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The R-Geo tuning fork F1 build


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#1 JimF

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Posted 07 February 2014 - 01:31 PM

Sorry that this is not a step-by-step. This was done over several short sessions with about a ten-day break in the middle while I was out of town. I just didn't get many pics as I went along so I took some at the end. I hope this is clear.
 
What you get with this kit is as follows...
 
1" bracket
1" nosepiece
bracket plate
Two nicely-formed tuning fork rails (.062" wire)
Four straight bronze rails (.062")
Two nice .062" thick pans. (I'm sure you can get the lighter pans as well)
  • You start from the inside out working with the wire forks running inside the bracket.
  • Next, you place the inner main frame rail which butts against the face of the bracket.
  • You want at least .005" clearance between the  inner main rail and the tuning fork.
  • You can just lay the rail in place and butt solder to the bracket face and the nosepiece.
  • If so, then your inner rail will be about .010"-.015" wider than the bracket sides
  • Thus... your outer main rail will have a small gap next to the bracket. No big deal, but...
  • I wanted the outer rail to go flush against the bracket and square and straight to the 1" nose plate.
So... See next pics.
 
2d612158-feba-48fe-908f-b80eb7fdbb6c_zps
  • This is the inner frame rail bent to go against the bracket face.
  • I filed a ~ .015" flat about 1.062" forward of the bend.
  • This allows the inner main rails to nestle around the tuning fork and still be 1.00" outside width.
  • Then your outer main rail will go flush to the sides of the bracket and nose plate with no gap.
4c899a09-2129-45e6-a84d-75bf399ecf4c_zps
  • I notched the nose plate aft of the axle upright .062" on each side.
  • The inner main rail is inset into the plate.
  • Then, your outer rail will lay flush with the front part of the plate which is still 1" wide.
927e6b0a-37eb-4ae0-9144-95fa49d51854_zps
 
Detail of finished front end.
  • I did these following steps before putting the axle in place so it's easier to get at the front bits.
  • Square 3/32" tubes form the front pan hinge tubes.
  • .047" piano wire forms your hinge rod. Bend one leg then slip through tubes and bend the other side.
  • When soldering up the hinge wire, I leave about .010" between the pan and the main rail.
  • Spreader wire is .032" but could be any size. Small wire allows the pans to be slightly independent.
  • Small bit of .047" wire goes right at the crux of the fork rails to tie them together. (Quick and easy to remove)
263afcec-c67f-403e-84c3-2f7548e9547d_zps
  • The bracket plate comes with fairly long ears going forward.
  • I cut the ears off flush with the front face of the bracket and soldered the cut offs on top.
  • This makes the bracket plate a little thicker than the pans which are .062.
  • Square 3/32" captures the .047" wire which forms a downstop and upstop.
  • Slight dogleg is bent into the .047" wire and a little scrap of wire reinforces the solder joint.
  • Note that the main rails are soldered together only about 1/2" forward of the bracket.
fb3da7da-af71-429e-91b7-a79e34e3c4b3_zps
  • Finished product: Bare frame as shown here is 56.5 grams. All up with body will run 98-100 grams.
  • This will get tested first on the "Korkscrew" flat track at MoTown raceway in Modesto.
  • This build might be a little light for that twisty 88' track or our other technical flat tracks.
0b6765fb-e9c9-460a-b2de-e329fbc5c265_zps
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Jim Fowler




#2 Half Fast

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Posted 07 February 2014 - 01:53 PM

Thanks, Jim,
 
Your builds are always interesting and informative as well as well written!
 
Thanks

Bill Botjer

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#3 TG Racing

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Posted 07 February 2014 - 02:22 PM

Nice job. Your pictures are worth a thousand words!
Thom Greene

#4 Tim Neja

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Posted 07 February 2014 - 02:27 PM

DAMN!! How do you get them SO CLEAN!!! :)  Nice job JF!!! I'm jealous of your skills!! I keep trying--but mine never come out so nice and neat!! Very nice!! Looking forward to seeing how it handles!! Rick--send me a couple of those kits!!  :) :)
Tim


She's real fine, my 409!!!

#5 TG Racing

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Posted 07 February 2014 - 02:48 PM

Tim,  It is very smooth and predictable on a Gerding King.  I wish my builds were that clean but once they're done I wanna get them on the track!


Thom Greene

#6 redbackspyder

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Posted 07 February 2014 - 02:59 PM

Beautiful work Jim, and great tutorial as well...


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#7 911GT3

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Posted 07 February 2014 - 05:26 PM

Lookin' good Jim. 


