Advice on how to stop my frames pulling apart when pinned

[pfbls]

I am fairly new to the picture framing business and have an issue with underpinning - and I would be very grateful for any advice! When I create my frames on basic equipment at the moment (pro-saw and trimmer) and when I under-pin my mitred wood in the studio joiner, the joins are perfect. However, once I put the frame together as a whole, I then see that the insides of the joins are slightly coming away - meaning I need to do some filling in. I have two issues that I desperately need help with. One is obviously why, when they appear perfect in the joiner, are the joins coming apart on the inside edges once the frame is completed? Second - if I do need to fill in, when I wipe away the glue/sawdust mix with a rag, it is leaving a residue on the wood face. Am I using the wrong technique for either joining the wood or filling in? My V-nails are appropriate for the types of wood I am working on, so I don;t think that has any relation to the problem. I know exactly how to do both these things, but for some reason that I havent been able to work out yet, there is problem with the way am doing it. These very simple issues are driving me up the wall. If you have any ideas/tips on how to rectify them, I really would be very grateful to know! Thank you.

[framemaker]

Hello, and welcome to the forum

I don't have experience of your equipment, but I'm sure someone will be able to offer some advice.

You don't mention glueing the mitres, are you doing this when joining on the underpinner, and then giving the glue time to set before putting the glass, mount, etc in the frame?

[pfbls]

Thank you! I am pretty impressed to have received a reply so quickly! Yes, I am glueing the joins too, but that doesn;t seem to be helping keep them together. It's all a little frustrating as I know these are basic skills that I can do perfectly well, but I have somehow altered my technique and now it's causing me a problem! Anyway, fingers crossed someone else has come across this and might have some words of wisdom! Thanks again for getting in touch. I think I will definitely be using this forum from now on.

[prospero]

Hi and Welcome pfbls

One corner on it's own will always go together perfectly because the ends are free. Even if the angles are 'wrong'. But When you come to join four corners they all must be 45deg. Remember, there are 8 faces and all must add up to exactly 360 deg.
So it one face is a tiny amount off 45deg, that error is multiplied x4 on the assembled frame. If both faces are off, and one is off in the other direction, then the error may get cancelled out to an extent, but if both faces are off in the same direction then you have a cumulation error of x8. On narrow mouldings this isn't so noticable, but as you get wider the divergence will increase exponentially.

With me so far?

We are talking very small increments here. On a Morso it is easy to tweak the fences to get a perfect angle. Not sure how to do it on your rig, but I think that's the root of your problem.

Using the glue/sawdust mix is a good way to fill big gaps, but it works better on plain wood that you are going to paint over later. You are always going to get minor gaps here and there. But you need to work on getting the best join possible so you don't have to fill massive cavities. Big gaps will also affect the strength on the corner. To form a good bond, a glued join needs to meet snugly along it's entire surface. It's the clamping pressure of the wedges that will achieve this. On a gappy corner the glue is only realy bonding on a small area, in this case along the back edge. Jamming glue/sawdust into the gap will fill it OK, but that area will not have the same bond as where the two faces actually touch. One small knock and the joint could fail.

To touch up hairline gaps, it's better to use a wax based filler (Liberon Cream?).

btw. What glue are you using? PVA should wipe off ok with a damp sponge. Even dried residue should flake off a finished moulding.

[pfbls]

Thank you so much for replying, yes I stayed with you throughout and I do think you are right actually. It did occur to me that it was maybe my trimmer that was slightly out, creating very, very small differentiations on the angle of each mitred corner, meaning when I put two together they looked fine, but when connecting the 4, they slightly pulled away - just as you have described below with the angle issue.

I also agree that the ideal is not to have to fill at all, but if I do continue to need to perfect very small gaps, I will try the Liberon cream as you suggest. It is a PVA glue that I have been using so I will try again with the removal of the residue with a damp cloth.

While you are here...(!!!) do you happen to have any tips on creating perfect mount cuts, without over or undercutting? I think the key is simply practice, practice, practice, but as you obviously have experience in the business I thought I would check with you to see if you had come across any trade secrets that I may not have found yet! Again, as I am just starting out, I am using the most basic mount cutter so it is very important to me that I develop really detailed skills so I make prefect cuts.

Thanks again for all your help so far, it is very much appreciated!

[Gesso&Bole]

Hi pfbls and welcome to the forum.

I'm with Prospero on this one. You are almost certainly a tiny amount out on the cutting. Having said that, if you are using a hand saw, and are only a tiny bit out, then you are doing very well.

