i have started to build the stab on a top flite T-34 mentor kit and it says make sure the jig tabs of the ribs are touching the building board. what are the jig tabs?

Jig tabs are sometimes added to symmetrical ribs to keep the aft end of the ribs up so that the centerline of the ribs will be level with the building board. They are little extensions near the trailing edge of the rib which are cut off when the wing panel is removed from the board. Is it possible that you removed them when taking the ribs off of the sheets they are cut from?

If the tabs are missing it is no big deal. The tabs are handy when the manufacturere cuts our the ribs with a metal die or a laser. But they are not practical when scratch-building and cutting the ribs out by hand. In those cases I just put a balsa stick of appropriate size to shim up the ends of the ribs. Simple and does the job.

This should help:

Paul, you have me alittle worried here, the fact that you are asking what jig tabs are makes me think this is your first kit. If so that kit is very well engineered but not designed for the beginner.

rc_sport-RCU. your right this is my first kit but i have a lot of help frfom friends that have been building kits for 30 years so if im not sure about anything i will not even attempt it without help. i have the stab already built and sheeted and it looks good. i also have a great tool to help me with this project and thats all the great guys on RCU. so with the right help, advice and a lot of time all should go well

Were theres a will theres a way..Have fun building you will be rewarded when you see it fly. New kits are almost fool proof just try and build a straight and lite as you can. Sanding is no fun at all.-Mike