Wood Veneer Quality

Is this your alter-ego Veneerman?

We are using a relatively small rotary peeler style mill. We work with aspen and birch to make small sticks and shapes for arts and crafts. We pull around 10,000,000 linear feet of veneer each year. The plant and most of the equipment are fairly old – old enough that I won't be able to tell the lathe/peeler manufacturer without some serious digging. Depending on the product line, we do employ a vision system to grade veneer based on the knots in a sheet.

Although the methods for verifying veneer quality that you mentioned may exceed our budget, could you discuss them?

In a larger setting, how is the pressure applied by the pressure bar controlled, and how is it checked?

Doorman, thanks for you response. By the way, are you in Fargo, ND?

"Although the methods for verifying veneer quality that you mentioned may exceed our budget, could you discuss them?"

Optical scanner and recognition technology. The technology is basically the same as size and color selection/rejection of any bulk product, and adapted to wood veneer. This type of system represents a fairly large capitol outlay (purchase and initial setup, maintenance, programming, and floor space), and lends itself well to large production runs. If I digest your estimate of ten million LF of veneer, that works out to about 20LF per minute. The peelers I have seen run about (I am guessing) 400-600LF per minute (it really shoots off of that knife!). This also allows semi-automated runs, which allows for a lot more up time (production). The scan equipment locates and identifies heartwood or sapwood, burls, worm holes, knots (open or closed) and pin knots, bark pockets, splits, mineral streaks... the graded flitches are diverted to a number of different lines as appropriate for each grade of veneer. All of the veneer, even if not grade-able, is used somewhere... there is very little waste.

"In a larger setting, how is the pressure applied by the pressure bar controlled, and how is it checked?"

I am not well schooled in the veneer peeler equipment available, but I cannot recall a 'pressure bar'. Is this the knife? I do know that veneering is quite an art, and those well accomplished in the skill make it look easy. What veneer thickness are you producing? Door skins are about 1/50".

I hope some of this is useful. Good bye, and hope to hear from you soon.

From Fargo, ND, USA, your friend Doorman

but I cannot recall a 'pressure bar'. Is this the knife?

I don't know any thing about this sort of thing but it sounds as though the arrangement looks something like this:-

pauls_14 is wondering how to control the force on the roller which compresses the wood just before the blade.

Paul, Is the picture approximately correct?

In a veneer mill w/lathe now days 1300 to 1600 lineal feet a minute is routine. The roller bar at the lathe pressure is regulated with hydralics according to product being peeled. Scanners are set up pre clipper and they just grade for width that panels of veneer can be cut into. Actual veneer grading is still done basically by hand by trained personel at least at our plant any way. I guess this doesn't answer your questions exactly but I hope it gives you more info.

Information relative to veneer processing and specifications can be found at:

http://www.hpva.org/ (hardwood plywood veneer association)

Thank you all for the responses.

Randall's diagram is fairly close. The pressure bar contacts the spinning block just ahead of the knife. When properly adjusted, it prevents splitting and cracking in the veneer. We hand pull veneer up to 0.15". Our peelers don't run full time, so they are capable of around 200 feet per minute, depending on the thickness. The thinner veneer is peeled on an automated system.