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A while ago I posted about drift, and recently decided to try to align my miter saw as best I can to try to account for the differences. A quick check showed that the miter slot wasn't parallel to the blade, meaning the fence wasn't either.
I was able to easily align for perpendicularity, both side to side (using the bevel stop) and front to back (using washer shims) on my G0555. However, aligning the blade to the miter slot has been tricky. Simply loosening the trunnion bolts didn't provide enough play. I think it's because there's a large amount of slop in the trunnions when they aren't tightened to the table. Removing the table altogether shows that there is essentially no play in the table bracket (held on by two bolts), but there is some sort of blade bracket that had play and seemed to be skewed sideways. When I fixed that, the saw still runs smooth but it's not easy to align the table.
When I quit for the night it looked like I could get it aligned, though I didn't actually do it. Is it supposed to be so hard to align? Shoddy manufacturing? This seems like it's a lot of work. I suppose that's why people shim their fence rather than try to align the table.
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I have two band saws, and one is leaning slightly left no matter what I do. I simply use a test board to start the cut, then adjust the fence or miter accordingly.
I don't think either saw is perfect, so I live with it.
There are those here who may be able to help you make it perfect.
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Small amounts of slop at the table bracket typically translate into quite a bit of adjustment range over the depth of the table.
Have far are you off?
Cut a straight line down a board where one edge of the board is within 1/4" or so of the miter slot, and post a picture or give us some measurements.
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Is this a brand new saw? If so, I would call Grizzly and see what their take is. If not, then what follows may be of use.
If you can't easily align the table so the miter slot is parallel with the blade then I suspect there's a more fundamental problem with how the wheels are aligned to the frame or each other. Is the distance from the edge of the lower wheel to the rear housing roughly the same at 9 and 3 o'clock? I'm assuming the housing is flat or symmetrical. I think that distance needs to be equal because the trunnion base is bolted to the lower casting and that's not an adjustable connection, at least not on my 14" Delta. The only way to adjust the table is where the trunnions bolt to the bottom of the table. Anyway, if the bottom wheel is not aligned properly I think you will need to adjust it so it is before doing anything else. And if you have to do that, you will likely have to realign the top wheel so that it's coplaner again with the lower wheel.
I would check if the two wheels are coplaner before adjusting the lower wheel. Perhaps your upper wheel is skewed CW or CCW and that's stealing the adjustment range away from what you can do with the table.
John
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(01-29-2019, 02:00 PM)jteneyck Wrote: Is this a brand new saw? If so, I would call Grizzly and see what their take is. If not, then what follows may be of use.
If you can't easily align the table so the miter slot is parallel with the blade then I suspect there's a more fundamental problem with how the wheels are aligned to the frame or each other. Is the distance from the edge of the lower wheel to the rear housing roughly the same at 9 and 3 o'clock? I'm assuming the housing is flat or symmetrical. I think that distance needs to be equal because the trunnion base is bolted to the lower casting and that's not an adjustable connection, at least not on my 14" Delta. The only way to adjust the table is where the trunnions bolt to the bottom of the table. Anyway, if the bottom wheel is not aligned properly I think you will need to adjust it so it is before doing anything else. And if you have to do that, you will likely have to realign the top wheel so that it's coplaner again with the lower wheel.
I would check if the two wheels are coplaner before adjusting the lower wheel. Perhaps your upper wheel is skewed CW or CCW and that's stealing the adjustment range away from what you can do with the table.
John
The saw is a year old, but otherwise I bought it new. I haven't used it as much as I'd like primarily because of the adjustment issues I've encountered. I haven't looked at wheel alignment, but I have not had any problems with blade tracking.
The things that are really sloppy are the tilt scales (I guess), which are secured to the trunnions with knobs. When they are really loose, the table can be moved quite a bit. This should only happen when it's very loose as this controls the bevel angle and if that affected blade alignment, that would basically make the bevel unusable.
I can't post pictures here, but I can post a link to the manual and illustrate what I'm talking about.
https://cdn0.grizzly.com/manuals/g0555_m.pdf
Page 18, Figure 14. Close to dead center of that image are the bolts that hold the complete blade guide bearing assembly under the table. Those bolts allow for a lot of adjustment and they were very much skewed prior to last night.
Page 19, Figure 17. It is my understanding that blade alignment in this case is based on the flange bolts, but those aluminum tilt scales are sloppy in certain cases. I will have to investigate this further. When everything is loose, this makes sense, but with the flange bolts tightened movement should be minimal. I am not sure if the movement I experienced was from an excessively loose knob or not.
Page 29 describes the squaring process.
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Grizzly's manual is confusing in that they use the wrong terms in places. What they call the trunnion on pg. 18 fig. 14 is actually the trunnion support bracket, as shown in the exploded drawing at the end. The trunnions are the semi circular castings that are bolted to the bottom of the table, what you might be calling the aluminum tilt scales. The trunnions are held to the trunnion support brackets via bolts through the trunnion clamp shoes with the two table lock knobs, and there should be absolutely no play when they are snugged tight. If those are loose I would take the table completely off so you can see what's going on between the trunnions and trunnion support bracket. Maybe you are missing a washer between the trunnion support bracket and lock knob or perhaps the trunnion clamp shoes are missing or not installed correctly? Look at the exploded diagrams at the end.
Once you are sure the trunnions are secure in the trunnion support brackets, then put the table back on and see if you can adjust it so the miter slot is parallel with the blade, as described on pg. 29.
