Fin slot templates

[tammaraki]

Hi,

I am trying to find fin slot templates. Just a simple paper one you can print and tape together. Specifically I need a 3 fin for 5.5" and a 4 fin for my 4" big bertha.

Thanks!

 

[Ronz Rocketz]

I tried the template that can be printed from OR (non-beta). It didn't fit the tube exactly so didn't try it. I ended up just free handing using the Estes tube marking guide. Seemed to work.

 

[Hobie1dog]

I was wondering about the same thing as if a place like Payload Bay had one?

 

[rharshberger]

I was wondering about the same thing as if a place like Payload Bay had one?

iirc they do, it works just like the Estes paper ones

Yep... https://www.payloadbay.com/page-Tools.html

 

[teepot]

Hi,

I am trying to find fin slot templates. Just a simple paper one you can print and tape together. Specifically I need a 3 fin for 5.5" and a 4 fin for my 4" big bertha.

Thanks!

Are you looking for a guide that is the root dimension or where the center of the slot would be?

 

[lakeroadster]

FWIW:

I used to make my own templates in CAD & print them out... but I've since found that just wrapping a pirce of paper around the tube, marking the circumference and then dividing the circumference by the number of fins is just as accurate and takes way less time than fiddling with templates.

Scribe your straight slot lines by setting the tube along some doorway trim, and then use @neil_w's aluminum angle trick for cutting the notches.

Eazy Peazy Slotting

 

[bjphoenix]

've since found that just wrapping a pirce of paper around the tube, marking the circumference and then dividing the circumference by the number of fins is just as accurate and takes way less time than fiddling with templates.

That's what I do, and I did one today for a BT-60.
I take a strip of paper an inch or two wide, wrap it around the tube a tight as I can, and put a pencil mark right where the paper overlaps. Unwrap it and measure this length with a metric ruler. Divide that distance by 3 or 4 then put marks on the paper at the calculated spacing. I use a metric ruler because it is easier to work with decimal numbers. I wrap the paper around the tube again and transfer the marks to the tube. Then I use a piece of angle just like in the photo to draw straight lines up the tube. This works for any size tube.

 

[Hobie1dog]

I think I'd like to make some out of the colored plastic paper type sheet stock that you can get, that way it would be a lot more durable than paper and hopefully reusable for a long time. I used to have some of that laying around, now I have to find it.

 

[prfesser]

FWIW:

I used to make my own templates in CAD & print them out... but I've since found that just wrapping a pirce of paper around the tube, marking the circumference and then dividing the circumference by the number of fins is just as accurate and takes way less time than fiddling with templates.

Scribe your straight slot lines by setting the tube along some doorway trim, and then use @neil_w's aluminum angle trick for cutting the notches.

Eazy Peazy Slotting

View attachment 507588

For most low-power paper tubes, roll up several sheets of paper and slide them into the tube to unroll (or use a long coupler) to make the tube very stiff. Holding the angle iron against a thin-walled paper tube can be annoying, as the tube will distort and you end up with non-straight lines. Phenolic is stiff enough even without a coupler inside.

 

[dr wogz]

just wrapping a pirce of paper around the tube, marking the circumference and then dividing the circumference by the number of fins is just as accurate and takes way less time than fiddling with templates.

Scribe your straight slot lines by setting the tube along some doorway trim, and then use @neil_w's aluminum angle trick for cutting the notches.

Eazy Peazy Slotting

View attachment 507588

I do (and was going to post) the exact same thing! But I then fold the paper in half, lining up the marks, then in half again.. With some practice, you can fold the paper into thirds, in an 'Z' pattern. but, it take a bit of practice & manipulation

Another method (for 4 fins)

1. Is to make a line diagonal from one corner to the opposite other corner, then do the same for the other 2 corners. (this assumes you have a parallel / rectangular piece of paper you've wrapped about the tube). you should now have an 'X' on the paper. Where the two lines cross in your mid point. Draw a vertical line thru this intersection.
2. Repeat the above 'X', but use this new centerline as your end points.
3. And add the vertical lines thru these new 'X' intersections.
4. Now you have divided the half into two halves; you've made quarters of the length / circumference

another method is to use a tailor's tape measure (very flexible). wrap it abound teh tube, measure teh circumference, and divide. But I prefer the paper method.

