Work Bench

I have built my workbench from scratch buying all the materials new from a local hardware merchant. I have found that my design while ok has not been sufficiently stiff to prevent the main table supports from sagging under their own weight. If I was to do it again I would build the bench like the one I saw at a local aircraft workshop. They had used dressed 100mm x 100mm (4"x4") posts for each corner with 250mm x 25mm (10" x 1") dressed support beams down each side rebated into the 100 x 100 posts and using dressed 100mm x 50mm (4"x2") framing timber rebated into each post at the bottom of the leg. I would also have used 25mm mdf for the bench top. I think this would stop any sagging and movement of the timber. My bench design is ok but I will just have to keep monitoring if for movement and/or sagging.

Date Started   : 06 July 2008
Date Completed : 14 September 2008
Effort         : 25 hours
Fitout Cost    : $657.00

Sunday 06 July 2008 - 2hrs
Purchased framing timber for the workbench from local timber supplier and made a start on cutting and rebating the 4x4 posts for the legs. My intention is to build the bench to the size of 2 standard sheets of MDF butted end to end. ie 1220mm x 4880mm.

Saturday 12 July 2008 - 6hrs
Visited local timber merchant to buy 16mm MDF sheets for bench top. Cost $55 per sheet. Once I carted this lot home I got stuck into finishng off the bench framework. Spent considerable time getting everything as level as possible.

Sunday 13 July 2008 - 9hrs
Finished off the framework and attached the MDF sheets. Note that I ended up shortening the MDF sheets to 2400mm as the longest length of framing timber was about 50mm short of the 4880mm required. The bench will now be 1220mm x 4800mm. I pre sealed the MDF sheets with urenthane to stop them absorbing moisture. I haven't coated the top working surface yet but will do this once the bench is completed. I checked the level of the table using my 1.8m spirit level and spent about an hour shimming the top surface to get it as flat as I could. Pretty pleased with progress.

Monday 14 July 2008 - 2hrs
Decided to check the level of the entire table using a laser this evening and found that the center of the table was some 5mm lower than each end. Not quite sure how I managed to do this but I ended up taking off the top MDF sheets and pulling apart some of the framing so I could adjust the frame to correct the error. Reattached the MDF sheets and checked everything for level and square. Much better result. Did not have to shim anything. Very glad I checked the table with the laser. Here is the finished table. Weighs a ton but I am happy with it. I spent a bit more money on it than I wanted but it should do the job.
Sunday 03 August 2008 - 2hrs
Checked level of the table and found the right side of the bench had sagged a little in the middle. Had to shim the bench top to get it level again. Will no doubt have to check the level of the bench from time to time going forward.

Sunday 14 Sept 2008 - 4hrs
Checked table once again and found that the main beams had sagged about 3-4mm in the centre of each beam. Used some 3 ply strips to reinforce the beams after using a car jack to lift and straighten them. Then used digital spirit level to check all levels and spent about 3 hours shimming and adjusting the surfaces. Most are perfectly level (0.00 degrees) however a couple show angles of 0.05 degrees which amounts to approx 1mm over the length of the 1800mm spirit level. I have also inserted some temporary supports under the centre of the beams to (hopefully) stop them sagging again. The photo was taken a couple of weekends later to show you what I have done.
Saturday 1 Nov 2008 - 4hrs
Checked table and found that the benchtop had sagged about 1-2mm between each cross beam. Used some 25mm x 75mm dressed pine to put in two rows of supports down the middle of the bench. Refitted tabletop. Better but not perfect.

Sunday 9 Nov 2008 - 4hrs
Purchased two sheets of 18mm MDF and fitted these to the top of bench under existing benchtop. Had to re-level the bench to get it all straight. Much improved.