Dining table top questions

[Arron]

I'm planning the making of our dining room table and I have a few questions about the making of the top. I want it to be walnut veneer and about 1500mm square. Because I really dont like heavy furniture, I'm thinking of making the core out of recycled western red cedar, in strips say 100 x 50mm - edge glued. To this will be glued 3mm mdf top and bottom to give a nice smooth surface. To the longgrain sides I expect to glue 20mm thick real walnut timber - flushed with the mdf. Then I expect to veneer over the whole thing including the real timber. My problem is with the endgrain sides. I am trying to think of how to handle the expansion/contraction thing. I can say
first that:
1. I'm not really very fond of breadboard ends as I dont like the idea of the edges of the breadboard end not lining up with the edges of the table in extreme weather conditions.
2. I dont see it as necessary to imitate the look of real timber in terms of having endgrain. If the end result is that it has longgrain on the edges all round then I'm OK with that - I'll adjust my expectations to fit.
Any suggestions please ?

Secondly, because this table top is so large I'm thinking of having the veneer
commercially applied by Specialty Timber Veneers in Smithfield (Sydney). Has anyone dealt with them, if so could you PM your impressions.

thanks
Arron

[Greg Q]

Hi Arron...

This top is going to weigh approx 70kg, and have a fairly unweildy dimension for transport, but a big enough truck or trailer will get the job done, I guess.

I'd put the edging all the way around, with mitered corners. The average person is used to IKEA furniture-no end grain there. As far as the
MDF goes, I will defer to more experienced veneer people. I'd be more inclined to farm the whole top out to someone with a wide belt sander, edgebander and big veneer press.

Greg

[Lignum]

Howdy Arron:) you have put a lot of thought into it but as greg pointed out it would weigh a ton, and i would have doubts on its stability. If you want to veneer it then it has to be a torsion box design. That way it will be very light, very strong and very stable. And also follow gregs advice and mitre short lengths of solid walnut around after you have made the torsion box, then get it commercially veneered over that:)

[Arron]

This top is going to weigh approx 70kg

actually I calculate the top at about 40kg, being
1.5 x 1.5 x 0.044 = 0.099
then 370 x 0.099 = 36.63 kg (wrc being 370kg per m3 at 12% moisture)
plus add extra for glue, walnut strips and mdf skin.
I wonder whether a torsion box of those dimensions made of 12mm mdf would be any lighter ?

still, torsion box is probably the way to go for stability and to avoid expansion/contraction issues. Has anyone made a torsion box table top of this size - if so can you tell me how you went about it ? I am most interested to know the size of the grid and the thickness of the top skin.

Also, has anyone used poplar blockboard for this ?

thanks
Arron

[Auld Bassoon]

Hi Arron,

The biggest that I've gone to with a torsion box is 820mm x 600 (actually 596mm); it's 6mm MDF on to, 4mm MDf on the botton and 15mm hardwood (TO) as perimeter framing with two interlocking and mirrored 'W' sections as internal braces, bridle joined to bring them flush.

I don't see any reason why such a t.Box couldn't be reduced to a n even divisor of the size you need, then interlinked to make up the full size.

My only major concern would be the thickness of the top surface veneer - standard sub-millimetre veneer wouldn't take much in the way of wear or abuse. On the other hand, going for 2+mm "veneer" would in and of itself lend itself to movement.

Brims to the rescue?

Cheers!

[Different]

If you made it all out of 20mm solid Wallnut it would weight less than 30kg tops. And look better to boot !!!

Ross

[Lignum]

20mm is to thin for a 1500 top, and you have the problems of quality bracing underneath that is large enough and strong enough to keep it flat and stable and not been seen. If you went that thin you would need a skirt like the traditional antique mahogany tables but if your going the contemporary way a torsion is the best.

A torsion that size would be lucky to be 15kg max and the clean lines esp underneath and stability of the whole top clearly superior than solid:)

[Different]

20mm is to thin for a 1500 top, and you have the problems of quality bracing underneath that is large enough and strong enough to keep it flat and stable and not been seen. If you went that thin you would need a skirt like the traditional antique mahogany tables but if your going the contemporary way a torsion is the best.

