fixing vices to mdf benchtop?

[Tom Lauder]

hi all

I am putting togerther a basic bench in an effort to learn how to use some of the hand tools I have accumulated.

I am using torsion boxes on edge for a base and have decided to deviate from the plans by using laminated mdf for the top rather than another torsion box.

My question relates to how I go abou fixing things to the MDF top, I am hoping to replicate the split top as recently shown in Popular Woodworking with the twin screw front vise and a record or similiar as an end vise. I cant afford the lee valley twin screw kit at the moment so I was intending to use 2 lee valley tail vise screws to achive a similiar thing. I accept they won't be linked but thats for the next bench.

I think I will need a deep skirt in the area of the front vise in order to fix the screws to a vertical face? Is this right? How wil the mdf take screws or lag bolts for the record? Should I put solid wood or ply in the lamination in areas where the fixings will be? or will a piece of 2x12 glued and screwed to the underside be ok?

Many thanks
Tom

[glenn bradley]

My top is 4 sheets of 3/4" MDF. After much thought and trepidation the repeated experience of others led me to just run 5/16" lag screws up from the bottom. I eased my stress by telling myself I could always back them out and sink threaded inserts if they failed. They have not shown any sign of distress. Four lags in each 10" wide by 12 deep vise; front vise and end vise.

Here's a pic before all dog holes were complete but you get the idea: http://www.sawmillcreek.org/attachment.php?attachmentid=65687&d=1180753948

[Tom Lauder]

many thanks Glenn thats good to know. As an aside what did you finish your top with?

thanks
Tom

[mike roe]

my bench looks just like Glenns - 3 sheets of MDF and the vise is held on with 4 lag screws - no problem - the screws are really course and when getting them in I really felt them bite.