# What screws to use in MDF?



## TomC

I am enlarging my router table. I am going to use 2 layers of MDF. I know there are special screws (spax) to use on MDF but I can not find them locally. While searching on the net I saw a recommendation to use sheet metal screws because they don't have a taper. It said to drill a pilot hole a little longer than the length of the screw. They had a table for the hole size verses the screw size. Has anyone used sheet metal screws in MDF? Do they work? I am going to glue but want to use screw while the glue sets up.
Thanks, 
Tom


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## Bob Willing

Here is a link for what I use and they are great. Some say just sheet rock screws but these are ment for MDF.

http://www.woodcraft.com/Family/2020607/2020607.aspx


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## TomC

Bob,
Thanks for the info. I was planning on gluing up tomorrow so I was hoping for a recommendation on a screw I can get locally. I have had time in the past when making a jig that the MDF would swell up where a screw was placed. I don't know if I didn't make a big enough pilot hole or wrong type of screw. Dry wall screws would be great as I have many on hand. Again thanks foir the info.
Tom


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## cabinetman

I've tried confirmat screws and I don't like them. I use coarse thread screws, like a drywall screw. The wide deep threads allow for any crumbling of material as it is driven in. 

I drill a countersunk pilot hole the size of the shank (gullet to gullet). IOW, the hole diameter is smaller than the outside diameter of the screw threads. The depth of the pilot hole is slightly less than the length of the screw, so the point has something to bite into. BTW, the screw is a straight shank.

I use a cordless drill driver on slow speed, and when nearing tight, just bump the screw until the head seats tightly in the countersink. Screws will strip out if driven fast all the way in.


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## TomC

Thanks Cabinetman,
I will give that a try tomorrow. As I said previously I have plenty of dry wall screws on hand.
Tom


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## Tony B

Another vote for course thread drywall screws.


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## Old Skhool

A vote for threaded inserts epoxied in place.


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## Tony B

*Do you have an air nailer?*

Normally in cases like this I use glue and a brad nailer.


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## mwhafner

Course thread drywall screws work well, but I have become a fan of the Spax MDF and Particle Board screws. The hold as well as drywall screws, with a trim size head. My local HD carries them.


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## TomC

I will look at Lowes again. The next time I'm at a HD (22 miles away) I will look for the spax. For now I am going to use dry wall screwa.
Tom


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## cabinetman

TomC said:


> I will look at Lowes again. The next time I'm at a HD (22 miles away) I will look for the spax. For now I am going to use dry wall screwa.
> Tom



If you follow my "how to install", you should have good luck. You wont be snapping off any heads, or heating up the screw. Just FYI, IMO, a corded drill doesn't have the slow speed torque to control the screw for a smooth drive.


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## Texas Sawduster

TomC said:


> I am enlarging my router table. I am going to use 2 layers of MDF. I know there are special screws (spax) to use on MDF but I can not find them locally. While searching on the net I saw a recommendation to use sheet metal screws because they don't have a taper. It said to drill a pilot hole a little longer than the length of the screw. They had a table for the hole size verses the screw size. Has anyone used sheet metal screws in MDF? Do they work? I am going to glue but want to use screw while the glue sets up.
> Thanks,
> Tom


Even though your project may be finished, here goes.
I used phillips head wood screws to fasten my MDF router table top to the router bench top. Of coarse the original top is 2 pieces of 3/4 inch ply, one on top of the other. With the 3/4 mdf that makes a thick top.
Try using as course of a threaded screw as you can get. They will hold better.


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## Texas Sawduster

TomC said:


> Bob,
> Thanks for the info. I was planning on gluing up tomorrow so I was hoping for a recommendation on a screw I can get locally. I have had time in the past when making a jig that the MDF would swell up where a screw was placed. I don't know if I didn't make a big enough pilot hole or wrong type of screw. Dry wall screws would be great as I have many on hand. Again thanks foir the info.
> Tom


Pre-drill the hole as you would normally do, then chamfer or countersink the hole to relieve the top of the hole. This will help, if not totally prevent the MDF from pushing upwards as the screw displaces the MDF as it enters the hole.


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## rcp612

I used the "regular" wood screws from either Rockler's or McFeely's, don't remember which, but, after reading somewhere in another forum long, long ago, I filled each pilot hole with super glue and let it sit overnight before driving any screws.
As Cabinetman said, drive them slow and don't overtighten them. I had no problems with this method.


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