A torsion that size would be lucky to be 15kg max and the clean lines esp underneath and stability of the whole top clearly superior than solid:)

Rubbish!!!
A skirt could be used but it is not the only option !
You need to think outside the square or in this case the box !

Ross

[Lignum]

Rubbish!!!
A skirt could be used but it is not the only option !
You need to think outside the square or in this case the box !

Ross

Instead of being cryptic, explain your idea on the subject

[Lignum]

Think out side the square. I think thats what im doing. Thats why in my thoughts a 1500 dia x 40 veneered torsion table top with solid edging under the veneer would be ideal.

The strength you couldnt compare to solid as it would be increadably strong.

The stability couldnt be compared to solid as their would be almost zero movement.

And 1500 x 20 solid at around 30kg plus some form of bracing would end up being close to three times the weight of the torsion.

Is that so outlandish it has to be termed "Rubish"

[Arron]

The style of table that I have in mind (actually the design I am shamelessly ripping off) will require a top at least 50mm thick. It may even be 65mm, I havent drawn it out yet.

Auld, I dont quite understand your design, were the hardwood W's the only grid inside the torsion box ? if so, what would the maximum gap between components be, and could you feel any flexibility in the top.

Lignum, what would you use for the grid inside the t. box. I have plenty of pine or cedar that I can use, or maybe hardwood, or should it be MDF ?

thanks
Arron

[Lignum]

Arron:) my advise would be (and this applies to anyone else out their who would like to have a go at a torsion box) is to get two 4mm MDF coversheets and tape them together and draw a 1500mm (dia) top onto it. That will be your template for the positioning of the torsion ribs.

On the template work out where the legs will be fixed to the top and mark those positions.

The thickness of your ribs will be determined by the skin thickness. I would favor 9mm both sides that will alow 32mm slats x 19mm and they are best in pine because of the lightness in weight.

First, draw your leg positions on the template and include a generous size there, as it will be of hardwood not pine so you have good strength for anchoring. As i dont know your design ill just assume its in four points near the edge and you can alter it to suit.

Draw 14 @ 19mm strips parallel down the length of the table starting dead center. My quick calculations are 14 strips x 19 thick = 266mm . 1500 top - 266 divide by 14 = 95mm. thats your spacing. Its closer than what i would use but again your first torsion should be overkill until you fully understand it. They might alter from 95 when you get to your leg spacing but thats ok. If possible 4 @ 95 x 32 x 300 Tas-oak would be good for leg blocks.

Once all the parallel ribs have been drawn, then its time to mark your edging on the template. Their will be two edgings here. The first "inner" edging 65 (w) x 32 (th) Tas-oak. That will secure your ribs strongly and allow the 9mm skins to be pressed over the entire top. The second lot of "outer" edging will be the same timber as the top veneer that is being layed and same thickness of your finished top, and will be glued around the edge of the top after the mdf and Tas-oak has been trimmed. That way when your veneer has be layed you will have a substantial solid edge that "wont" be sanded through and can also be routed with a profile if you wish.

(the 65mm edging isnt the final size. Once it has been routed parts of that will end up around 20 or so mill, you may find when you draw the template you need 70mm wide or maybe more, but you will work it out, because im telling you all this with out drawing one up and having exact measurements, so keep that in mind)

So you will have drawn two circles on the outer edge. The first the finished table size (1500) and the second the finished torsion size wich will be 30mm less in dia. Divide the second size into 12. (If it ends up to short making your edging to wide, just increase the amount to 18 and see what its like) As long as the final results in edgeing of around 65-70mm. So cut a strip of MDF to the final worked out length length x 65mm (or more to suit) for the thickness. Place that at the top of the drawn center rib, with the center top of the template overhanging the the line of the inner circle by around 4mm and trace around it. Then repeat all the way around just overlapping so you end up with 12 (or more) long segments x 65 (or more) that form a circle. Then with your rule mark a straight line through where they meet at the end as that will be the mitered angle.

