MDF router table top, what to finish with?

[Dissolve]

Hello,

My latest addition to the workshop is going to be a simple 2 metre long 36mm thick mdf bench for soldering and inlay work to keep space free on the woodworking bench.

I am violating one side of the "legs" as a yankee style router table stand just to add some drawers and storage space underneath. I will then be recessing my insert plate into the top and using it as a router table.

Hoping the mdf stays flat enough throughout the next few months, should I cover the top with anything? And should I finish the mdf in some varnish then sand smooth for a good router table surface/mixture protection for the mdf?

 

[Steve Maskery]

By far your best bet is to cover the top with a plastic laminate like Formica. It's almost indestructible as a surface and has good slick properties.
If that is not an option, a few coats coats of polyurethane varnish would be better than nothing. But the surface of MDF is not really very robust on its own. OK for a work surface, I suppose, but poor for a surface where sliding is the name of the game. It has too high a coefficient of friction.
S

 

[Myfordman]

B&Q used to sell suitable sized sheets of formica like laminate for use with their various fireplace kits. I've not looked for a while as I bought one for a round-2-it completion of my router table a while back and it is 'maturing' whilst the inclination strikes me to use it.

There are not many things that I would suggest anyone went to B&Q for but this might just be one.

 

[custard]

Hoping the mdf stays flat enough throughout the next few months, should I cover the top with anything? And should I finish the mdf in some varnish then sand smooth for a good router table surface/mixture protection for the mdf?

Hello Cheerup, MDF is notoriously "saggy". You can estimate the amount of sag you'll get using this,

http://www.woodbin.com/calcs/sagulator.htm

While I think the calculations are pretty accurate for the initial amount of deflection, I've found that MDF gets saggier with age (don't we all!). If you can include transverse bearers into your bench design to offer some additional support from below that would help a lot. Just a thought, unless the workpiece has a dead flat passage, both into and out of the router cutter, you get uneven depths on rebates and all sorts of frustrations.

 

[Steve Maskery]

Good point Custard.
If I were making an MDF top that thick, I'd laminate 3 x 12mm pieces in a vac bag, on the flattest surface I could.
S

 

[Dissolve]

Thanks guys! Is the Formica stuff like plastic covered mdf or more like a laminated chipboard worktop?

I'll take a trip to b&q tomorrow to see what they have, but I'm wondering if anyone could pint
me in the direction of other sources of Formica(type) offerings that would be more suitable for a router table.

I'm not one hundred percent set on the design if my table/stand yet, what sort of support would you recommend underneath the top to prevent sagging as far as possible?

 

[Steve Maskery]

Personally I think that Norm's design, available from any Brimarc retailer, is difficult to beat. Obviously you'd have to modify it for a 2m run, but the construction is straightforward and the support is excellent - the unsupported distances are really quite short.
S

 

[paul saunders]

Just get 2m length of kitchen worktop, cut off the bull nosing and put a 25mm oak lipping all the way around it. :wink:

 

[Dissolve]

Thanks guys! I'm going to do the rounds later and try and find some cheap worktop, Will any kitchen (Chipboard laminate) be suitable if it has a slick/smooth surface?

I'd like to find something plain white or black like the aforementioned Formica type stuff but I can't find it anywhere aside from expensive kitchen supply places.

Did B&Q sell this laminate type material as kitchen worktop or fireplace materials?

 

[Random Orbital Bob]

Actually B&Q near me have an offcuts bin and a damaged goods section. Usually this has kitchen worktop in odd lengths in it going really cheap. Any kitchen worktop will probably do because it's very thick, very stable and almost certainly has a laminated slick top, ideal for router table use. The only snag is if it's the 40mm stuff the thickness may be prohibitively deep for router use ie the bit wont extend much beyond the top of the table, maybe even only level with it. You can get collet extensions but they reduce the safe diameter bit size and introduce more vibration.

So don't go bigger than 30mm deep if you can.

 

[Paul Chapman]

The only snag is if it's the 40mm stuff the thickness may be prohibitively deep for router use ie the bit wont extend much beyond the top of the table, maybe even only level with it.

But he said in his first post that he's going to use an insert plate, so the thickness of the top doesn't matter - it can be as thick as he likes.

Cheers :wink:

Paul

 

[CaptainBarnacles]

I made my first router table from a piece of kitchen worktop and it worked OK but I found that the chipboard swelled a bit where it had been cut out for the router insert. I should probably have sealed it up silicone or something but I didn't and I ended up with a slightly wobbly surface. You live and learn!

My second attempt was made from MDF with a sheet of plastic laminate bonded to the top. This one worked nicely but did sag a bit. I fixed it by screwing a hardwood baton along the underside of the table - sorted.

I had to make a third table when we moved back to the UK and left my old table behind. This time I glued two sheets of 18mm MDF together and screwed a couple of batons along the underside of the table. I also cut a slot in the top and fitted a Kreg Combo Trak which gave even more rigidity and works really nicely for jigs etc. Currently it's just bare MDF on the top but I do want to add some plastic laminate again. As Steve pointed out Formica has a much lower coefficient of friction than MDF and in use my table is a bit jerky as I have to overcome the slight stickiness of the MDF.

 

[paul saunders]

Sand it smooth with some 600 wet &dry and then give it a couple of coats of briwax or similar. :wink:

 

[Graham Orm]

If you glue Formica or any other finishing sheet to one side you MUST glue it to the other side or it will warp.

 

[Dissolve]

If you glue Formica or any other finishing sheet to one side you MUST glue it to the other side or it will warp.

Thanks! Would this apply to already laminated kitchen worktop? If I were to stick a formica veneer onto an already glossy kithcen worktop would it still react differently with formica on just the top?

What would you use to seal the recess/hole cut out for the insert plate? Some sort of glue/varnish to protect against moisture?

 

[Graham Orm]

If you glue Formica or any other finishing sheet to one side you MUST glue it to the other side or it will warp.

Thanks! Would this apply to already laminated kitchen worktop? If I were to stick a formica veneer onto an already glossy kithcen worktop would it still react differently with formica on just the top?

What would you use to seal the recess/hole cut out for the insert plate? Some sort of glue/varnish to protect against moisture?

Not sure about double laminating a worktop but don't be fooled by the thickness, if not supported properly it will sag. Seal edges with gloss paint or varnish.

 

[Dissolve]

If you glue Formica or any other finishing sheet to one side you MUST glue it to the other side or it will warp.

Thanks! Would this apply to already laminated kitchen worktop? If I were to stick a formica veneer onto an already glossy kithcen worktop would it still react differently with formica on just the top?

What would you use to seal the recess/hole cut out for the insert plate? Some sort of glue/varnish to protect against moisture?

Not sure about double laminating a worktop but don't be fooled by the thickness, if not supported properly it will sag. Seal edges with gloss paint or varnish.

That's fine I think I'll start by getting an offcut and keep an upgrade in mind for future! How would you recommend supporting a 40mm worktop, I'm thinking of placing battons running just clear of the insert plate, either using hardwood or leftover ply, I'm not sure if there's a better idea for supporting the top closer to the center?

 

[Graham Orm]

That's fine I think I'll start by getting an offcut and keep an upgrade in mind for future! How would you recommend supporting a 40mm worktop, I'm thinking of placing battons running just clear of the insert plate, either using hardwood or leftover ply, I'm not sure if there's a better idea for supporting the top closer to the center?

That's probably all you can do, it'll be fine for a while. If you can, remember to wedge the router when not in use so that the weight isn't permanently pulling down. I do it with mine.