Vise makes benchtop sag...help?

[Dan Forman]

A week or so after mounting a Jorgenson 7" vise as an end vise, much to my chagrin I detected a bit of sag, around 1/16" at the end of the bench. The other end is still true. The bench top is a solid (particalboard) core door, which extends 14" past the bech frame. It can be seen here sans vise. http://sawmillcreek.org/showthread.php?t=22270

After removing the vise, the deflection is down to about 1/32". I'll measure it again tomorrow and see if improves any. My question is, what would be the best way to deal with this? I will be applying an apron of maple that's about 5/8 thick and the same height as the top plus the 1/2" MDF cover that is not in the picture either (total about 2"). Don't know if that will be enough to prevent sag or not. Thought about mounting a 2x4 along the upper rail extending past the frame and out to the vise (mounted on the right end near the edge). If the top doesn't fully rebound, I'm not sure how much good that would do. A fifth leg on the corner might be another possibility if there was a mechanism to jack it up to level the top, maybe a pair of wedges.

Has anyone out there ever had this problem, or have any ideas as to the best way to handle this?

[Donnie Raines]

The top of my first bench was constructed just like yours...I too experienced the sag. I "made" two support legs(much like a table saw with the wide extension wing). That worked well...but the legs did get in the way when I was trying to get in the right postion to makes cuts or whatever.

Of coarse the real fix is to make beefier top....

[Roger Wilson]

I agree with Donnie. Add brackets to support the cantilevered end. Look at these from Lee Valley:


http://www.leevalley.com/wood/page.a...57&cat=1,43326

[Phil Phelps]

MDF, particle board. Just not enough integrity for those applications. I have some 1 1/2" x 34" x 60"MDF that were used for drafting tables that sag under thier own weight. My shop tables are 60" x 144" x 1 1/2" MDF. But my frame is made of 2x6's YP. Make a hardwood frame for you particle board top.