Kermie,
There are a couple different ways to mount fins straight on a rocket. Some people use the "eyeball" method, some use assisted "eye" method and some use a jig. If you don't want to buy or build a jig, you can try the method I use, which is assited eyeball method.
What you do is lay your body tube on a table with the first fin slot pointing up. I secure the BT to the table with duct tape and if you have a paper tube, you can lay a piece of paper over the tube where the duct tape touches so it won't stick and tear up the bodytube. Next, I rotate the tube slightly until the two side marks or slots are equal distance to the table. With each side slot equal distant to the table, I install the top fin and use a "T" square to make sure it's perpendicular. You kind of eyeball it from the end, but this "assisted" alignment is free, doesn't require a jig and is more accurate than a straight "eyeball" method.
When doing the remaining fins, you will have to raise the body tube off the table. I use a small suitcase or toolbox to raise it off the table so the first installed fin clears the table. If installing 3 fins, you can just continue, but if you are doing a 4 fin pattern, the next fin to install would be the one opposite the first. That way you can use the first fin to assist with your alignment. Finish by doing the last two fins in the same manner. Listed below is a pic of this method:
<img src="reviews/align.jpg">
If you take a look at the post I did for my Maverick, I have four pics showing my lower fin mounting. They are also in the order that I mounted the fins...the first fin with BT on the table, the second fin mounted while BT was taped to a case, the third on a table, and the 4th on the case again.
Here is the link:
https://www.rocketryforum.com/showthread.php?s=&threadid=737&pagenumber=1
and here are the fins during mounting:
<a href="reviews/maverick/m15.jpg"><br>Fin 1 Installed</a>
<a href="reviews/maverick/m16.jpg"><br>Fin 2 Installed</a>
<a href="reviews/maverick/m17.jpg"><br>Fin 3 Installed</a>
<a href="reviews/maverick/m18.jpg"><br>Fin 4 Installed</a>
<a href="reviews/maverick/m19.jpg"><br>End View of Fins</a>
As you can tell, they are pretty darn straight. I have used this method for everything from Estes rockets to my Level 3 Rocket and it has worked well. Sure hope this helps ya...the price is free as you don't need any extra materials for a jig!
Good luck,
Carl
