Framers Corner PFK04 Frame Joiner review

Framers Corner PFK04
Framers Corner PFK04 unpacked out of the box

One of the key pieces of kit I bought to let me make frames is a frame joiner called the Framers Corner PFK04. It lets you join two sides of the frame using V-nails. Professional framers use a big, expensive piece of gear called an underpinner to do this. The PFK04 is one of the cheaper options at £79. My hope was that it would give me all the quality of a bigger machine but sacrificing productivity. Well, here’s my experience of using it for a short while. I’ve now made about twenty frames in sizes from 30×40 cm to 50×60 cm with mostly good results but that’s not entirely down to the PFK04.

I buy the mouldings for the frame already cut to size and mitred so they only need joining. You join them with a combination of PVA glue and V-nails. The PFK04 is the thing that inserts the V-nails while you apply the glue yourself.

The thing arrived promptly and unpacked easily. It doesn’t take much assembly and that’s mostly obvious. The instructions are fairly clear and there’s a video on YouTube that shows you how to use it. One thing you’ll need is a spanner. There’s a bolt that needs to be removed and replaced with a handle (supplied in the box). Not sure why they don’t ship with the handle attached but there it is. The handle allows the assembly to be moved up and down to cater for different height mouldings.

This bolt needs to be replaced with the handle
This bolt needs undoing and replacing with the supplied handle. You’ll need a spanner, as it’s tight
This is the handle
This is the handle that replaces the bolt the machine is shipped with. It allows adjustment of the assembly for different height mouldings

It all seems satisfyingly heavy and solid, apart from the long rod in the clamp, which is plastic. This seems like a weak point and is a little worrying. Time will tell. Everything else is simple and solid and seems like it will last.

The clamp, with the plastic threaded rod that seems like it might be a weak point
The clamp, with the plastic threaded rod that seems like it might be a weak point

There are two main parts to the machine – the clamp, and the press. The clamp is used to position two sides of the frame together and keep them in place while you then put them under the press to be joined. The clamp is fairly easy and obvious to use but with an obvious flaw. The clamping piece sticks out below the clamp. If you put the clamp on a flat surface, put the frame sides in, you can’t then tighten up the clamp without the whole thing wriggling about on the table top. My work-around for this is to use an L-shaped bit of wood (like two sides of a frame) and put the clamp in the corner of the L. This works OK but is a little annoying and awkward.

Annoying clamp design flaw
The annoying flaw in the clamp design – this bit of plastic means the clamp doesn’t sit flat and can’t easily be tightened.

The advantage of the PFK04 design is that you see the top surface of the mouldings as you join them in the clamp and tighten up. This is important so you can see before you nail that the front surface is (you hope) perfect. Then you tighten up the clamp and it holds the pieces pretty well. You can pick them up and put them in place on the press and they won’t move around.

Two mitred pieces in the clamp, on the machine ready to be nailed by the press.
Two mitred pieces in the clamp, on the machine ready to be nailed by the press.

The quality of the end result is very largely a result of how accurately the clamp positions the pieces. This is where I wonder whether a professional underpinner would do a better job. I mostly use tall and thin mouldings. You can adjust the two pieces so the top surface seems well joined but this doesn’t guarantee that the bottom face is well joined. When you then turn the pieces upside-down and under the press, any gap at the back side may get transferred to the front side and be a visible flaw.

Once you’ve positioned the pieces in the clamp and tightened up you then pick the whole thing up and turn it upside-down and put it under the press to drive home the V-nail(s). How many of these you use depends on the width and height of the moulding.

The press has various adjustments to allow the nail to be driven in the right places. It’s a good idea to do a dry-run without glue so you can adjust everything. This includes the height of the press above the moulding (to cater for different heights of moulding) and the two production stops to allow front and back positioning of V-nail positions. Once these are all set you can leave them set for all four corners of this frame (and any other frames you make with the same moulding). This is all fairly easily and quickly done though I find the screws on the front/back positioning bracket to be hard to undo once you’ve tightened them. These parts all feel very solid so I can’t imagine them breaking easily. Once tightened up the whole thing is very solid and the V-nail drives in easily.

