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roll-cage diameter tubing, 1/25 - 1/24

15 posts in this topic

Posted

I'm building up a roll cage for a '65 Dodge AFX car.  I'm not sure exactly what scale.  I intend to buy the material from an outfit in the UK that I read about on this forum: www.cornwallmodelboats.co.uk.  I purchased some styrene rod, 2.5 mm, for headers.  It was very reasonably priced and no problem shipping from the UK.  So I'm wondering what 1:1 diameter is used in AFX cars. By the way, this rod has the special property that it will not 'spring back' once it is bent.  I don't know if this is good or bad?  Thanks 

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Posted (edited)

1.5 inches to 2 inches is the range you'll find hoops and cages to be built from, depending on time period and sanctioning body. Since 1 inch equals very close to 1 mm in 1/25 scale, you'll need styrene round rod stock in the 1.5 mm to 2 mm range to represent roll-cage and hoop tubing correctly.

For 1965, NHRA required 1 5/8 inch minimum outside diameter tube for roll cages. This is 1.625 inches. Divide by 25 for 1/25 scale. 

You get .065", sixty-five thousandths of an inch. In millimeters, this is 1.65 mm. 

So, for a '65 car, you need 1.65 mm styrene rod for your roll cage in 1/25 scale.

        (1/16" is pretty close, but it's a little too small...and 5/32" is pretty close, but a little too big)

HEADER NOTE: Header primary pipes on that engine would be probably 2 1/8 inches. Your 2.5 mm styrene will look like 2 1/2 inch tubing, a little too large if you have ever actually seen these things. 2 mm stock would look better, and once it's painted, it would be about scale-perfect.

  

Edited by Ace-Garageguy

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Posted

Here is a Tubing reference chart for all inch size tubing I made a while back:

2v2uJmDjhxAhe9C.jpg

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Posted

Thanks Ace and Mooneyzs!

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Posted

Ace: These headers are to be Top Fuel headers.  

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Posted

Hey Chris, nice chart! If you would add a Metric column to it I think it would be even nicer. Keep in mind that an inch dimension in 1/24th or 1/25th scale is equal to the same number in Metric. Example:

1 inch in 1 /25th scale equals 1mm in metric.

1.5 inches in 1/25th scale equals 1.5mm's

This works really well for chassis, engine and other "scale" dimensions for comparing metric and inch sizes for fabricating.

Mark

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Posted

Ace: These headers are to be Top Fuel headers.  

"Top Fuel" is supercharged, and could run a larger header diameter because there's a LOT more exhaust to get out when you're pumping lots more air and fuel in with a blower.

To the best of my recollection, 1965 AFX cars were carbureted or fuel-injected, not blown.

 

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Posted

"Top Fuel" is supercharged, and could run a larger header diameter because there's a LOT more exhaust to get out when you're pumping lots more air and fuel in with a blower.

To the best of my recollection, 1965 AFX cars were carbureted or fuel-injected, not blown.

 

None of the LEGAL A/FX cars was blown, of course, but there were a number of '65 match race funnies that ran blowers.

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Posted

Hey Chris, nice chart! If you would add a Metric column to it I think it would be even nicer. Keep in mind that an inch dimension in 1/24th or 1/25th scale is equal to the same number in Metric. Example:

1 inch in 1 /25th scale equals 1mm in metric.

1.5 inches in 1/25th scale equals 1.5mm's

This works really well for chassis, engine and other "scale" dimensions for comparing metric and inch sizes for fabricating.

Mark

Thanks! Yeah I have been wanting to add mm to it so that it will fill in some blanks, I just haven't sat down and done it yet. I originally did this chart for my 1/16th scale projects and at the time decided to add the other scales since I had seen so many people asking what sizes of tubing to use for certain things. I though that having a reference chart could help others here. I will get the spreadsheet updated so it has both Inch and Metric sizes on there. 

I have a personal preference with working in inches myself over metric units but that  because it's what I work with on a daily basis designing parts in Solidworks for work along with working with my machine shop. I can easily relate if something is let say .030" , .050", etc vs  knowing 2mm, 2.5mm off the top of my head. I will usually convert the mm to inches so I can relate to the size easier. That's just me though.

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Posted

I seem to recall magazine articles of the day mentioning 2" steel tubing being used for roll bars, tube (funnycar) frames, and so forth. Two inches in 1/25 is .080. Common 5/64" materials look a bit too small, and 3/32" looks a bit too big. But Evergreen makes lovely .080" styrene rod which is absolutely perfect for all sorts of 1/25 projects. It's definitely worth going to some trouble to get.

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Posted

Got'a check your reference.  The Cuda T/A I'm working on ran 1.5" tubing for the cage.  I used .060" (1.5 mm) rod to build mine.

DSCN4768

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Posted (edited)

I seem to recall magazine articles of the day mentioning 2" steel tubing being used for roll bars, tube (funnycar) frames, and so forth. 

 

Got'a check your reference.  The Cuda T/A I'm working on ran 1.5" tubing for the cage. 

 

1965 NHRA rule book, page 6, section 1A. FACTORY EXPERIMENTAL (FX) begins.

                                     page 7   "ROLL BAR: Refer to ROLL BARS, SAFETY REGULATIONS" (which begin on page 32)

                                     page 36    (SAFETY REGULATIONS)  ROLL BARS begins

                                     page 37:   "Minimum requirements are 1 1/2-inch inside diameter steel tubing, with 1/8-inch wall thickness (1 3/4-inch outside diameter)............

                                                     ........Minimum requirements for cage type roll structure are 1 5/8-inch outside diameter steel tubing, with 1/8-inch minimum wall thickness..."

Feel free to read the rules:   https://www.dropbox.com/sh/2006u57wp7sqpxt/eZJPZZcJdZ?preview=1965_Drag_Rules.pdf   

 

                            

                          

 

 

Edited by Ace-Garageguy

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Posted

To keep things clear, you guys are now talking about 3 completely different cars.

'65 AFX Dodge

'70 T/A 'Cuda

Top Fuel from unknown year.

They are all going to have different requirements. Rule books, for the year and type of racing, are one of the best sources of information available (and an actual good use for the internet).

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Posted

To keep things clear, you guys are now talking about 3 completely different cars.

'65 AFX Dodge

'70 T/A 'Cuda

Top Fuel from unknown year.

They are all going to have different requirements. Rule books, for the year and type of racing, are one of the best sources of information available (and an actual good use for the internet).

Yes, and the OP requested information specifically for a '65 A/FX Dodge, which is what I responded to. Every time.  :D

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Posted

To keep things clear, you guys are now talking about 3 completely different cars.

'65 AFX Dodge

'70 T/A 'Cuda

Top Fuel from unknown year.

They are all going to have different requirements. Rule books, for the year and type of racing, are one of the best sources of information available (and an actual good use for the internet).

My point was that the OP needs to check his references to ensure using the correct size tubing rather that assuming a general statement is correct.  Each racing series and each era was different.

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