Replies

1. 
   HowardAcheson | Oct 29, 2009 11:37pm | #1

   Let me suggest that MDF alone has some negatives as a bench top. Probably the most important is that is is easily crushed by hammer or other blows. Dings along the edges will chip off the edge.

   An easy solution is to make a top sheet from 1/4" hardboard (masonite). Make it the size of the top and attach it with some thin doubles sided carpet tape of some contact cement. Hardboard makes an excellent top for a MDF workbench top.

   As to finish, I prefer an oil/varnish mixture. You don't want a film finish as it will quickly get banged up chip off. Mix equal parts of your favorite varnish or poly varnish, boiled linseed oil and mineral spirits. Apply thickly and let it soak in over night. Add another coat the next day. The second coat will not soak in as much so wipe off any excess after letting it set for 15 minutes. Let is dry for two days and then apply a coat of furniture paste wax. The wax will prevent glue from sticking to the surface and will make the surface easier to clean.

   Re-treat whenever the surface begins to get grungy.

   Howie.........
1. 
   kuni_nzuri | Oct 30, 2009 07:08pm | #5

   The hardboard sounds like a good idea. And since I haven't yet trimmed the vice jaws, I won't have to redo those.
   Thanks!

2. 
   xmike | Oct 30, 2009 01:09am | #2

   I have an MDF top on my bench and will someday replace it with a wood one as well.

   I finish mine with thinned (1# cut) shellac which soaks in and stabilizes the surface somewhat. I recommend against waxing it as you want the top to hold things in place and wax makes that much harder.

   One downside of MDF is that it sags over time around what ever frame you have under it. Not much, but enough to screw you up when planing a board or panel flat a year or so into the life of the top.

   However, you won't even notice this effect if you only use power tools, since it's slight.

1. 
   mikeddd | Oct 30, 2009 05:41am | #3

   Mike:

   One downside of MDF is that it sags over time around what ever frame you have under it. Not much, but enough to screw you up when planing a board or panel flat a year or so into the life of the top.

    Yes mine is three sheets of 3/4" and still sagged slightly, oh well live and learn my next one will be wood.

   Mike

1. 
   kuni_nzuri | Oct 30, 2009 07:03pm | #4

   Thanks for answering my next question. My top is two sheets of 3/4 in. MDF, 24"x62" (glued and screwed together). So unless yours is significantly larger, I guess I can expect sag. Maybe I'll add another support mid-run.

1. 
   xmike | Oct 30, 2009 10:48pm | #6

   Mine is also two 3/4" sheets, glued and screwed together. The top is 30" by 72". The dips appeared between the outside rails and the center rail after about a year of use. I planed them out (I removed the screws first). They're coming back. Oh, well.P.S. The 1/8" or 1/4" hardboard will sag along with the mdf.

   Edited 10/30/2009 3:50 pm ET by Mike_D

2. 
   mikeddd | Oct 31, 2009 06:27am | #7

     My next project after the bench I have now was a King Size Bed so the top on mine is 32"x72" so a bit larger than the one your working on, three sheets of 3/4" MDF glued and screwed, it also sagged in between the frame, like Mike D said in an earlier post for working with power tools you would never notice, but when hand planing it doesn't help. (and I can use all the help I can get) You have a great day.

   Mike

3. 
   SARGEgrinder47 | Nov 06, 2009 01:10am | #16

   "Thanks for answering my next question. My top is two sheets of 3/4 in. MDF, 24"x62" (glued and screwed together). So unless yours is significantly larger, I guess I can expect sag. Maybe I'll add another support mid-run".. Kuni

   You can indeed add another support mid-run. I do it on every bench I build and mine have 3" thick face glued tops. I simply run a beam the lenght of the bench between each end stretcher and tie it into the end stretcher itself with a bridle joint. That will cut the unsupported area in half as the center of the top will be divided by that beam or what I call a "whale-back" beam.

   And... for a bonus, it locks your entire base in before the top is even added which increases diagonal support to avoid any rack of the base when exerting force in any direction on top.

   If you are not clear here and need a picture of a "whale-back" beam.. let me know and I will get one posted.

   Good luck...

    Sarge..

   Woodworkers' Guild of Georgia

3. 
   tonyrays | Nov 01, 2009 06:29pm | #8

   I use Titebond III thinned down about 60 water to 40 glue. Brush on and let this soak in and recoat if you want. I have tested this with unfinished mdf and found that even soaking in a sink of water it is still waterproof. I put it in a sink with a piece that was not treated and after about two days the 7/8 mdf that was not treated was over an inch thick on the edges and the treated piece wiped off dry with a rag.

   tony

4. 
   Don01 | Nov 02, 2009 06:24pm | #9

   So if you are going to use it for more than 1 year, get a 3/4" sheet of almost any G1S plywood, cut in half and use.
   Why have the frustration for a few dollars.

   Don

1. 
   kuni_nzuri | Nov 03, 2009 08:45pm | #10

   That probably makes sense. I started down the MDF road because I had enough on hand and transporting large sheet goods is difficult for me. Maybe I can borrow a truck.Thanks!

1. 
   xmike | Nov 03, 2009 09:26pm | #11

   Have your supplier make two cuts for you on his panel saw to your top's dimensions - then easy to transport.

1. 
   kuni_nzuri | Nov 03, 2009 09:44pm | #12

   Not on a motorcycle!
   (temporary situation)

1. 
   Jammersix | Nov 04, 2009 12:00am | #13

   The experts here have a thread running about hauling wood in a car.I sense another thread starting...

2. 
   xmike | Nov 04, 2009 03:47am | #14

   I'm sure that you've seen the pictures from Asia showing just how much stuff can and is hauled by motorcycle :)Back in the day my only transportation was a lowly Lambretta motor scooter - how ignomious - not even a proper motorcycle. I can tell you that the sail effect of a piece of plywood strapped to your back - or anywhere on the bike - is just exciting.Maybe you should wait for a new pickup truck.

3. 
   kuni_nzuri | Nov 05, 2009 08:34pm | #15

   Yes, I do a lot of work in Africa and have seen amazing loads on motorbikes (also on small pickups. And on women's backs and heads, for that matter). I'm building a carrier to attach to my car's roof rack.