Some mitred scrap wood positioned in the clamp and tightened up ready to put under the press.
Some mitred scrap wood positioned in the clamp and tightened up ready to put under the press.

So, place the clamp and mouldings upside-down on the press table and move into position. Adjust the front/back clamp to the first V-nail position, tighten, and put a V-nail onto the press rod. Pull down the handle and the V-nail slides satisfyingly into place without much effort.

Here’s where a lot of the productivity is lost. Putting the V-nail onto the rod is very fiddly. The rod is magnetic and this holds the nail in place. This sounds simple but is very fiddly and you have to be careful that the nail is properly square. Not hard, but time-consuming. In the box you get a small pack of 10mm nails and one of 7mm nails. I’d suggest that the 10mm nails are the biggest the machine can use. You can buy 12mm and 15mm nails but I can’t see them working. The square tip onto which you put the nail is floating inside the press rod and it is possible to pull it out slightly to fit a larger nail but the slightest tap and it is pulled fully inside the press rod by the very strong magnet and that would leave a longer nail protruding and not properly supported. I haven’t tried longer than 10mm but I can’t see it working. This is a problem because you also can’t do nail stacking – see below.

Some scrap wood joined by V nails
Scrap wood joined by 2 V nails. You can see a failed attempt at stacking on the V nail nearer to you. Instead of stacking, the second nail has slid behind the first.

One of the selling points of the machine is that it can stack nails. This means putting two nails in the same place, one on top of the other, so you get deeper penetration. A 31mm tall moulding (which is what I mostly use) ideally needs 2 x 10mm nails stacked, to get 20mm of depth. Professional machines do this all the time (I believe) and the YouTube video I mentioned earlier shows it being done. During my early practices I managed to make stacking work on my first attempt but it failed on all subsequent tries. The second nail just ends up behind the first (see the picture above). This actually ends up weakening the joint, not making it stronger. I’ve basically given up on stacking. Given the limit of 10mm nails, this restricts the strength the nail can give to a tall moulding, quite a drawback.

So, assuming you’ve clamped the pieces up correctly and nailed them together, what does the result look like? Initially, not as good as I hoped. When you take the joined corner out of the clamp it opens up slightly to leave a small gap. This is not great visually but more importantly it severely reduces the strength of the glued joint. It turns out that most of the joint strength comes from the glue and the nail is there partly to hold the joint together while the glue dries (several hours) and to act as back up later on if the glue joint where to fail. If you take the corner out of the clamp after nailing and the joint opens slightly this means the glued faces aren’t in proper contact and the joint won’t be strong. However, having now made quite a few frames I’m getting better at it. It seems to help if you don’t overdo it with the glue and you only put on just the right amount. An excess of glue seems to keep the pieces apart, preventing a snug joint. I now use a small paint brush to spread the glue on thinly. Time consuming but it does a better job.

Anyway, you do this twice to get the two opposite corners of the frame then you have to join these two halves together. This is a bit more awkward, especially with a big frame, because you have the whole frame just supported on one corner in the clamp while the other, unjoined, corner flaps around. I’ve found that finding “shims” (basically anything that can support the flapping corner to the same height as the press table) is useful. If the opposite corner of the frame is sagging while you’re joining a corner, this will open up the corner you’re joining.

All in all, I was not happy with using the machine in this way on its own. I’ve ended up buying a Bessey strap clamp as well. I now use the two in combination. I’ll talk in another post about how I do this but the end result is a better joint at the cost of only being able to make one frame every six hours (how long it takes for the glue to dry while sitting in the clamp).

So would I recommend this machine? I’m not sure. It doesn’t do what I hoped it would. It doesn’t do nail stacking or support bigger V-nails which means I’m forced to use the Bessey strap clamp. The combination of the two is giving me good quality results but with quite low productivity and it’s quite a stressful job – any mistake and ten pounds worth of mouldings are down the drain. But I’m not sure what else I’d do so in the end I’d probably recommend it. It’s not too expensive and I can’t imagine the competition being any better.

An Ikea ready made frame on the left, one of my own home made frames on the right
An Ikea ready made frame on the left, one of my own home made frames on the right

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