Now you are ready to make the ribbing. First cut the Tas-oak edge exactly as its on the template. once you have it sitting on the template and happy with the angled mitered joins (but joined) then join it with what you have at hand I find staples are great, or skew nail. As they will be end grain to end grain, only certain glues are any good, so dont fuss put some titebond 111 on as its a no stress join and it will be fine.

Once the inner circle framing has been done and glued and fixed, cut and lay all the pine ribs into it including your tas-oak pieces for the legs.(dont glue or staple yet) Then cut a heap of 32 x 19 x 95 for the internal bracing. When they are cut glue and staple/nail the first rib (the one in the center) then working to the sides place the cross braces around 200mm apart next to the first rib with a dab of glue on the end and then put the second rib in and draw it tight and staple/nail, keep repeating it till you get to the last rib, then you will just adjust the final cross brace to fit snug. Also stagger them as its easy then to pin from the back of the rib into it. Just likr the frame work on a wall in a house.

If all went well you will now have a very good strong ribbing. But the MOST IMPORTANT thing is it HAS to be flat, so punch down all nails/staples and plane or sand all ridges of and drag a straight edge over it to make sure its as flat as you can possibly get it. this is the most crucial area.

Now you are ready to lay the skins. If you havnt access to a vacuum bag (1500 is wide) this is best done in two goes. And just as important, if the skins are glued and you have a twist or anything with the frame it wii STAY forever. Torsions are just impossible to alter once they are glued. And resist any temptation to secure your ribbs directly to a skin as it "isnt" strong. It appears to be a logical quick way but it defeats the whole purpose and will result in a weak torsion.

So prepare your top (you will need a 3600 x 1800 x 9 sheet of MDF cut in to two) cut them around 1500 (dia) each and get as many off cuts of mdf or chipboard etc to use as weights. Place your sheets on top and bottom and mark with pencil the positioning of the ribs.(always good to know where they are) Then using a roller, starting on the underside first roll on some good PVA all over the ribs and place the MDF on and carefully pin all over (dont staple as they dont penetrate properly) I do this when im sitting on it as extra weight is good. Once that is done place as many off cutsand weights as possible as evenly as possible all over and leave for a few hours. Then repeat the process on the top. but first do a final check with a straight edge to make sure its flat. I dont pin the top at all, i like it to be super clean and smooth so no blemishes show through the veneer.

When this is completed turn it over and with trammel and router trim it to its final diameter (excluding the outer edging)

Then the last stage which is the fiddliest is to apply your solid outer edging. The main thing to look for here is to get the ends to mate as good as you possibly can. If you dont get it perfect on the curve of the torsion dont stress, good epoxy is what i use here. Also take into account if you intend to route profiles later be carefull if you nail it from the back or anything so it dosnt interfear with the cutter. Use the same technique as the Tas-oak edging and when you have it applied, the same as before use a trammel and router and trim to final 1500 dia. Then its only a matter of laying the veneer.

If it all sounds complex and to much stuffing around, well its not. Once you have done one, you will find its just as quick as preparing a solid top.

Some might think this is all rubbish, but If all goes well, you will have a light and super, super strong table top that will have almost zero movement and excellent looking edging ready for veneering, with good strong hardwood inlayed blocks for securely anchoring your preferred legs to

Look foward to progress pic`s... Good luck:)





.

[Clinton1]

Lignum, I think the design is for a square table top?
Great "how to" by the way, I'll greenie you if it'll let me.

In the pics section there is a torsion box based Conference table some bloke in Qld made. Very, very large. I think monoman has done something similiar?

Must say I am leaning to veneer - particularly as I can no longer get some of the timber I want in the size I need. Good to see threads like this. Also its ecologically responsible... I've gotta admit that against my natural preference to solid timber.

[redwood]

Lignum, I think the design is for a square table top?
Great "how to" by the way, I'll greenie you if it'll let me.

In the pics section there is a torsion box based Conference table some bloke in Qld made. Very, very large. I think monoman has done something similiar?

