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DS on the DSF1


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#1 gascarnut

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Posted 17 August 2011 - 07:50 PM

A while back, a little brown envelope arrived in the mail, with the words See what you can do with this on it. The contents:

RgeoF1001.jpg

These are the basic parts of the R-Geo DSF1 frame kit, named by Rick after my very successful design that has helped many people (except me for some strange reason) win a lot of Retro F1 races. Rick wanted me to build it up in my style and post the results and some comments, so here goes. I am going to try to write this as a set of instructions with comments, so hopefully others can get some tips or hints, or just shake their heads and say Why does he do it THAT way??? (yes, TonyP, I can hear you!!)

Before I start, let me apologize in advance for three things my poor photography, my dirty jig, and my untidy workbench. You will quickly realize I am no DC65x-type builder! But I hope you will get the idea.

My good friend Mike Kravitz was in the market for a shorter, lighter F1 car than my regular design, so I decided to build his car with this kit. The .050 brass pieces help with the weight reduction over the .062 brass I normally use. I shortened the nose piece by ¼ and took ½ off the center pan:

RgeoF1002.jpg

I always start with the motor bracket. The R-Geo brackets are nice sturdy things, with 3/16 holes to accept bushings directly in the bracket. I like to use an axle tube to get the bushings out closer to the wheels, so I drilled out the holes to 7/32 and cut two pieces of 7/23 tubing:

RgeoF1003.jpg

NOTE: Sometimes I will cut a full length of tubing, but often I have pieces left over from cutting out the centers afterwards, so I keep them and then set the rear end up this way with a piece of 3/16 aluminum tubing inside the brass to keep them aligned.
I also add a small shelf inside the bracket, from the ¼ piece I cut off the nosepiece. (Waste not, want not is what I was taught!). This helps to stabilize the bracket and add a little rear weight.

RgeoF1004.jpg

The bracket brace is made from .055 wire on my trusty old K&S bending jig (a door prize at Sano1). I mark off ¾ for the first bend:

RgeoF1005.jpg

Then I clamp the wire in the bender, note that I have a mark on the bender so I can position the wire the same place every time. Bend the first bend 90 degrees.

RgeoF1006.jpg

Now comes the little bit of Duffy trickery how to get the second bend in the right place so the brace fits inside the bracket. I measure the inside of the bracket with my digital calipers, then zero the caliper and close it down by the wire diameter (.055) and half the wire diameter (.0275) to account for the spring-back. Then I set up the wire in the bender this way:

RgeoF1007.jpg

Now bend the second bend, cut the long leg the same length as the sort one, and there it is:

RgeoF1008.jpg

A perfect fit:

RgeoF1009.jpg

I took a photo of the soldered-in part, but like so many of my shots, it came out too blurred for publication, you will see it in later shots again.

Now for the rails: I use a combination of steel and brass rails on my F1 designs, and IMO this has been one of the reasons they work so well for so many people. The steel rails go against the bracket and nosepiece, and have two 90-degree bends in them, the first ¼ from the end of the wire, the second 5/16 from the first. They are handed for the left and right sides of the frame:

RgeoF1010.jpg

RgeoF1011.jpg

Solder them to the front and rear of the bracket and the axle tube.

RgeoF1012.jpg

RgeoF1013.jpg

See how well this braces the axle tube? Wait, there will be more!

Now for the front axle mounts. Normally I use .062 steel wire for these, but since Rick provided these neat little triangles, I decided to incorporate them. This is how I set them up:

RgeoF1014.jpg

Now we can start with the brass rails. The inner rails are shorter, going from the bracket to the rear end of the axle strut. They lay flat on the building jig, with no bends. I use low-fuming bronze brazing rod, and it does not like to bend much.

RgeoF1015.jpg

Soldering brass or bronze to steel causes all kinds of differential expansion issues, so over the years I have developed a few tricks. First off, I try not to solder brass rod to piano wire anywhere that I dont have to (clever, huh?). Then when I do have to, I try to apply the heat from the soldering iron to the steel rather than to the brass, so that the steel gets hotter and therefore expands more. I let the steel heat the brass, then apply the solder:

RgeoF1016.jpg

RgeoF1017.jpg

Here is one of the outer rails along with a little piece of filler rod that is needed in front of the axle strut. I filed a flat on the rod where it runs under the strut so it fits nice and tight:

RgeoF1018.jpg

RgeoF1019.jpg

Solder this lot together; here you can heat the brass as it is joining to brass in most areas.