I suspect that you are looking for perfection, and if so, you probably need to reduce your standards slightly, or suffer from long-term frustration. In our workshop we must have 20 or 30 assorted wax and cream fillers in all sorts of different colours and textures. These are in use every day.

Although in theory it should be possible to cut and join everything perfectly every time, it just doesn't work out that way when the moulding you are using isn't 100% consistent.

[prospero]

Glad that was of help...

As regards mountcutting, you are right. It's like everything else, practice makes perfect. Manual mount cutters are basically the same. They all should have means of fine adjustment even if the different brands use slightly different methods. First thing is to get the crossways back edge (where the board buts up against) exactly square with the bar that the cutter block slides along. Then tweak the margin width guide so that when it's set to 50mm, you get a 50mm margin at the back of the mount. The stops on the cutter bar are best calibrated by trial and error using scraps. With a bit of patience you can get them spot-on. But they do need checking now and then, particularly with a heavy-handed operator. If you use thicker board, you will need to allow a bit on the stops. No need to recalibrate, just have a try with some scraps of the thick board and remember how much extra you have to allow. After a while you will be able to do this by intuition.
It's best in my humble opinion to have a tiny overcut than and undercut that tears a bit out of the corner. I use 1200 blades and find that a small overcut generally doesn't show. That's if it's a sharp blade and the depth is set correctly.

btw. A handy tool to have is an Agate Burnisher. For a fine finish on a mount edge, run the burnisher along the edge of the top of the bevel to smooth down slight ridge that you always get. Also, if you do get a slightly rough edge on the bevel, a piece of very fine emery paper will take it off if you go gently. Stroke it, don't rub it.

[JFeig]

The way I was taught years ago to cut with a manual mount cutter to achieve a "perfect cut" was to always undercut (.5mm) and then use an old fashion double edged "blue blade" razor blade to cut the rest of the way. Allowing the blade to conform to the angle by itself and then a slight sawing motion to just kiss the corners to have the insert drop out.

[Nigel Nobody]

When I create my frames on basic equipment at the moment (pro-saw and trimmer) and when I under-pin my mitred wood in the studio joiner, the joins are perfect.

I wonder what you mean by a "trimmer"? Whatever this tool is, the angle is set incorrectly. As others have said, the problem occurs when you bring the four joints together, because each joint is out by a small margin.

[pfbls]

Thank you so much to everyone for your replies - I really am very impressed and grateful that you have spent your time offering me advice, much appreciated. And I have to admit, I think you are all right! My trimmer is mitre trimmer so once I have cut the wood, I place it in the trimmer against the struts and use a handle to push a very sharp, strong blade through just a millimetre of the wood to gently trim away the rough edge to create a smooth one - in order to prepare it for under pinning. I do this several times until the edge is smooth and also trimmed back to the length ir should be (as I cut 10mm over in order to trim back to exactly the right measurement).
I am a bit of a perfectionist and am trying to manage my expectations, but I would prefer it if I had perfectly pinned frames (no filling in!) and mounts with no over or under cuts!! Thanks again to everyone. I'm sure I will be on here again soon with more questions!

[blokman]

Speaking as a relative newcomer myself and having started off using a mitre saw and the studio underpinner, I can sympathise with your frustration at trying to achieve the perfect mitre.

I only stuck with the studio underpinner and saw for about a month before cutting my losses and purchasing the Morso and Cassese underpinner, however I did achieve some reasonable joins by gluing the joints and using a framing clamp (webbing) first of all and then, when dry underpinning the mitre.

Without gluing and clamping first, I found it very difficult to achieve a reasonable tight join......

Hope that helps.
Rob

[shepherdn]

I totally relate to your post. I started off with a studio joiner and felt it was totally unfit for purpose, I almost gave up framing as a result. However, decided to make the big leap and invest in a second hand Morso, CS88 underpinner and a keencut mountcutter - I have never looked back. If you are able to do the same I would strongly recommend it. Keep an eye on the forum, I have seen a few posts for second hand equipment or if you can go new, speak with Phil at Ashworth and Thompson he may be able to offer you a good deal.

[prospero]

I often use a webbing clamp. Mainly on big frames where the sheer bulk makes it difficult to pin all corners without disturbing the corners I have already pinned as the frame is moved around to pin the last corner. But I would always underpin the corners while the frame is in the clamp and before the glue has had a chance to set.

[pfbls]

Thanks again to you all for your support with this! Yes, it has been frustrating but some great advice which I will try out and see what works. I'd love a Morso so that's what I will work towards, just need a few more frames under my belt first! But all good ideas, and thanks again for the recommendations re: second hand equipment and your tips and tricks of the trade.