Hot Rod Frame Tutorial Part 2
Posted 25 March 2011 - 04:26 PM
Now get out your .010 styrene sheet. You need enough to cover the side rails completely…….see the example…these strips are about 30mm by 130mm to fully cover the sides. If you are crafty you can get the sides completely covered with minimal waste.
Now carefully glue the .010 styrene to one side of one of the rails. I coat the side rail with Tamiya Extra thin and then quickly place the rail on the sheet. Let it dry and trim the excess with a NEW SHARP #11 Xacto blade…….use the same process to “sandwich” both of the rails. When you are done it will look like this…..a nice smooth surface and a strong frame rail……NICE!!! Hint: trim ONE side at a time….NOT both….if you do both I will personally guarantee that you will gouge the frame rail……
By now you should be able to see pretty clearly where I am headed with all this fussing, cutting, sanding, gluing and fitting…….
SO….. let’s see how we did on the original measurements……… SPOT ON!!!
Now you need to round off the front of the interior side rails. This is done to give the frame a finished look and blends into the front extension rails cleanly. ……be careful that you radius the side rails in two DIFFERENT directions so the finished rails come out symmetrical……You also need to add the front rails after you measure the length needed. Again, longer engines get longer rails……be sure to account for radiators and the front axle mounts as well. By the way the front rails are just bare .060 X .156 stock….no need to sandwich them as they will be plenty strong as is. Once you have done that you can glue on the front extension rails. Glue them on with a 10mm overlap….EXACTLY the same on both sides…..this is where one of your key cross members will attach…..botch this one and you have a “horizontally ZEED frame” …… NOT GOOD!!!! Note: longer transmissions, like automatics, may need a longer overlap to get the engine / transmission pair to sit correctly in the cowl area.
Mock up the engine to see how it looks…..OK so far…..as you can see the engine you use and the headers….(don’t forget them) will dictate the width of the frame at this point. Everything else needs to accommodate that one element.
Still with me??? OK…now for the rear trim off. I want the rear frame to extend as far into the ’32 as possible so I can rig up a mounting pad so…….I do this….
I keep a slight angle on the end to match the body panel…this may change later……I cut ONE rail and check the fit….if it is OK I do the other……It was pretty much spot on so I ended up with two perfect ends. One more time I checked the engine width and location and fit of the cowl area and I am ready for cross members………the cowl points measure out to 32mm across and the rails are now 2mm thick so my main cross member is 28mm…..I double checked the front extension rail width with the engine and it provides the required clearance……I cut the cross members (three of them) nice and square and 28mm long…….glue them in place and I get this……
I only did two cross members at this point – the transmission main and the upper deck member – this allows me to make adjustments later and maybe even change the rear end and engine combo. If the main member gets in the way I just section it out and build around it. One last check with the frame in the 32 body and……………
Here is a quick shot of what is possible….the frame on this 34 was built using this technique and I hung all the appliances you see on it…..
That’s it for now….you need to hang your own appliances on this thing…..this should give you a good start on your own frame…..just work slowly and keep things square…..and remember the sandwich technique to strengthen the rails.
Regards Bill (Duntov)
Posted 25 March 2011 - 04:36 PM
Posted 26 March 2011 - 07:41 AM
I personally swear by the "sandwich method" for rectangular frame rails. Nothing beats it for strength and appearance! Your explanations and illustrations are superb and should be of enormous help to many of us. In particular the "fit and measure" approach you illustrate so well, so that the results are customised for the actual bodywork and application your are doing, can't be stressed enough. Along those lines, here's a picture of the approach I use to create curved rails that fit exactly to the sides of the body shell. I clamp the side rails and then measure, fit and glue the main crossmembers in place with the clamps still in position.
Thanx again for an excellent and important how-to!
Edited by gbk1, 26 March 2011 - 07:44 AM.
Posted 26 March 2011 - 03:48 PM
Posted 26 March 2011 - 05:53 PM
Posted 31 March 2011 - 03:55 AM
Posted 31 March 2011 - 03:43 PM
I've been planning to try this soon. I have a 29 sedan I want to make into a drag rod . Do you also Z the front?
Rob: I generally do not Z the front rails....I have had good luck working the front axle to provide a reasonable drop....one that would be driveable.... however, you can certainly Z the front.. I would suggest using a mild kick up or perhaps jsut a step up....
Regards Bill (Duntov)
Posted 31 March 2011 - 03:48 PM
Thanks for taking the time for this informative tutorial. It takes all of the guess work out of scratch building a frame. I will put this to good use on an upcoming build. One question though. Is there a particular reason why you don't trim the end of the interior side rail to match the angle of the kickup like you did the rear side rail? I just think it would lend to looking a bit cleaner. Thanks again.
In the past I have left the end of the interior side rail square so I can hang a stabilizer on it for the rear end I use..... however, you can trim it and it will look very clean....to your point....Just do what works for you in this instance...... On a previous version I actually used some half springs from the 41 Willy's kit to spring the rear end and I used the square ends of the frame to anchor those springs with pins and nut bolt washer detail....so again....it's up to you on this one.
Regards Bill (Duntov)
Posted 20 April 2012 - 08:26 AM
Posted 20 April 2012 - 08:36 AM
Very nice job. I will be using your ideas on my next build. Going to try aluminum or brass. Used the r&d unique
chassis for my first build. Started on the front suspension.