Once there was a saw

Once there was a saw

Back in the late 80s

LAST CENTURY I heard from one of my masterovityh COLLEAGUE ON THE EXISTENCE bandsaws With «Magic» feature, allows you to cut any thickness WOOD. At that time, I already in the ground to learn to work with wood, build a cottage, and begin to look closely to artistic techniques work with this material.

In those days, even the construction timber is practically absent in the sale, and only about wood for artwork and say nothing. In small quantities it can be a «get», t. E. To intercept the «borrowed» from the state. A circle of standing forests, gardens and parks with lots of, say, affordable wood (available in the sense of samozagotovki). Gradually matured in me the desire to have a band saw. Learn what it is, I could only tool stores abroad, where, during infrequent visits indulged in the study of these devices simultaneously measuring and sketching them.

First I bought a desktop band saw Black&Decker secretly hoping that it can eliminate the need for self-production of tricky for me the tool.

However, hopes were in vain, and 400 dollars were spent in vain: having a throat height of 100 mm (nominal thickness sawn billets), saw could really work with planochki only hardwood thickness up to 30 mm, and then only with difficulty and the risk of rupture of the blade. In 1992 I was lucky enough to buy a second-hand bookshop famous book by M. and J.. Dugin’s «Basics of band saw» (USA). Here, despite the presence of all sorts of useful particulars, to my surprise, there was no full information on the relationship between such important parameters of the band saw as the engine power, speed of the belt, pulley diameter and thickness of sawn blanks. I’m not talking about the characteristics of the tapes themselves. Thus, in the manufacture of blade I had basically guided own intuition. I must say that I do not have any knowledge of engineering, other than those acquired in the construction of cottages. Drawings of course I did, being content with simple sketches that because of years ago have not been preserved. Very important for me was the familiar lathe, a number of parts machined from metal, in particular, landing slots for bearings on pulleys. Basically Saw was performed from the closest I material timber in the form of boards, 25 mm thick and 10 mm thick plywood. From experience I can say that the tree is a very convenient and very reliable material for body bandsaw, also absorbs some vibration and noise (photo 1). Inside the vertical load-bearing part of the frame from top to bottom I glued 15 ribs made of plywood 20 mm thick to deal with the effect of the console. The front part of the saw blade consists of two plywood doors 5 mm thick, provide access to sites and pulleys that guide the tape motion. Pulleys 20 mm thick and 320 mm glued plywood and I were relieved cutouts. Their heartbeat was eliminated by the turning chisel with rotation, t. E. Almost lathe way. To avoid prescribing «eights» moving the saw blade I brought pulleys in a single plane with the help of a ruler and meter of gluing pieces of veneer under their base. I pasted the pulley rims with rubber tourniquet from the pharmacy: one side they have a convex shape that makes self-centering of the saw blade as it moves along the rim of pulleys (Photo 2.3).

Saw I created for my small workshop (12 m2), situated in a city apartment, and at that time already very cluttered with equipment, devices, and so on. D. Hence the relatively small dimensions of the structure: height 1320 mm, width 460 mm and thickness of 120 mm. Guideline for sizing served as one of the models of band saws companies Electra Beckum power of 0.8 kW, with a height of 200 mm throat and belt speed of 800 m / min — at the time I was able to find where the image of the device. Since manufactured Saw intended for such complex tasks as the dissolution of the logs of solid wood thickness up to 200 mm at first and then 250 mm, it was necessary to increase the power characteristics of my creation in comparison with foreign analogues of this class. First, I installed electric power consumption is 1.1 kW, and then, finding more efficient saw blade, changed it to the unit power of 1.5 kW. Settlement belt speed determined in accordance with the well-known to me then a maximum of 1000 m / min — tachometer on sale was not, so she remained suspected or, if you will, purely theoretical (photo 4).

Get hold of the bearings at the time was also difficult, had to be content with what was found. For this reason, the pulley bearings were open type small size 12x28x8 mm. Once a year, I washed them and stuffed with new grease until last fall finally not put here modern precision and dustproof counterparts, which considerably reduce the noise level when operating the saw, and to simplify the maintenance limit. Now it is limited to the removal of sawdust from the interior of the body, although the debris initially assigned vacuuming, join a work desk. By the way, household models are unsuitable for this purpose, and in recent years I use a relatively small industrial vacuum cleaner with reusable bags Kercher (photo 5).

Already mentioned throat height of the saw 250 mm at its published specifications is fully implemented, ie. E. Is not only the face but also the effective (real) when dealing with the hard wood, for example, such as elm. Mass construction is about 60 kg, which makes it possible each year without much strain to move it to the country where I have been turning operations.

Control over the movement of the tape is carried out by means of two guide blocks — the upper movable and lower stationary. Both are made of metal. Obushok tape motion rests on the rear bearing support, not allowing it to recede under the pressure supplied the wood. Side bearing prevent lateral displacement of the tape and can move back and forth and side (fixation is carried out with the heads of the screws) (photo 6, 7). Because until recently installed here bearings are open, I made them in machined steel cups to prevent rapid deterioration and pollution, which is especially important for the rear support bearing. So, last summer, when the saw carriage to the country with one of them jumped out and lose the protective cup, resulting in three months is not too intensive exploitation of the bearing was completely disfigured butt saw blade. Though now, replacing the old with modern open bearings closed, I still put them in the new (replacement) protective cup.

