; A chassis reconstruction & test build
Topic Started: Dec 3 2014, 10:47 PM (4,345 Views)
Duffy
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A buddy and I have been yakking back & forth about the great DRAGMASTER-framed jobs of the early '60s. Somehow we got to talking about this one from 1962, Mickey Thompson-prepped and Jack Chrisman-driven. My friend got all excited, rummaged around and came up with enough parts to replicate the mill and drivetrain, and in a fit of enthusiasm I popped up and said "I'll supply a chassis!" and -

Jeez. What was I thinking? But it's what I do.

So, while I prep for making the frame, I'm also drafting up a dimensioned drawing of it, to go into this databank/photodump we're doing on FaceBook (join "Arnie Paitch's Backyard Foundry" if you wanna come play along). There's enough interest - well, enough in MEE - that I built up a basic frame jig with rail spacing set with the standard 19" width of DRAGMASTER frames, so I can do up any number of these.

I'll also post any progress here, in hopes that I can shake loose some good criticism and advice from you guys.

'dust

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krwasson
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:))) :))) rlr
Kevin
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USMC E5
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I like the frame jig!!
   You're not drunk if you can lie on the floor without holding on.
-- Dean Martin
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Duffy
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Thanks ES - I build slot cars too, & we use jig plates to make chassis - flat plates with axle locators & centerline/edge pins &c. &c. - it makes sense to have something like that for static scratch building too. I've been trying to cook up a universal jig, but it's eluded me thus far.

Here is just the jig - the vertical posts are 19" apart in 1:25 scale, & it's made hefty enough to stay put on a table while I add bits; but I still can clamp it easily in my PanaVise to hold it steady and secure. Gonna see how this one works & see if I can improve it or scrap it and start over.

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resin-daddy
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My hats off to you :))) Im trying to do a promod chassis in 3D in order to have it printed.
The Smell,Rubber Burning,Nitro In the Air...Never mide me im just looking for my Meds
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Duffy
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..."PRINTED." Well, that's just cheating, isn't it?...
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Duffy
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Continuing from rear to front, which was the direction I discovered good photos to work from. Wow, it looks way worse in this close focus than when I take off my glasses and squint at it, Especially by candlelight. Heck, if I was dating it. it'd probably look downright gorgeous after the second bottle of Brut.

This bit-by-bit sort of thing ain't all as simple as I started out thinking. I was purely joking with resin-daddy about 3D printing being "cheating," but as prissy as I'd like to be I still gotta admit you'd end up with far more structural integrity by going that route. Still, this is my first attempt at this sort of build. As I work, I become aware of tools I wish I had to help me along, and I might try & experimentally work some up as I go. Can anybody point me in the direction of any builders who've gone down this road before?

Once I get this basic frame glued up, I'll sand down all the fuffs and start thinking about filling in the weld joints, especially the t-joints where I didn't radius the ends of tubes before fitting in. Gonna try brushing Tamiya Surface Primer into the joints and see if it works first, I'd rather not go through the heartbreak of Squadron Putty on these tiny spots. We shall see.

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Duffy
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Here we're beginning to see how the frame jig is meant to help in the building, other than just establishing rail spacing. Bit by bit I am figuring out how to use it - I only just realized I could loop rubberbands around things like you see here - and I vaguely remember thinking when I made it how I would want all the components a little long so I could use 'em in SOME way that had not become clear when I was building it. Funny thing, that's a bit of "design" thought that I've kinda grown in my brain over the decades of being a machinist & all; I may not know quite where I'm heading with a project when I begin it, but I have some sense of how to avoid painting myself into a corner most of the time.

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krwasson
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carl
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:))) rlr :)))
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old coyote
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That is really cool sir fbr :))) B) :))) B)
I may have to grow old ....... but I refuse to grow up !!!
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Another Rick
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jsm That is some amazing scratchbuilding. I think I may need to try one of those jigs - is it just brass tubing and square stock soldered together?
I build models because GOD allows me to and because I can't afford the real thing!!
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Duffy
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Yep, Rick, exactly. Two bars of !/16 x 1/4 with some oblong tube spacers, then the uprights and "bed bars" of 1/16 bronze brazing rod. I built it to the inside width of the stock Dragmaster frames (19") which works out to .760" in 1:25.

