View Full Version : Giro-Z Bridge

2012.04.15, 09:22 AM
i've ordered Giro-Z to replace our Core system and have begun building a new bridge for the system and thought i would share the process in case anyone else was looking for ideas.

i've owner Giro-Z in the past, when they first released to be exact, and lets just say the pre-manufactured bridge is not worth the cost, space it takes up, etc. nearly everyone gets a couple dollars worth of PVC pipe, elbows and T's to make a very simple, functional bridge but being an designer, i would never be satisfied with that so i began planning for a custom build with off the shelf parts that requires a bit of elbow work, patience, and determination. it's not the easy route for sure but i'm going to be far happier with the outcome. it also gave me an excuse to buy some more tools. you can never have enough tools.

2x2x36 aluminum channel (aluminum is cheaper than PVC) $19.32
1/8x36 steel rod $1.25+/- each
rustoleum protective enamel paint and clear coat $3.98
tamiya mask tape $3.00+/-
1x1/2x doube line clamp and 3/16 fasteners (have not found the fastener i want yet) $5.00+/- box of 50
M4x16 cap head screws $.80 each pair
nylon washers $.56 bag of 4
black cable ties $4.54 bag of 100
1/8 ferrules $1.48 each pair
m4 hex nut $.80 bag of 10
25' cat5e shielded patch cable $12.64

clamping bench vise $21.00+/-
wire bending jig $11.02
locking pliers $4.00+/-
adjustable wrench (already had this one)
linemans pliers $9.97
plastic bag from store $.5 each (yes, maryland charges you for bags)


i'm new to complex wire bending and my tools are limited so i've been using the wire bending jig and adjustable wrench up until yesterday when i picked up the bench vise and locking pliers. having already bent 2 prototype legs, i have a better understanding of the limitations of the tools.

2012.04.15, 09:24 AM
i've sketched out a bunch of ideas on lunch breaks at work so most are on post it notes.




the exception was a 3d modeled mock up


eventually, when i can secure access to milling i would prefer to have solid plastic legs made with integrated wire molds to secure the patch cable. simple top bolt would be nice vs. worrying about creating a snap fitting that would weaken over time. i want the legs to be removable. i have been designing the base to connect to the rails in some fashion vs. the floor. while using wire doesn't present an issue for space, plastic would. i don't want anything squeezing between tiles.


recessing the nut on the bottom makes it easier to thread the bolt without having the worry about aligning the nut and dropping it.


2012.04.15, 09:35 AM
i wanted to personalize the bridge simply because i can :p printed out some text patterns and picked one.


applied the mask tape to the surface where the lettering is to go. i framed the entire channel with a border using parma line tape.


triming the lettering is tricky on aluminum. the guys that do this over car skins have some amazing skills. i kept cutting into the surface to make sure the tape was cut cleanly.


i also added a bit of flair with the MZR anniversary logo.


the lettering masking turned out well enough for my first attempt on this surface.



2012.04.15, 09:41 AM
i gave the channel 3 coats of the protective enamel paint. the respray time and dry time is much longer with this paint than what i'm used to so the paint build up made it more tricky/delicate in removing the mask.



some of the edging pulled up as the paint was thicker than what i deal with for autoscales.



i got a bit antsy with the clear coats and did them after work, whic for me has been 8-9pm lately. i couldn't see the paint go on very well in the poor light so i got some overspray and drip spots. i will likely give it another coat to clean it all up later.



2012.04.15, 09:49 AM
my first bent wire leg was very basic. i wanted to know how hard it would be to bend circle base and symmetric sides while going from point to point. turns out i made it to tall and the left end doesn't have a complete circle.


my second bent wire leg added more features. this one has the turn in at the top for the double line clamp. the intent is to provide 2 horizontal surfaces in the leg to batter fight the tendency to sway side to side with this type of leg. i don't have the clamps yet, i had to order them from mcmaster-carr so dimensions used on this were just a guess. i gut the height by 4" so i now have enough length in the wire to get all the bends in. this sets the channel at 14" above the track.


i'm still working on better ways to bend eyelets in 1/8 wire. pliers and the cheap jig are not doing the job to my satisfaction.


2012.04.15, 09:52 AM
i mocked it up this morning and will need to adjust direction of the clamping area so the attaching fastener doesn't go right through the logo. in hindsight, i should have kept that a couple inches off the edge but wasn't thinking that far ahead at the time.


2012.04.15, 10:37 AM
nice work on the U section , did you have to use an etch primmer on the ally ,do you have acsess to a welder or brazing equipment ? Im thinking an L shaped plate on the bottom of the legs welded on , this would spreed the weight of the gantry making it less prone tp rock and also give you a better mounting method than the loops
Just an idea great work so far

2012.04.15, 10:59 AM
i sanded the u channel faces with fine grit paper before painting for a clean surface. there is rustoleum primer for metal surfaces but i started painting before i found that stuff so it's multiple thin coats with clear coat. i would recommend using the primer when it's available.

love the idea. would really like to add some triangular supports to brace the gantry but i don't have access to welding equipment nor experience with anything other than soldering. right now i'm limited to mechanical means but these are typically bulky looking. if i could weld/braze, i could use 1/2x1/2 angle to make the legs with 2x2 angle for the base mounts.

