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 Tip for building roll bars, roll cages. by Brent

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Zbuckster
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PostSubject: Tip for building roll bars, roll cages. by Brent   Mon 25 Feb 2013, 8:22 pm

Title
Building Roll Bars

Author
Brent

Original draft created Friday, April 11, 2003

So you want to build some roll bars

How cool is that! It’s a great way to personalize and or customize your kit! I’ll do my best to give you some ideas and get you started. And that is what this is intended to do “Get you started” You will come up with your own tricks and ideas as you build. Now lets get to some building!

Tools of the trade

Various files, Hobby knife, Solvent glue, Calipers, Wood Square (not shown), Piece of wood, some nails, and a hammer. And all the styrene you can get your hands on (You will find uses for it trust me)



What styrene size do I use?

To scale down the bar roll size of a real car or truck simply take the real bar size and divide by 24 or 25 depending on if it is a 1/24th scale or 1/25th scale kit I will use 1 5/8” as an example so 1 5/8” or 1.625” divided by 25 = .065 You need .065 styrene. Or .060 close enough! But how do I know what 1 5/8 is as a decimal? Simply take 5 and divide it by 8 and you have the decimal for 5/8. Add your 1 in front and you have 1.625. Works that same with any fraction!

Getting started

First off I made a little bending jig. It's as simple as drilling relief holes and hammering two nails in a board. The smaller the nail the tighter of bend radius you will get etc. This also helps to get bends like on a roll bar perfectly flat so one leg doesn't stick up. When you drill the holes (Better get a scrape piece as drilling through your table might get you in some hot water) drill some far apart and some as close as you can together. Also drill some on the edge of the wood and some right in the middle. The reason on the edge is you might be doing some complex bends and need the bar to drop off the side of the wood so it doesn’t interfere with another bend. The holes in the center make a nice large area to keep everything nice and flat. Also you can make pen marks on the wood for a 90-degree bend or a 45-degree bend so it is easy to see. Make lots of reference marks as usually the hardest part of scratch building roll bars is getting both sides the same.

This picture shows how you could work off the end of the board. (Holes can be much closer to the edge) For this particular bend I should be working in the middle of the board, as I want both bends to be flat and parallel.



Hints on bending styrene

Solid styrene seems to want to break when trying to do a full 90 degree bend so a little heat helps it a long. But just a little! Hollow tubing seems to be more forgiving and all you need to do is over bend it a bit and it should hold its shape. If it doesn't again just give it a little heat with a candle or lighter and it will soften the plastic. When it hardens it's solid and ridged. Some trial and error here!!

Carpenters Square is your best friend!

A carpenter’s square is a must! You can use it to check your angles and also use the adjustable end to check length from one side to the other and trim as necessary.

Here I am checking both square and length on my bar.



Here I am using the adjustable ruler to lay out my next bend to the bar. Also notice how nice and equal the bends are. The radius's are the same, my angles are good. This is what we are after!



After laying out my bends (That are directly across from each other) I use the ruler and the edge of a table (Or your jig) to line up the marks . This ensures the bar stays flat (Is under the ruler) and that the bends will be in the same place. Now all I have to worry about is the angle of the bends nothing else!



And this is what we have:





Now what about test fitting?

Test fit, test fit, test fit. And if I have to say it again I will, test fit! There that should be drilled in about now. This is part of the game! I often will start a bend and stop and see how the bend is going. Am I too high with the radius? Am I bending in the right direction? It is easy to tweak the bend as we bend it. It isn’t so easy once you have completed the bend. Minor tweaks can be done!

Also what is very important is thinking ahead. For this Jeep I wont be using the top but if I was this should be thought about before I start.

Oh and I have two jeeps here. One I have build many many years ago and the other I am doing now. This made it really easy for me as I used the already build jeep to test all my fits and later I will build the new jeep and assemble it all. For your project you will need to do some building first depending on the project. A simple roll bar in the back of a truck you won’t have any clearance problems so no worry. But in a racecar you will have to make sure you don’t put a roll bar in the way of a seat etc.




How do you measure and what glue should I use?

For measuring I have a set of calipers. A simple plastic set will work. If they lock into position with a setscrew better yet! These come in real handy for measuring lengths on the subject it’s self.




For glue I use a solvent glue that uses capillary action and seeps into the joint . It is thin like water and you use a paintbrush to apply it ,dip it into the glue and touch it on the joint. Hold, and if you used just a little it dries very quickly. Maybe not as quick as Supper Glue but way faster than traditional glue. And if need be the joint can be gently pried apart. Unlike Supper Glue!


The rest of the roll bar

Now with what we have learned so far we can carry on with the rest of the roll bar.

After measuring the roof bar I cut the pieces and glued them into place.


Then made the back roll bar and glued it into place and also designed and made the door bars. Back to the jig!





We keep plugging away using reference pictures (the Internet or magazines are great) or designs from our head.

One thing I would like to add is use a flat surface when possible to make sure everything is flat and square. But most importantly does it look right. Sometime a perfect parallel bar might look better with a slight angle to it to give the bar some shape and not just be a square box. I feel at this point my roll bar is looking a bit squarish so I will add some more bars to give it a better look to it.

Here I have flipped the bar on its roof to use the flat surface to make sure the roof bars are all flat. You can see I have one bar slightly higher than the rest. An easy fix!



I often use the bars as a reference to each other to make sure I don’t have any bars that aren’t square to each other.




And now a bar for the spare tire.



A “J” bar and a removable knock off to hold the spare tire in place




Tire in place. I forgot to put the knock off on !!



AH now we are getting somewhere

So hopefully you get the idea. You can use these methods to build all sorts of things like Bumpers, Nerf bars even Exhaust.







Here you can see the completed Roll Bar, Nerf Bars on the side and front Shock Mounts off of the frame. All built using the method I have shown you.



Here is the jeep completed.








This is my very first project using styrene making rollbars.





And here is one of the most complex builds I have done so far (Still in progress)


The possibilities are endless!!!


I hope this has given you some ideas to get you started.

Happy building and good luck with your next project!!
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Johnag
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PostSubject: Re: Tip for building roll bars, roll cages. by Brent   Wed 12 Feb 2014, 6:37 pm

Hi Mr Z,

I hope you don't mind me bringing this one from the past, but, may I ask, when you are building a complete chassis, did you have to make a jig first to hold the complete floor section (hope that makes sense)...

Many thanks...

Andy...
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PostSubject: Re: Tip for building roll bars, roll cages. by Brent   Wed 12 Feb 2014, 8:06 pm

Things are always more accurate if you have some type of jig or holding fixture to keep everything in place until it is strong enough to man handle. Hope this helps.
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