Really, all this jig gives me is flat and parallel. I just figured out yesterday that I could hold down with rubberbands in several combinations (see my comments above about "accidental foresight"), but it will have a limit. I'm about to add the second underneath crossmember, and at that point I can't jig on this any more. I will turn the chassis upside-down and glue the X-member to the front of the bottom rails, but that'll be the end of it...well, wait a minute: if I hold off putting that crossmember in, I can keep the frame in the jig while I fashion the front torsion unit. Yah, that's right, I can hang the front axle on here too. I'll do it that way.

Still thinking about how I might make a jig to establish front & rear axles at ride height, and also register and clamping for the chassis. That gets complicated.

I'm pretty OCD about this stuff. Sometimes I tell people that my hobby is overthinking.
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Duffy
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Done with the basic frame. Now it's a choice as to whether I clean up, fill, and sand to make everything squeekyclean, or whether I ship it out to my buddy in this state and let HIM do some work for a change! We shall see what I decide, anon.

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There's a pile of eye-foolery in the front end. I still am not comfortable working down to this level of teeny, and either I try to show too much detail with too little stock or vice versa. I've just suggested the torsion bar linkups here (resisting putting hex bolts on the link ends &c.), and we'll just drop the tip into the clevis on the axle and call it bolted down. Done. Photos of the lower Y-bar don't make it clear as to how it fixes to the X-member, so I just joined the rods and hid anything else beneath a small plate. On to the next prollem.

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Here you can see the condition the raw frame is in without any trimming or filling. Actually it looks not half bad at eye distance and could probably pass at this stage, but it will be better with some finish work. I think I might try mixing up a thick slurry of plastic scrap dissolved in solvent cement and brushing filets into all the welds - that would be structurally stronger than any of the market fillers. Hmm, as I type I realize I've already decided to do the finishing myself. Darn typing anyhow.

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krwasson
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Duffy
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Think I'm gona call this as done as, & ship it down to my buddy who's building the Thompson-modified 421 Hemi for it. Here're the last things I played with:

First, remember how I needed that jig to do the main rails &c., and was agonizing how to make a more universal jig to mount axles and such? I figured it out.

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How universal is that, huh? Infinitely adjustable and 100% re-usable. I tell ya, after I hit on the basic concept, my work was only mostly over. Took uncounted seconds of head-scratching to finalize the design, but I think I did pretty well.

I gave up on replicating every last little detail here, and you'll see it best when the axle is mounted: I couldn't bear to make teeny clevises and all so I just "sketched" with plastic bits in approximately the right spot & made it look busy enough for the eye to pass over it and not stop in alarm and horror. That's the plan anyhow.

Like this. It'll be better when it's painted. Less white and glare-ish, too.

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Duffy
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More fancy jigging - who knew the pushbar would come in so handy? Here I'm shaping the two seat braces around the much-modified seatbag from Revell's 22 Jr kit (which is where the axle came from too). More of that in a moment.

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Yup, cut way down, a much smaller seat all 'round than what Tony Nancy uses five years later. The DRAGMASTER's seat lays back more too, so there's a visible slant to the cushioning. I was lucky to cut the seat down to almost a tuck, and then I just filed in the vertical tucks to make it look like it curls over on top or something. More visual misdirection...

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And a Vain Shot of present progress, & it's off to Pontiac Lowry to continue. He located a Halibrand 4-Slot 8x15 rim, which is correct for this car, and is sending it to me to backpour. After that, MAY-BEE I can get back to some early '50s LSR action!

I'll post any progress here, including the finished scale drawing I'm working up for this frame. See ya.