Must say I am leaning to veneer - particularly as I can no longer get some of the timber I want in the size I need. Good to see threads like this. Also its ecologically responsible... I've gotta admit that against my natural preference to solid timber.

Oh well lucky he didnt realise that in the first place because square or rectangle are a piece of pizz

[Lignum]

Lignum, I think the design is for a square table top?
Great "how to" by the way, I'll greenie you if it'll let me.

In the pics section there is a torsion box based Conference table some bloke in Qld made. Very, very large. I think monoman has done something similiar?

Must say I am leaning to veneer - particularly as I can no longer get some of the timber I want in the size I need. Good to see threads like this. Also its ecologically responsible... I've gotta admit that against my natural preference to solid timber.

Sorry about that Chief :) As Red said at least now you got a good run down on a round torsion which is a bit more tricky than a square. Id love to have a camera and do a small one just to post for people to see. soon maybe:)

Do you know where the conference table pic is, i had a look but couldnt find it... And Shhhh on the "ecologically responsible" bit as we dont want to start another bun-fight that will end in tears:)

[Auld Bassoon]

Auld, I dont quite understand your design, were the hardwood W's the only grid inside the torsion box ? if so, what would the maximum gap between components be, and could you feel any flexibility in the top.

Arron
Hi Arron,

The T/B I was describing has an internal layour as shown in the attachment.

No interval between internal elements exceeded 120mm in any dimension.

As mentioned it has a perimeter frame of Oak of 15mm (thick) by 19mm wide (as are the internal "W's), and an MDF top and bottom, 6mm and 3mm respectively. All bonded with PVA.

After placing on a floor standing frame of the same dimensions as the planned shelf support, and placing some 90Kg of weight across it, a dal gauge registered less than 1mm movement after 36 hours - so I guess that it's ok for what I want.

I'll admit that a true honeycomb interior structure would be stronger, but the T/B that I've built seems strong enough.

Cheers!

[Arron]

Hi Lignum, thanks for taking the time to write such a detailed post. I have printed it out and studied it but still have one area that I am uncertain of. You have written these three statements:

'And resist any temptation to secure your ribbs directly to a skin as it "isnt" strong. It appears to be a logical quick way but it defeats the whole purpose and will result in a weak torsion.'

'Then using a roller, starting on the underside first roll on some good PVA all over the ribs and place the MDF on and carefully pin all over'

'I dont pin the top at all, i like it to be super clean and smooth so no blemishes show through the veneer.'

The first seems to indicate that you should not fix the mdf skin to the pine ribs at all - and I assume that means with either glue or metal fixings. The next two seem to be saying that you both glue and nail the bottom skin, and glue the top skin. Can you please clarify this - are you talking about fixing the top and bottom mdf skins to the pine core. If so, what is preferred, nail or glue or both.

Incidently, I'm looking forward to making it, it looks like an interesting thing to do for its own sake - and challenging when it is your first.

cheers and thanks again for the response.
Arron

[Arron]

and while I'm at it, another question.

I am, in fact, talking about a square table, not a round one. Does this change the use of the Tassie oak edging. I assume that it could be quite a bit thinner. I am also wondering whether it also should perhaps be pine, same as the ribs, as I read on one web site that it is better not to mix materials.

Also, thanks for your reply Auld. It is interesting to see how rigid these things are - but then hollow core doors are rigid and they are made of veneer over cardboard inside.

thanks again
Arron

[Lignum]

Hi Arron, sorry about the confusion as i typed most of it as i was having breakfast and was still a bit sleepy:) to answer your questions -


'And resist any temptation to secure your ribbs directly to a skin as it "isnt" strong. It appears to be a logical quick way but it defeats the whole purpose and will result in a weak torsion.'

What i meant was, some people try to cheat by quickening the process. They will use the bottom skin and directly draw their template patern onto that, and then build up their framed ribbing by glueing and nailing directly to it as they go. Then when thats completed just glue on the top skin. Years back when i first started mucking around with torsions i also done it that way, and without exception they would all sag. You must make your framed ribbing as a totaly seperate structure that is strong and ridgid when you pick it up. It shouldnt move or twist. If you follow the way i described that will be the case.


