Threaded Inserts in MDF ??

[Doug Shepard]

Does anybody know how well (if at all) threaded inserts will work in MDF?

[Lars Thomas]

Not particularly good, the 'fibers' lift out.

[Dan Racette]

on patwarner's site, and in his books he taps it with a coarse thread.

[Doug Jones]

Ask anyone that has bought Wal-mart furniture.

My guess is not very well.

[Ian Barley]

I use 'em when I need to for jigs etc. Wouldn't use them in furniture. Whenever possible I put the insert on the back of the board so that the thing has to be pulled through. I would not bother using on the edge of board as the fibers seperate much too easily. What is your application?

[Lee DeRaud]

My CMS is anchored with four 1/4-20 bolts into inserts in the 1" melamine top of a rolling cabinet. No problems so far (6 years)...and I use the handle on the saw to push/pull the cabinet around the garage.

[Tyler Howell]

http://images.rockler.com/rockler/images/54681-lg.jpg (http://images.rockler.com/rockler/images/54681-lg.jpg)
Stole this off Dave Dukes Thread,

I've had good luck with these in MDF
T nuts have also worked

[Matt Day]

I've used T-nuts and corse thread inserts for feet on speakers and both work okay. You just have to be careful when inserting so the board doesn't flake apart. Also be careful when drilling the holes and use a sacrificial piece on the backside so you don't blow it out.

Not sure if that pertains all that well to your question, but take it FWIW.

[Scott Loven]

I would use epoxy to help hold the inserts in place, I would also use CA glue on the threads or striped threads in wood. Make the wood swell a bit, and makes it much stronger. These are both old R/C air plane builders tricks.
Scott

[Frank Chaffee]

Whenever possible I put the insert on the back of the board so that the thing has to be pulled through
Me too.
Tyler shows some nice nuts in his link also.
Frank

[Murray Hensch]

Try countersinking the insert edge slightly to help minimize/prevent fiber tear-out.

[Jim Becker]

I have them in the top of my cantilevered miter station to hold both my Kreg jig and my Leigh dovetail jig. No problems with durability, although they were harder to get started and in straight just due to the way that the MDF "flakes". A slightly larger (but still snug) pilot hole combined with epoxy would probably be better than how I did them "dry".

[Don Selke]

I have used them in MDF for jigs and other applications. As with wood screws in MDF, I drill a over size hole and glue a poplar plug into the hole then drill out the plug the appropriate size to accomidate the insert or the screw. Make sure you allow the glue to set up first. Make your own plugs and do not use dowells as you will be drilling into end grain.

[Tom Andersen]

I need to fix T-nuts into my router table top of MDF. Today I made an experiment with a scrap piece of MDF and hammered the T-nut into the MDF plate. I couldn't get it complete in, and when I took it apart for inspection, I noted that the four self-gripping prongs of the T-nut were bent. I wonder whether it would not be better to saw away the four prongs altogether and then epoxy the T-nut into the MDF? Has anybody tried that? On the other hand, I am a little scared by the perspective of getting epoxy into the threads...

Here's a picture of the type of T-nut I am talking about:

[Doug Shepard]

Thanks for the feedback y'all. I haven't been able to stop by here much lately except from work (which aint too cool). My laptop got sent in to have the motherboard replaced a week ago Saturday, and it will probably be another week before I get it back. The power cord developed a short which continually had to be wiggled/bent into a position so power was getting to the machine. Appararently this wiggling eventually snapped the PS jack off the MB and there was no way to get power to it.
Anyway, my application for the inserts was going to have force potentially trying to pull the inserts out of the MDF across 2 halves of a jig used to clamp some wood in-between, so I ended up finding some cross-dowels (barrel nuts) that should work out better.
Must not be my month for electronic stuff, as the power switch on my 4-month old MM16 BS seems to have given up the ghost this weekend. Doesn't seem to be an issue with the micro-switches on the doors or brake, so I need to give those guys a call when I get home today.

[John Lucas]

You have lots of input. I have one little thing to add, I put a dropp or two of superglue in the hole to strengthen the MDF, then I insert the T-nut or threaded insert.

[Marcus Ward]

They make a version of the t-nuts that have nail holes for small brads to hold them in. Also you might try drilling the hole out oversized, mixing up some thickened west system epoxy, wetting out the fibers of the hole and packing the hole around the insert with the thickened epoxy. I tried to thread an insert into a piece of laminated mdf this weekend and it just made a mess. I ended up drilling the hole slightly smaller than the threads of what I wanted to screw in and just letting the bolt tap the hole, works great.

[Gary McKown]

Tom - a good bet for driving the pronged T-nuts into hard materials (or in end grain to avoid splitting) is to mark the location of the prongs with a light tap, then drill shallow 1/16" or 3/32" holes to guide them in. Best to straighten up the prongs beforehand. Also, you can get T-nuts with mounting holes in the flange rather than prongs - 3 or 4 times more expensive but also machined instead of being stamped.

FWIW, I use blind T-nuts wherever practical instead of threaded inserts in soft wood or flaky material. Insert a T-nut in the end of a short dowel with hole bored for the bolt, then glue the dowel into a hole bored in the substrate. And the final tip - use old style wooden thread spools for the dowel - the hole being already centered and bored.