How to Build a Roll Cage

[afx]

This is the technique I use to build a roll cage.  Not the only way to do it but it works for me.  This gives you the basic structure, you can then add all the cross bars, down bars (kickers) head rest etc. as you desire.  Only variation I usually make is I fabricate the rear kicker bars to lock in the position of the main roll hoop before measuring and fabricating the forward bars above the door and down the "A" pillar to the floor.

 

Edited March 2, 2020 by afx

[afx]

My technique Phase 1:



Phase 2:



 

Edited March 2, 2020 by afx

[afx]

A common mistake I see builders make is using too large a diameter material.  Most cages are 1.5" to 1.75" tubing, a 1/4" difference in scale is very difficult to discern.  I typically use is .062 (1.6mm) solid rod for two reason:

1.    The size in scale splits the difference between 1.5" and 1.75" and therefore can be used nearly universally
2.    Solid rod doesn't kink as easily as hollow tubing when you are creating bends

Edited March 5, 2020 by afx

[afx]

In this example I followed the approach in the Wheeler Dealer video.

[misterNNL]

As a builder that has a real problem making two of anything exactly alike,I seriously doubt I could build one of these cages. Do you use some some of a pattern to make the sides identical? Great work on pieces like the intersecting cross bar in the back. It is arrow straight and all the pieces are perfectly molded in.  Cudos!

Edited March 3, 2020 by misterNNL
Kindle thinks it knows what I need to say

[afx]

Thanks Tom.  No I don't use a pattern, just eyeball it.

[89AKurt]

Ok, I now need to get that styrene rod.  ?  I used aluminum rod, which is delicate to handle after assembly.

[440 Dakota]

looks great are you doing fish mouths or notching the tubes where they intersect with main tubes ?? if so what are you using ? what is your glue of choice ??

[afx]

On 3/3/2020 at 11:47 AM, 440 Dakota said:

looks great are you doing fish mouths or notching the tubes where they intersect with main tubes ?? if so what are you using ? what is your glue of choice ??

Ron, 

• I cut the joint flat then file a v-notch in the end. Sometimes I'll drill and pin the joint as well
• I typically use liquid cement (Testors is my personal favorite) but have also used super glue. 
• I also like to dissolve bits of scrap styrene in Plast-I-weld and brush it on the joint like metal weld.  After it's has setup I file to joint to shape very similar to what you might do in a 1:1 application.
• I create the bends using my fingers or round needle nose pliers - then holding the bend in my fingers heat the joint over a candle flame to set the shape.

Edited March 5, 2020 by afx

[afx]

You can see just the ends of the brass pins (on the backside of the main roll hoop) in this picture.  The bird mouth notches are visible on the ends of the cross bar along the top of the windshield opening.

Edited March 3, 2020 by afx

[440 Dakota]

Awesome thank you, been thinking about this a bit and thinking I might try and build a copy of my Berrien rail, I should try to build a couple cages for practice first

[STYRENE-SURFER]

Great tutorial JC,  ?

Ive been searching for a good set of (non-tapered) round files for making fish mouth joints.

Found this set,(haven't ordered them) the largest one being 1.5mm. or .059" which is pretty close to that Evergreen rod.

Still looking around for a set w/larger diameters.

[afx]

Thanks Kurt.  I use a small triangular profile file and make the birds mouths in a "v" shape.  Those non-tapered rounds files look like they would work well.    

[Hotrod 97]

Excellent tutorial, JC. This will certainly come in handy for some of my upcoming builds.

[CabDriver]

1 hour ago, STYRENE-SURFER said:

Great tutorial JC,  ?

Ive been searching for a good set of (non-tapered) round files for making fish mouth joints.

Found this set,(haven't ordered them) the largest one being 1.5mm. or .059" which is pretty close to that Evergreen rod.

Still looking around for a set w/larger diameters.

I found that set on eBay from one of the Chinese sellers for a dollar shipped, or some ridiculous price like that.  Took 2 months to get here but it did arrive and the quality is pretty good - plenty good enough for fishmouthing styrene rod!  
 

The red handled one is my most used one by far, but I’m sure I’ll find a use for all of them eventually ??

[MeatMan]

On 3/3/2020 at 8:38 AM, misterNNL said:

As a builder that has a real problem making two of anything exactly alike,I seriously doubt I could build one of these cages. Do you use some some of a pattern to make the sides identical? Great work on pieces like the intersecting cross bar in the back. It is arrow straight and all the pieces are perfectly molded in.  Cudos!

Ditto! I have difficulty tryna match the bend point from piece to piece but I'll give this a try.

[afx]

Glad you guys find this information useful.  It takes a little practice and I still screw up from time-to-time but getting a custom fit roll cage is worth the effort to me.

[swede70]

Just short notes consistent with suggestion minor alternate directions, with the appropriate technique being that which for any potential builder discovers best...

Not absolutely necessary this, but a spare body and chassis to establish the tightest fit with the dash and plastic 'glass' installed helps a lot.  I realize this isn't an option for all and that resources can sharply restrain ambitions in this regard - but it helps!  A good supply of file cards and scissors to come up with initial shapes is advised - sort of what 1:1 fabricators would call CAD, or rather Cardboard Aided Design.  Sometimes too I'll take fuzzy pipe cleaners to establish the rudiments of what will be required for multiple bends and angles I'll need to reproduce.

