help cutting and joining veneers

[trollhameran]

I am currently working on a table which will have a large geometric pattern veneered on the top, I am really struggling to cut the veneers without them ripping and tearing to pieces and also I am having trouble getting them as tight as possible so there is no gaps. Does anyone have any good methods they use for joining veneers together tightly before gluing and for cutting them in the first place.

I have attached a picture of the design for the top if that is at all helpful.

Help would be greatly appreciated.

[Arron]

You could do a bit of a web search on marquetry and especially on 'veneer packets'. thats apparently the proper way to do it, though I think overkill for this relatively simple pattern.

I do simple jobs like this a fair bit. I just cut with either scissors, exacto knife or veneer saw depending upon the grain direction and the timber species. When using the exacto knife, I make sure the wanted side of the cut is held down firmly with a straight-edge right up to the edge of the cut and do several light cuts before cutting right through. Naturally, I cut from both ends towards the middle so as not to break an end away.

I cut and assemble the pieces separate from the work, then attach it as one piece.

To assemble the pieces I just wipe PVA glue on the edges and then press them together, using ordinary cellotape to hold things together while they dry. You wouldnt think that a thin smear of PVA on the edge of the veneer would hold them together but it does (assuming you handle it carefully). The celloptape stays in place till after the final glue-up in the caul press, so naturally it has to go on the outside. Alternatively, you can buy veneer tape which has holes in it and doesnt interfere with the glueing so can be used on the glue side - though again it is overkill for this job.

Another possibility is to glue the veneer to something else first. This is usually called a 'lay up'. For example, you may glue the veneer to tough paper or another sheet of veneer with grain going in a different direction. However I dont think this should be necessary for this job.

I've also tried various paper cutters and guillotines for cutting veneers but never really found them worthwhile.

Also dont forget there are big differences in veneers, some split badly but some like birch are very resistant to splitting - you can cut it easily with scissors even into tiny shapes. Perhaps you have just chosen a difficult veneer. Coarse grained timbers like wenge make difficult veneer. I have found the reconstituted veneers especially prone to splitting. The pale veneer in your illustration appears to be ash - its pretty splitty.

I generally dont get too worried about small gaps as they are surprisingly hard to see once the job is finished. Of course it depends on what you mean by small gaps but a 0.5mm gap is usually not evident - I guess it gets filled up with glue or something.

I hope some of this helps
cheers
Arron

[trollhameran]

Thanks alot for your reply Arron, you've given me some great information.

I have always been told that veneer tape has to go on the outside, but if it can be used on the glue side without interfering with the glue then that would be a big help to me.

I have now managed to cut the veneers, using a straight edge and a scalpel. The ash was quite good really, only split a couple of times, but the oak I found to be extremely challenging to cut.

How easy do you find it to remove cellotape once the piece is glued? I have been told that the glue in it melts in the press and makes it almost impossible to remove.

[Artesano]

Have you tried a proper veneer saw instead of a scalpel? Here's how they say it's done:

YouTube - Jointing Veneer: The Cutting Edge of Marquetry

YouTube is full of videos on the subject , some of them are realy VERY useful:wink:

[Arron]

I dont have a problem removing the cellotape at all - but I do cold pressing not hot pressing. I use the cheap thin chinese made rubbish cellotape. Maybe the good quality stuff would not be a good idea. Also the fact that I usually use standard PVA glue might have a bearing on this.

The cellotape leaves a bit of residue behind but this sands off easily. This mightnt seem ideal to most people but my approach to veneering is to use a large amount of glue, so much that it liberally comes right through the veneer, stains the top surface and needs a fair bit of careful sanding to remove. This is the approach taken by the professional veneer company that I have used so I just copy it. I guess the philosophy is that if you have too much glue you are in no danger of not having enough glue. The latter is disastrous, the former is just a minor annoyance.

I hope I'm right about veneer tape being usable on the inside. You now have me wondering if it was just an assumption I made. In any case it hasnt caused a problem.

Another approach I forgot to mention is that you can use a thing like a long shooting board to joint the veneers after cutting. I have a jig made for the purpose which accepts a block plane and is good for smaller bits. Its good for those veneers where the tendancy of the knife to follow the grain is overwhelming. When jointing really long bits of veneer I have used several sheets of mdf placed on top of each other with the veneer in between and the whole thing acting like a giant shooting board. Use whatever nails, screws or clamps are needed to hold it together while you shoot. This has also worked well.

I should point out that my approach to veneering is based on doing it at home with limited tools, supplies, finance and space. It probably isnt the canonical method. A professional would no doubt do it different , but I know it works.

Arron

[Arron]

Oh, just remembered. If the veneer is hard to work you can spray it with various concotions which are basically mixes of water and gelatine. It will become so supple and pliable you will be able to roll it tightly around a pencil without splitting. Obviously this makes it effortless to cut with a pair of scissors. There may be some issue with expansion/contraction though I havent noticed any.

cheers
Arron

[Wongdai]

What a great thread. I love useful informatin such as this.

[trollhameran]

Definately some great info here, thanks alot arron, its really helped with what I was doing.

I usually use cascamite and hot press so I presume celotape would stick down quite bad with this method, I will try pva on the edges then veneer tape, I think that is the best method for this.

I will also have to try a scrap piece with veneer tape on the glue side and test it out because that would easily half my clean up time.

[Arron]

Better make sure we are talking about the same stuff when we say veneer tape. I'm talking about the very thin paper tape with the large holes punched in it.

I've always assumed that, because its at least 50% hole, the worse case scenario is that the glue is reduced to half strength directly under it. But thats the worse case, I also thought that as the paper is thin and permeable the glue easily wetted and penetrated the paper and in effect bound across it.

cheers
Arron

[Woodwould]

I wouldn't leave any veneer tape on the underside of the veneer, not even the perforated paper type.