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HOW
TO BUILD A STARTING GATE
the basics
This
should help get you started on the right foot if you're thinking
of building a starting gate. If y'all want more detail, let
me know and I'll do my best to get it added to this page.
All of this is from memory, if you want me to double check
this stuff let me know.
I
started off with basically a 3/4/5 ratio triangle (just because
it's easy to calculate) 3 for the upright, 4 on the ground,
and 5 as the face - the face is 3 feet. It's a li'l too steep
in my opinion though. We ended up sinking the back leg a bit
to decrease the angle of the face a tad.
 
I
wanted more than the standard 10 starting slots since I figured
we would like to run at least 12 cars from time to time (it's
already come in handy more than once). So, our gate is 20'
wide with 12 slots. The track narrows down from a li'l over
20' to about 16 or 17 for the front straight. Seems to be
working out well. The slots are on 20" centers and the rods
the car sits on are 7 1/2" outside to outside. This gives
us roughly 8" between the cars (using a 12" wide car, some
are wider than others, but this seems to work really well).
The gate up at Action in OKC is 16' wide and holds 10 cars
(according to my memory), so they must be spaced just a little
bit tighter than ours. I think they have had good results
too.
We
started by making the face of the ramp. Using square tubing,
we fabbed up a 3x20' rectangle and built support throughout.
We then continued on contstructing the main triangle frame
and then laid out all of the slots on another bar. We made
a couple of little jigs out of a spare piece of our square
stock (just drilled a couple of holes in each piece that were
properly spaced to 7" outside to outside) that would
hold the rods the proper distance apart for welding. Once
we had all of the car support rod welded to that bar, we just
laid it on the gate so that it was flush with the top bar
of the triangle* and welded some legs off of the car support
bar coming down and back (these are square to the main bar
that holds the cars up). We drilled these legs (all in the
same place) before welding them up so we could have a place
to put the bolts through that act as the hinge. We then bolted
the stand-offs for the hinge (just some flat strap material)
onto the legs. Holding the main bar down with vice-grip clamps
(the main bar had gotten a li'l U-shaped from all of the welding
on the top of it), we welded the strap to the frame. Since
the rods were sitting on the face of the ramp, we knew we'd
have it in the right spot, and not have to bend the rods to
meet the face properly. Even with the U-shaped main bar being
forced into position, the gate has a very smooth action with
no binding.
I
just received the necessary stuff to make this thing operate
off of a switch this evening. Got some more buiding to do
on it I guess. It oughta be pretty cool once we get it all
wired up and working properly. Right now we use a gate latch
I picked up at home depot, and it works well I just want full
control of the thing. Sometimes the gate operator will trip
it before we're ready to start. I'll hafta get some pics of
how the latch and pull cord are set up, cheap and easy.
 
*I
would also recommend putting a few 1/2-1" stops between
the bar that holds the cars and the one that it butts up against.
It would be easy to do, if you plan on doing it. This thing
will smash a finger if you're not careful. Put the stops so
that they're directly under a few of the "standoffs"
that hold the cars out, that way it will be less likely that
someone might get their fingers on the stops.
UPDATE
1-8-04:
There
has been considerable interest in how we built our gate and
made the electrical drop work. I went to the track today and
took some measurements and got some pictures of the latch
and electric release solenoid.
The
tines are 24" long each and they are spaced 7" on
center, since the tines are 1/2" round bar stock this
means the outside to outside of the tines is 7 1/2".
The 24" of the tines does include the overlap onto the
rear support bar, which is 2", so this means that the
tines protrude 22" from the rear support bar. I'm sure
this length can be adjusted with success, but this setup works
well for us. As you can see in the above pictures, there is
a standoff for each car that holds the cars away from the
rear support bar. This allows the front and rear tires to
hit more simultaneously. The further back the cars sit, the
more in advance the rear tires hit of the front tires. It
probably makes little to no difference, but it is easy to
do. Our standoffs are adjustable to accomodate longer cars
- the Associated Monster GT needs the standoff shortened,
for example (this is the only car that needs it so far).
The
starting slots are spaced on 20" centers. 12 slots on
20' wide gate works out very nicely. There's enough room between
each car that tangling off the gate can be avoided with smart
driving. You could go tighter (I think some tracks' gates
are tighter), but this is a pretty good compromise of space
between cars and overall width of the gate. I *think* that
most gates are 10 slots and 16' wide. With the 20" spacing
a 10 car gate would require 16' 8". I don't remember
feeling particularly cramped on any of the other gates that
I've raced on, so the 16' for 10 cars is probably fine.
I
recently added an electric solenoid to drop the gate from
the race director's booth. It has worked wonderfully and virtually
eliminated the false starts. The gate latches much more positively
and we don't have to worry about getting someone to pull the
gate at the right time. An excellent upgrade. I picked up
the switch at Radio Shack and mounted it in an electrical
box from Home Depot (like the box that houses a typical 110
outlet). The switch is a momentary on, push button style -
I used a red switch for that dramatic "launch the nukes!"
effect. The solenoid came from McMaster Carr (www.mcmaster.com)
and is part number 7723K5, it is the more heavy duty model,
you could likely get away with the weaker model and save a
few bucks.
You
can see on the pics above how we used to release the latch.
It put a side load on the latch itself causing it to bend
and bind. When it was bent it wouldn't allow a solid latching
of the gate in the upright position and when people would
lean on it to pick up cars, sometimes the gate would drop.
With the relatively straight pull of the solenoid, this has
been eliminated. The latch works free and easy.
The
spring on the latch helps to insure a positive catch when
people pull the gate back. It works really well and the solenoid
has no trouble overcoming the spring's tension. Since the
latch isn't mounted vertically like it normally would be,
gravity doesn't automatically close the latch when the gate
is pulled back. This is a simple solution that utilizes toy
car parts!!! (If you must know, it's a Trinity spring for
a Tmaxx) I took an old freebie tuperware thing and made a
rain sheild for the solenoid, the weather probably won't hurt
it, and this won't keep it totally dry, but it will keep the
rain from directly falling onto it.
The
only "problem" I've had with this new release is
someone trying to release it without knowing what they were
doing. The linkage got bent, I guess they just reached under
and started pulling stuff - makes me sad.
Here
are the pics. Sorry for not capturing the whole thing in one
shot, but I didn't want to lay on the ground to get the pics.
UPDATE
5-30-04
If you wire in an electric drop similar to what we have, make
sure to use a good wire and great connections. I ended up
soldering our switch in (also replaced the Radio Shack unit
with a more heavy duty unit- can't remember where I got it
now though). If your USB cable for your AMB scoring system
runs close to the wiring for the gate, you can have trouble
with the lap counting. Keep the wires as far apart from one
another as possible. For added insurance, I purchased some
of that flexible metal conduit stuff and ran our USB cable
through it as well as the wires going to and from the switch
for the gate in another piece of the conduit. Haven't had
a problem since. The problem would occur when we dropped the
gate. Seems the feedback from the solenoid would interrupt
the USB signal and the connection wouldn't become re-established.
It took a number of false starts to determine the problem.
I replaced the wiring for the gate with a heavy duty extension
cord that I cut to fit. I went ahead and used all three wires
and grounded the gate itself with the ground wire of the extension
cord - I don't know if that helped or not, but I figured it
couldn't hurt.
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