corners aren't very good

[pramsay13]

I've just pinned a particularly large and heavy frame and there is a gap at every mitre. I think it was the weight and doing it myself combined that has meant they have separated slightly. Probably for next time I will do 2 corners and let the glue dry before fixing the last 2. Is there any framers' secret to fixing this one or is it a write-off?

[easypopsgcf]

Depends on the moulding? If your not getting a good join , it's almost always a cutting issue. How sharp are your blades? What support did you have to help you while joining this big frame?

[pramsay13]

every other frame is fine, it's just this one particularly big one. I didn't have any help to join it which is where I think the issue is coming from.

[Trinity]

Do you mean an open joint along the mitre length or as in 44.5 degrees. . I've had similar issues and invariably it's because I didn't have a second pair of hands. Massive amount of force when your joining the 2 L's together. I'm not lucky enough to have the underpinner + bench setup, insufficient room. I have managed to split the frame apart, extract the wedges with pliers (but watch it when they release they do so with a vengance), shave a tad off and repin changing the location of wedges - making sure that second pair of hands are available.

[prospero]

Big frames with big mouldings are always a challenge. The sheer weight of the thing acts against you. Also, the longer the length the more any slight twists are going to be apparent. And you can't 'persuade' a big meaty mouldings like you can a small ones. And the wider it is, the more any angle inaccuracies will show as gaps.
I would be reluctant to join any big finished moulding nowadays. Any big frames I do now are hand-finished. You can make good any gaps more easily.

Not a good idea to glue 2Ls IMHO. You would probably end up cracking the dried joints trying to do the last two. If I had to tackle it, I would assemble the frame 'dry' first and throw a webbing clamp around. You can spot any likely mis-fitting that way before you commit yourself to the gluing. If there is a gap you can sometimes correct or at least improve it at this stage with a bit of judicious shaving on the Morso.
And when you are working single-handed, biscuits in the corners will help a lot. You have to work fast - glue and insert the biscuits in one go and strap it up. The biscuits allow lateral adjustment, but keep everything in alignment up and down. Once you have the frame clamped you can take it to the pinner without risk of disturbing the glue.

The worse one I ever did was a 4" wide moulding that I got by mistake. Sent in error - should have been a small moulding. But I stuck to it as I only got charged for the small one. I thought I would make a mirror to use up the 2 10ft sticks. Ended up putting 6" woodscrews in the corners.

[Not your average framer]

Large frames are something I worry about, especially if it a hardwood moulding, which makes it difficult to stack wedges in the joints.

Some of my up market customers have a house in London and one in Devon. From time to time they bring in something they had framed in some posh place in London and want me to do something to it. This gives me the chance to see how the other framer does things and can be quite instructive.

During such ocassions, I have seen large hardwood frames, where the joints have been reinforced with slots cut into the outside edge of the mitred joints and thin pieces of hardwood (known as feathers) set into these slots, or even dovetail sections inserted across the mitred joint at the reverse of the frame.

I was asked to make a replacement for one frame which got damaged and broken on one corner and was able to see that the broken corner contained three size 20 biscuits set spaced apart between the front face and the reverse face of the frame.

The problem for many of us is the lack of bench space to carry out heavy duty joinery type solutions, where all four corners have to be camped, glued, joined and left on the bench while the glue sets. Unfortunately in my small shop, I just have to turn away jobs which are just too big for me to handle, without blocking up my whole workshop.

I have just in this last week made a frame using Simons BRET/11 and to get good solid joints, I double stacked the wedges in five positions spread across the mitred joint. Obviously there are limits as to how many wedges you can sensibly insert into each mitred joint, but with a moulding which has the space for plenty of wedges, it is at least a step in the right direction.

Ten wedges double stacked in five positions.jpg

Sorry about the not very good photo, but it's an old camera which is only just adequate. I thought that I would add the picture to show those with plain old manual underpinners, that neatly and successfully stacked wedges are possible even with a manual underpinner. I have a laser printed paper rule stuck in place on my CS-88 and held the sliding plate in the same position by hand while inserting each pair of wedges.

To those who may be relative newbies, or who may be put off from trying something like this, I would say that it's just a matter of practice, technique and a paper ruler stuck down onto the top of the underpinner. I used to do the same with a CS-79 before I got the CS-88. It looks more difficult than it really is!

[pramsay13]

Thanks everyone, some good advice as always. I have made bigger frames, and I've used this moulding before for smaller frames, so it seems to have been the combination of both that was the problem. I'll probably have to do it again, but I'll take more care and get an extra pair of hands to help this time.

[IFGL]

You got it, we often make large frames, by large I mean over 48 X 36" around 2 per week at the moment, the trick is to take your time on cutting, make sure everything is flat, rebate supports are perfect, on the last shave hold everything tight, you don't have to stitch the frame together when pinning, this can actually make it worse , or fill, glue as normal and pin if done right it will not give, here is the last 2 we did just this week. the main one in the pic the glass size is 1495 mm x 995 mount is 4" , Very heavy and very strong. and the one lent up against the wall was not much smaller.

[IFGL]

made another big frame this morning 1850 x 950, easy method of pinning without anyone to hold the frame.

[prospero]

That setup looks familar. Then all you need are arms like a gibbon.

[StevenG]

Gees guys this is a great thread. Very interesting to hear about stuff that I reckon only happen to me. Thought I was plagued with bad luck most days!

[pramsay13]

Okay, so I think I've discovered another issue. When I took this frame apart I noticed that even though I was stacking 3 wedges, at no point were they ever 3 high, they were either 1 or 2 high, with some in beside each other. I then had a closer look and noticed I had somehow managed to put the pins into the underpinner upside down.
I have a wooden stand that I use to help when I'm doing a bigger frame, and when I redid the frame using this to help I did it fine by myself and the corners are great.

[IFGL]

at least you know why, I have done the same thing.

[Steve N]

I think you're asking for a lot to stack three under pins, I would say two was the max

[pramsay13]

I did a frame before with 3 under pins and I had to take it apart for a different reason. I'd 5 groups of pins and they were all perfectly stacked. I'm using 7mm pins.
I have done 4 before although that would be my lot, although of course you almost have to assume everything is okay as you can't see what is going on inside.

[prospero]

This is where a manual pinner scores over a pnumatic machine. You can tell when a stacked v-nail has not gone in properly.

[IFGL]

You can tell, with the feel , if it hasn't stacked right even with a pnumatic machine, the advantage of the pnumatic machine, is the tighter clamping, smother operation ( no leg lifting ) means everything is held still allowing a much higher chance of a successful stack.

We have both manual and pnumatic pinners, the only real advantage for having a manual under pinner is they don't need a compressor, the pnumatic is superior in every other way in my opinion.

[Steve N]

pramsay13 wrote:
"I did a frame before with 3 under pins and I had to take it apart for a different reason. I'd 5 groups of pins and they were all perfectly stacked. I'm using 7mm pins."

I tend to go for the biggest pins that will go in the moulding, and so 2x 10mm pins or just 1x 15mm IMHO would have been better and stronger, of course this is without seeing the moulding

[pramsay13]

The problem with my underpinner is that I need to swap the head if I want to change the pins so it is more effort, and in this case I would have only got 2 x 10mm so 20mm rather than 21mm with 3 x 7mm.
Probably in an ideal world I would do this but I'm quite comfortable with how things are just now (assuming I don't put pins in upside down).

[StevenG]

@IFGL - just reading this thread again (nearly always find something I missed the first time!) and I've just realised that moulding you used was quite nice, do you remember what it was?