Good Days, Bad Days and the Quality of Ply

[wizer]

(Posted elsewhere, interested in this forums views -especially trade)

Yesterday was great. I spent a good few hours in the workshop making a 'Mailee Dado Jig TM'. All went swimmingly, floated out of the workshop all please with meself.

Today was a different (and more lengthy) story.

I'm making a rolling cabinet for the bandsaw. The ply was delivered a couple of weeks ago. I had the guy bring it straight into the workshop onto my cutting table. I set about cutting it up into manageable sizes according to my cutting sheet. As I went through it I quickly found that both sheets where warped over width and length. I carried on anyway and stacked it up neatly.

My design calls for dadoes and rabbets. I chose this joinery because i'd like to learn more about it and become competent.

Today, I realised that the warped boards where really going to be a problem. The dadoes and rabbets where either different depths across the length OR would effectively have to be banana shaped.

I persevered with it but in the end I gave up knowing that the impending glue-up would be a complete nightmare. Clamp City.

The ply was 18mm Brazilian Virola WBP. It's better (and cheaper) than the B&Q stuff. It has one reasonable attractive side, the other it still better than B&Q. Hardly any voids, although I did have one component split (glue failure I assume). I can't really blame the supplier as it's not intended for furniture, he told me it was "good for tiling".

So, should I:

A: Bin the lot and stop expecting good quality for £20 a board. Go for good Birch Ply from a reputable supplier and swallow the cost.

B: Have a word with myself, this is workshop furniture. Use different joinery and make it fit through brute force.

C: Something different.

(if you hadn't yet realised, I'm very much a novice woodworker)

[engineerone]

are you sure they delivered ply

seems very strange, the whole process of plying is to
stop this thing happening, or am i like you missing something???

paul

[Scrit]

wizer said:

Today, I realised that the warped boards were really going to be a problem. The dados and rabbets where either different depths across the length OR would effectively have to be banana shaped.

You've hit the problem of using plywood in general, even the almost mythical Finnish stuff; it tends to move somewhat and cutting it can actually release stresses....... Oh, and ever the pedant, might I also point out that "dado" is an American term? We call them housings or grooves in the UK

wizer said:

The ply was 18mm Brazilian Virola WBP. It's better (and cheaper) than the B&Q stuff.

Not if it moved that much it ain't, surely? In the past I've had Chinese hardwood plywood with so much stress in it that it has ripped itself off the vacuum pods on a CNC router mid-way through machining. Impressive when you consider how much downforce is applied through the pods.

wizer said:

I can't really blame the supplier as it's not intended for furniture, he told me it was "good for tiling".

Yep. That's all I've ever found it any good for, flooring to be covered by something more attractive. You're lucky to have had only one major fault. I've seen some very ropey stuff passed off as B/BB equivalent grade in the past.

wizer said:

So, should I:

A: Bin the lot and stop expecting good quality for £20 a board. Go for good Birch Ply from a reputable supplier and swallow the cost.

B: Have a word with myself, this is workshop furniture. Use different joinery and make it fit through brute force.

Don't bin it. Do consider the joinery techniques. After all pocket hole screws or carcass screws with a spot of glue on the butted edges can make remarkably solid workshop furniture. Not swanky, but effective. My feeling is that some of uncle Norm's (Norm Abraham: New Yankee Workshop) techniques don't transfer well to the UK, partly because of the relatively high cost of plywood here and also the relatively poor quality of much of the cheaper plywood sold here.

On the other hand it may well be worth considering other boards for future projects. MR-MDF is a useful board, stable and generally warp free albeit extremely heavy. OK, it does require a coat of paint to seal it against moisture, the dust is 'orrid and it blunts hand tools at a rate of knots - but it's cheap and strong enough for short-term jigs, workshop furniture , etc. Another, more expensive, but even more durable board is MF-MDF (melamine-faced MDF) which is so often used in retail stands these days. The melamine facing gives it extra rigidity, protection from moisture and good wear characteristics and means it will take real kicking before it breaks. Pity it normally only comes in jumbo sheets (2600 x 2000mm), but with a jumbo 18mm (5.2sq.m) at under £40 + VAT as opposed to a similar price for a 2.4 x 1.2m (2.9 sq.m) sheet of B/BB Baltic birch plywood the maths aren't tooo hard to do

I'll now stand back whilst everyone pokes fun at my choices ;D

Scrit

[jfc]

I dont use ply cause it warps , funny how people worry about the glue in MDF but not ply

(if you hadn't yet realised, I'm very much a novice woodworker)

Doesnt matter what scale of woodworker you are here mate , all levels are welcome

[engineerone]

even more interesting is that most undertakers use a lot of formaldahyde in daily life, and although you get a lot of drunk
undertakers, few of them seem to die from the formaldahyde

paul

[wizer]

I did consider MDF but dismissed it due to weight and mess. I have a back problem and lifting a full board of any 18mm is dangerous/impossible.

That said, it seems the general consensus is that MDF is the answer. MF-MDF might be too much of a PITA with edging etc. MR MDF could be a good option, is there an easier/less messy option to painting? Oil? Osmo Poly-X? Or what about the pre-painted MDF?

I have 2 more rolling cabinets to make, and am tempted to bin this Ply as it will bug me everytime I look at it. Or save it for something that needs less finesse.

Thanks for your comments guys.

[Scrit]

wizer said:

I have a back problem and lifting a full board of any 18mm is dangerous/impossible.

Why not get the yard to do the initial break-down on the board for you?

wizer said:

MF-MDF might be too much of a PITA with edging etc.

