Hey Robin
as to the finish I don't think you need one at all. assuming you have a glued together double layer of mdf for you top the edging you can use standard wood glue and finish nails but melamine glue is made for melamine and it holds best if you want to buy something you may not use again unless you plan on making things out off melamine. along with the nails it would help to clamp the trim until the glue drys. if you have clamps?The trim could be made form 3/4" by 1 1/2" thick fir,pine,or any wood you have available, and the corners ether butt jointed or mitered.

 

Robin….....First of all welcome to LJ's. There are no supid questions. Sealing MDF is an easy process. Multiple coats of shellac. As for the edging I used poplar on mine, but any wood will work. I used poplar because thats what I had on hand. You will notice that some of the guys will use oak, walnut or another hardwood. Attaching the edging can be done numerous ways. The problem with MDF is that it doesnt hold screws well especially in the edge. If you use screws predrill the edging and the MDF, remove the edging and countersink the MDF slightly. The countersink will give the screw enough room as it pulls the MDF material out of the hole as you drive the screw. I would also apply a good healthy bead of yellow glue to the MDF and the edging as you attach it. Make sure to spread the glue evenly. You will notice the MDF will absorb the glue quickly, it is very pourous on the edges. If you dont wanna go with the screws you can also use finishing nails, I used 18ga 2" nails on the edging on my bench and it has held well. I would apply the edging before you finish the top and apply shellac to the top and edging as well. Good luck!!

 

I heve never tried this on MDF, but Tung Oil is an excellent sealer and finish wich hardens very well…...why about trying on a small piece? it takes a week to dry.

 

Are you planning on painting it to lighten it up as MDF is awful dark. I know some like it that way. If you are going to paint it to lighten it up. Use glue sizing, basically watered down yellow glue. Like 6-8 parts water to glue brush it on let dry (it will look pasty white when dry) lightly sand (220-400 Grit) to smooth then repeat one more time sand smooth again (be careful not to sand through) and then paint. As for trim choose what you want to use cut it then same width as the top is thick and glue and nail (I used brads) to the MDF, as noted above, MDF is thirsty an even more so on the edges, so make sure you heavily glue size the edges have don't worry so much about sanding it. Down the road when you have completed finishing a project with a oil, take the rag/brush and work out the excess on the trim.

Take a look at my Miter Bench ….. I used Maple as that is the trim I have used on all of my benches.

 

Another way to prevent chips would be to route your edges with a round over bit.

 

Robin, I used MDF on my bench recently. Considering the cost and ease of construction and just starting out I am very pleased. I finished mine with 3 coats of Minwax Polycrylic and then paste wax. It a little slick, but, nice to keep glue off. I use a rubber mesh pad or bench hooks when sanding, routing or planing. Anyhow works for me and makes a nice little bench for my small shop.

 

I have my MDF bench top mounted on top of 1-1/8 sub floor plywood with screws (slightly recessed) and that combination makes for a solid bench top. It has no edge protection and I have no problem with chipping although Dennis's idea of rounding the edges sounds good.
I sealed it with two coats of Varathane because that is what I had on hand and it had been around the shop to long to trust using it on a cabinet or furniture piece. It worked quite well. When the MDF gets messed up I just pull it off the plywood base and put a new piece on. After 10+ years the MDF is just about ready to be change (-;
On other work tops I have used 1/4" tempered masonite over a plywood base held in place with small finishing nails and when the masonite gets scarred up I just put on a new piece.
It beats worrying about damaging an expensive laminated maple top and works just as well for me.

 

I don't finish at all, when it gets damaged I just turn it over and have a clean place to work. Then when that wears out, resaw it for other projects and put another piece on.

 

All good tips! Thanks everyone! I'm 6'2" and the bench is < 3' high, < 2 1/2' deep and only 54" long (not counting top size) so I am already planning up my 2nd bench . Given the chances that it will be come a storage platform… I think I am going to go with the routed edges and basic finishing on top. The key advice above is why I went with MDF… for the $$$ of it… don't care if once a year I have to replace the top .

Cheers,
R.

 

For my last bench I did this:

1) Two layers 3/4 MDF. Lots of 1-1/4 screws acting as clamps to hold the pieces together as the glue set. See the video over at FineWoodworking on getting started and building a bench for ideas.

2) Cut up some poplar to make edging for the top. To keep it aligned while the glue set (and lots of glue, the edge of the MDF will just drink it in) I pre-drilled for small 1-1/2 finish nails every foot or so and used them to pin the edge. Clamps and scrap the squeeze-out after an hour.

3) Sealed the MDF with lots and lots of inexpensive sanding sealer. Happens to be a store up the road from me that buys old and shipping damaged stock then just puts it out on the shelf for pennies on the dollar. Can't remember the brand but it was "in date" just dented. Got a couple quart cans and a cheap brush and went to town. Sanded down with 100 and 150 between. I think 2 coats for the bottom side and 4 for the top with a liberal application on the edging too.

4) 220 for last sanding then waxed the top with Johnson's Paste wax. Glue, etc pretty much just pops off.

After a year, it is about time to sand and re-seal just to clean it up. A few dings but then it is a workbench after all!

 

Myself, I don't worry about sealing and edging - the top is disposable. The top of my bench is 3/4" MDF, and when it gets badly bunged up I'll cut out whatever portion I think can be recycled and toss the rest.

 

I wouldnt worry about finishing it , nor edging it… just use it as is, less work for you.. and when it's beat up to the point it won't take it any more - just replace the top.

my guess is - you won't be replacing that top anytime soon… so like I said - nothing really to worry about, or lose sleep over. you'll probably get better ideas and built a better bench way before that top will become obsolete.

 

Robin,
MDF is an extreemly stable sub structure if well supported (a torsion box works well). However, before placing an edging around it, cover it w/ 1/8" masonite (finish nailed down) and bring your edging up flush. Now coat the entire surface with paste wax and buff. The wax doesn't allow glue to penetrate so it scrapes off easily.
After a few years of abuse, the masonite can be removed and the nails pulled an it is ready to be replaced without destroying your torsion box.
Good luck, Kimball

 

Hey Kimball, please describe what a torsion box is or does. I've never heard of it.

Robin, Don't know too much about MDF but I used it in a small garage workbench over a year ago and it's pretty much like the day I put it in. My Woodshop bench top is a solid core door I got from salvage because it was damaged and unuseable as an office door.

Good Luck and welcome to LumberJocks!!!

 

I just keep adding more Johnsons paste wax! Maple edge!

http://lumberjocks.com/projects/14133

 

Hi Thelt,
Simply put, a torsion box is a double layer of sheetgoods (in this case 3/4" MDF) seperated and held together by a glued and nailed gridwork of, say, 3/4" x 2" pine or other inexpensive wood. When all pieces are cured, they act in concert to support each other and distribute loads across the entire box giving it unbelievable strength and flatness.
Kimball

 

heres a video on torsion box's by non other then our very own wood whiperer torsion box's are extreamly ridgid and heavy duty. mater of fact i read in fine working onceabout a guy who builds these as a sort of floating shelf in the artical he joked that if you wanted to sell the self youd have to buy the house it was attched to.

http://thewoodwhisperer.com/episode-18-assembly-table-torsion-box/

ps by far one of the bes ways other then solid wood to build a bench top

 

I used two sheets of mdf for the top, the top one floating to it can be flipped over when it gets damaged. I faced the edges with doug fir that i ripped from 2/4s. and then rounded over the frame with a router.