70 



HARDWOOD RECORD 



We shortly found it to be to our advantage to cut our box material 

 to length and resaw it as a last operation, tying the bundles up In shocks 

 as they left the resaw. We saw the field of the band resaw to be such 

 that we incurred the expense and annoyance of building several of these 

 machines for our own use, I making the drawings in many cases on ordi- 

 nary yellow manila paper and my millwright whittling out the patterns. 

 At the same time we were, of course, studying the peculiarities of the 

 hand saw ; methods of filing, brazing, etc. In those days there were no 

 automatic filing machines, which I suppose could have been used for this 

 purpose, which were in use in saw mills for fitting gang saw blades, etc. 

 So at the commencement we used the little semi-automatic emery grinders 

 such as Rogers of Buffalo was building at that time for sharpening cir- 

 cular saws, tipping the machine up on its side and bolting It to vertical 

 4x4s alongside of the wall of the filing room. We used Disston upsets 

 or spring sets for setting the teeth of the saw, and all of the operations 

 were made with the crudest of tools and with considerable expense of 

 patience and pain. 



But commencing at the bottom and working out ail the various prob- 

 lems for ourselves, we naturally became quite thorough in our work and 

 as a rule understood the why and wherefore for the various operations. 

 We found that many of the mysteries in connection with the fitting of 

 saw blades soon disappeared and we found that the same general prin- 

 ciples apply to a band saw as apply to any saw, whether it be a hand 

 saw, meat saw, circular saw or a band ; that the toothed edge that does 

 the cutting has to be taut ; that the teeth themselves have to have 

 proper clearance ; that a band saw especially is a good, rigid tool for 

 cutting In a plane parallel with the blade ; and that it is a poor tool, 

 indeed, to withstand any pressure perpendicular to this plane, or, in 

 other words, to withstand any side pressure. We found that to give 

 the blade the greatest capacity for withstanding shocks and pressure in 

 a fore and aft direction, namely, in the direction of the feed, that the 

 saw blade had to be fitted to the wheel, the greatest amount of strain 

 being exerted by the wheel towards the toothed edge of the blade to give 

 it the tautness referred to above ; the next greatest strain towards the 

 rear edge of the blade so as to form it in a truss, as it were, to withstand 

 any tendency to deflect the blade by the crowding of the feed, dulling of 

 the teeth, etc., and that it was necessary to expand the blade by means 

 of the hammer or stretching roll so that the wheels would give the least 

 strain to the central portion of the saw blade. 



It will be seen that a saw blade thus tensioned by the hammer or roll, 

 made to run on the wheels with the toothed edge projecting beyond the 

 face of the wheel a suflicient distance, so that, say, % inch, more or 

 less, of solid metal would project beyond the face, likewise would be 

 made to alter its form entirely if it be forced backward on the wheel 

 this Vi inch. This 'A inch of ribbon just back of the base of the 

 teeth, being the shortest part of the blade, being made to mount the 

 wheel and being elastic, would stretch and tend to make the rear edge 

 of the saw appear concave and thus would automatically guide the blade 

 forward on the lower wheel until it regained its normal position and the 

 blade again became straight in the back. It will thus be seen that we 

 learned why it was necessary and desirable to properly tension the saw, 

 that is, the correct tensioning of a band saw is that which forces it 

 (against fore and aft strains) to retain its normal position on the wheel, 

 as, in shifting forward or backward, the saw-blade changes its entire 

 form, rendering the back edge more or less concave or convex as the saw 

 goes backward or forward. 



Having indicated why the band saw holds its place on the wheel and 

 becomes a rigid and substantial tool for withstanding strains and stresses 

 exerted in the plane of the line of cut, the next thing I wish to explain 

 Is the theory on which a band resaw should he fitted in order that It 

 may cut in a straight line and not be deflected from side to side. The 

 two essential things to be borne in mind are to so treat the saw as to 

 give the cutting points of (he teeth the most rigid support. This is 

 accomplished by the tensioning of the saws as above described. A saw 

 thus tensioned and strained on the wheel has a "puckering string," as 

 it were, located directly at the base of the teeth. A sheet of paper can 

 be drawn in a straight line through a lump of soft wax and cut It 

 through and through, leaving a plane surface, if the sheet of paper Is 

 held taut at its front edge. This would not be possible if the sheet of 

 paper were made taut back an inch or two from its front edge. This 

 shows that by the tensioning of a thin saw blade from edge to edge we 

 have provided the best support for the saw tooth which projects from 

 the extreme edge. 



Thus having fitted the saw so as to support the tooth in the best 

 possible manner, the next thing to he studied is to remove all possible 

 side pressure from the points of the teeth, and, by so doing, to remove 

 all tendency for the tooth to dodge from side to side. This is accom- 

 plished by allowing only the sharp cutting edge of the tooth to come 

 Into contact with the timber to be sawn. In other words, the point of 

 the tooth is spread or expanded and filed so as to give a chisel like edge 

 thereto. As this cutting edge is provided to cut solely in the direction 

 of the line of cut or parallel with the saw blade, the corners of the 

 teeth should represent only a line extended, namely, a needle point, and 

 the steel supporting this needle point should recede so as to give clearance 

 both in the direction in which the timber Is fed and in the direction 

 in which the saw blade travels. 



The old Disston upset or conqueror swage gives an ideal form to the 

 point of the tooth. We used to describe this form as being bugle shaped. 



