# Tube Calculator

#### jflis

##### Well-Known Member
Well, I've used youse guys as a test-bed for many of our newest designs, so why not something different...

I had a nice long quiet drive out to New York and back today (my Great Aunt's 95th birthday party ) and came up with an idea (well, several actually, but this one I got down on paper real quick cuz it was easy and cheep )

I've uploaded a pdf file that I would like some of you to take a quick look at. If you folks think something like this is useful to the community I'll go ahead and make it public (with instructions of course). Just don't want to waste my time if something like this is of little use...

The file is a Fin Spacing and Circumference Calculator and can be found here: https://fliskits.com/products/free_dl/fin_calculator.pdf

What you will see when you open this file are 8 rulers on a page. The top most and bottom most are standard 1:1 scale rulers and are used for reference purposes.

this is how you use it:

1) Assuming you know your body tube diameter (up to 10 inches), you lay a straight edge at that point along the standard (gray) rulers on both the top and the bottom (so you know it is aligned properly)

2) Looking at the second ruler you can read the circumference of your tube right off of that scale called the Circumference Scale) (NOTE: On ALL scales, the smallest division is 1/32")

So, now you know the circumference of your tube directly.

Now, you may wish to create a fin marking guide for anywhere from 3 to 7 fins. Let's say, for example, you want 5 fins. With your straight edge still in place, you can go to the 5-Fin Spacing scale and read directly from the scale how many inches along the circumference the center of each fin would be.

This would allow you to quickly mark out a fin marking guide on a piece of paper with proper markings for each fin.

On the sheet, I show an example using a BT-70 tube.

Being a visual scale, it is not as exact as a calculator would be, but I beleive that it is plenty close enough for the vast majority of scratch builders wanting to assemble something quickly and accurately.

I am looking for some input.

Is this a useful tool?
Is this something that you would use?

Understand... ...it's stuff like this that keeps me up nights... LOL

thanx for any feedback, positive or negative!
jim

#### powderburner

##### Well-Known Member
I suppose there are some folks that would prefer to do things this way.

Myself, it's no big mathematical deal to figure out, but your DIY guide really is kinda cute and handy.

I suppose if I could be king for a day, I would ask for a guide-generator: you click on what BT size you want to use, click on the number of fins you want, and a little bit of software would generate the fin guide and throw an image on the screen, ready to print. Oh yeah, and a scale guide should be included to make sure my printer isn't shrinking or expanding the image (give us like a five or ten inch scale mark, not just that little one inch bar).

And that's what I think about that.

#### Silverleaf

##### Well-Known Member
Jim,

Powder has the same idea I thought of, simply input your tube size - number of fins, and viola. Heck, I'm someone that can't remember what size in mm's any engine is..so anything like this would help. lol

Very nice process here though. I like how simple it is to use, BUT my only addition would be to include a Metric and Decomal Equivalent Scale. I must say this is something I'd like to have available to print out to have handy by my work area.

Here is the Metric scale..

and Decimal..

#### Rocketmaniac

##### Well-Known Member
Originally posted by jflis
Is this a useful tool?
Is this something that you would use?

I like it........ I also like power's and silver's idea about being able to input the tube size and number of fins......

#### Zippy

##### Well-Known Member
I think it would be most handy if included with a print catalog. Some non-computer types would probably love it. For a lazy computer user like myself a simple program thats prints out what I need with just a few inputs is what I tend to use though.

#### rbeckey

##### Well-Known Member
Powder,
Your wish is granted, my liege.

Search for the "Template Widget" in the forum.
Input by BT, inch or metric measurement.
Output fin marking guide, angle tube cutting guide or transistion,

#### daveyfire

##### Piled Higher and Deeper
TRF Supporter
VCP does the "print a fin wrapper with X fins on a tube Y diameter". But I like the paper version that Jim has, cause sometimes I'm in the shop and need one RIGHT NOW, and getting glue on the computer is bad

#### powderburner

##### Well-Known Member
Originally posted by rbeckey
Search for the "Template Widget" in the forum.

OK, so I'm a dummy, but I can't figure out what/where/how you are telling me to search. I clicked the 'search' button, went to the 'keyword' slot, and tried a search there with no results. What did I do wrong?
(And thanks ahead of time for the help)

#### rbeckey

##### Well-Known Member

I had a small problem when I reinstalled the widget after switching to WinXP last winter. I got a missing file error. "TABCTL32.OCX" was apparently not included in my load of XP for some reason. I did a google search for it, downloaded the file and dropped it into C:/Windows/system32 and it works now. This didn't affect anything else as far as I can tell.

#### jflis

##### Well-Known Member
Originally posted by daveyfire
VCP does the "print a fin wrapper with X fins on a tube Y diameter". But I like the paper version that Jim has, cause sometimes I'm in the shop and need one RIGHT NOW, and getting glue on the computer is bad

Well, that was *my* thinking too. I mean, for example I have patterns already drawn up for each body tube size and for many fin combinations up to 12 or so and it's real easy for me to make up other, custom setups.

But I often find myself in the shop and just gathering up parts and ideas hit me and I start building. It's a pain to interupt myself and run upstairs to load up and print out a fin marking guide...

Also, I imagine that there are many folks out there who either don't have the computer access or tools available to make such things *easy* to do and this is another quick option.

I have another idea that I'm working on but it will involved some expendature so I have to feel it out some first...

#### DavRedf

##### Well-Known Member
Jim
I just wrap a piece of paper around the bt, cut too size and fold the number of times needed.
David

#### jflis

##### Well-Known Member
Yea, actually that's what I do for all my 3 and 4 fin, but 5 or 7 fin get a bit complicated...

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