It doesn't need to be edged. You could also varnish/paint the exposed edges.

wizer said:

MR MDF could be a good option, is there an easier/less messy option to painting? Oil? Osmo Poly-X? Or what about the pre-painted MDF?

Oils will soak into MDF like blotting paper, so I don't think they'll work. The only pre-painted MDF I've ever come across is the 3.2/4mm stuff sold for carcass backs

Scrit

[mrgrimsdale]

So, should I:

A: Bin the lot and stop expecting good quality for £20 a board. Go for good Birch Ply from a reputable supplier and swallow the cost.

B: Have a word with myself, this is workshop furniture. Use different joinery and make it fit through brute force.

C: Something different.

(if you hadn't yet realised, I'm very much a novice woodworker)

As a novice woodworker I wouldn't compromise on material quality - you just give youself another problem or even find that the project is impossible.
Also birch through ply is very nice to work with compared tp cheap stuff. I'd say always buy the best. Ask yourself what the extra cost is, compared to the value of your time, the quality of the finished product and how much you spend on tools.
cheers
Jacob

[paulchapman]

wizer said:

is there an easier/less messy option to painting?

I've had good results using varnish on MDF (not the water-based stuff). Liberon do a good one - nice and runny like the old Furniglas PU15 which you can't get any more. It's good for workshop stuff as it makes it resistant to moisture and oil.

Cheers

Paul

[wizer]

thanks again guys. I'm going to use as much as whats left with screws and biscuits and then go for a better quality board next time.

You live and learn.

[nickw]

Use a small foam roller to apply gloss to MDF, it gives a good finish easily. Chuck the roller at the end of the day, it's not worth the hassle of trying to clean it.

EDIT: So why is there a gap in the word 'small' above? There is no space in the source text.

[wizer]

Thanks nick, I take it even MR MDF still needs a coat of MDF Primer?

[engineerone]

the most important part of painting mdf is sealing the edges.

i have found that dilute pva is valuable for this too.

i also agree with scrit, get the boards sized at the woodyard/shed and that makes life easier.

good luck.

actually what you will find is that once you have built the first couple of cupboards, you will discover they are wrong for what you want, so you will need to build again, hence another reason for not going over the top on your first cupboards/storage

paul

[wizer]

Back to good days. Took a swing at option B and got some good progress. Worked out an approach that will minimise wastage. Won't look pretty tho..

Thanks again guys.

[pitbull]

What ply was it, 5, 9, 12 ?

[wizer]

wizer said:

The ply was 18mm Brazilian Virola WBP.

[pitbull]

I don't really deal with sheet materials but what was the ply count, sorry I knew it was 18mm but how many ply was it.
It tends to be the higher the ply the better the quality, hence shuttering is 3 or 5 ply where as the furniture lads would probably use something that has 9 or more ply in it.

[wizer]

oh i see, sorry. Will check later for you.

[dunbarhamlin]

engineerone said:

even more interesting is that most undertakers use a lot of formaldahyde in daily life, and although you get a lot of drunk
undertakers, few of them seem to die from the formaldahyde

paul

Not any more - it's been banned. And it is very nasty stuff - no one ever woke up after they were embalmed!
Embalmers did commonly suffer health dibenefits from its use (respiratory problems (plasticised lung tissue doesn't work too well), conjunctivitis, topical 'burns' and more serious stuff in the case of accident), but H&S were very strict with venting, storage and use requirements, and safety makes up a significant part of the embalmer's qualification.

Cheers
Steve

[wizer]

it was/is 5 ply

[engineerone]

long time since i was embalmed so did not know it had been banned, but the number of undertakers who seemed to carry the smell was always interesting when i was a little younger

rather like the doctor who smoked telling you to stop doing so

mind you i am sure that the killer in mdf is the small size of the cuttings rather than the chemical content.
paul

[Scrit]

engineerone said:

mind you i am sure that the killer in mdf is the small size of the cuttings rather than the chemical content.

Oh Lordy! The Daily Mail MDF story resurfaces yet again!

European manufactured MDF is the a standard called E-1 and has been for more than 10 years - a good reason to avoid cheap Chinese-made MDF boards IMHO. E-1 is very low in formaldehyde, but it is recognised that the cutting and routing of MDF creates a very fine dust which must be extracted at source of production (the real hazard of utilising MDF), and it is now recognised that almost all extremely fine dusts are potentiually carcenogenic. But that is nothing to do with formaldehyde. If you'd like to inform yourself better then why not take a look at these pages over on the TTF site

Scrit

[nickw]

One of the ladies on Trade Secrets helped perpetuate the MDF/Formaldehyde myth last night. Grrr.

[Scrit]

nickw said:

One of the ladies on Trade Secrets helped perpetuate the MDF/Formaldehyde myth last night. Grrr.

The other oft repeated urban myth is that America has banned the production of MDF............ Funny one that. Read FineHomeBuilding and MDF is often referred to as some form of wonder material. If you'd like a chronology, how's about this:

1974 - American production of Medite MDF starts in Medford, Oregon (hence MEDite).

1976 - MDF arrives in Western Europe.

So it seems to have started over there...........

Scrit

[engineerone]

ah scrit too long have you been away, i did not say the forma was dangerous, i was confirming i thought that there are other things in it more dangerous than that substance

i agree about the banning of mdf in the us it seems to be the second biggest myth in building, the first of course being that
work can get done on time

actually i have never seen the mdf story in the maily dail

paul