Toast rack vee blocks
Cutting square section tube on a bandsaw is not always straightforward. The problem is that the saw cuts through the flat top section slowly but once it is through this part it then cut very fast through the vertical sides of the tube until it reaches the bottom of the tube and then it cuts slowly through the flat bottom part of the tube. Because the saw cuts fast through the thin vertical sections there is a danger that some teeth are torn from the blade. If the cut rate is reduced for the vertical sections by taking some weight of the saw blade then the cut on the horizontal sections will be very slow. One way round this is to use a hydraulic cylinder to control the rate of fall of the bandsaw arm.
Rick Sparber has suggested an alternative strategy for cutting square section tube, see: https://www.youtube.com/watch?v=bYBik4KZYAk . If the tube is oriented so that it is cut from corner to corner rather than face to face then the cross section is much more constant during the cut and cutting proceed at a more or less uniform speed. One advantage of this is that the tube is cut about three times faster compared with the normal method.
In order to achieve corner to corner cutting then the tube must be held solidly with one diagonal vertical. Rick Sparber uses conventional vee blocks to support the square tube in this orientation. This works fine. Ideally the opening of the vee block should be just a little less than the diagonal length of the tube to achieve best support. If the opening is greater than the diagonal then an additional pusher block is needed to push the tube into the bottom of the vee. If the vee block opening is too small there is the tube may twist and come out of the vee block. Another down side of conventional vee block is they take up quite a lot of space the effective vice opening of the bandsaw is reduced. Of course this could be solved by making thinner vee blocks.
This project was started in order to find a way of clamping a wide range of tubing sizes reliably in the required orientation for corner to corner cutting.
The solution arrived at is shown in the header photo. Each vee block consists of two arrays of triangular sections that are screwed to a central block. The central block is screwed to a plate. The two vee block can be pushed together so that the triangular pieces interleave with one another.
Rick Sparber has suggested an alternative strategy for cutting square section tube, see: https://www.youtube.com/watch?v=bYBik4KZYAk . If the tube is oriented so that it is cut from corner to corner rather than face to face then the cross section is much more constant during the cut and cutting proceed at a more or less uniform speed. One advantage of this is that the tube is cut about three times faster compared with the normal method.
In order to achieve corner to corner cutting then the tube must be held solidly with one diagonal vertical. Rick Sparber uses conventional vee blocks to support the square tube in this orientation. This works fine. Ideally the opening of the vee block should be just a little less than the diagonal length of the tube to achieve best support. If the opening is greater than the diagonal then an additional pusher block is needed to push the tube into the bottom of the vee. If the vee block opening is too small there is the tube may twist and come out of the vee block. Another down side of conventional vee block is they take up quite a lot of space the effective vice opening of the bandsaw is reduced. Of course this could be solved by making thinner vee blocks.
This project was started in order to find a way of clamping a wide range of tubing sizes reliably in the required orientation for corner to corner cutting.
The solution arrived at is shown in the header photo. Each vee block consists of two arrays of triangular sections that are screwed to a central block. The central block is screwed to a plate. The two vee block can be pushed together so that the triangular pieces interleave with one another.
This shows the two blocks interleaved. Note the square hole in the middle. By pulling the two blocks farther apart the square hole gets bigger. Conversely pushing the blocks together makes the hole smaller.
Also note the countersunk screw heads. These screws attach the triangular pieces to the steel block shown in the header photo.
There is a washer between each triangular piece so that they are separated by more than their thickness. This allows the blocks to interleave easily.
Also note the countersunk screw heads. These screws attach the triangular pieces to the steel block shown in the header photo.
There is a washer between each triangular piece so that they are separated by more than their thickness. This allows the blocks to interleave easily.
The underside of the plates has been drilled out 12 mm in two places. These recesses accept 12 mm x 2 mm neodymium magnets. These magnets allow the two vee blocks to be attached to the bandsaw vice jaws
This shows a piece of large (70 x 70 mm) square plastic tube held firmly in the bandsaw vice using the vee blocks
At the other end of the size range a piece of 17 mm square aluminium tube is also held securely. The vee blocks will hold even smaller tube in necessary.
Pieces of tube as short as 13 mm can be held.
Pieces of tube as short as 13 mm can be held.