2018.09.13, 03:12 PM
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#46
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Join Date: Sep 2002
Location: Washington, DC
Posts: 35,480
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We’re talking the same thing . The other seller, while they work well, are finicky with VE cars. They had two versions at least, maybe three.
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2019.06.08, 11:48 AM
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#47
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Moderator
Join Date: Sep 2002
Location: Washington, DC
Posts: 35,480
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So I've been working on a new bridge for Hobby Works again... Found and bought a PVC U channel this time and that seems to have been an enormous mistake. I've wasted about $15 in paint and 3 weeks time trying to paint the channel only to have the paint strip off with any mask tape every time. I cleaned the plastic, sanded it down, primed, tried various brands of plastic specific paint and nothing wants to stick. I should have just bought an aluminum channel like the 3 others I've built, I could have been done a long time ago had I done so. Now, I've got 1 week left before race day and so frustrated I don't even want to dress it up at all anymore. I'm not desperate enough to use PVC pipe yet but getting close. I think I'll take the loss and just buy an aluminum channel and start over on the paint design.
I also designed new end caps and leg supports to use 1/2" PVC pipe that you can buy in 12" sticks at the hardware store. Basically just bottom plates with pegs that are attached to the rails with standard rail pins and a channel end cap that slots right onto the end of the channel. Kris was kind enough to print some prototypes out for me for test fitting, etc. and will be using them for the time being as I'm interested in making further revisions to the design. For the time being I've simply drilled and cotter pinned the legs so that i can easily disassemble. It would been much cleaner to plastic weld the parts together and will do that with finished parts.
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2019.06.08, 11:57 AM
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#48
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Join Date: Sep 2002
Location: Washington, DC
Posts: 35,480
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Last edited by arch2b; 2019.06.08 at 12:12 PM.
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2019.06.08, 12:08 PM
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#49
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Join Date: Sep 2002
Location: Washington, DC
Posts: 35,480
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The goal is to create an easy and economically cheap build that looks professional. The bridge you an buy with Giro-Z is horrible. I absolutely refuse to build form PVC pipe as it just looks like your not even trying (for retail environment, just fine for home garage/basement bashing). I run out of a retail hobby shop and to a certain extent its my reputation and lesser extent the hobby shop that are on display and I don't like putting forth an image that well, this guy just cobbled together some home depot piping to rig this up.
The bent wire supports built on the previous 3 bridges have worked great and are least intrusive visually however they are very time consuming to make since you can gt 3/4 way done, make a wrong bend and have to start over some times. They are not easily repeatable. I want to work with something that is easily repeatable to make it cheap and easy to build and look the part at the same time.
With this kit of parts so to speak, you can have two channels and swap out to use on 2 tile or 3 tile tracks. Sensors are placed with velcroe at marked locations. Everything would be easily adaptable except for channel height. to do that I would have to design adjustable angle pegs for the leg attachments and that is a bit ahead of my modeling curve at the moment.
Last edited by arch2b; 2019.06.08 at 12:16 PM.
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2019.06.08, 12:25 PM
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#50
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Join Date: Sep 2002
Location: Washington, DC
Posts: 35,480
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I’ll amend to say, I have seen some nice looking PVC pipe bridges when they have been painted or decaled to look the part. One in particular I saw on FB Had the top pipe painted in a checkered line pattern that looked nice, on simple T style leg.
Who knew, you an buy checkered flag duct tape... Never thought to use something like that.
I'll show how I make most of my stencils for painting, more of a poor mans light box than anything else.
I grabbed a left over plastic container with shallow depth and large enough for letter size paper. tape that to the bottom. turn on flash light on a cellphone or tablet facing up and put the box over it.
overlay with mask tape, trace out the design and carefully take up and transfer to your item. use a sharp xacto to trace the pattern and you have templates made from on hand materials.
Last edited by arch2b; 2019.06.08 at 02:02 PM.
