Replies

1. 
   Jamie_Buxton | Mar 03, 2004 02:53am | #1

   Or get a plug cutter and glue in plugs of real wood.   The MDF/wood interface has lots of glue area, and won't pull out.   The screw-wood interface is one you understand.   (Use plugs, not dowels, so the screw is going into face grain, not end grain.)

2. 
   Alan | Mar 04, 2004 02:53am | #2

   Mr Micro,

   I would saturate the mortise area with some thinned epoxy.  I'd let it soak in as much as possible; and let it cure completely.  I would then drill over-sized holes for the screws, pour more epoxy into the holes--not so much they will overflow when the screws are inserted--and then put the pull in place and insert the screws.  Use some masking tape or the like to hold everything until the epoxy fully cures.

   Alan

   
   

   ---

   Edited 3/3/2004 7:05 pm ET by Alan

1. 
   gdavis62 | Mar 04, 2004 05:57am | #3

   That sounds good.  I have used thinned epoxies when doing fiberglass skins on balsa-skinned airplane structures, but it was a long time ago.  As I remember it, the thinner was an alcohol.  What will work for me in this application?  I don't want to buy large quantities and a pump and all that stuff I used back in my RC airplane-building days.

3. 
   JohnWW | Mar 04, 2004 06:40pm | #4

   A much easier approach is to use longer straight shank screws, such as sheetrock or sheet metal screws.  If they're 1 inch to 1 1/4 inches long they'll have plenty of strength.  Drill a pilot hole as large as or even slightly larger than the root diameter of the screw to prevent splitting.

   John W. 

   
   

   ---

   Edited 3/4/2004 10:41:33 AM ET by JohnW

1. 
   jagwah | Mar 04, 2004 07:02pm | #5

   On a lot of similar work I've dovetailed in a pine wood key. Any glue would be fine but I like the polyurethanes because of their expansion into the porous surface.

   I would stand the 3/4" panel on edge against the fence and using a 5/16-3/8" dovetail bit run it through.

   A simple dado insert would likely work as well. 

1. 
   gdavis62 | Mar 04, 2004 07:38pm | #6

   Here is a pic of one of the four doors.  They are reasonably small, and probably won't get much action in their lifetime, being for near-the-floor hatches under an entertainment center.  In the pic is shown the edge-mounted pull, a piece made by Sugatsume, essentially a little piece of stainless steel angle.  Two SS screws, about 7/8" long, were supplied with each pull.

   I think I will use the method of reinforcing the hole with thinned epoxy, and I will rough up the back unexposed surface of the pull, the part that will mate into the edge mortise, and use epoxy under the pull, in the MDF mortise.  That ought to do it.

   
1. 
   Jamie_Buxton | Mar 04, 2004 09:38pm | #8

   The sketch is very informative.   I think you're way overthinking the screws.  The stresses on them are not going to be trying to pull them out along the axis of the screw.   The only stress on them is shear.  That's not going to strip the theads out.  On top of that, the force on the pulls is only what is necessary to pull the door open -- maybe a few ounces.   Just screw the screws into the MDF and call it good.

   Now, the hinges have a much bigger problem.  Doors which are much wider than they are tall can put big stresses on hinges and their screws.   There's also the issue of fitting the hinges so that the door hangs correctly.  I'd use cup hinges.  The cup takes a lot of the stress away from the screws in the door, and the adjustability lets you get the door to hang just right. 

1. 
   gdavis62 | Mar 05, 2004 01:25am | #9

   The doors are outfitted with Blum cup hinges.  I have been using the type that require no tools for installation.  Both the base and the hinge have flip-snap covers that expand studs in base and cup in hinge.  Greatest thing since sliced bread!

   They do the usual in-out and sideways adjustments with screws in the hinge, and the base has an up-down adjustment screw.  Slick!

4. 
   4DThinker | Mar 04, 2004 07:38pm | #7

   We've put together many computer cabinets using 32mm metal brackets and 5mm screws.  The larger (than drywall) screws have several times more surface area in contact with the MDF, and tend to stay in place even when those cabinets are tilted (racked) up onto a dolly and moved around.  The screws (from Hafele) go into a 5mm hole, and so long as you don't overtighten (strip) the hole, they stick far better than smaller diameter screws.  These screws work just as well in plywood, so long as you are screwing into the face not the edge.

   4DThinker