John
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(01-29-2019, 03:43 PM)jteneyck Wrote: Grizzly's manual is confusing in that they use the wrong terms in places. What they call the trunnion on pg. 18 fig. 14 is actually the trunnion support bracket, as shown in the exploded drawing at the end. The trunnions are the semi circular castings that are bolted to the bottom of the table, what you might be calling the aluminum tilt scales. The trunnions are held to the trunnion support brackets via bolts through the trunnion clamp shoes with the two table lock knobs, and there should be absolutely no play when they are snugged tight. If those are loose I would take the table completely off so you can see what's going on between the trunnions and trunnion support bracket. Maybe you are missing a washer between the trunnion support bracket and lock knob or perhaps the trunnion clamp shoes are missing or not installed correctly? Look at the exploded diagrams at the end.
Once you are sure the trunnions are secure in the trunnion support brackets, then put the table back on and see if you can adjust it so the miter slot is parallel with the blade, as described on pg. 29.
John
I thought the terminology was what you described, but the manual confused me. I was right the first time.
What I did today was square (visually, as best I can) the upper and lower blade guide assemblies. This helped a lot. The trunnions have play only when things are loose, and I couldn't tell if it was because the flange bolts were loose or the trunnions themselves were loose (or both). In any case, with the blade guide assemblies straightened, I was able to get things as square as I can. It's hard to tell since a straightedge doesn't exactly sit flush against the blade, but it seems a lot straighter. Visually, it looked a bit out of alignment before and it doesn't now. Most importantly, I can loosen the trunnion knobs, adjust the bevel, and readjust without any play. I assume a lot of the slop was only there because everything was very loose. We'll have to see when I make a few test cuts.
I also tweaked a lot of the guide bearings to be as quiet as possible (minimal contact with the bearings spinning) but I am not sure how much I want to spend on them since I planned to move to guide blocks. I know the bandsaw adjustment video everybody references doesn't think highly of guide blocks (or really anything replacing the original blade guide, whatever it was) but I might do it anyway.
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I'm glad to see you're getting it dialed in. The best way to set the blade guides is after the tensioned blade is centered on the upper wheel and runs smoothly there. The upper guides should move up and down w/o changing position with respect to the blade, either on the side bearings or rear one. Your manual should discuss how to fix that issue if you see it as a problem. In any case, a combo square should fit up against the side of the blade with no gaps after the table is adjusted for zero, and it should be pretty close to gap free against the back of the blade, too.
I use cool blocks with my 14" Delta, which are just a more blade friendly version of the steel blocks that were on it originally. My 17" Grizzly has bearings. I've never had any trouble with them. I don't see any advantage of one over the other to be honest. Unless what's on your saw is causing a problem I wouldn't spend money to change them. The only part of the guides of much real importance on those 14" Delta and clones is the rear bearing. The side bearings/blocks, etc. on any bandsaw are only needed for cutting curves. Relying on them to keep the blade straight when making straight cuts is a sign something else is wrong.
John
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I thought someone would have pointed this out before now. I don't necessarily need my blade, that's only 1/4"- 1" wide anyway, to be square to the miter slot. I need the miter slot to be parallel to the line of cut; like on a table-saw. On my Uni. the blade is fixed, so I rotate the table. on my band saw the table is basically fixed so I rotate the blade by moving, usually slightly backwards, where it tracks on the upper wheel. Different tensions on my saw will also change the drift slightly but it's easier to change the rip fence to match than adjust all the guides again. I suggest you adjust the drift so the line of cut is parallel to the miter slot. Blade towards the back cuts to the right, blade forward cuts left.
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01-30-2019, 07:23 PM
(This post was last modified: 01-30-2019, 07:24 PM by jteneyck.)
(01-30-2019, 04:57 PM)MstrCarpenter Wrote: I thought someone would have pointed this out before now. I don't necessarily need my blade, that's only 1/4"- 1" wide anyway, to be square to the miter slot. I need the miter slot to be parallel to the line of cut; like on a table-saw. On my Uni. the blade is fixed, so I rotate the table. on my band saw the table is basically fixed so I rotate the blade by moving, usually slightly backwards, where it tracks on the upper wheel. Different tensions on my saw will also change the drift slightly but it's easier to change the rip fence to match than adjust all the guides again. I suggest you adjust the drift so the line of cut is parallel to the miter slot. Blade towards the back cuts to the right, blade forward cuts left.
The best approach is put the blade in the center of the top wheel and adjust the table so that the miter slot is parallel with the blade. That's your zero point, or fixed as you stated, but only after this adjustment process. You do this once when you set up the saw. A good blade will cut straight and parallel with the miter slot, and you should be able to change blades with the same behavior. However, nothing in the world is perfect (Except our wives of course. Oh, you don't believe that? Just go ask yours.) so if the blade wants to push or pull the work piece a little, yes, then you adjust the upper wheel to move the blade forward/backward until it again cuts straight and parallel with the miter slot. You should never have to adjust the fence for drift except if the blade is no longer symmetrical, such as dull on one side. The guides play no role in any of this.
Setting up a bandsaw is exactly like setting up a TS. Adjust the table so the miter slots are parallel with the blade, and the fence parallel with the miter slot. The only difference is the position of the blade on the tires of a BS is not fixed like it is in a TS. Putting it initially on the center of the upper wheel simulates that fixed position of the TS.
John
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