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2019.06.08, 06:10 PM
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#51
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Join Date: Sep 2002
Location: Washington, DC
Posts: 35,480
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Thinking about other ways to build this with alternative materials, the channel could likewise be built from a high strength cardboard or foam-board (stuff they build RC boats and planes with). I really should have given more consideration to the channel construction vs. standard plastics or metals. Foam boards have the rigidity needed and come in large sheets for building RC flight vehicles and I'm sure are very easy to paint.
I'm finding I do not like Rustoleum 2X for plastic. It doesn't seem to bond as well as Krylon, nor does it dry as fast. Krylon for plastics are harder to find though as local Walmart doesn't have a good selection, nor does local hardware store.
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2019.06.08, 10:51 PM
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#52
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Registered User
Join Date: Oct 2016
Location: Tri-Cities, WA
Posts: 207
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Thank you for sharing this. I am currently on the same journey. We have a cheesy PVC and wood bridge that is zip-tied together that I made in about 10 minutes the day we got our timing system. We are still using it 3 years later. I designed and 3d printed towers with the intent of creating a scale look. My bridge was made of 3d printed brackets and styrene, and it was a huge failure, so the bridge construction is the biggest challenge for me currently.
Last edited by TPDazzle; 2019.06.09 at 02:50 PM.
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2019.06.09, 10:13 AM
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#53
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Moderator
Join Date: Sep 2002
Location: Washington, DC
Posts: 35,480
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I actually like the stand you design a lot! As a designer, it's pretty cool looking steel construction aesthetic. Pretty tempting to design both stand and bridge component to look like 1:28 scale trestle bridge. I had been designing with simplicity of form vs. scale realism but got me excited to try a bit of modeling to make it scale materials.
Plastic U Channel is nice to work with. Easy to cut, prep and handle but I'm beyond frustrated with finishing it. I put as much effort into the paint work as the construction as it's a work of art to some extent for me, much like painting custom autoscales.
I like aluminum U Channel by default as it's sturdy, good prep makes paint work a sure thing but it's difficult to cut and work with unless you have some basic metal tools. This time I've actually bought another aluminum channel that was less expensive than the plastic which was surprising.
I follow a bunch of crafting RC youtube channels and the things they build with foam board are amazing. I would have tried this long ago but sadly there are no local sources and hesitant to order online only to have it damaged in shipping. I have a bunch of card board boxes from things like TV purchases that are heavy gauge, acceptable finish for paint, etc. and may just have to give that a try for fun.
In the end, I am for something that looks presentable, a fair representation of my efforts and simply works. preferably cost effective and easily replicated as I've done this more than 4 times now and previous methods chosen, while valuable in that they are minimal materials, least intrusive visually, are very difficult to replicate. I've though about laser cut acrylic panels but that's costly unless you have access to a laser cutter which I no longer do. You can do some very nice detailed engraving with laser cutter that could make an outstanding appearance but at great cost and I'm not rich, nor interested in making something that is very costly and not useful to others. Once I get my system down, i'll gladly share the model so others can print. Not that it's terribly difficult to model on ones own, there really isn't much to it other than getting the angle of the pegs correct.
If anyone else has inspirations to share please do so! TPD's towers are very cool.
One other aspect I've been struggling to incorporate is the ability to inset IR blocking screens to the towers. Ideally something as long as the tile and as tall as the tower is most effective in my testing. I've been looking at how to incorporate letter size acrylic sign holders for example as you can buy these online, slip in the IR film and still not cause any visual obstruction. This is jut belts and suspenders overkill really but ensures you don't get any errant signal detection's from adjacent lanes, etc.
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2020.04.09, 01:50 PM
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#54
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Moderator
Join Date: Sep 2002
Location: Washington, DC
Posts: 35,480
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OK, I spent some time on version 2.0. New design in timely.
End caps snap onto channel and have grommet for cabling to pass through.
Legs are left a bit ambiguous for users to make something on their own as 3d printing has real limitations on length of prints. The end caps for the legs are hinged to accommodate user made leg length. The hinge at the bottom connects to rail pin harness. The hinge at the top snaps into the end cap so this can be replaced if needed without replacing the entire end cap.
