Woodworker's Central Woodworker's Gazette Gazette Archive Bandroller Response

Below are excerpts from two emails received from Louis Iturra and my response: Dear Jim, First of all, I salute you for taking on such a monumental and difficult task in this review. Doing comparison testing on new or unfamiliar products is an inexact science at best, but I believe as your staff does, that any feedback helps the end user make a more informed choice. This is especially true today, with the constant barrage of media hype and dis-information we seem to get from many companies. Your website is truely a sanctuary in this regard and I urge you to keep up the good work! <snip> There are several differences I do wish to point out that may have been overlooked in your excellent review. First, the guide assembly on the Delta 14" bandsaw was originally patented, since its design was an important safety feature, in that it brought the adjustment controls (especially on the lower guide assembly) out toward the operator. This kept his hands away from the blade, adding a measure of safety. One does himself a disservice by converting to an after-market design which doesn't encompass this important safety feature. You also seem to like the Carter thrust bearing design, but we have found no advantage to this design, the contact point is smaller which may produce slightly less heat, but you must remember that the thrust bearing is the hardest working bearing in any of these designs. We feel that the additional surface area of contact in a face mount bearing provides more support for the blade and dissipates feed pressure over a greater surface area,leading to less mushrooming of the back of the blade. The bearing can also be reversed if one face becomes damaged or scored. We also have closely examined our competitor's design especially the Johns guide and have found the machining quality to be poor and the bearings (as you point out) of the shielded type, which we believe do not belong in any woodworking machine period. Since wood dust can and will enter these bearings and contaminate the bearing grease leading to premature failure. Also by not supplying bottom ball-bearing guides the woodworker only receives half the benefits of this design. We don't feel your test of heat production was a true indication of heat produced by actual cutting, since I'm sure we all have encountered that burning wood smell from time to time when sawing! The truth is, the blade can and will reach extreme temperatures from time to time hot enough to burn wood or your hand! This is one of the major causes of blade dulling and is the reason so many company's are now selling bi-metal blades which tolerate this heat better. <snip> Again Jim, I want to personally thank you for a very well written review and will refer my customer to it in the future. Keep up the good work! Thanks, Louis A. Iturra ------------------------------ My response: Dear Louis, Thanks for the kind comments and the corrections.<snip> About the thrust bearing orientation, I still like Carter's setup. It's also my impression that 99% of the heat created while bandsawing is a function of the blade's interaction with the wood - not the bearings. I probably won't make any changes here. <snip> Thanks for responding so quickly, Jim Mattson ------------------------------ His response: Dear Jim, You're very prompt with your e-mail, thanks for responding so quickly. I probably won't be able to convince you that there is indeed, improved heat reduction with ball-bearing guides, but I thought for the sake of argument to give it one last shot. You are correct that the largest area of heat generation will, in the majority of cases be, within the workpiece being cut since that is where the majority of friction is created. Metalworking engineers realized this years ago and cool the blade with liquid coolant to reduce the harmful effects of heat when metalcutting. Unfortunately because of the material we woodworkers use, this is not an acceptable answer. So the only answer we have is to reduce any other sources of friction which may be adding to the problem, primarily the friction created when the metal rub blocks are in contact with the blade. The easiest solution is to use ball- bearings, since as you pointed out, their surfaces are less prone to wear than other materials. Although you feel that the heat generated by even solid metal rub blocks is small, I believe that if you were to place a metal temperature probe on or in place of the metal guide you would be surprised. Realize that this heat is rapidly drawn away by the heatsink properties of the metal block itself, the guide holder and the rapidly moving blade. Although the teeth of the blade is subjected to this heat only for an instant, it can be enough especially on regular carbon blades to soften the metal to a degree leading to eventual dulling of the teeth. <snip> Thanks again, Louis