Dumb question about MDF

[rusty105]

Ok , I have a stupid question about MDF (medium density fiber board) it looks like I am going to use 3/4" MDF for my bench, it's about $25 a sheet at Home Depot (in NY). And before I look stupid taking a caliper in to Home Depot to measure the 'real' thickness of 3/4" MDF, is it really .75" thick, or is it off a tiny bit like ply wood??

Thanks

[Thomas Vaught]

I guess I am stupid too, as many time I take a dial caliper to places
where I shop. Usually I wind up only making one trip though vs the people who don't take measuring instruments or the old part and then
make multiple trips.

I am trying to figure out how to dado MDF to a hardwood edge so that
when you use screws, the screws do not pull out as easily under a load.

Tom V.

[rusty105]

I was just trying to avoid the strange look the sales associate would give me for measuring 3/4" MDF, they would say it is what it is 3/4". The HD by me has a lot of inexperienced help, they mean well and all, but the sign says '3/4" MDF'. I guess I will have to take that plastic caliper with me next time. Don't feel like accidentally leaving a good one behind.

[MMack]

A guy I work with who does wood all the time told me that there are special screws for MDF that work better than other screws. I didn't get any additional info but he said that there is a website that he buys specialty fasteners from.

Mike

[bruce]

Walk over to the area where they keep the tape measures, pick one up and carry it over to the MDF, measure your thickness, carry tape back to it's sales location . . . I've done that a few times at the local hardware store. Or ask a sales associate to borrow his tape measure.

You should see the looks you get while standing in the plumbing area looking at the fitting trying to engineer something in your head and the sales clerk asks you what it's for and you blurt out something they have no clue of . . . I tell them I'm going to machine such and such a part and I need a peice of PVC that would work for my raw stock. I think some of them have no clue that "people" actually machine parts?

Now they see me coming and don't even ask anymore at the local hardware store . . . all in the name of R&D!

[rusty105]

[rusty105]

OK I stopped at Home Depot last night on the way home from work and measured some MDF. YEP !! 3/4" MDF actually is 3/4" thick as well as the 1/2" is really 1/2". AND it is also 49" x 97" instead of 48" x 96" like plywood is. This is handy when you need 2 48"x48" pieces cut from one sheet.This is refreshing. Anyway I also started to look at what they have in the way of PVC and assorted fittings, they seem to be a little lacking in the way of flanges for PVC, might have to stop at a plumbing supply, or try Lowes Home Supply.

[200cfm]

Make sure it never gets wet from water or moisture. If I were to use it again for a bench I would prime the pieces first then bolt the pieces down.

[rusty105]

[200cfm]

I used latex as the primer and final coat. The board soaks it up so several coats of primer will be needed.

[Griffin]

Use the rattle cans of Kilz oil based primer for MDF. The Latex stuff just seems to soak into it. (The oil based does too but not as bad) Do NOT use regular oil absed paint though - use quick dry rattle cans or you will be waiting 3 weeks to assemble the bench.

Better yet follow Bruce's lead and just build the whole #### thing out of PVC - If I had it to do over thats what I would do.

[Tony]

Save yourself some real long term grief, use quarter inch bolts and a welded steel angle frame.

As far as sealing goes, pink wood primer, clear estaopol, or marine varnish. Almost anything will work, depending on the final desired appearance.