2012.04.15, 10:26 PM
nice work arch...
just a suggestion... instead of having the legs bent towards the track, why not have them bent outwards (towards the outer edge)...

2012.04.16, 09:06 AM
If the concern is hitting them, the design puts them 1/4 min inboard of the face of the rail. I'm still working on the final layout based on what I can fabricate vs. what I can design.

2012.04.16, 01:03 PM
Nice job ray.

2012.04.19, 11:39 AM
here are the latest wire leg drawings with the clamps included. FULL (http://mini-zracer.com/mini-zgallery/data/960/Timing_System_Bridge_Model_1_.jpg) size here in case anyone wants it.

2012.04.19, 11:52 AM
the bridge you made looks fantastic. Love the logos you added to it as well.

2012.04.21, 12:10 PM
had some time this morning so i did another test leg. the bends are so much easier with the bench vise. also allows me to plumb it all back up as well.

here you can see the bend which will anchor to the bridge. got the turns just right and fits the clamp like a glove.


i need to make yet another trip to the hardware store for some black zip ties, more metal rod (home depot rod is shorter than lowes), double sided tape (didn't come with the giro-z kit) and some type of non permanent glue to hold the wires to the channel. someone recomemended pvc pipe glue but that seems a bit to permanent. i just want the wires to be held in place but removable if i need to take the sensors back out. also need to pick up a much longer patch cable. the giro-z kit came with a 3' cable. i', thinking something like a 14' or 20' cable just so i'm not hampered by bridge location. the track pc can't move, it is where it is.is there anything special about the cable? says stp patch cord cat6.e

2012.04.21, 03:12 PM
ok, tried working with what i have meaning making an adapter piece. took a rod and bent it into a support base that wraps the pins and bends up to meet the top leg i made. this would have to be joined with more clamps or welded together. i don't weld so i'd have to find more clamps.



tricky part is making a duplicate...

Daddy Rabbit
2012.04.21, 04:50 PM
If the concern is hitting them, the design puts them 1/4 min inboard of the face of the rail. I'm still working on the final layout based on what I can fabricate vs. what I can design.

Great looking job

2012.04.21, 06:52 PM
left the store with another $30 is stuff. i can never seem to leave the hardware store spending less than $30. picked up some crimp clamps to keep the wire legs together. i don't have a crimp tool but the bench vise should do nicely. the rest was cap screws, washers, nuts, wire cutting pliers. couldn't seem to find double sided tape at this store so have to hit another tomorrow.

2012.04.21, 07:32 PM
got the half the legs crimped with a hammer. turns out i am 1 bag short of the crimps. :rolleyes: so, 1 more tip again tomorrow....



2012.04.21, 07:36 PM
i should have done this long ago but recommended sensor height above the track is 12-14" correct? turns out the bottom leg supports put my sensors at about 17" above the track. is this ok or do i need to crack the crimps off and shorten the top legs to get back down to about 14"?

2012.04.22, 09:04 AM
no one.... it may be worth noting that the channel leg is 2" and will have side closure panels.

made side panels this morning out of autoscale plastic. one will hold the rj45 board. already painting them. i'll glue these to the metal legs when they are attached to the channel with goo so it's somewhat flexible.



2012.04.22, 09:11 AM
have you thought off plastic trunking ? (uk its egatube yt1 or yt2 used for running electrical cables in) come with sticky tape on the back then just cut the lid to length where the sensors will be then if you want to remove them just pull the lid off

2012.04.22, 09:28 AM
some of that stuff is rather bulky. it's cable raceway here. i can get some 1/2"x3/4" self adhesive stuff. it's something i will keep in mind to get it to the button up look i prefer.

2012.04.22, 11:53 AM
We have a bridge that puts the sensors 18" up, and one that puts them about 12" off the track. The only problem with the taller one is that it is more likely to detect a car in the adjacent lane. You have to be careful with the short bridge as well, but it just doesn't quite have the range of the tall one.

2012.04.22, 11:55 AM
bought 1 set of crimp clamps and the tape. finished the other leg but don't want to paint anything till i confirm the bridge height as i might have to break it apart to modify it.

the finished dimension to the sensor pick ups is closer to 17.5", see this (http://mini-zracer.com/mini-zgallery/data/960/1201.JPG) full size picture. i really need to know if this is ok or if i need to lower it.

also covered the exposed side of the sensor plug in bar just so it's all consistently black.

