Shelby-Hendrix Speedway (SHS) under construction

[slothead]

After years of thought and planning I'm finally getting started on building a road course. SHS is named after Carroll and Jimi, both world changers in their fields. Shelby's Mustangs are the reason why I own a retro one now, and I still listen to Hendrix's music more than anything else. So I'm a half-deaf lead-foot baby boomer with Trans Am fever in need of a road course to race my slot cars on.

My first track, Shepherd Speedway (named after humorist Jean Shepherd), is a flat oval routed into a 4' x 14' hardboard table top. My grandson and I have run countless thousands of laps on it in 7 years and it's still in use. SHS is going to be a 2 lane track made from sections of 1/2" MDF on a 6' x 14' table with a variety of features and elevation changes. I don't have a need for more lanes so I'm trying to maximize the lap length. If I ever need to expand the racing I'll add an AC2car type lane change switch and go digital.

I'm now laying out the track design in detail on graph paper and getting ready to cut out the sections. I'm hoping the HRW crowd will offer thoughts and guidance as things progress. I'll post pictures as soon as possible.

My first issue is figuring out the hairpin radius. The track itself will be 10" - 11" wide, with varying gutter and lane spacing dimensions around the track. Three areas around the track will be no passing zones, where there will essentially be one racing groove created by reducing the lane spacing to about 2". The hairpin will be one of those areas, but I also want to ensure it's not too tight and will be driveable.

Question #1 - anyone know what the radius or diameter of plastic track hairpin turns are? What's worked for your non-magnet hairpin turns? My initial design has a 6" radius for the inside lane and 8" for the outside lane, but I can kick that out a bit if needed since there would be a 5" outside gutter.

Question #2 - some track building sites suggest slightly banking as many turns as possible to limit de-slotting. Supposedly 1/2" MDF sections can easily be banked by 3/8" to 3/4" and this makes a big difference and adds realism. Anyone have suggestions or know of a tutorial for doing this?

Thanks for any and all comments.

Slothead

[munter]

re question two.....flat tracks are fine and offer a challenge to the car tuner. Some banking is OK but not essential at all.

[slothead]

munter & Dave - thanks for the initial comments. The hairpin turn will be flat and I might only slightly bank the corner after the back straight and the loop turn that will have the highest elevation on the track and then spiral down to towards 'ground level'.

Also, if I cut out sections so they fit together and then bank a turn in one or more of them, they aren't going to fit together afterwards are they? My understanding is if you had 4' straights leading into and out of a 90 degree turn, and then banked the turn, the straight sections would get pulled in and no longer be at 90 degrees. Saw the math somewhere on how to compute the angle change ahead of time so things fit together, but don't remember where. Or, is that overly complex and not needed?

Slothead

[Florida_Slotter]

[waaytoomuchintothis]

[slothead]

Marty - I listened to Jean Shepherd on WOR too and got see him perform at Princeton a few times. He was a master storyteller and I still listen to recordings of his show online. If you haven't seen his PBS show 'Jean Shepherd's America' or the short film 'Ollie Hopnoodle's Haven of Bliss' do check them out.

I am trying to be creative with the layout, and not have it be like a plastic track. The series of turns in your second photo are very interesting. That kink leading into (or out of) the big turn is scary. Any idea what the radius of that might be? Without anything for a size reference I can't guess.

waytoomuch - yes, that is a quite a sweeping corner. Don't think I have room for something like that in my layout, but now you make me wish I did. My design loops around within itself quite a bit to increase lap length without an overpasses. I love my oval but with good cars can run laps in under 2.5 seconds, so a 10 lap heat race is over in less than 30 (insane) seconds. I'm hoping for much longer lap times on the road course.

That turn at the lower right of your photo is similar to my hairpin turn. Do you know what the radius is?

Thanks guys.

Slothead

[waaytoomuchintothis]

Its been a while, but I think the middle lane was at 12 inches entering the turn and leaving, with a 9 inch arc at the apex.

[Retro Racer 44]

A suggestion: Recreate your tightest turn on a scrap and route it. Push a Carrera car and a car with the deep Slot.it guide around to make sure it will pass. If not, open out your turn a little to avoid future problems on the good track. You may have to squeeze the lanes at this point to allow a wider turn.

[slothead]

Test routing my tightest turn makes sense and I'm going to find some scrap wood to do that.

Any tips on how to route changing radius turns? I never got around to ordering a track building kit from Luf. I'm not brave enough to try it freehand after seeing how quickly a router can get away from you when working on my oval. So I used a piece of wood as a radius rod and settled for constant radius turns.

Slothead

[waaytoomuchintothis]

Drafting the changing radius turn is easy once you know how. Routing it is another matter. Better invest in some kind of guide, even if its one you make from scrap. To draft a compound curve, set the apex first, then experiment with the lead-in (point of initiation or PI) and lead-out (point of tangency or PT). I include the terms so you can find them in a geometry book if you have one lying around. Generally speaking, my preference is a sharp lead-in and a gentle lead-out, so hard braking in front of the turn and power out. Lots of times, this means I can use the apex radius from the PI around the turn and the larger radius to power out to the PT. When you have the inside lane all plotted you can simply parallel the other lanes.

If you make a pattern to rout the inside lane, you can use a parallel guide to rout the next lane, and so on. This means you will be using a bushing insert to stay on line all the way around each time without starts and stops. If you have problems, Durham's Rock Hard Wood Filler is your best friend. I used to use Bondo, but Rock Hard is much better.

If you get confused and wonder if 6 was 9, don't slip into manic depression or a purple haze, just ask yourself, "Hey Joe, are you experienced?" hohoho

[HomeRacingWorld]

[Nor Cal Mike]

6" Radius is fine. I have gone less before down to about 4 1/2" but big Carrera guides would not go through them without trimming. The hairpins are fun to toss your car into especially if you route a compounding radius spiralling into them into them. They add variety to a track of well designed corners. I really like the sweeper in the track shown by waytoomuch. In fact, if a sweeper is broad enough, it can be used in place of a straight. I have done that several times in the tracks that I have built. In most cases, I like a little bit of very mild banking more for the visual effect on the track rather than the racing of the cars. I just think slight banking looks nicer and isn't hard to do with a few well placed wedges.

[slothead]

Harry - did you cut out sections first or route the lanes first?

My table is on wheels and not as sturdy as yours. Thought I'd put a sheet at a time on saw horses downstairs (where you drive in the barn) and then carry the cut out sections upstairs to the loft that's the mancave. Then, I'll beef up the table as needed under the sections to support elevations and twisting.

Checked out the link and Midmo build, every bit of info helps. But that slotburger threw me off 'cause now I'm hungry and need dinner.

Nor Cal Mike - I drew out a 6" radius turn last night and pretend drove a Carerra GTO around it. Even with that ridiculously long guide it should be okay. And, since I don't think Carerra makes any Trans Am liveries based on actual cars that raced in the series, I don't expect to be using any on the track. The GTO is a real looker but handles like crap on my oval with that huge guide mounted behind the front axle.

After quenching my slotburger craving I'll be doing some test cuts and finish the cookie cutter planning to get all sections laid out on the MDF sheets.

Slothead

[Nor Cal Mike]

[dreinecke]

All good points here. My track started as a template and morphed as I started redoing sections. No logic, I just draw lines, line up the strip and let it rip.

In other words: no single corner is the same.