Planning a workbench - questions about MDF and other things.

[BigShot]

Hi folks,

Well, the time has finally come to start planning my first workbench. There's one rather hefty drawback though, I don't have any real budget to speak of.

I do, however, have a nearly limitless supply of free MDF in (roughly) 1200x800 sheets. It's mostly about 15-18mm thick. It comes from a kitchen manufacturer which would rather give it away than sling it.

Apart from the logistics (it's first come, first served... no reservations... no idea what they actually have in stock till you get there... but whatever you can carry away is yours... and it's about a 15 minute drive away) it struck me that this might be the perfect way to get a bench together on my practically-zero budget.

Herein lie the questions.

If I was to cut 15mm MDF into 90mmx1200mm strips and then glue and clamp 6 strips together to make a 6-ply 90mmx90mmx1200mm block - would that be suitable to use as a leg for the bench? (Repeat 3 times for a complete set, of course.)

Is there anything I would need do to other than gluing face to face? Biscuits? Dowels? Screws? Obviously I wouldn't want the bits to start coming apart at any point so if anything is needed to improve the integrity of the legs I would like to do that.

My "workshop" is the garage, and there will be some humidity issues in there until I find the funds for a dehumidifier - will I need to seal the MDF in any way? If so, what with?

Finally, if I do glue up MDF in this way, is it then likely to be suitable for traditional joints like mortise and tenons, half laps and dowel techniques like drawbore?
(I don't want to give the impression I'm in anyway experienced with woodworking by using those terms, I know what they are but have made a grand total of ZERO joints using them... well, there were some half laps on a rubber band powered plane I made from a kit as a kid - but I'm not counting that here.)

I'm not really concerned with looks, though I do think well made, sturdy things tend to look quite good almost by default, but I do want something functional.
A flat, stable surface to work on, a decent size, storage underneath for grinders, bench drill, maybe a table saw... things like that.
I'm not so much asking about plans here (though if someone has any suggestions I'll be glad to hear them - I'll be using the bench to make furniture, shelves, a desk or two, and garden stuff such as planters and the likes) as I'm asking about the sense in using MDF like that.

I look forwards to any responses you come up with.

Cheers folks.

 

[pren]

Hi.

There was a thread on here a while back about a workbench made entirely from plywood sheeting. I've had a quick search but can't seem to find it.

The mortice & tennons were made by joining layers of ply together in the way you mentioned and leaving a gap in the center layer to make the mortice. Tennons were formed by leaving the center layer sticking out on the corresponding rail section.

I don't see why a bench made in this way with MDF wouldn't work.

Finishing wise: I'd coat the finished sections in a mixture of PVA and water, sand flat then coat in a clear varnish like yacht varnish or Rustins Plastic coat.

Just my thoughts!

Cheers,
Bryn

 

[RogerS]

Someone is going to come along and tell me I'm wrong but my initial reaction is that the inherent structural strength of MDF is all in the wrong place if you get my drift and it won't work for the legs. Ply can work because you're alternating the wood fibres (and strength) in different directions. A good top made from several layers of MDF prepared the way you're suggesting would work however.

 

[lurker]

There is no benefit in cutting into strips & "plying" as there is no grain to utilise

It would make a good top just sticking four of those boards together and edging them with some real wood.

I'd then look out for some reclaimable wood for the rest of the frame.
Find a window replacement /conservatory outfit & ask for access to their skip - works for me :wink:

 

[Karl]

BS - check out my workbench thread here. May provide some ideas.

You will see that my bench has two kitchen carcasses as the base, and an MDF top. It'sbeen in for 18 months now, an is rock solid. Surprisingly, there is no racking, which was something I expected to happen.

Cheers

Karl

 

[Paul Chapman]

No reason why you couldn't laminate strips together to make the legs, although personally I would rather use softwood. The main problem would be to ensure that it didn't get wet (like if you parked your car in the garage and it was covered in snow and it melted and made the bottom of the legs wet, for example). I'd glue them together using biscuits and water-resistant glue.

Forget about traditional joints with MDF - I favour this sort of knock-down fitting, with cross dowels and bolts http://www.woodfit.com/product_info.php ... +30mm+long

If you go with MDF for the legs, I'd varnish them well with a traditional (not water-based) varnish.

