# Hinges and MDF



## Walt447 (Aug 18, 2010)

I am in the process of building a shop air cleaner. The plans call for a sliding bottom to remove the filters. I have altered this because I want full acces to the filters and the fan for cleaning.The top and sides are made from 3/4 inch MDF. I am installing weather stripping on the bottom to allow for a trap door arrangement and still provide a air tight seal. Looking for information on how to attache this trap door. Should I keep it 3/4 of and inch or switch to 1/2 inch due to the weight. I am sure a piano hinge would just create problems since I would be screwing into side grain of MDF. I was leaning towards some sort of strap hinge. Any suggestions welcome.


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## Sawkerf (Dec 31, 2009)

MDF doesn't really have a "grain direction" since it's just glued up, compressed, wood particles. On the rare occasions when I use it with screws, I either attach a hardwood strip where I'm using screws, or drill and dowel at the screw locations. The need for the added strength depends on how often you'll be opening and closing the hinges, and the weight they're carrying.


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## richgreer (Dec 25, 2009)

I'm very leery of putting screws into MDF. They just don't hold. I would recommend a MDF panel in a solid wood frame. You could probably get by with a rabbet on the upside and use 1/2" MDF. I would glue and brad nail the MDF into place so that it stays secure when the door is open.


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## Maggiepic (Aug 26, 2010)

If you drive screws into the edge of MDF it will split very easily. I have drilled pilot holes for a firm but loose fit for the screws and then put yellow glue into the holes and insert the screw. The MDF soaks up the glue rather quickly and within an hour it is pretty solid. A bit off the norm, but has worked for me.

P.S. The screws are not removable since they are glued in. It just shreds the MDF around the hole. Don't ask…


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## WoodyWoodWrecker (Jul 1, 2009)

Good timing. I was just thinking about how to attach hinges to MDF doors last night. I had decided to not use them since this is going to be a shop cabinet that will be opened allot.


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## Walt447 (Aug 18, 2010)

Thanks guys great information. What if I glue a hardwood strip to the MDF on the hinge side then screw into that. This will be on the bottom of an air cleaner and wil be opened at least once a month.


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## Pie (Jan 28, 2009)

Hey Walt
Any chance of getting a picture of those plans. I am trying to visualize your project but my it ain't working ha-ha! If you are venting to the outside, not sure if you really need a filter (but I could be wrong). If you are venting inside (recirculating the air) it may be easier to make a channel in front of the fans so you can just slide the filters in and out from one side. This will eliminate hinges or trap doors. But again, without seeing your plans etc, my advice may be way off.


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## Walt447 (Aug 18, 2010)

Pie:
I will post the project tonight. It is a 24 in wide 31 in long and 13 1/2 Inch high box. Inside the box I have mounted a Twin window fan. Behind the fan will be two 12×24x1 furnace filters and one will be in front. The box is made out of 3/4 MDF the filters are held in tracks made from 3/4×3/4 plywood strips. Currently the project is upside down. when mounted to the ceiling the bottom will be open to change filters. The plans I had called for a sliding bottom that was in a 1/2 in dado. I did not think that the MDF would hold up sliding so I have decided to mount a hard wood strip on the bottom edge and place a hinged plywood bottm so I can not only change the filters but clean the fan when needed. I plan to hang the filter from the ceiling on chain to reduce any vibration.


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