RgeoF1020.jpg

The photo of soldering the rear needs of the rails to the steel rail came out way fuzzy, but I think you can get the idea. Watch as you apply the solder that it does not run between the rails any further forward than the front face of the motor bracket. (You do heat the work, THEN apply the solder, right?)

RgeoF1021.jpg

To finish up the center portion of the frame, there are two more axle tube braces to bend, from .055 wire. Once again, they are handed to fit left and right sides in front of the axle tube

RgeoF1022.jpg

Now this next part is one of the reasons I like the thickness of the R-Geo building jig:

RgeoF1023.jpg

There are times when gravity is your friend! Place one brace is position and flow in some flux to hold it in place, and then solder it in. Flip the jig over onto its other side and repeat. When youre done it should look like this:

RgeoF1024.jpg

RgeoF1025.jpg

And that, friends and neighbors, is the center section done:

RgeoF1026.jpg

A quick scrub down under running water with a steel brush and on to the pans, but thats in the next post.

RgeoF1027.jpg

RgeoF1028.jpg


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Dennis Samson
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#2 gascarnut

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Posted 17 August 2011 - 08:01 PM

Part Two

I hope the first section was informative, here we go with the pans and the finishing touches on this R-Geo DSF1 kit build.

Since my friend Mike runs in SoCal and therefore has to conform to a 3 1/8 width rule, I had to make some changes to the R-Geo pans, which are designed for the IRRA Rules. I decide to follow my normal design approach and turn them on their edges. I also had to shorten them from the front a bit to accommodate the short wheelbase I was building. Since the pans are now on-edge (but not nervous fortunately :D ), the pin tube holders will be too high so I removed them:

RgeoF1029.jpg

I took the shortened center pan and attacked it with a belt sander until it fitted inside the rails with about .008 clearance each side:

RgeoF1030.jpg

Thats part of a TSA bag search notification being used for spacers. (No comments about it being the only thing useful about the TSA please, I have to fly again soon!) The paper they use in just a nice thickness for shims of this sort.
I mark and drill two holes in each side pan for the pin tubes. The tubes lie on the main rails and connect the side pans with the center pan:

RgeoF1031.jpg

Here again, your eagle eye will spot the non-Duffy, non-DC65x workmanship. Whats that saying about measure twice, cut once? :dash2: I messed up and had to drill 4 holes in each side pan sorry, Mike! The little brass rods on the center pan make up the space between the top of the .050 pan and the pin tube.

Solder in the center pan first, and then solder the tubes to the side pans.

RgeoF1032.jpg

At the rear of the pan assembly, we need a brace to connect the pans, as well as to stop them dropping below the clearance limit. Using the same techniques revealed earlier for the bracket brace, I bend a pan brace from .055 wire that fits between the inner surfaces of the side pans:

RgeoF1033.jpg

The brace lies right on the motor bracket brace and fits along the pans, creating a side-to-side movement limiter.

RgeoF1034.jpg

Once all this is soldered together, the whole pan section can be removed from the center part for cleaning :

RgeoF1035.jpg

This is what the frame looks like now:

RgeoF1036.jpg

Nearly there all thats left are the retaining stirrups for the pans, and the front axle. The stirrups can be bent any way you like to do it, I have 3 different methods that I will discuss in a separate thread some time.

The big deal here is to space the pans to get the movement you want. Put the whole thing back in the jig, set the TSA Shims back on each side of the center pan to stop it moving around, then space up the outer pans for the desired amount of movement. On this and other builds, I generally use about .010 under the front of the pans and .032 under the rear. Heres another nice shimming material, Slick 7 product cards are just nicely .010 thick, good for shimming guide tongues upwards and for spacing F1 pans!

RgeoF1037.jpg

Lay the wire stirrups in place (I use .032 wire for these). Make sure the pans are positioned correctly fore-and-aft on the center section, and that the stirrups lie in the groove between the two brass rails, with their tops leaning all outwards, or all inwards. It doesnt matter much which, but they should all lean the same way to get even movement from side to side.