I plan on using heavy gauge metal wire to bend legs from. Cheap, easy, just need pliers. No real weight to speak of so the legs themselves don’t need to be substantial.
Once the parts are confirmed in prototyping/assembly, I can arrange to have the model file shared. I’d like to make sure it all works as intended prior to sharing.
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2020.04.12, 04:38 PM
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#55
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Registered User
Join Date: Sep 2008
Posts: 1,356
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Ray, I can make you some C-channel out of sheet metal if you want me to. A buddy of mine has a sheet metal break to bend sheet metal. Just tell me the dimensions.
__________________
DG-Designs / Brooklyn Hobbies
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2020.04.12, 04:48 PM
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#56
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Moderator
Join Date: Sep 2002
Location: Washington, DC
Posts: 35,480
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Good to know, never though to use brake metal. Most channels I make are 2x2. For this build, I painted an aluminum channel, same kind as Remnants bridge. The bent metal legs are least intrusive and most challenging as well as the least repeatable which is why I've only made 2. Trying to find the best way for minimal visual distraction but easy to repeat and adjustable if possible. Helps if it's also easily fabricated so I can share the best design. I doubt anyone will take on bending metal wire, even with the dimension drawing.
Now, if somehow a jig could be made to easily repeat the wire leg, that would be nice as well but I'm sure that's a lot less efficient means/methods vs. 3d printing parts.
If by chance you ever want to make a bridge for 3 wide l lane, using brake metal would keep it light weight. then all you have to do is move over the feet and sensors.
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2020.04.14, 08:57 PM
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#57
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Registered User
Join Date: Sep 2008
Posts: 1,356
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I can make heavier legs then what they are made out of now. I would have to braze them to the main C-channel and to some sort of base
__________________
DG-Designs / Brooklyn Hobbies
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2020.04.21, 06:19 PM
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#58
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Registered User
Join Date: Oct 2016
Location: Tri-Cities, WA
Posts: 207
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Okay, so since I have my work modeling computer and 3d printer at home, and a little more time on my hands, I have started working on v2 of a timing bridge with more scale appearance, while maintaining or improving functionality. I am going to try using four 36 inch 1/4 inch aluminum rod as the cross beams and then add the rest with 3d printed parts. The final bridge cross beam will hopefully be wrapped in a mono kote type material used for heat shrink wrapping model airplane wings. This model doesn't show my sensor mounts and few other details, but it is the basic idea. I have started printing parts, but have a ways to go.
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2020.04.22, 09:33 AM
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#59
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Moderator
Join Date: Sep 2002
Location: Washington, DC
Posts: 35,480
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I love the technical nature of the design! How do you print with all the void space?
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2020.04.22, 01:50 PM
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#60
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Registered User
Join Date: Oct 2016
Location: Tri-Cities, WA
Posts: 207
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Quote:
Originally Posted by arch2b
I love the technical nature of the design! How do you print with all the void space?
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The printer slicing software creates temporary supports that are fairly easily broken off. I don't have any photos with the supports in place, but I do have what has been printed so far. The disadvantage is it is a waste of filament, and not necessarily good design for this type of manufacturing process. I teach tech and 3d design to middle schoolers, and I would discourage this kind of thing with my students. The most efficient way of doing it would be to design the pieces so they print flat and then assemble. I am thinking about that, but it is not what I have done. Surprisingly, the triangular vertical supports printed with very little support. Printers can handle a gradual overhang, but not large bridges. The horizontal bracket took 7 hours to print, and used a LOT of support material. I need 3 more, so I am trying to think of a more efficient option.
Ignore the orange color. These will be painted with filling primer, sanded and painted if it all fits together and looks like it will work. I wish I could melt the waste down and reuse it. Such machines exist. But they are very expensive and create subpar filament from what I have read.
This hoizontal structure will have a 36 inch aluminium rod in each corner. This was the one that needed massive printed supports.
Horizontal structure with sensor mount. Clips can slide back and forth to allow sensor positioning.
Vertical support as it was printed. It only had a narrow strip of support material under the middle support pole, and tiny amounts in a few other spots.
Two vertical supports in their assembled position.
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