Stretched frame question

[BobS71]

Hi everyone. New to this forum. This will be my first build in like 40 years.

I am planning on building my version of a truck that my father used at one time in his sign shop.

I will be using either a AMT Autocar or an AMT Diamond Reo, unless I can find a Diamond T.

I need some help with one issue- I need to stretch the frame so that it measures approx. 24feet from the back of the cab to the

end of the frame. I have no clue how to do this and keep the scale the same.(1\25)

Anyone with a quick and easy method on doing this I would appreciate the help.

Bob

 

[Warren D]

You could get a resin conversion kit for the Diamond T at aITM:  http://aitruckmodels.com/product-category/conversionkits/diamond-t/

The scale length would be 24/25 feet.  Take that number and multiply by 12 to get the measurement in inches.  Works out to about 11 1/2".  You'll need a second frame to donate a section to make up the difference.  I usually cut the frame behind the cab and then graft in the length needed.  You could also find a donor frame from a different kit or aftermarket.  Inside the C channel I usually put a short section of sheet stock cut to size to act as a bridge across the joint.  I also do my cuts using a hobby-sized miter box to make sure they are square. 

Edited August 16, 2018 by Warren D

[clayton]

As you get more into modeling and scaling I use scale app called scale calculator. Or use contractors calculator from wall Mart, it the yellow one in hardware. 

[clayton]

On 8/15/2018 at 8:21 PM, Warren D said:

You could get a resin conversion kit for the Diamond T at aITM:  http://aitruckmodels.com/product-category/conversionkits/diamond-t/

The scale length would be 24/25 feet.  Take that number and multiply by 12 to get the measurement in inches.  Works out to about 11 1/2".  You'll need a second frame to donate a section to make up the difference.  I usually cut the frame behind the cab and then graft in the length needed.  You could also find a donor frame from a different kit or aftermarket.  Inside the C channel I usually put a short section of sheet stock cut to size to act as a bridge across the joint.  I also do my cuts using a hobby-sized miter box to make sure they are square. 

Is that multiple or division?

[dshue76]

To find the amount to add you have to first measure what you have.

If the kit frame is 6 inches from the back of cab to end of frame then multiply 6(real inches)x25(scale inches in one real inch)= 150(real inches)

150 inches divided by 12(inches in a foot)= 12.5(real feet) this is the length of the frame you have to start with.

You need 24 real feet so 24-12.5= 11.5 feet, This is the amount that would need to be added to the real truck.

 To get that in 1/25 scale you can start by dividing 1 inch by 25, this gives you the size of 1 scale inch= .04 inch, multiply that by 12 and you get 1 scale foot= .48 inch.

Now you need 11 feet 6 inches(or 11.5 feet) so you multiply .48 x 11.5= 5.52 inches. 5.52 inches is the amount to add, but 5 1/2 inches would do just fine as the extra .02" is a scale 1/2" (some perfectionists would cringe at this, then again they don't mind using what amounts to 3/4" spark plug wires) This is all assuming you use a 1/25 scale truck kit. You just need to plug your measurement into this and it will give exact results. Measure twice and cut once...

1/24 scale is much simpler as 1 real inch is 24 scale inches or 2 feet, this means a 1/2 inch is 1 foot, 1/4 inch is 6 inches, 1/8 inch is 3 inches, 1/16 inch is 1 1/2 inches, 1/32 inch is 3/4 inches, 1/64 is 3/8 inch. And you can always use the same exact math as above for 1/24 scale just substitute 24 in place of 25.

 

Edited August 17, 2018 by dshue76

[BobS71]

Thanks to all those that replied to my post. I really appreciate it.

The info you guys provided will be of a great help.

What had me confused was  I watched some videos about stretching frames only these guys

just stretched the frame 4"-5" without doing any scale conversion. The resulting model ended up

looking way too long.

Bob

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[clayton]

How I do mine. I'm kinda into the walkins. Say 144" divide by 25 scale is 6". So 6'' into the frame then I add quarter more for clearance of the trailer. I build the frames like he does. Build the frame. Eyeball the rear axial center to the steer on both sides making there even before I make the cut.

If I have a parts box will use frame parts from it.

 

[DrKerry]

There are a couple vendors that sell Cnc extruded frame rails at various lengths or custom cut lengths. 

[Bubba]

Just remember as well that if you need 24 feet behind the cab take into consideration that you will need about 120 scale inches of frame from the bumper to the back of cab. (BBC measure) and most standard highway trucks are 120"BBC, not counting the sleeper.

 Brent

[PettyKW43]

A simple measurement to use is a tape measure that has metric measure. I/25 scale is very close to 1 inch equals 1 millimeter the difference is so small that you won’t be able to see the difference in the finished product.