I've heard that MDF is prone to strip screw holes if you have to disassemble and then reassemble.  If having difficulty, Google <striped wood screw repair insert>.  You can drill oversize hole for repair insert.  If worried that insert will be too close to edge and chip MDF you can drill large enough hole to slip insert into, place metal bolt into hole so it is flush with end of insert, use a nut to lock metal screw in place,  tape end of insert that is going into hole, use good glue, epoxy or whatever you know will hold insert.  Use bolt to turn insert into hole.  Then keeping bolt from turning, back locking nut away from glue, careful not to get any glue on bolt.  Then when glue is dry remove bolt. Then reassemble with bolt/metal screw.   Try on a scrap piece of wood to perfect tecnic so you are comfortable on speakers.   On past projects repairing holes in metal such as door hinges on pickup I have had to place one bolt into hinge, then drill another hole that overlapped 1st bolt, to move hole due to bent hinge that I cold not repair.  I never use Heli coils anymore, just drill for oversize hole.  Tap for larger bolt, then drill larger bolt to  tap for original size bolt.  If concerned that oversize bolt won't stay, you can drill smaller hole that intersects the threads, tap and place small bolt, then grind flush if needed.  Much less expensive and has worked well for me several times.

     You can even build your own insert for using in wood by tapping a piece of round stock metal, or threaded stock that can be obtained at most hardware stores.  I have even heard of fixing cracked Tractor engine block by interlaping a series of bolts.  Farmer saved the cost of buying new engine, or at least engine block.  (I ramble, but you probably know that by now). 

I find that using a few drops of wood glue into the pre-drilled mdf holes reduces the chances of stripping the threads......it acts like a self healer

Sounds a lot simpler.  So do you do this with newly drilled holes or can it be used after disasembly?  Also how do you box in the statement or question you are replying to?  It makes it easier to follow what you guys are refering to when I see it done.  I would like to be able to do the same.

Thank you,    John

So do you do this with newly drilled holes or can it be used after disasembly

Also how do you box in the statement or question you are replying to

John W. Henderson:

Also how do you box in the statement or question you are replying to?  It makes it easier to follow what you guys are refering to when I see it done.  I would like to be able to do the same.

When you hit the reply button for the post you are replying to, you then highlight the text you want to quote and then hit the quote button. You can do it far more quickly than the time it took for me to type this... 

Bruce

Marvel:

When you hit the reply button for the post you are replying to, you then highlight the text you want to quote and then hit the quote button. You can do it far more quickly than the time it took for me to type this... 

Bruce

Now that makes it so simple even I can understand.       Thanks

I typically use a trick my father taught me. Depending on the size of the hole a golf tee will work. Drill the hole out a little bigger to match the outside diameter of the golf tee, cut the top off of the tee, wood glue it into the hole and redrill when dry. It should be like drilling into new wood. If the existing hole is larger than a golf tee then you can use a larger dowel rod. As far as metal?????

an old carpenter trick......fill the hole with slivers of wood and wood glue, wait until dry, there ya go!

Pretty much what others have said. 

I just use toothpicks and wood glue... I dip them in wood glue and just break off however many I need in the hole.