The basis of the mechanism of a tension of the saw blade is a powerful spring with section turns 4×11 mm — it managed to get to some enterprise. Due to the fact that my hands got ready to tape length of both European and American standards, it was necessary over time to provide a fairly large power reserve (of the order of 100 mm or more) of the mount upper pulley. However, wood design makes it easy to alter anything (photos 8,9).

The obvious shortcomings of my saws include immobility desktop that does not allow to cut the workpiece, for example, at an angle of 45 °. But until now, it is me once and was not required. Table dimensions 400×400 mm up. For cutting long block of wood, for example, more than 800 mm I built an additional roller bearing, which is mounted on the substitutes to the saw stool. It is made in the form of a rotating section of plastic pipe with bearings, pressed on the sides (photo 10).

Bandsaw advantage compared to other species is not the accuracy and efficiency associated with the fact that the load is distributed over a large number of teeth of the tape running without strain and overheating. Each tape wiring due to the nature of the teeth and the presence of so-called «drift» sawing the workpiece is not straight, but under a different angle, which according to the rules, you must first define and then put on a special home-made guide fence (fence). At first I did so, but eventually found the procedure quite a chore. Then he began to cut either by eye or by using a piece of wood the size of 300x120x70 mm, weighted with lead, as a simple fence. Inside the bar, you can put a brick. This method I practice, including, when cutting veneer. In the process of cutting the workpiece always remain traces of the teeth, so called «harmonics», followed by post-treatment are fixed on other machines or manually, for example by a gluing tsinubelya (photo 11).

A separate important task is the selection of the saw blade. First, I use the German ribbon of spring steel 2240 mm long, 13 mm wide and 0.5 mm thick with three or four teeth per inch, ie. E. Step 6 or 8 mm respectively. However, I soon realized that they do not hew wood, quickly tupyatsya and tear. At this time in our country it has become a tool to shape the market, and I had the opportunity to experience all of the tapes that have been able to buy here or abroad. I sat for hours and reface Needle teeth tapes, trying to increase their size and aggressiveness — all to no avail. I often battered tape, not welded into the ring, I had to learn to solder them yourself, which I booked through a friend in the United States with a special set of silver solder (70% silver). I acquire and threw the tape up until finally stumbled upon a bimetallic strip Sandflex NF (Sandvik, Sweden): the effectiveness of its operation I was quite satisfied.

If overloads arising, for example, due to too sharp turns blank tape usually is not torn but simply slips off the pulleys. This phenomenon can be observed in rounding wooden pieces before installing them on the lathe.

Three years ago, I suddenly came across the Internet to the latest development of the company’s Lenox Tools (USA) — carbide tape TriMaster with characteristics suitable for small drinking width of 12.7 mm, thickness 0.64 mm with a step tooth 8 mm. I could not resist and ordered by paying $ 150 including shipping. Efficiency sawing surpassed all my expectations. Saw not feel like wood, but this tape, as did all the others, is intended not only for wood, but also for non-ferrous metals and steels, t. E. Universal.

However, it was necessary to rejoice for long: a year had passed, as the tape began to explode and no soldering is not helping.

Verdict — full metal fatigue due to its low quality. You can, of course, to blame too small diameter pulleys my saw, on which the tape should bend-bend at high speed, but I think the reason is quality. After all, on the same pulleys I have long and quite successfully operate bimetallic tape from Sandvik with the same physical characteristics (well, except that they are thinner by 0.04 mm). And do not rush. Probably should not have been so mercilessly twisting tape when rounding turning blanks, as I have done, keeping it only for equity cut thick pieces (resawing). Again had to go back to the tried and true Swedish saw blades, good once I bought the entire bay, though, of course, the efficiency of cutting them significantly lower than krupnozuboy carbide ribbon (photo 12). From time to time, bimetallic sharpen canvas with a small abrasive wheel for jewelry works installed on the drill.

My homemade drink served me faithfully for 20 years. And if I had to today to make it again, I almost all have done exactly the same, although increasing the pulley diameter up to 400 mm, as in the second model, a self-made wooden saw Canadian Matthias Vondel (Matthias Wandel), which used a number of very interesting non-trivial engineering solutions. However, the product on it due to low motor power (300W) and low belt speed (420 m / min) is not easily sawing thick logs only 270 mm. By increasing the size of the pulleys and, accordingly, the length of its blade tape while maintaining its other features, I could easily dismiss the log thickness of at least 300 mm. Yes, and to the choice of the saw blade, I would have approached more carefully than Matthias Vondel may once again returning to the Carbide version. This would allow me not to work at the limits of its current saws, for example, when rounding workpieces with diameter up to 250 mm for turning operations. A more detailed account of them can be found on my blog link www.tokarpopov.ru

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