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#8 team burrito

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Posted 07 February 2014 - 05:55 PM

Hey, Jim.  Maybe you & I should do a tutorial on how we clean our chassis.  What do you think?  :sun_bespectacled:


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Russ Toy (not Troy)
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#9 JimF

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Posted 07 February 2014 - 06:07 PM

Hey, Jim.  Maybe you & I should do a tutorial on how we clean our chassis.  What do you think?  :sun_bespectacled:

 

I think you're a much cleaner guy than I am.................... :)


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Jim Fowler

#10 Dominator

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Posted 07 February 2014 - 06:40 PM

Simple and SWEET!


A motor is only as fast as the chassis it's in.
 
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#11 Rick

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Posted 07 February 2014 - 08:36 PM

Another great build JIm. I asked him to run the chassis as is and he said he would give it a run. I built one very similar to this and was quite surprised how well it worked at 102 grams, considering, most of the F1 builds being raced are laced with lead and weigh in about 112-118 grams. He wanted to add some center weights to bring the total up a little but is humoring me. I am sure he has the weights read to go. LOL

 

I sold a few of these kits in proto-type form and the reports have been very positive so far. My car also had the older .050 pans and this one is the new .062 pans.

 

I used  shaker loops about the same place he has his cross bar and solid cross wire in the front, but his build is a better way switching this around.

 

Thanks Jim for a super nice build and the pictures to help other builders, now we have to wait for a test run report..............


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#12 Tim Neja

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Posted 07 February 2014 - 10:16 PM

YES YES---a chassis cleaning tutorial!!! WE COULD USE IT!!! :)


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She's real fine, my 409!!!

#13 team burrito

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Posted 08 February 2014 - 12:40 AM

 

I think you're a much cleaner guy than I am.................... :)

 

Maybe just a little. Bring your cleaning tools on the 23th & we'll compare & do a photo report.


Russ Toy (not Troy)
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#14 Jocke P

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Posted 08 February 2014 - 03:32 AM

Rick,
will there be a new number designated for this chassis, or should it be ordered with ref. to the build thread?
Joakim Pegers

#15 Bill from NH

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Posted 08 February 2014 - 08:59 AM

 

 Bring your cleaning tools on the 23th & we'll compare & do a photo report.

 

How many different ways is there to use a can of Spic-N-Span & a SS braid brush? :laugh2:


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#16 slotcarone

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Posted 08 February 2014 - 09:48 AM

Cleaning the chassis is very easy during the build--just scrub it in the sink with a SOS pad. Dont use Brillo as it is too coarse. I usually cut the SOS in half first. This will remove any acid residue and make the brass shine. I also use metal polish for a final finish.  Of course you must start with shiney metal before you solder anything!!


Mike Katz

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#17 JimF

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Posted 08 February 2014 - 11:12 AM

Mike pretty much covered it right there ^^^^. I use either a steel brush or more often a brass one as I go along. I don't use cleanser very much but use dish soap a lot. I'll probably scrub the frame 4-5 times during the build. This allows me to visually check each solder joint and I'll sometimes find that I didn't get a complete flow and I'll redo that joint. When I'm shooting pictures for an article, then I'll clean more often so the pics are clear. Towards the end I'll use scotchbrite. The steel brushes will actually remove solder to some extent and the coarse scotchbrite will too.

 

Russ one time pointed out some flexible abrasive "starfish" wheels that we get from McMaster-Carr. Those are useful for cleaning up solder joints. At times a rubber abrasive wheel is useful as well.

 

I'll see if I can get some pics and cobble something up in a separate thread but I'm pretty busy for the week or so.


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#18 team burrito

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Posted 08 February 2014 - 11:16 PM

As promised, here's what I use to clean my chassis:

 

1656183_780352671993634_1128918299_n.jpg

 

The abrasive wheel on the left are 3M 3/4" dia radial bristles; I get mine from McMaster for $1.18 each (p/n 4494A52).  I like using the 80 grit for all-purpose cleaning & it cleans in-between the teeth on motor pinions as well.  I use three at a time on a standard Dremel shank for maximum effect.  They last a long time & works better than anything else (& believe me, I've tried them all).

 

The other tool on the right is a pencil wire brush, great for getting in tight spots & corners.  I did use the fiberglass brush for awhile & they do clean the best, but the glass fibers break off & get in your finger tips, even with gloves.  I found the steel wire version also at McMaster (p/n 3034K48) for $9.44 & the refills are only $1.50 each (p/n 3034K68).

 

Another tool I like using is solder wick.  Sometime you get a little too much solder & the wick makes cleaning so much easier, followed by the radial bristles.  For flowing those solder joints, I use a butane-powered micro torch; I got mine at a cooking supply store for 25 bucks.  To hold down large pieces while torching, try a 1/8" dia aluminum rod.  Soldering is so much easier when you have the right tools.

 

Burrito out.