RgeoF1038.jpg

Soldering these in place can be tricky. Lots of flux helps to hold them in place, and a piece of bamboo chopstick is a useful tool to hold them once you have applied the solder. When youre done soldering the stirrups, flow a little solder between the two brass rails from front to rear so they are joined all the way. This helps a bit with strength and stiffness. For flat tracks sometimes I dont do this if I think I need a bit more flex.

RgeoF1039.jpg

At last, we reach the front axle. I use a 3 long piece of 3/32 piano wire, which I polish in a drill press or Dremel with Scotchbrite till it shines. This smoothes the surface and gives longer life to the wheels, as they will rotate directly on the steel. Mark the center of the axle and slide it into position with the right size jig wheels:

RgeoF1040.jpg

Solder the axle to the struts. I found that the slot in the struts is a bit wider than 3/32, so I held the axle up against the front of the slot, and soldered it to the front edge of the strut first. Since I wire-wrap the axle mounts on all my frames, I used the wire to help transfer solder into the rest of the slot. My wire wrapping technique uses 32AWG steel wire, two turns around the axle and the strut, and then the ends twisted together using a hemostat:

RgeoF1041.jpg

Flood the wire with flux and then heat up one side at a time and flood the whole joint with solder. Let one side cool before doing the other so you dont upset the alignment of the axle.

And that concludes the build, just the cosmetics left. The frame weighs in at 58 grams:

RgeoF1042.jpg

7 grams under my normal design:

RgeoF1043.jpg

The last thing before Tumbler-time is always my logo and serial number. I should really have given this one a K-### number as it is a kit build, I will polish out the S-### number (for Scratch builds) before I deliver the frame.

RgeoF1044.jpg

After 4 hours or so in the tumbler, heres the finished product:

RgeoF1045.jpg

RgeoF1046.jpg

I hope this has been instructional, and gives you an idea of what can be done with Ricks kits.

Happy building and racing!


  • Jocke P likes this
Dennis Samson
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#3 havlicek

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Posted 17 August 2011 - 08:11 PM

VERY nice Dennis!

-john
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#4 John Miller

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Posted 17 August 2011 - 08:33 PM

Noce work. . . and pics.


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Coming soon: Miller's Killers


#5 Bill from NH

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Posted 17 August 2011 - 08:41 PM

Another nice build article, Dennis. Thanks for posting it. :)

Bill Fernald

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#6 Mopar Rob

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Posted 17 August 2011 - 09:39 PM

Immaculate build as always :good: I like the axle tube bracing / main rail. For that I'll give you :good: :good:
Rob Hanson

Shops at Mid-America Raceway and uses R-Geo Products
 

Rob was right!


#7 Tim Neja

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Posted 17 August 2011 - 11:34 PM

Excellent build thread Dennis--and per your usual--very nice clean build!!
T
She's real fine, my 409!!!

#8 Jacob Shiplet

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Posted 18 August 2011 - 06:33 AM

very nice
Do you know the difference between education and experience? Education is when you read the fine print; experience is what you get when you don't.

#9 munter

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Posted 18 August 2011 - 01:43 PM

Thank you Dennis

Even though I dont race this class of car I still picked up a few pointers for when I build my next brass/wire frame.

You have given me a desire for a tumbler though....are there any cheaper alternatives?

and remember "A man who hasn't made a mess hasn't made anything"

regards

John Warren
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#10 Dave Fiedler

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Posted 19 August 2011 - 09:27 AM

really sano article!
Dennis, my friend, you are the dude.

#11 Tim Neja

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Posted 19 August 2011 - 03:41 PM

The "Cheapest" alternative is a wire brush and comet cleaner!!! Works great---but if you want REALLY SHINEY CLEAN---there's NO SUBSTITUTE for a GOOD tumbler!!! Steube taught me that one!! I've got the same model--Dennis too. They work really great for final clean up before assembly. YOu can also tear the car down after a few months of racing--and clean it up again like new!!
FYI
T
She's real fine, my 409!!!

#12 gascarnut

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Posted 19 August 2011 - 04:36 PM

really sano article!
Dennis, my friend, you are the dude.


Thanks, Dave, but you are still the "Super Dude". No-one can beat your "dudeness"! Glad to see you posting, my friend, how are you doing these days?

