Drum Head Problem

Alright, lets see if you guys can help me, because I've searched all over google and can't find any help.

The drum head of my floor tom kind of "pops out" in a way on one side, when it gets bad enough, the area that pops out doesn't touch the top of the shell. On that side you can see more of the metal rim (the one connected to the drum skin) than anywhere else on the drum. And after retuning it, it works fine, then when I play for about 10-20 min in starts to pop out again, severely detuning it, and causing part of the head to become so loose you can hear it vibrate when the bass drum is hit. the spot (or edge) that pops out can change positions when you re tune it by sliding the rim around. would the problem be too big of rim? My kit is fairly new, about 2 months or so.

EDIT
This is the part that pops out.




This is what the top of the shell looks like -- How it should look.

Make sure the drum and rim are in round by measuring them.

Can you maneuver the rim to make this happen without playing?

Does this happen really quickly - one note is fine and the next is a flat tire? Or does it back off over a few minutes? Try checking to see if the tension rod is backing off at a few spots while you're playing. If that's the case you may only need to spend a few bucks on lug locks.

If everything seems fine (drum and rim are in round; can't maneuver this into happening; rods aren't backing off gradually) I'd take it to your local drum store for them to look at it; you may also want to try a new head in case that wasn't entirely round or has started to pull out or something weird.

What brand of drum do you own? It initally appears that your shell is out or round....or the rim....

I cannot move the rim into doing this and they are Gammon Percussion drums. It happens gradually, but still pretty fast. 5-10 min or so. i'll re tune the drum and watch the tension rods

Sounds a lot like a bent rim.

Lay the rim on something flat, like a counter-top. Is it flat? If not it can usually be (carefully) bent back into shape.

i had this problem with my snare, tried several different heads (be sure to do this first) and that didnt fix it, so i ended up replacing the stock hoops with Gibraltor 2.3mm - this fixed it, the heads seated nicely on the drum and tuned up better as well

alright thanks guys, I'll try some of those solutions out and get back to you.

Edit:

After further examination, the reverse side does this too, it just hadn't poped out yet because you don't hit the reverse side.

Both heads are the same size, same with the rims. Heads fit snuggly on the shell when tried without the rim. but when I put the rims on the shell without the heads, I could make one side fit snuggly, but the other had a tremendous amout of free space, would this be problem? Judging by this I'd say i need new rims?

Also when I put the heads against the rims without the shell, the gap is still there

Head against shell, no rim



Rim against shell, No head, on the side that works


Rim against shell, No head, opposite side from upper pic ^