 

 


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#19 JimF

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Posted 26 February 2014 - 03:23 PM

Here's the first track test results.

 

I got the new car on track for the first time last weekend and tested it on the challenging 88' Korkscrew flat track @ Motown Raceway in Modesto. Depending upon how you count 'em, this little track has 8 or 9 turns in it's short length. The key area is as shown here with 6 key turns in about a 40' track section. The turn that I've marked as #1 is actually the second turn of each lap and the turn at the end of this section (dogleg #6) does not have to be driven if you car is set up to come out of #5 cleanly. OTH, if you are loose out of #5, then you have to blip for #6.

 

b766cf61-40c9-47b5-9919-fe86b55cea9b_zps

 

This is the baseline car. This was the race winner last Sunday with a new record lap total and best race time ever @ 4.50. By far the best car I've ever had on this track.

 

  • 3X.047 with a space between the two inner and the single outer rails.
  • R-Geo bracket, nosepiece and pans.
  • Weight added under front axle and at the sides of the bracket (115.5 all up)
  • Best gearing was 7-28 and raced on Alpha Treated (narrowed)

 

8aec2dfa-afad-4026-a74d-c24f868b33c7_zps

 

The contender:

 

99.8 gr all up but weights ready to go on. 8-28 gears, JK 8703T narrowed.

  • Given the light weight, this car was surprisingly good. It was touchy in #2 and loose out of #5.
  • Could stay punched through #6 but was all jiggery going under the bridge into the donut. (a handful!)
  • Changed to 7t pinion and that fixed #5 but still touchy in #2
  • Tried 8713 untreated and settled it down most everywhere. Laps were about 4.65 but still a little twitchy.

 

44daa88a-aacb-47df-8d50-d8ca58a5e58b_zps

 

Weights go in as shown. Total of 7.5 gr for the two weights.

 

7658b959-3ccb-4610-a875-90ae3757d2b1_zps

 

Back to the track @ 107.4 gr. Still light for this track.

  1. Weight fixed everything. Car was now capable of 4.56-4.62 and was settled in all turns.
  2. At this point, I probably would have narrowed the untreateds slightly and gone for the race.
  3. But.....my other car has over 3 months sorting out on it and was good on all lanes so I raced that one.
  4. I think if I had switched out the motor/gears from the race car, this might have been even better.

This was a very positive first test and I think that this car might be even better than the other one on a more conventional flat track like the MTT @ Fast Track Hobbies in Rocklin for example.

 

cf4005ee-5c7b-46b8-a78f-766b46a38927_zps


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Jim Fowler

#20 Rick

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Posted 26 February 2014 - 03:44 PM

Jim, Great to hear your report and positive, I might add. This idea came to me on a whim and thought I would give it a try. I was also quite surprised how well it worked , for me, at 102 grams RTR. Usually around here, F1's are between 112 and 118 grams. That track does look like a handful! Your build is super nice, as always, and good for those buying the kits to follow along. I have switched out the 1" bracket, with a 3/4", per your suggestion, and everything now is straight up and much easier to lay out. The tuning fork now goes on the outside of the 3/4" bracket, instead of inside.......


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#21 TG Racing

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Posted 26 February 2014 - 08:32 PM

Jim, Great report!  Does the triangle soldered to the tuning forks limit there flex too much?


Thom Greene

#22 JimF

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Posted 26 February 2014 - 10:58 PM

No, it doesn't. Here's why.....................

 

This is the original build. You can see a bit of .047 wire (arrow) soldered right at the rear of the forward straight leg of the fork. This is a flex limiter and I've found that most of the tuning forks I've built run better with the forks joined solid right there.

 

e37ab895-4b8d-4049-9d78-6d59edcdb1ff_zps

 

This is the frame after tuning. The weight block is suspended from a longer bit of wire in the same spot The block itself is not soldered to the fork rails, just to the long bit of wire.

 

1e207f89-4ab8-4708-b8a5-37ad1fc95287_zps

 

Hope this makes sense.


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Jim Fowler

#23 Tex

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Posted 27 February 2014 - 08:04 AM

I love seeing little do-dads that for the life of me I can't figure out what they are there for....

 

OK, Jim... you've got a piece of wire soldered to the backs of the pans, extending into the square tubing to limit movement. BUT... right next to that piece of wire that extends into the square tubing, you have another smaller piece of wire(at the back of the pans) that I'm not sure I understand it's purpose(?). Is it there just to brace the other piece of wire?


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#24 Rick

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Posted 27 February 2014 - 10:27 AM

Tex, that is just there to reinforce the solder joint on a short piece of wire...


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#25 Tex

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Posted 27 February 2014 - 10:50 AM

Thanks. I kinda thought that but wasn't sure.


Richard L. Hofer

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