MDF top - How to attach hardwood edging

[bookleaf]

I started a new bench for myself some time ago comprising 3 layers of 18mm MDF glued together (very heavy but lift able - just). I have since put a coating of Poly/BLO over all sides.
To date I have not made a base for it, it just rests on a couple of trestles for now but as I am limited for space I have to shift everything a couple of metres out to the path/lawn. This has shown the need for some more durable edging.

I have 12mm hardwood available for the task, but how do I attach it to the "edge grain" of the MDF without the MDF splitting/bulging if I use screws? Gluing would seem to be out of the question due to the lacquered edges.

Any advice welcomed.

[LanceC]

I have glued with PVA and held in place whilst drying with panel pins. It works well and has stood the test of time on multiple tops.

What's to stop you planing/cutting the edges back a couple of milometers to allow a fresh edge for gluing?

[Mountain Ash]

Hi BL. MDF will take screws fine as long as you pre drill and use the right screw. I have had no trouble with chip board screws. You could also rough up finish on edge with coarse sandpaper ang glue should stick, especially in conjunction with screws.

[China]

No need for screws sand the finish off and just glue and nail.

[mature one]

if using screws on mdf edge use clamps at each screw point to stop any splitting it works a treat

[woodPixel]

100% on all advice here so far.

Simply sand the BLO off, or trim the edge with a saw and track (even home made is fine).

Screws hold EXTREMELY well in MDF if the hole is pre-drilled for the size.


But, it wont be needed. Simply use glue. It will stick like crazy. A few pins to hold while it dries is all you need.

If you can, leave a little lip above the benchtop and plane (or sand) it flat. Getting it dead flat is impossible during a glueup, so a small lip ensures getting it even later is easy.



On screws in MDF while doing tricky glueups, which I've done a LOT, I found this style of gyprock screws does a great job. Notice how the neck diameter is the same as the body, but the threads skirts stick out beyond the neck? This ensures the single hole you drill in both the edging and MDF align and the edging screws up hard against the surface. Bloody excellent screws.

I see no reason to leave them in once the glue is dry however.... take them out, dowel the hole.... trim, sand and done :)

507011

[Siggykc]

Screws hold EXTREMELY well in MDF if the hole is pre-drilled for the size.



I Concur,

Because I am an engineer, i like having backups for backups of backups haha.

So a chemical fastener - glue, followed by a mechanical fastener - screws (perhaps every 200mm or so) would be plenty strong enough.

As for what glue, anything really. If you use an expanding glue like polyurethane, I would use cauls at first to give even clamping pressure to stop the force of the glue as it expands from causing your edging to pop up in areas.


Best of luck with it mate!

Siggy

[rustynail]

Sanding off the BLO should be interesting. MDF soaks it in like a sponge.

[GraemeCook]

... Because I am an engineer, i like having backups for backups of backups haha.

So a chemical fastener - glue, followed by a mechanical fastener - screws (perhaps every 200mm or so) would be plenty strong enough. ...

Why take short cuts? Do it properly and add a sliding dovetail!

[Siggykc]

Do it properly and add a sliding dovetail!

Haha absolutely!

[Camelot]

I made some panelled doors years ago using 3 layers of MDF the outer 2 layers had the shape of the panel cut out before gluing. I knew that I was going to edge them with hardwood from the start, so I set the middle layer back by 10mm this increased the surface gluing area for the edging piece and made it look like a "T" section when looking at the end of it. So if you want extra strength you could router out the middle piece of MDF and do what I did.

[China]

Sorry, complete waste of time unless you are gluing a T-piece onto it