You don't mention the top - MDF is fine for that in my experience. Here's mine (three layers of 18mm MDF, lipped with softwood)

Cheers :wink:

Paul

 

[woodbloke]

Having seen Paul's bench I'd agree that mdf makes a good top (even better if it's free and gratis) but I reckon your idea about fabricating the legs from the same stuff is not so good. Even thick mdf legs under compression would tend to bow and as Paul has said, if they ever got wet the stuff goes mushy instantly (well...almost) Better to use some reasonable quality pine for the framework and joint it together - Rob

 

[wizer]

My bench is made out of ply. The top is a sandwich of 2 layers of 18mm Ply between 2 sheets of 9mm MR MDF, wrapped with softwood. This is how we ensured the top remained flat and solid:

The top is replaceable.

I reckon your idea of laminating mdf for the legs would be absolutely fine. Just make sure you apply a finish to them and use the MR stuff.

 

[BigShot]

Exactly the kinds of responses I was hoping for!
Thanks all (and keep them coming if anyone else has a spare oar to stick)...


Having read a few other things about bench tops I had already decided to go with an MDF top, hence no mention. I suppose maybe I should have said something for completeness, but yes, I do intend to make the top from MDF (and probably a sacrificial MDF top too because "why not?")


Wizer
That detail is about as explicit as they come, thanks a lot for posting it.
Thinking along my other sure sources of free material, what would you make of chipboard as opposed to ply for the core of the top? I'm guessing it won't have the resistance to sagging that Ply might have, but I am only guessing.

Can I ask though, how do you attach the softwood edges? I believe screws into the edge of ply can be a bit hit and miss (though I think I saw some way of putting a dowel through ply and then pilot drilling the end and screwing into the dowel - I might have imagined it though). Or is it just clued on? Screwed/nailed from above and/or below?


Paul
(Nice Bench by the way)
I've seen those cross dowels before (probably in a bit of Ikea flat-pack I put together for someone once) and though I hadn't thought about using something like that I can see how it would work. I'll give it some thought.


Karl
I'll have a look through your thread now. I can always do with more ideas.


Bryn
I hadn't thought about leaving gaps in the laminate... that's a nice tip.


RogerS, Lurker, Paul and Woodbloke
I'll address all in one here.
Firstly, the only issues with moisture will be general atmospheric humidity (and possibly user-stupidity if I decide to dump a drink on it) There's never going to be a car in here with or without snow, in part because of all the stuff that will be in here and in part because it's actually too small to take a car!
I guess a good sealing should do the job on that front.

As for the structural integrity of MDF for the legs...
I've taken on board what you've said about it not being up to much, and I will see if I can get a load of free wood from skips (Would pallet wood do the job? There's a couple in a skip up the road now I think about it - pretty clean looking too.)
That said - I might make it from MDF and just see what happens. I can always re-make the base in ply, pine or similar if MDF does bow as some have suggested.
It'll cost nothing more than the petrol and glue - and I'll be going there anyway so petrol cost is negligible anyway.


Thanks again for all your replies.

So far I've posted a couple of threads on this forum, read it a few times, and I've got to say, this forum is ace. Helpful to a fault!

I think I'll stick around a while.

 

[wizer]

Just glue for the softwood edging. The fit has to be very tight to do it's job.

AFAIK Chipboard is much more likely to sag than ply.

 

[big soft moose]

bigshot

ive just sent you a pm - if you are with a reasonable drive of me i'd be happy to swap some softwood (or possible hardwood offcuts) suitable for bench legs for a similar ammount of mdf.

 

[BigShot]

BSM - I've sent a reply, we can do the rest by PM if it's going anywhere.
It is a bit of a trek from Manchester to your end of the planet though.

 

[BigShot]

Wizer - I can probably manage a pretty tight fit, at least it will justify the table saw I've still not used!

I didn't think chip would be up to much, but thought I'd ask on the off-chance.

Thanks again.



EDIT
I just read-read your initial response and see you suggested I use moisture-resistant MDF. Unless that's what my source of free MDF has - and I don't see why it would be - I'll be getting bog-standard stuff. Beggars can't be choosers and all that.
If it comes to spending money on materials, I'll get some MR-MDF for the top and some "proper" wood for the rest.