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Another Rick
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rrr That is just some completely awesome scratchbuilding. Fantastic job.
I build models because GOD allows me to and because I can't afford the real thing!!
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krwasson
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:))) :))) :)))
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resin-daddy
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B) :)))
The Smell,Rubber Burning,Nitro In the Air...Never mide me im just looking for my Meds
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Duffy
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....An open announcement to the Admins: I only just noticed that I should be limiting my photo size to 640 wide / high...okay, I'm a little slow. I will amend this, starting now. I'll also try to replace the pics in these threads of mine, but that may prove beyond my skills. Working on it.
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resin-daddy
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640x480 is the size,dont worry about changing them Duffy its all good :)))
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Bernard Kron
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Really stunning fab work. I'll go over this several times to get clued in on the jig and what it can do for me. I do a fair amount of chassis building but up to now I do it largely free-hand or just laying things out over rudimentary drawings.

From the look of it, it appears to be 1/24th/1/25th scale although there's a not in one of the photos indicating /th which is a fairly unusual scale if you were to use a kit-supplied motor. What diameter styrene rod are you using and how are you bending it?

That's the later Dragmaster Dart frame, often overlooked because of the arrival of the simplified SoCal style chassis, but really quite sophisticated and very successful.

Can't wait to see more.
Keep on buildin'
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Duffy
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Hey Bernard, thanks for the comments - darn, I fancy myself a decent writer, & then I go and leave out an important bit like defining what scale I'm working in, just 'cause I take it for granted! My bad. It's 1/25, and indeed I did slip in a hint back in post #4 in this thread, but - nope, not good enough.

Most of the frame is 1/16" rod, just bigger than 1.5" in 1/25; the roll bar is designated as 1.75" and the two seat braces are .625", so I found a bit of oversize stock for the roll bar and used .025" for the braces. The X-member and sway brace are .040" & all flat stock is .010".

For bending, I have a Top Flite MonoKote sealing iron left over from my Flyer days; it's got a fine-pointed, Teflon-coated shoe, and a thermostat control. For tight bends like the body formers, I can just barely touch the iron to two or three spots around the bar to start it warming, & bend when it gets soft. Takes about five minutes' practice to become good at it. The big radii are all the same, so I tried different jar tops &c. 'til I found something that'd give me that curve; pulled the rod around it, then glided the hot iron around the curve to heat the rod up. It'll spring back a bit (which is why the trial & error jar search), so, again, practice.

The jig-making thing - well, it's a hobby all in itself, I think. There's a trick to "seeing" what is needed and then constructing that. Like I said in the thread, this is going to be unique to the Dragmasters, but that's a lucky thing because they're standardized & we can get a lot of frames off of it. (By the way, I hesitated to specifically call this one part of the Dart line, since in my homework I couldn't place the date of that name being applied. I just sidestepped it by talking about the tapered front and blah blah blah.)

I would very much like to open up a discussion about how to devise a more universal jig arrangement, or better yet, just to start talking about problem-solving & jigging in general. I've been thinking about it a lot, but I'm just one guy and I got blind spots (yeh, like forgetting to mention what scale I'm building in!). Maybe we oughta start a thread.
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Bernard Kron
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Duffy,Dec 29 2014
12:49 PM
...The jig-making thing - well, it's a hobby all in itself, I think. There's a trick to "seeing" what is needed and then constructing that. Like I said in the thread, this is going to be unique to the Dragmasters, but that's a lucky thing because they're standardized & we can get a lot of frames off of it....

I would very much like to open up a discussion about how to devise a more universal jig arrangement, or better yet, just to start talking about problem-solving & jigging in general. I've been thinking about it a lot, but I'm just one guy and I got blind spots (yeh, like forgetting to mention what scale I'm building in!). Maybe we oughta start a thread.

Thanks! I'll look into the heater thing. You're the first to offer a solution that's any more than just wingin' it with a candle or the all-to-mysterious "hot water", neither of which have worked out too well for me. The bottle cap radii are known to me however, but up to now smaller diameter rod has proven a real problem.

So, yeah, jigs, their care a feeding. The specific nature of your jig I guess is determined by the fact, more than anything, that the width is hard wired. I've also noticed that a lot of purpose-built jigs include specific alignment point in other axes as well. So adjustable jigs would have to be pretty complex. But adjustable or not, it's a subject I'd definitely like to pursue.
Keep on buildin'
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