How to measure 4 x 6 bandsaw alignment
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Hi
The way to measure the alignment is laid out on pg4&5 of in "Buying a used 4x6 Bandsaw" in the files section of this site, /g/4x6bandsaw/files/Buying%20a%20Used%204x6%20Bandsaw%20v4.pdf?. It is along the lines of November -X-ray's method? method but uses 1x4" joinery timber and give a measurement of how far out of square it is and a standard for what is good enough. Unfortunately it doesn't say how to adjust it once you find it needs adjustment, that's another story which can be told if you wish. Cutting square horizontally across a workpiece and square vertically down through the workpiece are controlled by different set-ups (though they overlap in one crucial area).? Horizontal squareness is easy to get, but vertical squareness can be tricky unless you're aware of all the influences, but once you understand (as with most things) its reasonably simple - jv |
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For adjusting the blade guides?here's some thoughts to bear in mind: 1. I mentioned in the 'Buying a 4x6' guide that to cut both horizontally?(your East/West?) and vertically (N/S?) square at the same time, the workpiece needs to be parallel to the pivot shaft
in both Plan View and Elevation
AND the sawblade needs to be square to the pivot shaft in both Plan View and Elevation. When Rick Sparber and I were trying to come to agreement over adjustment procedures, it came out that the above wasn't the easiest way to look at it. Now I think it is easier to separate the two types of squareness (since they can be adjusted separately): Horizontal squareness is achieved when the back of workpiece is parallel to the pivot shaft and the run of the sawblade is square to the pivot shaft when looking in Plan View (looking down from above the vice table) Vertical squareness is achieved when the bottom of the workpiece is parallel to the pivot shaft and the body of the sawblade?is square to the pivot shaft in Front Elevation? (looking across the vice table from the front) 2. You can always adjust any saw to cut horizontally square without difficulty, as it's only affected by the angles between the work, the sawblade and the pivot-shaft, the 'geometry' of the bits if you like.? However vertical squareness is more of a problem, because, although the saw can be adjusted to move geometrically as though it was going to cut vertically square, the blade can be thrown off line by what happens when
the teeth start to move, think of them as 'dynamic' effects.? Horizontal squareness is only about the geometry Vertical squareness is about both geometry and dynamics 3.Adjusting Horizontal squareness: a) Back of the workpiece parallel to the pivot shaft = Fixed vice jaw indicated parallel to the pivot shaft per the article as you noted b) To get the run of the?sawblade square to the pivot shaft, you shift the joint between the sawframe?and the pivot arm (LH rear of the sawframe?when it's horizontal) in the right direction until the test piece?you cut is parallel (per test on pg4&5 of the buying article) 4.Adjusting vertical squareness (You need to do them in the following order) a) Preparation:?
Adjust the side-guideroller-to-blade clearance with the eccentric on the bearing outside of the loop of the blade, until there is 0.000" to 0.001" clearance, i.e.?touching but not overtight, since this is what keeps the blade upright when cutting (The squareness of the blade body to the vice table changes when the roller-to-blade gap changes so its got to be adjusted first)? b) Blade body square to the pivot in front elevation =? blade body pretty much square to the vice table.? You judge and adjust this per the method on pg 14 in the Wilton 4x6 manual which is available in the files section as m_3130.pdf? ?(/g/4x6bandsaw/files/m_3130.pdf). This is probably the best manual of any 4x6 and you should print yourself a copy.? b) Bottom of workpiece parallel to the pivot shaft = vice table parallel to the pivot shaft.? As you've found out this is built into the saw at manufacture and can warp out of flat as the base casting ages.? That you've had to file yours, probably means it will not be parallel to the pivot, you'll find out just how much out it is by doing the test in the article. If it's?out by more than a few thou it is really annoying. If you've adjusted the blade back?square as in a) above then any vice table out of parallel will show up as taper in the test piece.? It can be temporarily fixed by packing up the low side of the infeed table with a strip of steel shim+double-sided sticky tape, until the test piece comes out parallel. A permanent fix?for this is probably the most difficult thing you can do to a 4x6. 5) Dynamic effects (the blade not cutting vertically down even when the geometry is correct) is mostly due to one of two things a) Too much weight on the teeth when cutting soft materials (like wood, plastic and aluminium) and the gullets of the teeth fill up which then tips the blade to one side?or the other (fix by holding up the sawframe?by hand so it doesn't cut so quick, or increasing the tension in the counterbalance spring (handle on LH front). b) blade worn or damaged on one side so it doesn't cut straight any more. (new blade is only fix)? ? Rick Sparber explains it a little differently from me and you should look up his article????.? Between the 2 explanations?you should be able to figure it out. Rgds - jv?? On Thu, Sep 24, 2020 at 8:22 PM <dpidwerbecki@...> wrote:
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Hi Dave I've been out of the loop for a couple days. Yes the wood only gets you so far vertically, but can't do any better horizontally cutting steel. The dynamic movement of the blade means in?the end, the vertical squareness is always 'cut metal?then adjust', but you should be able to get it pretty close with wood. If it changes a lot from wood to metal, then most likely your blade is damaged and if you adjust it to cut square in steel, it will be out-of-square again when you put on a different blade.? Wood bandsaw people have a special name for when they have to angle the work to the blade just to get it to cut straight., they call it 'lead'.? A brand new blade does not 'lead', but since any little thing will damage a wood saw blade they have to cope with it. In a metal bandsaw you should be able to change from one blade to another with no change in squareness (it might change at the very fine level, but should not put it outside the 0.003"/" squareness)? Getting the vice back square to the pivot should not be much of an issue, I use 12" Verniers, and Rick uses a bar clamped to 1-2-3 blocks, but that's no use unless you've?got verniers or 1-2-3 blocks.? Ricks method works just as well if you clamp the bar to a set square (plastic drawing square or engineers), you've just got to be more careful lining things up. Within +/-0.004" over?the width of the fixed jaw is OK.? As you probably found, the pivot bolt in the fixed jaw can be sloppy and the whole lot moves when you tighten it.? I drilled mine out and tapped the base to take a much bigger bolt, with no thread where it pivots, to get a good fit. Pinning the jaw (tapered pin is best but a?steel dowel pin is OK too) is easier than having a threaded adjuster.? This relationship can never change, so no need to adjust.?? But getting the blade square to pivot is an issue when you are just tapping the pivot arm-to-sawframe?joint.? Attached is a picture of a little push-push adjustment screw device I made so that I could micro adjust the joint and then its dead easy,?so long as you push it the right?way - that takes a bit of getting your head around.? It's bent out of 1/8" mild steel strap and fixed with the pulley guard bolt, and sundry tapped holes in the edge of the sawframe?with washers to get the spacing right.? I used M5 so 3/16UNF would do. You slacken the 5/16" clamp bolts then slacken one side and push from the other to make the joint move slightly and retighten the clamp bolts and retest squareness.? Just a small movement here makes for a BIG movement at the point of cutting, 1/4 of a turn on UNF threads make a noticable difference in squareness.? That would be too much if the thread of the push bolt was UNC - jv On Sat, Sep 26, 2020 at 3:46 PM <dpidwerbecki@...> wrote: Thanks guys so much for the help.? ?I pretty much followed the Wilton manual for alignment of both the vertical (N-S) and horizontal (E-W) alignments.? ?? |
John Vreede