MDF for workbench top - edging?

[Jim Jones]

I have read several posts about using one or two layers of mdf for the top (and maybe topped with disposable fiberboard). How do you attach a strip of solid wood to the edges to protect the mdf? The mdf seems to soft to hold nails or screws on the edge... Is glue enough??

Thanks

[Peter Pedisich]

Biscuits and glue would work well.

[David Christopher]

Jim, glue will hold fine but for some of the things that I have made I put a tongue and grove on the material then glued it

[Dan West02]

I have read several posts about using one or two layers of mdf for the top (and maybe topped with disposable fiberboard). How do you attach a strip of solid wood to the edges to protect the mdf? The mdf seems to soft to hold nails or screws on the edge... Is glue enough??

Thanks

I use two pieces of 3/4" MDF for my table top and don't put any kind of edge on it. The only thing I do is radius (1/2") the top edge so I won't have a sharp edge that can be fragile.

I have had it this way for a number of years with no problems.

[glenn bradley]

I used just plain old TBII and clamped it (http://www.sawmillcreek.org/attachment.php?attachmentid=64515&d=1179080281) for 24hrs (KD fir to 4 layers of 3/4" MDF (http://www.sawmillcreek.org/attachment.php?attachmentid=70746&d=1188335473)). I've been working it for quite awhile without any sign of failure.

[Mike Heidrick]

Biscuits and glue would work well.


Thats what I did on my orevious delta saw extension table - used red oak as the edging - then laminated the top.

[joe milana]

I used just plain old TBII and clamped it (http://www.sawmillcreek.org/attachment.php?attachmentid=64515&d=1179080281) for 24hrs (KD fir to 4 layers of 3/4" MDF (http://www.sawmillcreek.org/attachment.php?attachmentid=70746&d=1188335473)). I've been working it for quite awhile without any sign of failure.

How well do bench dog holes hold up in the MDF?

[Prashun Patel]

I edged mine with solid wood. I used dowels. Truth be told, this is more for looks than anything. You really don't need an edge.

If you're mounting a vise, I suggest you use through bolts instead of screws. Recess the bolts below the surface of the top. If you cover with hardbard, you won't even notice the holes.

[Jim Jones]

Lots of good ideas.

I finished the base and was thinking of using 2 layers of 3/4 mdf as a quick interim top before making a glued-up solid wood top. Sounds like it might become my permanent top. :D

Do you use a jig to make sure the bench dog holes are vertical, or is eyeball good enough? Also, I guess you have to use a Forstner bit to drill the dogs?

Thanks for the tips.

[glenn bradley]

How well do bench dog holes hold up in the MDF?

Mine is 3" thick and I have been using the dogs (http://www.sawmillcreek.org/attachment.php?attachmentid=102897&d=1228504888) since May of 2007 without issue. I would not use the iron 'hook' style of holddowns or others that require a friction grip on the inside of the hole as MDF construction does not lend itself to that. I have used through-clamps (http://www.sawmillcreek.org/showthread.php?t=90754) that I cooked up in the shop with great success. A bench stop (http://www.sawmillcreek.org/showthread.php?t=105636) is a great help as well.

[glenn bradley]

Lots of good ideas.

I finished the base and was thinking of using 2 layers of 3/4 mdf as a quick interim top before making a glued-up solid wood top. Sounds like it might become my permanent top. :D

Do you use a jig to make sure the bench dog holes are vertical, or is eyeball good enough? Also, I guess you have to use a Forstner bit to drill the dogs?

Thanks for the tips.

I used a block of wood (http://www.sawmillcreek.org/attachment.php?attachmentid=65523&d=1180501803) as a guide for vertical angle as well as distance between. Vertical alignment becomes more important if you will use ans jig that expects consistency in the holes; a sub platform that can mount in different locations on the bench for example. My multi-sided dog (http://www.sawmillcreek.org/showthread.php?t=118563) relies on decent vertical alignment as well.

[Jim Jones]

I used a block of wood (http://www.sawmillcreek.org/attachment.php?attachmentid=65523&d=1180501803) as a guide for vertical angle as well as distance between. Vertical alignment becomes more important if you will use ans jig that expects consistency in the holes; a sub platform that can mount in different locations on the bench for example. My multi-sided dog (http://www.sawmillcreek.org/showthread.php?t=118563) relies on decent vertical alignment as well.

Glenn,
Neat idea on the block of wood. Also the multi-sided dog.

Also, I think I should get a regular 3/4 drill bit like you have instead of burning up Forstner bits.

Another question: Do you glue the two mdf boards together with a thin coat of Tightbond?

[Gene Howe]

Mine is 2 layers of MDF, faced with 3/4 red oak, screwed and glued.
I cut the top layer short, laid in a piece of red oak, that was just a little wider than my bench vise, then finished the layer to the end of the bench with MDF.
Then I drilled holes for the dogs.
My Bench is 4'X8', so my vise is mounted on the long side about 16" from one end. The red oak goes from the vise to the other side.
Works for me. (Except the sucker is too heavy to move!)
Gene

[Stephen Ash]

I also have a 2-layer MDF bench top, and I used a hole saw to cut my dog holes. If you have access to the underside of the bench top, this does a nice job and generates less dust than a forstner or regular drill bit. Clearing the plugs is a minor inconvenience with this approach though.

-Steve

[Jerome Hanby]

I used a few countersunk screws to help hold everything in place and get things lined up. Then I removed the edging, glued, put it back with the screws, then clamped it up.

I just don't trust screws by themselves in MDF.

[Howard Acheson]

Just PVA adhesive has been holding hardwood edging to one of my work surfaces and to may router table for 10 years. I used a couple of biscuits to for alignment prior to clamping on the work surface and nothing on the router table.

[Jim Jones]

Thanks for all your replies to questions and your experiences. I finished the assembly today.

I used 2 layers of 3/4 mdf and with my wife's help, we spread on 2 coats of Tightbond Extend. I put the mdf on top of my old hollow-core-door bench for assembly. Had to prop up a bit in the middle. I used some 2x6x36" treated lumber cutoffs as cauls to clamp and hold it tight after we applied the glue.

I let it cure over night and then today added 1 1/2" x 1 1/2" spf to the edges all the way around. I applied the glue and pre-drilled and put 2 1/2" screws to pull the edging tight to the mdf.

Tomorrow I plan to spray a 2 or 3 coats of Sealcoat shellac. Then I plan to put on a coat or two of polyurethane. (The poly is because I have a bad habit of putting down a cold water bottle or glass of iced tea down without a coaster. Didn't care on my hollow-core top but it cold be a disaster on the mdf.)

Thanks again for your help.

[Matt Ranum]

Just one more story for you. I made a bench top quite a while back from 3 layers of 3/4" mdf with a 1/4" tempered hardboard for the top. Great work surface and I used a trammel to set up a grid of 3/4 dog holes over the entire top at 8" apart if memory serves. Works awesome for squaring things up. The only drawback was not enough support under the center, with time the top began to sag from its own weight. Your door platform may be enough support just keep a watchful eye in case its not. It won't happen right away it may take several months before you see it, just be careful.

[Jim Jones]

Good point Matt. I am actually not going to keep the door under it. But with sag almost a certainty, today I will joint and true up a couple of 2x4s and attach them with pocket screws down the center of the base for more support in the middle. That should prevent sag.