The "Cheapest" alternative is a wire brush and comet cleaner!!!


Tim's right, although I guess Sano Dave would say that the best way to get a super-sano build is not to make it messy in the first place! Dave's stuff is a good example of that.

I have the AR-12 Tumbler from Thumler's. At the time I bought it, I did not think the extra cost of the Model B like Steube has was worth it, and so far I think my assessment was spot on. Mine is over 4 years old now, and has tumbled for more than 600 hours without incident. I'm still using the first bag of media I bought, but I'm getting to the bottom of the first bottle of soap solution.
Dennis Samson
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#13 ejgehrken

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Posted 21 January 2013 - 09:52 PM

How are the rear axle tubes cut perfectly straight?

 

Who makes the 3/16" jig axle that was used to align the rear axle?


Eric Gehrken

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#14 JoB

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Posted 30 January 2013 - 04:01 AM

ejgehrkenWho makes the 3/16" jig axle that was used to align the rear axle?

 

NOTE: Sometimes I will cut a full length of tubing, but often I have pieces left over from cutting out the centers afterwards, so I keep them and then set the rear end up this way with a piece of 3/16” aluminum tubing inside the brass to keep them aligned.

 

K&S makes aluminum tubing and others as well. Check this out: http://www.hobbylinc...m/k s/k s104.htm

 

Cutting tubes? Here is one sample of a tube-cutter, but there are several on the market: http://www.hobbylinc.../k s/k s296.htm

 

Have a good day  :D


BrassChass AKA Jens Backman

#15 gascarnut

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Posted 30 January 2013 - 05:10 PM

My apologies for not replying sooner.

 

Eric, I face off the ends of the axle tube on a lathe before installing the tube in the bracket. I know not everyone has a lathe, so if you don't just eyeball it and then be careful when you install bearings to be sure they do not bind.

 

As Jens says, there is no jig for the axle tube pieces, just a length of K&S 3/16" aluminum tubing inside the 7/32" brass tubes.I use aluminum so it does not get soldered to the tubes while I'm working. The aluminum is shorter than the brass, and then I use two bushings in the ends of the brass tubing to adapt down to the 3/32 axle as usual.


Dennis Samson
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#16 Pablo

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Posted 30 January 2013 - 06:44 PM

Thanks for sharing, Dennis :clapping:  :good:  :heart:


Paul Wolcott


#17 macman

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Posted 05 May 2013 - 07:54 AM

I recently finished one of these kits , built to IRRA spec, & it is a great kit, as well as a super easy build. This thread was a great help on the centersection, but not so much on the pans, but I got it done anyway... however it once again seems I can't post  picture here... Car is much faster & much better handling than my first F-1 which I did a couple of years ago based on this design. OS 436 body really does a great job on this chassis!!!


Ben Kernan
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#18 Duffy

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Posted 08 May 2013 - 02:38 PM

This thread recently popped back up (the last scenes in Deliverance are running on my inner movieola as I type) and I was kinda tickled and a little disquieted by the following references:

 



...Now comes the little bit of “Duffy trickery” – how to get the second bend in the right place so...

 

...Here again, your eagle eye will spot the non-Duffy, non-DC65x workmanship...

 

Wow, 'Nut, I may be getting assigned a skill level I don't measure up to there! Duffy workmanship includes plenty of - let's call 'em "Lessons," okay? That has the proper ring of denial to it.

I pondered the measure-and-bend sequence shown here to see how it translates to what I do, since I don't restrain the wire during bending: it may (a big "may" there) impart uneven stresses around the bend (which phrase has often been applied to me, and I can't claim uneven stresses as my cause).

 

Anyway, pondered - there are lotsa ways to describe an operation, and sometimes one description will be the one that someone finally Gets out of all of them - and I figure it might be time to go elsewhere & put up some tho'ts myself on the procedure. Thanx Dennis.

Duf


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#19 macman

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Posted 11 May 2013 - 12:34 AM

DS F-1.jpg

finally figured how to post a picture in this topic... irra width version


Ben Kernan
Formerly of SARN

Yes, I am a sarcastic, smart-azz, know-it-all old bastard of a genius. 
What is old is new again... Retro... Gotta love it !!!
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The Englelman: a truly superior design.
 





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