

The Question of Veneer Presses ^§^ 



"If you were going to put iu a panel department, Tvhat kind of 

 press would you use?" was the question put to a group of men 

 including a panel manufacturer, furniture manufacturer and a ma- 

 chinery man. 



"A hydraulic or a hydrostatic press, of course," said the panel 

 man. 



"I would have a hydraulic and some hand presses, too," said the 

 furniture manufacturer. 



The machinery man looked as if he wanted to say something, 

 started to, and then changed his mind and waited. By and by the 

 inquirer turned to the machinery man and said: 



"Well, come on, and tell us what you think about it." 

 ' ' I think, ' ' said the machinery man, ' ' that it depends a whole 

 lot on what you intend to do and how you intend to do it." 



"What has that to do with it?" inquired the panel man, "a press 

 is a press, and where there is any quantity of gluing up to be done 

 it is a waste of too much time and elbow grease to do it by hand, 

 and when it comes to power presses I think the hydraulic press is the 

 thing no matter what you want to do." 



"Perhaps it is," the machinery man replied. "I know you get 

 along with hydraulic presses and don't use any other kind, but just 

 the same I recall that you let lots of work go by that you might do. 

 I recall talking to you about special jobs in planing mill work and 

 show window panels and you said you didn't want to bother with 

 them because they call for special equipment and you wanted to 

 reduce your equipment rather than add to it. Special pjanels of 

 large size and of other shapes than flat call for the use of hand 

 presses of various kinds, and if yon had a room fitted up with hand 

 presses you would find that there is lots of work, now passed by, you 

 .could take in and make something out of. ' ' 



' ' Well, ' ' said the original inquirer, ' ' can you tell me anything 

 about what conditions of work or what circumstances make advisable 

 the use of any one particular kind of press?" 



"That is a pretty large order," said the machinery man, "but 

 maybe I can give you some light on the subject of the press question. 

 ' ' First you must take into consideration that there are three 

 general divisions of presses used in the veneer business, the hand 

 press in all its different forms, the power press driven with a belt 

 on tight and loose pulleys or with clutches, which is simply a modifi- 

 cation of the hand screw press with power applied. Then we have 

 the hydraulic or hydrostatic press which uses a chamber and ram 

 and the well-known principles of hydrauUes to apply pressure. Usually 

 with it the pressure comes from below, while in the belt driven power 

 press the pressure comes from above and is downward on the press. 

 "As to selecting a press for different uses, several factors enter. 

 One, of course, is the quantity of work to be done. Where the quan- 

 tity is limited and the variety is wide hand presses naturally have 

 the preference. They cost less and are easier to handle and can be 

 spread out so as to take in more dimensions. For this reason plan- 

 ing millnien and practically all users of limited quantities of veneer 

 stick pretty closely to the hand press in various forms. Others with 

 somewhat larger quantities use both hand presses and the power 

 driven presses which are simply a modification of the hand press with 

 belt power attached. They can do a wide range of work with these 

 and do it satisfactorily. 



' ' Ordinarily one would argue that where there are large c|uantities 

 of flat panels of practically uniform size to be made, the only propo- 

 sition worth entertaining is that of using hydraulic presses. Yet 

 in the face of all this, I know it to be a fact that a concern making 

 enormous quantities of flat plain built-up work practically uniform 

 in size uses nothing but hand presses. It has a perfect sea of these 

 presses, an immense room like a big warb^ouse practically fuU of 

 them with little runways between for putting in and taking out 

 stock, and it keeps quite a crew of men l)j»v screwing down and 

 loosening up these presses. 



"There, you might argue is a place where the hydraulic press or 

 the power press should be doing the work, and it is a waste of time 

 —22— 



and elbow grease to be doing it with hand presses. It suggests the 

 idea that these people may be- big factors but they are behind the 

 times. That, however, is not the case, for these people are very 

 progressive. The truth is another factor enters, one that perhaps 

 you folks have not given consideration to. They use a glue mixture 

 that will set in a very short time, say from an hour and a half to 

 three hours. Instead of using hydraulic or other power presses for 

 squeezing the stock together, and then clamping it up in forms and 

 running it to one side tUl the glue sets, tliey simply provide an 

 abundance of hand presses, screw the stock down in the presses and 

 let it stand there untU it sets. They provide enough of these presses 

 so that before they axe aU filled the first ones are ready to open up. 

 Hence it becomes a sort of continuous process of putting in stock 

 on one side and taking it out on the other, and by the use of these 

 presses in this way they eliminate entirely the work of clamping the 

 stock up in forms and trucking it to one side to stand wliile the glue 

 sets. 



' ' So you see there are many factors which enter into this, and 

 glue is one of them. Incidently it should be mentioned that we are 

 developing many new things in ihe glue line that cut some ice in the 

 matter of presses. Some call for special hot presses, some for special 

 shapes and forms that it is difScult to handle on any kind of a 

 hydraulic or power proposition. 



"Wherever there is work enough and it is practical to apply me- 

 chanical power it is generally advisable to do so. Whether that power 

 shoulil be hydraulic or applied to screw presses with a driving gear 

 is a matter open to some debate. 



' ' One of the strong points claimed for the hydraulic press is not 

 merely that it is a powerful press and can be made to exert all the 

 pressure required, but it is easy to attach a pressure gage to it so 

 that the user may know positively just what pressure he is using. 

 This is undoubtedly an important point, too, for positive knowledge 

 of the amount of pressure used is a good thing. 



' ' The makers of the screw power press, though, claim that the 

 gage registry of a hydraulic press is not a register or a record of 

 the pressure per square inch applied to the surface of stock in the 

 press. It is not either, but it is practical to figure out from the pres- 

 sure used the amount of pressure that is being applied per square 

 inch of surface of the stock in the press. Even with this, though, 

 there is some uncertainty. Leaving out entirely the matter of friction 

 and th^ loss in transmission, there enters the question of thickness, 

 of the amount of stuff that may be piled in a press at one time. 

 Given material of the same dimension if one press full is built up 

 of a thickness of six inches, while another has twice the quantity 

 making up a thickness of twelve inches, there is certainly some 

 difference. Just what difference or how the pressure distributes itself 

 through varying thicknesses is a matter that it is a little difficult to 

 determine satisfactorily. 



' ' The question of pressure is one thing that we have very little 

 definite information on. Every once in a while we hear of a piece of 

 work being spoiled through excessive pressure causing a spreading 

 of the core body or the mass of veneer and the opening of joints. 

 Yet we find ourselves lacking in specific information when we under- 

 take to investigate and analyze these. There is not enough positive 

 record of pressure used; neither is there other definite information. 

 Sometimes it may be the shape of the forms or cauls, and at other 

 times it may be carelessness in matching and fitting up stock in the 

 press that causes spreading, so we are left to guess at quite a lot 

 of it. 



"Some authorities claim that the only harm which can be done 

 by extra pressure is the crushing of the wood — that untU we get 

 pressure enough to cause crushing of the wood there is no harm and 

 no objection to high pressure. This point is probably open to debate. 

 The writer has examined some veneer work that seemed to suffer 

 from too much pressure. The pressure seems to have forced the 

 glue out until the glue joint was starved and did not hold weU. 

 Moreover, some of the best glue work has been done with hand presses 