'Then using a roller, starting on the underside first roll on some good PVA all over the ribs and place the MDF on and carefully pin all over'

Yes, just as it reads. The underside isnt as important as the top in apperance but you need the strongest possible bond. So after a nice even spread of rolled glue, place the 9mm sheet on one edge and drop it hard onto the ribbs. The resulting force even though not that great will help expell excess glue and create its own little vacuum. Align so your previously drawn pencil marks line up with your ribs and grab a piece of 18mm MDF and put it on and get up on it and start to nail it all over. Dont be shy, the more the merrier.

'I dont pin the top at all, i like it to be super clean and smooth so no blemishes show through the veneer.'

Thats right. i will use about four pins just to keep it aligned and prevent it from creeping. Again drop the top 9mm skin on and push it around from side to side to create the little vacume, then align the pencil marks with the ribs and pin in four places. Then put as many sheets of MDF evenly on it as you have to weight it down and leave the whole top overnight.

The reason i dont go crazy with the pins on the top is when veneer is vacuumed on, the pressure is so emence sometimes the veneer will sink into a hole, dip or divet. The pins have to pe punched in and filled and sanded and that means the top can easly be distorted. Weights are enough, but idealy putting the top and bottom skins on together with four pins each side and placed in a vacumm bag is the best way

I am, in fact, talking about a square table, not a round one. Does this change the use of the Tassie oak edging. I assume that it could be quite a bit thinner. I am also wondering whether it also should perhaps be pine, same as the ribs, as I read on one web site that it is better not to mix materials.

Yep sorry bout that, i had just finished reading a thread on a round table and it was stuck in my mind. It dosnt realy matter if you mix and match materials as it wont make any difference, but its just habbit for me to use Tas-Oak on the inner edges of the box for a strong frame and pine for the ribs for its lightness. Because you are attaching the same timber outer edges as the veneer onto the Tas-oak inner edge, i feel more comfortable in gluing hardwood to hardwood instead of hardwood to pine (i use epoxy for this). And the thicknes of the inner edges are for me ok at 20 - 23mm depending on what stock you get it from.

Also, thanks for your reply Auld. It is interesting to see how rigid these things are - but then hollow core doors are rigid and they are made of veneer over cardboard inside.


Just like Steve pointed out above, torsion boxes are unbelievably strong. Iv made about twenty torsion table tops and im still amazed at the strength. The longest i made was 3400 x 1200 x 65. and before the venneer was placed on, four blocks on the extreem outer edges were placed under and three of us got up on top and their was only the slightest deflection.

Thats why i stressed stongly that your frame has to be flat because when the skins are on you cannot get a twist or sag out

Hope you can photo your progress - Lig :)

[Different]

Think out side the square. I think thats what im doing. Thats why in my thoughts a 1500 dia x 40 veneered torsion table top with solid edging under the veneer would be ideal.

The strength you couldnt compare to solid as it would be increadably strong.

The stability couldnt be compared to solid as their would be almost zero movement.

And 1500 x 20 solid at around 30kg plus some form of bracing would end up being close to three times the weight of the torsion.

Is that so outlandish it has to be termed "Rubish"


Mate as usual you have gone of like a frog in a sock.
I was not knocking the torsion box idea I use them all the time .
What I called rubbish was your assertion that a 20mm top was somehow not strong enough and that is rubbish !

Ross

[Lignum]

as usual you have gone of like a frog in a sock.
I was not knocking the torsion box idea I use them all the time .
What I called rubbish was your assertion that a 20mm top was somehow not strong enough and that is rubbish !

