Hot Rod Frame Tutorial Part 1

[Duntov]

This "partial" tutorial will hopefully give you some ideas on how to build a simple, cheap and effective street rod frame from styrene scratch materials. There are a few absolute requirements you will need to fill here prior to starting….otherwise anything you do will be pretty much for practice. The tools needed will be a SHARP #11 Xacto knife, sanding stick, various styrene glue (Tenax, Tamiya Extra Thin, gap filling ACC), a new razor blade, machinist square and the major vehicle components. The three most important vehicle components will be the body you plan to use, your engine choice and at a minimum the rear end. The body will determine the length and width of the interior side rails, the engine will dictate the length and width of the front extension rails and the rear end will dictate the "K-brace" or kick-up rail angle and length. If any of these are out of whack then you will have a nice pile of styrene scrap. That out of the way….let's get started. Take a look at the drawing below and the terminology used.

You will be building two frame rails like this with a slight variation. Each completed side rail will be comprised of six pieces of styrene. One front rail extension, one interior side rail, one kick-up, one rear side rail and TWO .010 styrene veneer sheets to tie the three rear pieces together seamlessly.

First take a look at the materials you will need. Two types of styrene are needed. I use .060 X .156 strips for the various frame components. Use larger dimension stock for heavier cars and trucks or different scales. You can vary this by width and depth to suit your needs but be aware that all of the frame components EXCEPT the front rail extension will be .020 wider when you are done. You'll see why shortly…..

Next take a look at the components that will dictate the critical measurements. Body, engine and rear end. You can pretty much wing it with regard to the front axle when you get there….but these items are critical. Here the engine choice is the old AMT Buick nail head and the custom rear end from the new '72 olds Cutlass Supreme kit. You can see that the springs on the rear end will dictate how the cross members will be built and placed. Also the depth (height) of the kick-up gets defined here as well….but then again the higher / longer the kick-up rail is the lower the car is going to be. Keep that in mind….it's your choice.

Your first step will be to measure and cut to length the interior side rail. This is cut from the .060 X .156 strip. In this instance I measured from the front of the cowl on the '32 sedan to the beginning of the rear fender well ridge. It comes out to 55mm. Cut two of these "exactly" and keep the end "SQUARE"!!!

Now cut four more 55mm pieces just as you did before. These will form the rear side rails and the front extension rails. They will be too long but that is not an issue. You can always trim them back to the correct length. Make them too short and you will be filling up your scrap box. (Note: if you are building something with an absurdly long rear end or very long engine you may actually want to make the front and rear rails longer…..I'm sure you get the idea…) Any way now you know why there are six pieces in the picture!!!

Next is the touchy part. You need to determine the angle and length of the kick-up. Remember, this dictates how low the car will sit in the back and sets the overall tone for how low this beast will really be so you need to go slowly here and get it right. Unfortunately, you will have to "eye-ball" the work at this point but you can still be pretty exact and get good results. I am using some old Aluma Coupe rolling stock here (or some other similar variant) and I want the axle point (center hub of the rear wheel) to sit just above the "bottom" of the door line. Now follow this closely……The length of the spring on the rear end is 7mm so that is how far the "bottom" of the rear side rail must be from the "top" of the interior side rail…..now we are getting closer to the needed kick-up dimensions.

Now we can lay out the rails for the first time…… lay one interior side rail down with a rear side rail….you guessed it…. 7mm apart…..roughly end to end…..AND PARALELL!!!!!!!!!!!!!

It's now a simple matter of laying the kick-up in place, marking it carefully and cutting it correctly. Lay some scrap .060 X .156 stock on the pieces as shown…..I use tape to hold the rails square and parallel to one another (VERY IMPORTANT!!!!)

Now cut the kick-up (keep the ends nice and flat) and you can mock up your first side rail…..if you cut the kick-up correctly it will slip right into place between the rails…….now make the other side…..hint…..leave the rails taped in place and just repeat the process….that way you get two near identical if not exact pieces for the kick-up (Again – VERY IMPORTANT!!!)…..

Now tack the two assemblies together with Tennax (or similar) and allow it to dry…..if you did it right the kick-up piece will slip right into place and the frame rail will look like this..............

Once the pieces are tack glued together I use the grid marks on my cutting matt to make sure they are parallel. I adjust accordingly and SPARINGLY apply a bit of gap filling ACC to one side to set them permanently. Once dry I carefully sand the surface flat and repeat the process on the other side…..Next, CAREFULLY trim the top right corner of the rear side rail in line with the kick-up…..you may leave this in place depending on what your interior needs are……your side rails should now look like this…..

That's it for part 1....see the next post for the rest.....

Here is the link to part 2

http://www.modelcars...showtopic=42483

Regards Bill (Duntov)

Edited March 26, 2011 by Duntov

[Dr. Cranky]

Love it, excellent tutorial so far. On to part 2. Thanks for doing this.

[Danno]

Good stuff!

Thanks.

[Mooneyzs]

Nice tutorial so far

[LDO]

You use Metric measurements???

(actually I do too, at work. I do not like adding fractions. I'm a plumber and when gluing up PVC pipe, it's a lot easier to add 3 whole numbers than adding fractions. A millimeter in smaller than my tape measure's smallest increment; 1/16th, so I'll never have to split a millimeter. Yes, my coworkers think it's weird)

[Duntov]

You use Metric measurements???

(actually I do too, at work. I do not like adding fractions. I'm a plumber and when gluing up PVC pipe, it's a lot easier to add 3 whole numbers than adding fractions. A millimeter in smaller than my tape measure's smallest increment; 1/16th, so I'll never have to split a millimeter. Yes, my coworkers think it's weird)

I sure do...especially for scratch building.....easy units to use and it is rare tht I have to use a smaller increment (your point about splitting a MM!!!) ....the conversions are pretty easy too..... It's actualy an old model railroad habit that I picked up many years ago..... works rally well in S scale narrow gauge which is now my primary ralroad scale.......

Laer

Bill

[cruz]

Very cool tutorial, thanks for sharing!!!!

[JTalmage]

Bumping this so I can find it easier later when I get home...

[Duntov]

This is the link to part 2---

http://www.modelcarsmag.com/forums/index.php?showtopic=42483