2012.04.22, 12:02 PM
By the looks of it, I would probably shorten it by 6" or so. It would be a shame to have to make side plates to block the adjacent lanes when you have basically an unobstructed view through the small legs.

2012.04.22, 12:22 PM
thanks, i was afraid of that but anticipating it as well. oh well, i'll have to go back and get 8 more crimp clamps.

i think i'll take the sensors down to 14"+/- as i don't want to go to close to 12" and don't want to go over 15".

2012.04.22, 12:59 PM
R. If the sensors are mounted well up inside the cross bridge there is little liklihood of a ghost signal from an adjoining lane at that height but with just a bit of tweaking you could mount the legs under the RCP and lower everything about two inches.

2012.04.22, 01:36 PM
the pick up sensor is taped to the channel so it's as tight as it's going to get. the leg on the channel is 2" each end will have caps as well.


yep, with 2 added bends i can get the base to sit on the floor and lip under the rail to bend back over the rail and up to the bridge. quick measurement shows that will drop it to 16"

i think i'll try it like it is and if it causes any issues, break the ferrules, trim the legs and re-crimp them to get down to 14".

2012.04.22, 01:48 PM
ordered a 25' cable so this should allow us to put the bridge just about anywhere at hobby works. i picked red so i could write on it and make it noticeable as well. i would have preferred black but i don't want people tripping on it and want to mark it clearly as club property.

Mike Keely
2012.04.22, 07:57 PM
Very nice work Ray. Where did you get the wire bending jig?

2012.04.22, 09:07 PM
cheap on amazon. i think it was $11 or less shipped if you have a prime account. it's useful but once i got the bench vise, i use that more. 1/8" wire is about the upper limit for the jig so it's not easy working with 1/8" wire. and to think i was going to go with 1/4"... i'd need a mighty wire bender for that one and those run about $20 something.

i edited the first post with costs for materials

2012.04.28, 04:00 PM
Brilliant work R! :D Where did you get the height values from? I'll see if I can measure ours for you if you like! :)

2012.04.28, 05:01 PM
various suggestions.... nothing on trp website other than pick up sensor spacing, 10.25" btw. i will likely build a new set of stands once i get the bug to fix the height issue. just not motivated to do them all over again just yet. let me know what you set your bridge height at.

finished painting/clear coating the legs over the week. had to add another clear coat to the channel due to drilling out the double line clamp screw holes. the clear coat delaminated from the base coat as the bit punctured the surface which looked horrible. so, i need to wait another 48 hours for that to cure. it's all just a matter of assembly and testing now. all the fabrication has been completed. :)



2012.04.28, 07:44 PM
made this little bracket to hold the extra sensor wire. i can wind it around and it will stay attached to the board.


2012.04.29, 11:41 AM
i glued on the end panels today.





as soon as the glue sets i'll take the leg with the connector back off and finish off the connections and winding of the excess wires. i'll also add some wire ties to the wiring end cap in case the glue fails or someone knocks it just to keep the panel from falling off.

2012.05.04, 01:53 PM
ran some tests over the last couple days.
current height 16"
pick up zone is approximately 18"x48". this means it picks up within 5" of either side and the full depth of the tile it's installed over. i need to shave 2 minimum, 4" preferred off the left/right to avoid miscounts on adjacent lanes.

adjusted height 14.25", no change to stand
pick up zone is approximately 16"x44". this means it no longer picks up cars against the rail in an adjacent lane. it shaves 1" off either side of the depth of the tile.

as is, it will work by placing the stand base on the floor vs. attaching to rails as designed. in order to function optimally and install as designed, i will need to modify the existing or remake the top portion of wire bend. i'm confident i can shave it down to 14" just by putting more bends in the stand to correct for the track width at the stand base. it's not optimal but possible.

2012.08.05, 11:14 AM
anyone local (metro dc area) weld aluminum? looking to make 1/2"x1/2"x1/8" aluminum angle support legs but need to weld the joints at bends and ends to ensure durability and stability. i want it to be rock solid.

2012.09.23, 03:40 PM
i've replaced the bridge stands with new ones in the design i had originally intended. the bridge height has been lowered to 13" to the bottom of the channel/15" to the top of the channel. the tested pick up zone has been reduced to approximately 15"x36". this means it's impossible to pick up traffic in an adjacent lane. the sensor spacing has been reduced from 10.25" to 9.5" as well.

if your wondering what the paper is for, i plotted a full size portion of track to track pick up zone info so i can fold it up and put it back in my bench for reference latter if needed. can't right on the track so this works well.


2015.05.29, 11:44 AM
Ray, that looks beautiful, awesome.

Mike Keely
2015.05.29, 03:57 PM
anyone local (metro dc area) weld aluminum? looking to make 1/2"x1/2"x1/8" aluminum angle support legs but need to weld the joints at bends and ends to ensure durability and stability. i want it to be rock solid.

I can get it welded for you. Next time I see you I can pick it up and get it back to you.