Ross

No idea what your problem is, but thats up to you to sort out. If you call "gone of like a frog in a sock" for saying..... "20mm is to thin for a 1500 top, and you have the problems of quality bracing underneath that is large enough and strong enough to keep it flat and stable and not been seen. If you went that thin you would need a skirt like the traditional antique mahogany tables but if your going the contemporary way a torsion is the best" ..... well you do have issues. Arrons initial question was for a 50mm thick top. not the 20mm you replied with. If you read on you would see i was under the assumption it was 1500 in diameter. But you do delight in jumping down on me at any given chance, hence the introduction as "Rubbish!!!" and now followed up on how as usual i go off. You said you wernt knocking the torsion idea if thats so why did you say that i " need to think outside the square or in this case the box !" If you havnt any constructive words of critisism then just dont bother at all

[TEEJAY]

What a beautiful forum and a lovely thread :) two greenies coming ;)

Cheers

[Clinton1]

Great stuff Lignum.

Been checking out the prices on vacuum press bags. :( lotsa dollars for the larger sizes.

I've really enjoyed your threads and answers on veneering - again, great stuff.

[Arron]

Another question please. I can use either recycled pine or recycled western red cedar for the core. I'm thinking cedar would be lighter and more stable. If its lighter I can use more bracing. I have some concerns about the tendency of pine to twist and warp - especially when it is remilled. Are there any problems using cedar instead ?

Whichever I use, I'll probably mill it to rough size and shape this weekend and leave it for a month or so to reveal any bad tendancies before using it.

Incidently, I rang Specialty Timber Veneers today and asked them how much to veneer a table to of this size in American walnut. Its about $180 per side - but the catch is they wont veneer torsion boxes - only onto solid wood or composite. Apparently the press they use will cause slumping between the ribs, no matter how close they are. I'll have to keep searching.

thanks again
Arron

[Greg Q]

actually I calculate the top at about 40kg, being
1.5 x 1.5 x 0.044 = 0.099
then 370 x 0.099 = 36.63 kg (wrc being 370kg per m3 at 12% moisture)
plus add extra for glue, walnut strips and mdf skin.
...snip...
thanks
Arron

Hi Arron.

Sorry on the over estimate of the weight. I used your 1.5m squared X 50mm, but then used the wrong density because I was too lazy to go check. Doesn't matter anyway, because I agree that the torsion box is the way to go.

Cheers

Greg

[Lignum]

Another question please.

Another question please. I can use either recycled pine or recycled western red cedar for the core. I'm thinking cedar would be lighter and more stable. If its lighter I can use more bracing. I have some concerns about the tendency of pine to twist and warp - especially when it is remilled. Are there any problems using cedar instead ?

Iv never used red cedar but see no reason why it wouldnt work. It dosnt realy matter what you use except use hardwood where their will be anchoring for the legs and the external frame (of the torsion frame) Pine is notorious for twisting but i just make sure its flat using hand preasure when i join them all up. But iv done alot so id suggest you use the cedar until you get a few under your belt

Whichever I use, I'll probably mill it to rough size and shape this weekend and leave it for a month or so to reveal any bad tendancies before using it.

No point, just rip and prepare and use it straight away, especialy if you are going to use the cedar. Why wait? just get stuck into it. Once the frame is made and skins on, its impossible for the torsion to twist or move.

Incidently, I rang Specialty Timber Veneers today and asked them how much to veneer a table to of this size in American walnut. Its about $180 per side - but the catch is they wont veneer torsion boxes - only onto solid wood or composite. Apparently the press they use will cause slumping between the ribs, no matter how close they are.

Im puzzled about that. Is it Specialty Timber Veneer or Speciality Wood Veneers. i looked in the yellow pages on line and found Speciality Wood Veneers, so i hope its them as i e-mailed of to them some questions why they would say that. Obviously if the ribbs are to far apart that will happen. Maybee they had some torsions a few years back that wernt made properly and they slumped. A 9mm MDF skin with ribbs 95mm apart would need amazing preasure to cause that. If they use a mechanicle or hydralic press a cover sheet would be used so it couldnt happen, and in all the years iv either vacuumed or seen others do it, spacing that close just dose not slump. I hope i get a reasonable response from them When i do ill pass it on to you.:)

[Different]