 

[bjphoenix]

I do (and was going to post) the exact same thing! But I then fold the paper in half, lining up the marks, then in half again.

When I did this yesterday I was marking a BT-60 for 4 fins. I pulled a scrap piece of paper out of the trash and cut a strip about 1" wide x 7" long. I wrapped it around the tube and marked the overlap, then I measured. Between marks it was 131mm. Divide this by 4 and you get 32.75mm. So I put marks at 32.75mm, 65.5mm and 98.25mm. Now I can't see or accurately mark 32.75mm but I can mark just to the side of 33mm. I figure this method is as accurate as I can see and mark with a sharp pencil. Measured using the other side of the ruler I get just over 5 1/8". If I try to divide that by 4 I get just over 1 9/32". This would be a lot harder to see and mark on my ruler which is why I used mm.

 

[dr wogz]

and this is where the world of "tolerancing" comes into play.

the measure should be 32.8965874...mm
is 32.897mm accurate enough? too accurate?
maybe 32.89mm.. or just 32.9.. or just 33mm

how thick is your pencil lead? how accurate are you at scribing, then cutting a slot on a scribed line?!

What is the fin? exactly 1/8" (.125000") or is it more like .115" after sanding? (or .135" with added fillers & such?!



(I see this with some new engineers, a hole is at ±.005".. it's a loose hole, a vent hole.. ±.030" is good enough..)

 

[rharshberger]

and this is where the world of "tolerancing" comes into play.

the measure should be 32.8965874...mm
is 32.897mm accurate enough? too accurate?
maybe 32.89mm.. or just 32.9.. or just 33mm

how thick is your pencil lead? how accurate are you at scribing, then cutting a slot on a scribed line?!

What is the fin? exactly 1/8" (.125000") or is it more like .115" after sanding? (or .135" with added fillers & such?!



(I see this with some new engineers, a hole is at ±.005".. it's a loose hole, a vent hole.. ±.030" is good enough..)

We have too many anal folks who try and build to the nearest .001" when our tools are generally only good to the nearest .01" (eyes and hands with manual tools).

 

[tammaraki]

Are you looking for a guide that is the root dimension or where the center of the slot would be?

Center of the fin slot.

 

[teepot]

I have printed templates from PayloadBay.com that I use and reuse. After I have a center line I use a Taylors tape measure to mark the fin width. Extend the lines with an aluminum angle and then cut the slots out with my Dremel and a reinforced cut off wheel. I can cut 4 slots in a minute. Nice and straight too.

 

[jqavins]

and this is where the world of "tolerancing" comes into play.

the measure should be 32.8965874...mm
is 32.897mm accurate enough? too accurate?
maybe 32.89mm.. or just 32.9.. or just 33mm

"[T]oo accurate?" There's no such thing. Just too precise.

• "I am in the State of New York." Absolutely accurate. Terribly imprecise.
• "I am standing on the north-east corner of Ninth Avenue and 51st Street in Manhattan, 3' 4.7" due east of the east end of the northern outline of the 51st Street crosswalk." Extremely precise, and completely inaccurate.

 

[dr wogz]

and my favorite: "You're in a Helicopter"

Precise & accurate, but totally irrelevant..



The joke is, is that there is a heli tour touring abut Seattle. it's foggy, and suddenly the heli looses power to the nav system. they fly around a bit, and find a building, and stpot a person inside. The pilot writes on a pad of paper he has: "Where am I?"
The person in the building writes back: "You're in a Helicopter".
The pilot then smiles, and plots a course straight home.
"How did you know where you were from that?" the tourists reply..
"Easy.." he replies.. "That type of answer can only come from Microsoft.. That was obviously Microsoft's headquarters.."