If something is a scale replica of a period racer, definitely pile on the research.  Some problems will 'go away' for careful analysis of why this team or that opted to do things in a particular fashion.  This said, plastic model cars have thick floors and thick roofs, and this reality will impact how much carries over.  

Concerning materials, I don't use rod plastic, but rather employ plastic tube with a brass wire core inserted and glued within.  Tubing collapse isn't a terrible problem if the wire chosen is appropriately sized, while sharp bends won't strictly disturb the shape of material both 'upstream' and 'downstream' of the bend.   Ideally, the brass wire will be stiff enough to resist distortion along the lengths of material you'll wish to keep straight.  Moving along, sometimes a brass 'core' can be used to site a particularly tough bar relative to another; i.e. drill a discreet hole in one, and factor in the reality that the brass core may have to be a bit longer to plug into it from the tube to be attached to it after properly filing and preparing a fishmouth contour or contours as required.  

As for bending, I have a small bread board that has a nail tapped into it; i.e. a mandrel bend in miniature.  If a softer or rounder bend is called for, on occasion I may press some plastic rod into service in keeping with replicating the radius desired.  Just to be consistent, even the tiniest bars will have a brass core on my efforts.  Happily none of my scale drivers has thus far been hurt...

For the use of a pointed tip Sharpie marker, I'll try to ink mark where the bend has to begin.  It's an approximate process given it's all too easy to place a bend too high or low, while the angle and factoring in having extra material to trim to size both 'upstream' and 'downstream' again is important.   With regards to matters related to symmetry and the battle to secure this quality, I always endeavor to do bars in matching pairs.  Go in expecting to waste a fair amount of material for misjudging much; i.e. it's too short, it's too tall, it's asymmetrical, etc.  When something is 91% of what you need but doubts linger, part of the satisfaction of scratch building is knowing that you can toss matters aside and start again without suffering huge guilt.  I pretty much expect to fabricate each bar twice or three times over, while if I'm any better or more accurate, personally surprise is registered.

Alignment of materials as they attach and as the glue sets can be a challenge, with the creation of a rudimentary fixture to hold this or that bar 'just so' sometimes required. Although basic, stacked audio cassette boxes and small scrap sheets of plastic with quickly made extensions of rectangular stock can serve very well, stabilized for the use of a discreet length of two of Tamiya tape holding everything securely to the table the total setup rests upon.  Do allow things to properly setup and dry.  No need then to court bitterness for trying to achieve too much, too soon. 

Concerning glue, again - nothing set in stone, but I like thick CA glue and typically touch in bends with additional applications combined with a dusting of a filler known as MicroBalloons. Residue removal and final shaping follows this.   Your mileage may vary.  Tax, title and license extra!  

Mike K./Swede70

Edited March 12, 2020 by swede70

[afx]

Thanks for you comments and tips Mike. 

[STYRENE-SURFER]

Great information being shared here.

One thing I have tried is using soft jewelry wire to mock up and get the fit inside the body. 

This is cheap stuff from Hobby Lobby or Michael's that I have cut into short lengths and 

rolled/straitened out between two kitchen cutting boards. 

After trial attempts you can get a handle on final hight ,width, Etc.

Then use as patterns for bending your styrene rod or tube.

You may still end up w/a pile of bent rejects. LOL

 

 

Mike K.

Try using milliput for fixing joints. less messy than micro balloons and can be smoothed out perfectly with some H2O.

Edited March 12, 2020 by STYRENE-SURFER
blah blah

[swede70]

Thanks - I'll explore the possibilities suggested.  I could be saving work thus from the impressions gleaned here.

Mike K./Swede70

 

Edited March 12, 2020 by swede70

[CabDriver]

On 3/11/2020 at 7:38 PM, swede70 said:

Sometimes too I'll take fuzzy pipe cleaners to establish the rudiments of what will be required for multiple bends and angles I'll need to reproduce.

I saw some of those fuzzy pipe cleaners at Target the other day and was trying to figure out a good modeling use for them...guess I found it!  Good tip Mike!  

[alan barton]

Firstly, thanks to everyone, JC and Mike in particular, for some great ideas here.

I build a lot of racecars and scratchbuilt rollcages just go with the territory.  One idea I gleaned from another site many years ago was to determine where the cage is going to touch the floor of your car and then drill four  holes at those locations to match the size of the Evergreen 222 ( my favourite as well!).  You then start construction by first inserting oversize lengths of styrene through those holes. As you cage takes shape, you can pop the body onto the chassis and push the cage structure up as tight as it will go into the roof, then put drops of glue at the floor junction.  When it's all nice and dry, snip off the excess lengths below the floor, sand and paint!

This technique gives you a solid foundation to work - it is as if the floor is your jig!  It also guarantees that you won't finish up with the dreaded "rollcage half way through the driver's window" look. It makes me groan every time I see a model where this has happened.

Edited April 22, 2020 by alan barton
thought of extra words to say!

[Tom Geiger]

I pretty much drill and pin everything! This photo is of a kit roll cage I had to cut down and reconfigure to fit in a smaller and lower car. 

I use straight pins for strength, they cut easily with standard wire cutters. 

[935k3]

Great work and technique JC. I have found Plastruct better for bending, it does not beak as easily as Evergreen. Pinning really ads strength I use .020 " diameter brass wire from K&S