The ultimate bandsaw

THE ULTIMATE BANDSAW 

OK. This the deal.   I do a fair bit of  hand woodworking,. However, I cannot/willnot live without my narrow bandsaw. I can manage without my circular saw. Every time I do use it I think 'this thing is messy and pretty dangerous'. (Ever watched videos of American wood workers? Their circular saws never have guards or riving knives which is really scary.

I have an alter ego as 'The Saw Doctor' from when I trained saw doctors from around the world. Sharpening and setting saws is easy and largely automatic. The greatest invention for the saw doctor was the introduction of 'throw away hard point' handsaws. Filing a handsaw or dovetail saw only serves to spoil your eyesight. Most of the skill comes with pre-stressing and levelling of large circular saws and wide bandsaw blades. How wide is wide? Well let's start at 75mm and go up to 300mm wide and from 15 to 20 metres round. Saws like this can cut with great accuracy and minimal waste. If you apply the same principles and standards to your narrow bandsaw, you can achieve amazing results, especially accuracy. For one of my clients I cut thousands of 1mm veneers, 100mm wide. Just 1mm of wood is lost in the saw cut, the finish is almost planed and the accuracy is minus 0 to plus 0.2mm. What I am going to tell you may be contrary to text books, but trust me, there is sound logic for it all.

Let's start with the blade. On a wide bandsaw, the steel strip is relatively thick and stiff and is strained up so that the blade is stiff. This demands that the frame of the machine is suitably robust (more on that in a moment). These wide blades, if considered as a beam being loaded by the pressure of the wood going into the saw, have considerable stiffness. Now consider your little bandsaw whose blade may be only 6mm to 18mm wide: it has very little beam stiffness at all. If you push back on the saw it will twist and start to wander all over the place. The solution to this initial problem is found in the geometry of the saw teeth. If the teeth have enough hook angle, the saw will tend to self-feed. You may have experienced that when you start sawing with a brand new blade: it will start to pull itself forwards. That initial excessive sharpness is quickly lost and the saw becomes controllable and doesn't need any force to feed the wood into the blade. If it does need  force, then the blade is blunt and it is time to change it. The thicker the material that you wish to cut, the fewer teeth you need. More expensive blades are thinner and can take a higher strain. They save a lot of sawdust.

When you buy a new blade, closely examine the weld where the ends are joined. A quality welder will never lose a tooth at the weld. A lost tooth will leave a tramline mark on the cut surface. Also, the tooth after the missing one will be overloaded such that the sawdust produced can't be carried out of the cut but instead is forced to leak down the side of the saw. This results in inaccuracy and wandering. If things are working properly, the sawdust should have a granular texture like sugar and not be dusty. Fine dust is a sign that the rate of feed is too slow – either the saw is dull or has too many teeth.

So now you have a good blade (I will only buy from Tuffsaws) and it is time to look at the machine.

Start by looking at the frame. Without a blade in the machine, take a firm hold by the top guides and push back. How far does it flex? If it flexes at all, when you are cutting the blade will only contact one of the thrust bearings which results in the blade bending. A baby Burgess 3 pulley machine suffers from this, and the Black & Decker even moreso. Many larger two pulley machines are not very good either. This can be solved though. The Burgess machine has a cast metal front cover and by substituting bolts and wing nuts for the quick release catches, you can make the whole frame into a box beam with great stiffness. You can apply similar techniques to 2 pulley machines, rigidly clamping the pressed steel covers. Some machines have plastic covers (like the B&D) and that requires a different solution. A bit of welded steel tube can provide the necessary support.

Next, let's look at the pulleys. These may have rubber tyres or hard pulleys, or with the blade running on the outside of the drive belt on the driven pulley. If the driven pulley is hard (typically nylon) and has been allowed to slip, the teeth may have cut grooves in it.  You may be able to reface it on a lathe or may have to replace it. The faces of the pulleys must be clean. If you are frequently cutting softwoods there may be a build up of resin which can be carefully scraped off or removed with thinners. I apply a bit of silicone spray after to help to stop resin sticking.

Time to fit the blade. Slacken all the adjustments on the guides above and below the table. Apply some strain to the blade. It should be within the range of the tensioning spring. If it almost gives a musical note when you pluck it, it is probably about right. On all  my machines, the blade can be deflected by 1 to 2mm with steady finger pressure. Now turn the pulleys by hand and track the blade until the teeth just overhang the lower pulley.

Next, we will take a leaf from wide bandsaw technology. Crucial to sawing accuracy is getting rid of the sawdust. If this is not really thoroughly done, sawdust will be trapped between the blade and the lower pulley. The saw will start to wander off track and you will have all that bother of cleaning them. Worse still, large bits of wood such a splinters can actually bend the blade. The first solution, one not found on any narrow bandsaw that I have seen, is to have a shear board set below the table and touching the saw. This throws any waste forwards away from the pulleys. You will have to be a bit creative here, but it will become a consumable item on the machine that needs adjustment every time that you change blades. Secondly you can improve dust extraction. Many machines make little or no provision for this. Often it is just a 4” pipe at the back of the machine. You will get better results by arranging a piece of 32mm plastic waste pipe connected to your vacuum cleaner IMMEDIATELY below the table. You can shape the pipe so that air is sucked across the blade at the point where it leaves the cut. This will catch 99% of the sawdust and cleaning the pulleys will become a thing of the past.

Next you can apply yourself to setting the guides. The blade is largely feeding itself, but when pushed back is steadied by thrust wheels or occasionally a thrust block (as on old Startrite machines). Thrust bearings have a hard life. Always have spares because if they seize, the saw will quickly wear a groove in the face and this can harden the back of the blade. Adjust the top and bottom thrust bearings so that they don't quite touch the back of the blade.

Next adjust the side guides. These may be ball bearings, hard metal pads or slippery plastic. If solid they will need to be reground so that they are square. Now we can borrow from wide bandsaw technology. On all modern wide bandsaws, the blade is pushed outwards from its natural line which greatly increases its stiffness. It only needs to be pushed by 0.5mm or so. If you have ball bearing guides, they will therefore be spinning at high speed and making a fair noise, but 'no pin no gain' as they say. Of course solid guides will wear as a result and will need rechecking every time that you change blades. Finally you can set the outside guide just as close as you can without touching. Finally, put a set square between blade and table and adjust the tilt of the table to suit.

Time to switch on and cut that first piece, measure it with calipers and set the reference line on the fence to match. Why not fit a lens to the scale so you can exploit your new found accuracy to the full? 

When cutting harder woods, you may have noticed that sometime the sawn surface is corrugated. What is happening is that the regularly pitched teeth set up a resonant vibration in the blade. The solution to this (and this is the only blade I use) is to buy a 'Vari-pitch' blade where no two teeth have the same pitch. They just hiss when they saw and that is how I achieve this extraordinary finish and accuracy. They cost a bit more but largely I can avoid planing to size. I even cut all my tenons this way.

Love my big bandsaw, but don't mock my little Burgess. It is the best tool that I ever bought.