Scale tubing sizes for gun barrels and pitot tubes

I have just rechecked all the calculations and part numbers. The only error was the one Gigatron found: In 1/32 scale, the part number for .50 cal. should be HTX-22R, not HTX-27R. (Okay, so my name is Liz Dexia—youse can call me Dizzy… [8-]) I have corrected the table, below.

Sorry for the error. If you, or someone you know, has downloaded the table, please let them know of the correction.

BTW: I will have a new table listing outside diameters as well in the near future.

Also, Small Parts now has a limited selection of heavy wall tubing that might be useful in the larger scales.

Here are the scale equivalents for Small Parts hypodermic tubing, taken from the measurements given in their online catalog. I hope I did the math right…[D)]

Where two numbers are given, the one underlined is closest. Since scale and
true I.D. don’t always match, I chose the nearest smaller tube, as
wall thickness is already too large for scale, most times.

1/72 Scale

Caliber Gauge True tube I.D. Scale I.D. Part No. #304
pitot 25, 31 HTX-25R, HTX-31R Sleeved
0.30 33 0.00400 0.00417 HTX-33R
0.50 29 0.00700 0.00694 HTX-29R
20 mm 26 0.01000 0.01094 HTX-26R
25 mm 23 0.01300 0.01367 HTX-23R
30 mm 22 0.01600 0.01640 HTX-22R

1/48 scale
pitot 21, 25, 31 HTX-21R, HTX-25R, HTX-31R Sleeved
0.30 30 0.00600 0.00625 HTX-30R
0.50 26 0.01000 0.01042 HTX-26R
20 mm 22 0.01600 0.01640 HTX-22R
25 mm 21 0.02000 0.02051 HTX-21R
30 mm 20T, 20 0.026, 0.023 0.02461 HTX-20R THIN WALL= HTX-20T

1/35 scale
0.30 27 0.00800 0.00857 HTX-27R
0.50 23 0.01300 0.01429 HTX-23R
20 mm 20 0.02300 0.02250 HTX-20R
25 mm 19 0.02700 0.02812 HTX-19R
30 mm N/S 0.03800 0.03375 HTX-051R not standard gauge

1/32 scale
pitot 22, 28 HTX-22R, HTX-28R Sleeved
0.30 26 0.01000 0.00938 HTX-26R
0.50 27 0.01600 0.01563 HTX-22R
20 mm 21-1/2 0.02300 0.02461 HTX-21-1/2R
25 mm 18 0.03300 0.03076 HTX-18R
30 mm N/S 0.03800 0.03691 HTX-051R not standard gauge

You’re welcome.

Hey, just saw this from your other post. Thanks, exactly what I was looking for!

This is geat info. Someone just posted a message on this forum looking for this kind of info, so I’m replying to send this post back up to the front. Thanks for posting.

ahem Mr. Herne, do you think you could be so kind as to sticky this here thread? I can see where this question would be asked a few times…

Tri, thanks, man. I printed this out the first time you posted it and keep it in my decal box. Great help!

Thanks!

Thanks again Ross for compiling all of this information. I just found this topic again after a lengthy search of the forums…I knew I had seen it before somewhere!

Perhaps we can make this one a technique STICKY post…(hint, hint) :slight_smile:

Andy

As an afterthought, Ross, how many of the tubing sizes have you used from this manufacturer? I only ask because I see that many of the part numbers you’ve referenced are for stainless steel “regular wall” sizes. I wonder how perhaps the “thin wall” sizes would look in comparison … perhaps more in-scale due to a thinner thickness in the wall size?

Andy

I have most of the sizes listed in the table. If you think about it, the differences are barely noticeable, at least in 1/72 and 1/48—I have to use magnification to see the opening in .30 cal., and .50 cal. is barely there. In the larger scales (1/35, 1/32, and definitely 1/24) it might be worthwhile. That being said, thin wall might be good for barrel shrouds. But if I recall correctly, the price differential is substantial. I’m certainly not going to worry about it for anything less than a contest buster or something fairly large scale.

Yeah, I ask because I’m thinking of scratchbuilding this:

1/32nd scale 7-shot 2.75" rocket pods, shown outboard here…

I’m thinking that this is where using a thin-wall size may be more beneficial / noticeable?

Andy

Thin wall would be good, there, but there is an alternative if you have a Foredom, Dremel, etc. and a conical carbide cutter. Use the cutter to thin the tube wall only at the end or ends. This results in a sturdier assembly.

I’m after building some rocket pods. Can you fellas give any tips as to how you cut the darn things as my hacksaw blade doesn’t even scratch the surface.

Thanks,

Rich

Abrasive cut-off wheel in a motor tool (most electric drills are too slow.)

You can also cut them with a granular carbide blade by hand. Someone once told me they cut them by rolling them under a knife blade, but that seems tedious and will leave a turned-in edge on the opening.

Gigatron has discovered an error in the part numbers for the .50 in 1/32 scale. I will be rechecking the entire table and posting a corrected one as soon as possible.

Sorry! But I did warn you about my math skills! [:I][D)]

Thanks Ross…et al! That is a great reference!

Actually tried to hit the ‘most local’ LHS tonight. Posting on doors was closed at 6 pm. We were there at 5:40…ON A FRIDAY!..closed.

Another sign of the apocolypse…appreciate the help.