Test Track Continued from Car and Semi Truck Construction

[cubdad]

Here are some construction details for a test track fyi.

5 pieces of betacraft track plating $70
4 pieces 8' 3x1 vinyl trim $45
12 feet 1x3 poplar $15
Swan Tech timer $35
1 lot screws, nuts, bolts, switch, dowels,
battery holder, 4 d cells, etc... $30

So it came to $195, not including various little bits I had lying around like small wood plates to protect the timer and peel of stick on weather stripping for the stopping section.

This was way past my guess that I could do this for less than $80 when I started. Well at least delusion helps gets things done.

The track is 32.25 feet from start pin to timer sensor. Plus a 2.5' stop section. The stop section needs to be 3 feet but I had no more room.

In retrospect I would not use poplar again as I've since found out that its not a dimensionally stable wood, perhaps I'll seal it after PWD season. In retrospect the track plating and vinyl trim are great: straight, impervious to heat and humidity and did I mention straight and square as wood stock never is.

Assembly method was to first build the poplar support, bolt the first two vinyl piece together end to end then screw the vinyl trim into the poplar support, then once the curve was established, screw the track plating into the vinyl. The plating needs a pilot hole. The vinyl does not.

Here is a view of the start gate and ramp. The pin is 42 " above the ground as per the original BSA plans from the old handbook. I think no one uses 42" anymore but 48" so track time is in the 2.6 second range for a good run as opposed to 2.4 or lower. The track is also 1" above the ground due to resting on the vinyl molding. If I did it again, I'd make the start gate a little higher.



The slat and paper under the left support are to level the track. The fishing line behind the ramp are to help shape the descent ramp into a more pleasing curve. Here is a closeup of the underside:



The two hooks stopped track twist that was there when one hook was used. Twist can also be controlled by moving were the fishing line wraps around the the horizontal wood crosspiece. The bolt with the two wing nuts was to fine tune tension, but it was unnecessary and 3" ss 10-24 bolts are $3.50 !!

Here is a closeup of the only stressed joint:

This is where the first two piece of vinyl trim are joined. I used a scrap piece of 1" pine. It is joined by 8 (4 each side in a square) 10-24 2" bolts with wing nuts.

Something that was very convenient is that the track plating is 93" long and the vinyl molding 96". This allowed the track and vinyl joint to never be at the same place and thus the plating supports the vinyl joints and the vinyl supports the plating joints.

The plating is screwed into the vinyl with 3/4" #6 pan head screws, about 18" apart plus another at 1.5" from the end of each piece of track plating.


Notice above how paper shims (can't get away from the infernal shims) are required to smooth the levels when going from one piece of track plating to the next. The track plating has a space to enter pins to help with line up. They can be hard to force in but do an excellent job. The track is not perfectly square at the end but is close enough to not really matter.


The vinyl support is butt joined (??) by small home made metal strips for the horizontal run:


Below is a closeup of a housing for the Swantech timer. There is a small incandescent light under the track. The timer works very well when its within 4 inches. I initially had the timer about 5 inches above the track and it would not consistently recognize the light. I painted the space around the light hole black to try to improve this but it made it worse. I guess the black reflects more infrared? Who knows! I covered the black with a piece of blue tape wich made it much better. Then I lowered the timer to about 4" above the track and it has since performed flawlessly.



I used a small light that you get to light buildings for a train layout (other hobby) because it was not too tall to fit. All the lights and light socket combinations from Radio Shack where too tall to fit.

The track also needed some shims (shims!!!) every few feet to keep a very level surface. Its the little white bits of index card and wood slat every few feet:

The track was straight and would have even and level on its own, its my house that doesn't have a level line in it.

Ok so here is the ugly part. When it was a week before the car hand in date we had to start working on the car. So I had to do a quick stop section. The stop section was initially just a 1" wide piece of wood with foamy weather stripping glued to it. But the cars rode off the end, so I added a padded vertical stop. Then the cars would bounce off so I added a padded box. Its not pretty but it works.


Other observations:
I wonder if I could have just bolted the start of the track to the wall and skipped the poplar support structure.
The track needs to be cleaned every day. Basements are very dusty.
The vinyl trim and track plating saved a tremendous amount of time and I think help to make a long lasting low maintenance test track but ti still took about 7 nights to get it ready. Problems with start gate consistency used up about 3 days.

info on the start gate is in this post:
viewtopic.php?p=30663&sid=f8c313ab437cd ... 34ea34c258

Hope this is useful. Sorry its so long.

[Derby Dad for 3]

Such a great idea and seemingly pretty simple too. It is the answer for us to our test track questions! We will refer to this post often while we complete our project. I'll let you know how it goes.

You said you would not use the poplar again due to dimensional instability. What would you use if you did it again?

Thank you so much for sharing all this insight and knowledge. It is greatly, greatly appreciated!! May we impose on you for a question or two during our project if the need arises? I do not wish to wear out our welcome and I'm sure you have "bigger fish to fry".

Thanks again!

[joe]

Its not pretty but it works.

Beauty is in the eye of the PWD enthusiast!

I've used poplar before for car bodies. It worked really well. Where did it warp on you, maybe it was too green? Generally it is used quite a bit in furniture, especially kitchen cabinets that are going to be painted.

[cubdad]

I am glad this may be of use to you Derby Dad for 3.

"You said you would not use the poplar again due to dimensional instability. What would you use if you did it again?

I guess maple or oak. However the poplar is still very straight and beautiful. I just later read that it was a wood prone to warping. So I do not have a reason to regret the selection of poplar so far. I just have a reason to worry a little. I'll seal it in a few weeks and then we'll see if I need to redo the framework next year when I pull this out of storage. I guess there was a reason the poplar was 1.19/ft but the oak and maple where over $3/foot.

I still think there should be a way to do this for less than $195 in parts. However the track plating and vinyl are very straight and stable and easy to put together so I guess there is a premium for the convenience.

So far the only change I'd definitely make is that I would make the start pin 46" (instead of 42")above ground to get a 45" drop (there is a one inch loss as the track is one inch above the ground) as this would give me more representative racing speeds.

Thank you so much for sharing all this insight and knowledge. It is greatly, greatly appreciated!! May we impose on you for a question or two during our project if the need arises?

My pleasure. Ask away. I hope I have some good answers.

[cubdad]

Its not pretty but it works.

Beauty is in the eye of the PWD enthusiast!

I've used poplar before for car bodies. It worked really well. Where did it warp on you, maybe it was too green? Generally it is used quite a bit in furniture, especially kitchen cabinets that are going to be painted.

Thanks. It actually hasn't warped. The stock is surprisingly straight and easy to work with. I read somewhere it was more prone to warping than maple or oak.