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20th June 2021, 09:11 PM #46GOLD MEMBER
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20th June 2021, 11:34 PM #47SENIOR MEMBER
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The slots!
That's the way the sled/gauge is moving, via the slots. So your fence has to be perpendicular to that movement. If your blade isn't dead on parallel to the slots and most aren't then you can't reference off the blade and get perfect accuracy. In the case of a sled where the base covers the slots then you should reference off the kerf after the first cut as that kerf will be 100% parallel to the slots, or even better use the dial indicator method as mentioned earlier in this thread. Did you watch the movie? It explains it perfectly!
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21st June 2021, 12:29 AM #48GOLD MEMBER
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So you are saying the slot can't be straight along its length therefore can't be made parallel to the blade? OR are you saying that very few users attempt to make the slot parallel to the blade as the first step? And I did watch the video and I am puzzled by what seems to be a missed step.
CHRIS
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21st June 2021, 06:43 AM #49GOLD MEMBER
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Yes I watched it. Too much fluffing around for me. What you’re saying is then, use the table slots, which is obvious, however as far as I can see, the table and it’s slots were nowhere near parallel to the blade, which I would imagine would be the first thing to get right. Squaring the fence then off either the slots or the blade would then be a simple exercise. My main gripe is, if you’re paying 6 grand or whatever for a Sawstop saw, the bloody table and it’s slots should be set up perfectly at the factory, end of story. Using a dial indicator is definitely the most accurate way, but not everyone owns one, and I would be mightily if I’d just paid good money for a machine that’s not accurately set up and then have to spend more dough to purchase measuring equipment to do it.
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21st June 2021, 08:43 AM #50SENIOR MEMBER
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Chris, I'm saying that most table saw blades aren't perfectly parallel to the slots and one of the first things that should be done when you buy a table saw is adjust the blade so it is parallel and I think most users attempt this crucial adjustment but it is often the case that you end up close but never perfect. Some users even just accept the factory setting. So when adjusting the fence on a gauge you should use the straight slots as your reference as that is the way the fence is moving to get a perfect 90 degree. This then takes away any blade parallelism error. Also some blades aren't perfectly flat and referencing off a slightly buckled blade would cause another error.
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21st June 2021, 09:03 AM #51SENIOR MEMBER
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The over exaggeration of that blade parallelism in the video was to prove a point as most blades even after adjusting aren't perfect but you are right it should be the first thing checked when you get a table saw. I was horrified that my Sawstop was about 10 thou of parallelism. I even contacted them and they said it was within tolerance but I'd read that an acceptable figure was around 3 thou or less. Fortunately the adjusting method is really easy as opposed to tapping the table with a dead blow hammer. It took me 10 minutes with a $20 dial indicator and some scrap wood to get it close to 1 thou or even less. Once I got it to practically perfect I could now reference off the blade if i wanted too and get a good result but I decided to even get more accuracy after seeing that video and the dial indicator video that all my sleds and gauges would be referenced off the slots. One simple way I forgot to mention was just place a board in the slots and shim it to get a tight straight fit. Then you can reference off that board. 5 minutes and no expensive equipment.
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21st June 2021, 10:33 AM #52GOLD MEMBER
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I think the video is totally misleading and those watching it will believe that this is the correct way to align a mitre gauge. I have been around for a few years now and years ago it was known that the FIRST thing to be done was align the mitre slot. Back in the newsgroup days there was a raging debate on a special jig with the inventor saying it was the only way to do it and others saying it was not necessary to use his special jig. Videos such as these mislead people because those are the ones who do not have the knowledge to question what they are seeing. It is possible and practical to align from a blade if the fundamental alignment of the slot has been done. Yes, use his method if that suits but align the slot first.
CHRIS
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21st June 2021, 11:00 AM #53.
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I did that yesterday. I found a 19mm square chrome pated steel bar (SR - from an old hospital gurney) in my stash that fits neatly into the mitre slot - then I used my long precision square (SQ) against the fence to check the squareness.
IMG_4984p.JPG
When I reference the fence against the blade it turns out to be significantly different from referencing against the slot.
IMG_4985p.JPG
Turns out to be about 1mm in 250mm , or about 0.23º - this explains a lot of my probs.
Saw is a 15 year old contractor type saw, mainly used these days to rip timber and cut Al so that was probably why I hadn't noticed it.
Now I need to do something about the blade/slot parallelism.
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21st June 2021, 11:05 AM #54
Chris, if you align the slot to the blade it would require taking a wedge shape amount of one side of the slot then another wedge shaped amount off the opposite side (think folding wedge) thus increasing the overall width of the slot this would in turn require additional changes to any mitre bars running in the slot.
Since the shaft trunnions etc are in a constant state of change through height/angle adjustment which creates wear on all the moving parts as well as build up sawdust and in some cases movement of the whole machine, it is logical and sensible to reference off the one constant, that being the mitre slot.The person who never made a mistake never made anything
Cheers
Ray
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21st June 2021, 12:35 PM #55GOLD MEMBER
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The table is moved, most if not all true cabinet saws have the movement built into the mounts to do this. I have done it on two saws myself, the holes in the frame are well oversize to enable the adjustment. Contractor saws may not have the adjustment but not having looked at one I can't say.
CHRIS
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21st June 2021, 12:47 PM #56SENIOR MEMBER
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21st June 2021, 02:07 PM #57GOLD MEMBER
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He at no time recommends or shows how to adjust the table so the mitre slot is parallel to the blade which is the first thing that should be done. Anyone reading this should take note, release the table clamping bolts and the slot can then be aligned. Then align the fence with slight toe out to prevent contact with the back of the blade and then check if the mitre gauge is set to zero against the blade or slot.
CHRIS
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21st June 2021, 04:35 PM #58SENIOR MEMBER
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That's not the point of the video. Its called "squaring a miter gauge correctly" regardless of what state of parallelism your saw is in. He mentions that lack of parallelism in the video and describes how very few are bang on parallel and that he would never run a saw the way he's set it up. So he shows an accurate method of aligning a gauge/sled taking the blade out of the equation whether its parallel or not. Its all about aligning fences on gauges NOT the general usage of a table saw.
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21st June 2021, 08:22 PM #59GOLD MEMBER
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Gee, I hope no one takes the video at face value and ignores the first step. Aligning a mitre slot is not using the saw it is the first step needed to calibrate the fence and slot to the blade.
CHRIS
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21st June 2021, 08:56 PM #60GOLD MEMBER
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“Taking the blade out of the equation whether it is parallel or not”
Are you taking the mickey here? If the blade is not parallel with the table slots, or the slding carriage in the case of a panel saw, THE SAW IS NEVER GOING TO CUT ACCURATELY.
Fences on gauges? This is a new one to me.
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