With a saw fitted with the Disston Conqueror Swage and not otherwise 

 treated I have no difficulty in sawiug with what might be also termed 

 "absolute accuracy." I have brought with me today for Inspection some 

 samples of picture backing ; made seven pieces from stock 1 Inch in thick- 

 ness before resawing. The saw kerf in these cuts removed was but 

 1/20 Inch. The saw blade which did this work was .030 inch thick, prac- 

 tically 1/32 inch thick. One-half pound pressure exerted against the 

 saw blade from side to side would have made this saw dodge over 1/16 

 inch and spoiled this work. In actual practice we have run saw blades of 

 the thicknesses stated, sawing this material, for days at a time and have 

 had remarkably few saw culls. 



Other technical points have to be considered: the amount of hook given 

 the saw — a sufficient amount to prevent its shifting on the wheel and 

 not enough at any time to cause it to run ahead, as in doing so any 

 teeth which might be at that instant in the cut might suddenly Imbed 

 themselves in the timber and great damage result. I have before now, 

 in sawing black walnut, happened to give the saw a little too much 

 hook, when suddenly an upward curve of the grain has caught the teeth 

 of the saw in such a way that they have jumped forward like the teeth 

 on the Boss dog, and the blade has been instantly stopped in the cut. 

 This was done so suddenly that the lower wheel of the resaw continued 

 to revolve for a short space of time, actually slipping around within the 

 saw blade. 



The possibilities of the band resaw can hardly be stated. The more 

 familiar I become with this tool the more I hesitate in saying what can 

 be done or what cannot be done. We recently built a machine and sold 

 it with the guarantee that two piano sounding boards could be sawn 

 from planks 54 inches wide by % inch thick. This would only allow 

 for loss in saw kerf and imperfections of about % inch, and you can 

 imagine the difficulty in supporting a 19-gauge saw in the middle of a 54- 

 inch cut. You, of course, appreciate that there is nothing which can be 

 done to reinforce or support a band saw blade other than the strain on 

 it and the stability of the blade itself. The side pressure of a pound 

 against this blade, 27 inches below the top guide and 27 inches above 

 the lower one, would undoubtedly send it out one side or the other. I 

 have some photographs showing the machine actually doing this work. 

 We had confidence enough, indeed, so that after having tested it In our 

 own plant we sent it to the Pacific coast, guaranteeing it practical to 

 do this class of work in this manner. 



Possibly your association is more interested in the resawing problem 

 connected with a sawmill. I have given this subject my attention since 

 1894, at which time we sold three of our 54-inch band resaws, equipped 

 with 5-inch saws, 18-gauge thick, to Wisconsin sawmills. These little 

 machines were successful and not only actually took care of all of the 

 plank that a circular sawmill could deliver to it, but in the R. D. Pike 

 mill at Bayfield it took care of all of the plank that one band mill sent 

 to it, as well as the dog plank from the second mill. 



In those days, say fifteen years ago, there was a good deal of trouble 

 in the hand mill because of the dog plank or the last cut on the carriage 

 being imperfect, usually thick at the ends and thin in the middle. It 

 seemed desirable in the sawmill resaw to often employ what is known 

 as a self-centering device — that is, to resaw 2-inch plank in the center — 

 and if surplus thickness existed to divide this surplus thickness up so as 

 to make the material look even in the piles. But you can readily see 

 that this kind of treatment will not do at all in connection with these 

 defective dog planks ; hence the peculiar invention which is embodied 

 in our resaws alone and which we term our discriminating self-centering 

 device, which self-centers pump stock and automatically slabs or recurls 

 from scant stock one piece at least of standard thickness. 



We repeat, back as far as 1894 we were using our 54-inch resaws in 

 sawmills, using IS-gauge saws 5 and 6 inches wide, and these light blades 

 resawed at the rate of something over 40,000 feet of board measure per 

 day. Of course, we soon found that these machines built for planing 

 mill service were too light for sawmill use. We then designed another 

 and heavier resaw especially for sawmill use. On it we used first 7- 

 inch saws, straight 17- or IS-gauge thick. Later we had occasion to 

 strengthen and improve these sawmill machines, now building them 

 heavy enough for S-inch saws 16- to 18-gauge thick. As the sawmill 

 resaw has become more popular with sawmill operators from time to 

 time, we have been compelled to design heavier machines. Although my 

 hobby has been the use of thin saws fitted so that they will do the work 

 of thicker saw blades, we have urged their use by sawmill men, except 

 in a few cases where he have furnished wider faced wheels to carry 

 saws up to 10 inches wide and as thick as 14-gauge, if so desired. I 

 feel strongly, however, that the evidence before you of the work done by 

 thin saws under proper conditions, namely, the sample of picture backing 

 and the cuts of a 5-inch saw, making a perfect cut 54 inches deep, Is 

 sufficient to warrant more attention in the future on the part of the 

 sawmill operator to the value and the possible economy that the thin 

 and relatively narrow saw blade insures when properly made use of. 



In America we are perhaps a little bit too much self-satisfied and 

 think that we have the rest of the world beaten. Some years ago I 

 received a letter from a Belgium concern to whom we had supplied one 

 of our pony band mills on which he said he was sawing from the log 

 "canary whitewood at the rate of 20.000 foet per day, removing but 1/lft 

 inch saw kerf." You can see that in Belgium, where timber is timber, 

 he could make money on a capacity of 20,000 feet per day in his saving 

 In saw kerf where an American mill would lose It sawing double the 