[quote=Lignum]No idea what your problem is, but thats up to you to sort out. If you call "gone of like a frog in a sock" for saying..... "20mm is to thin for a 1500 top, and you have the problems of quality bracing underneath that is large enough and strong enough to keep it flat and stable and not been seen. If you went that thin you would need a skirt like the traditional antique mahogany tables but if your going the contemporary way a torsion is the best" ..... well you do have issues. Arrons initial question was for a 50mm thick top. not the 20mm you replied with. If you read on you would see i was under the assumption it was 1500 in diameter. But you do delight in jumping down on me at any given chance, hence the introduction as "Rubbish!!!" and now followed up on how as usual i go off. You said you wernt knocking the torsion idea if thats so why did you say that i " need to think outside the square or in this case the box !" If you havnt any constructive words of critisism then just dont bother at all[/quote

Proxac is the only suggestion I have after that little tirade!
You are hypersensitive and I should have known better than to bother posting in response to any comment you make but dont tell me what to post or not it simply isnt your place!

I missed Arrons desire for a 50mm + top and was suggesting that there was another option as it turns out wrongly the result of not reading the first post correctly.

Ross

Ross

[redwood]

Proxac is the only suggestion I have after that little tirade!
You are hypersensitive and I should have known better than to bother posting in response to any comment you make but dont tell me what to post or not it simply isnt your place!

I missed Arrons desire for a 50mm + top and was suggesting that there was another option as it turns out wrongly the result of not reading the first post correctly.

Ross

Ross

thats a woosie triade if ever i seen one:D :D lignums contribution to this thread has been fantastic:D you say no ones to tell you wat to post but telling him to take prozac isnt very nice. especialy after the discussion yesterday about the tragic consiquences of being taken of the drug:(

[Arron]

Just when I was getting excited about making a torsion box, I get a reality check. It seems Sydney veneer people are not as amendable as Melbourne ones.

Specialty Wood Veneer Panels - wont touch a torsion box top
Briggs Veneers - dont do outside jobs
Veneercraft/Architectural Veneer Supplies - n/r
Woodstock Veneers - Supply only, dont press
Timber and Door Supplies - won't risk a torsion box plus too wide for press
Yates Wood Products - No to a torsion box
Processed Forest Products - will only press onto own board or ply

It seems I may be back to a soild top after all. I will persist with Veneercraft till I get through, but am not hopeful. The guy at Yates was very helpful, patiently explaining that even though he could alter the force on his press he has still had bad experiences because the pressure is not consistent due to the internal structure, and this had led to some nasty disputes with customers.

I'm considering a solid table top - or is there some other way.

thanks
Arron

[Auld Bassoon]

Arron,

Even without a vacuum press, veneering isn't that hard. Give it a go on a smaller piece as a trial.

The only major issue would be in getting a single sheet of veneer big enough to cover the table top; joining veneer invisibly is a tad tricky (I haven't been able to do that). What I have done is to intersperse elements of one veneer type with a small inlay of a contrasting timber, so as to break up the overall with a designed pattern. This might not be to your taste though.

[Lignum]

Arron:) just thinking out side the square. The table you posted in the other thread. As you got it for nothing. have you concidered giving it a good clean (not restore) and putting it into an Antique Auction. Im not familiar with Sydney prices on furniture but id be surprised if you didnt get around $400 for it, maybe more. If Specialty Wood Veneer charge $180 per side, thats $360. total $760 ish. Why not look at the small Vacsack from Cloudmaker in Perth for $420.

It needs a min 75psi / 2.5cfm air compressor to opperate and is suplied with only a 1000 x 1300 bag. But that size is great for general cabinet panells and you will have a great time with smaller torsions and solid cores. If you do decide its an option, i will write a detailed description for you on how to make a veneering table that you place a 0.5mm (20mil) vinyl "sheet" not bag, over it and clamp/seal the edges and use the Vacsack Venturi to vacuume it.

And Steve mentioned joining veneer. It is surprisingly easy if you follow some standard procedures. Again ill give you a run down. But i dissagree that it isnt that hard with out a vacume. Its very fiddly and time consuming to do panells larger than a meter square with cauls or hammering. and get it right. But having said that its been a while and im spoilt by having vacuum power:o .

