Mounting vise to mdf bench

[Alan Tolchinsky]

Hi All, I need a small bench for my shop and have a torsion box that is made of 1/2" mdf and is 24" X 48". I want to mount a vise I have but I don't feel comfortable screwing into MDF. I'm thinking of screwing and gluing a 3/4" board to the bottom and lag screwing the vise to that. You think that will be strong enough for a vise? Thanks for any ideas.

[Mark Engel]

I have a Sears workbench in my shop that has a 1" thick MDF top. I mounted my 5" vice to that top. I drilled all the way through the top and bolted the vice down using (3) 3/8" x 2" bolts from the top. Under the top I used washers, lock washers and 3/8" nuts. The vice is more stable on the top than the entire bench is on the floor. It has been serving very well for about 8-9 years.

BTW, I got the vice from Harbor Freight, don't tell anyone,

[Alan Tolchinsky]

Mark, If I understand you correctly you have the bolts on the top surface of the bench? Does that get in the way with work? I thought of using a bolt/nut through top to bottom but with 1/2" mdf I didn't think I could counter sink the bolts on the top. I'm looking for a smooth top that I'll cover with hardboard or something more durable than mdf. Thanks for your help.

[Jim Becker]

Some folks actually embed a piece of solid stock or plywood inside of an MDF sandwich to provide a mounting point for a vice. At the very lease countersink so you can use large fender washers under the head of the bolts and do lag into something solid on the bottom as you are thinking about.

[Mark Engel]

Mark, If I understand you correctly you have the bolts on the top surface of the bench? Does that get in the way with work? I thought of using a bolt/nut through top to bottom but with 1/2" mdf I didn't think I could counter sink the bolts on the top. I'm looking for a smooth top that I'll cover with hardboard or something more durable than mdf. Thanks for your help.

My apologies. I misunderstood your query.

I have an industrial style vice that is mounted on the TOP of my workbench. This is NOT a typical woodworking type vice. This is a general purpose, I guess machinists, type vice.

[Alan Tolchinsky]

No problem Mark, I probably didn't explain it adequately. At least my wife always accuses me of this. :)

[glenn bradley]

As Jim states, ideally a solid block would have been built in and sandwiched between the skins to receive the vise fasteners. I sandwiched oak blocks into my four layer MDF bench top so I could just mount the vises from underneath with lag screws.

Even with a block attached to the bottom I would be cautious about how much you lever on the vise once attached. The torsion box is strong for its purpose but, like a hollow core door; doesn't accept objects mounted to it very well. Hmmm, that wasn't any help at all, was it? Sorry.

[Bob Barkto]

Could you route a recess in the underside, almost through to the top and glue in a piece of solid wood?
That should provide a good mount point.

[Alan Tolchinsky]

Thanks guys. This "bench" started out as an outfeed table before I moved my shop. So I didn't think of inserting some hardwood into it so now I'm a little stuck. I think I'll glue and screw some ply to the underside about 5" x 48 and mount to this. If it comes loose the ply will still be supported by the base so I should get some warning. Not the ideal solution but... Maybe I should be wearing steel tip shoes in the shop from now on.. :) Thanks for your ideas here.