Dont waste an opportunity because some company wont lay it for you. Its not expensive to start up and you will have a kit to use on a multitude of great projects in the future. If you dont do it now, maybe you never will. Whats that famous saying- Just Do It:)

[Arron]

Well today I got in contact with the last of the veneer specialists in the yellow pages (Veneercraft) who confirmed that they would not do a torsion box. I guess that is the end of the torsion box idea. I understand what Lignum is saying about going the vacsak -> homemade veneering table route but bearing in mind my current veneering skills, work committments and cost of multiple learning curve derived failures, I am still inclined to get the veneering commercially done. That puts me back to thinking about solid table tops. It is integral to the design that I am ripping off that the top be 50mm thick and have lines as clean as possible. A solid wrc top would be about 40kg which is tolerable, but the problem is having to veneer over natural timber with its expansion&contraction without doing a breadboard end (unnacceptable, remember the clean lines). My next thought was to obtain some poplar blockboard like this http://www.eco-core.com.au/2.1.html. Poplar blockboard is apparently extremely stable and quite suitable for veneering over - and there is no need to worry about e&c. I rang and asked price and was quoted $662 for one sheet !!! I am therefore thinking why not make something similar myself using recycled cedar ripped to size and glued with pva. Presumably all you need is three layers of poplar battens 12mm x (say)50mm x 1500mm, glued up like three-ply plywood, and 6mm mdf on top and bottom. Of course it is a lot of frigging around with the thicknesser and there are issues to overcome in keeping it all flat. But here is the question - If I make it up myself wont the individual timbers still be expanding and contracting, and as those forces combined across a wide area are extremely strong wont it tend to slowly delaminate? I guess it is the same question one might ask about the commercial blockboard. Clearly the
different layers are expanding and contracting independently, with each layer's expansion constrained by the different grain direction of the layers to which it is bonded. Is it the case that the expansive forces are simply suppressed by being so tightly bound to one or more other layers that cannot expand in the same direction? If so the whole thing relies on the integrity of the glue. If so then can the same thing be achieved using one layer of natural timber and two of mdf, rather then 3 of timber? Can this be achieved in the home workshop?

Anyone ever used this method of construction, or have any thoughts on these questions ?

Arron

[Auld Bassoon]

And Steve mentioned joining veneer. It is surprisingly easy if you follow some standard procedures. Again ill give you a run down. But i dissagree that it isnt that hard with out a vacume. Its very fiddly and time consuming to do panells larger than a meter square with cauls or hammering. and get it right. But having said that its been a while and im spoilt by having vacuum power:o .



Hi Lignum,

I'd be VERY interested to hear about your methods for joining veneer - perhaps you could point me in the direction of some books / texts on the matter?

Cheers!

[Lignum]

Steve:) i usually get the veneer in flitches around 20 odd per flitch and 280 - 310 mm in width. If im doing a table around 900 mm ill take the top four and use a lesser quality four (from a different flitch) for the bottom of the table. Ill lay the top four side by side and arrange to get the best match. I favor slip matching, most favor book matching. When iv got it right ill roughly match up the bottom four then place all eight on top of each other and masking tape it at the ends. ill aim for a 910 mm width so ill rip some 19 mm MDF to 228 mm and 60 mm longer than the finished top length. I then sandwich the veneer between the MDF and clamp together at the ends and three or four places along the middle. I'll then trim the execs veneer of with a chisel or knife. Then ill take it to the jointer (with the fence pushed right back) and joint the edges flush. This method works very well and you will get very good straight edges. Then to join them ill place the leaves on a table upside down and every 100 mm from the top stretch masking tape (blue 3m is by far the best) across the leaves bringing them together tight. When the four leaves are joined with help turn it over and use some veneer tape and apply to the top in the same position as the masking tape underneath. When the veneer tape has dried carefully flip it back over and remove the masking tape. You now have a lay-on that will have spot on joins that will be invisible:)