Setting Blade Height on a Contractor Table Saw
user-3646902
| Posted in Power Tools and Machinery on
Besides trial and error test cuts are there any other reliable methods that can be used to accurately set blade height on a contractor table saw using measurements from a ruler, gauge block, dial indicator or other measurement device?
I intended to make a single reference mark on my table saw surface to use for all height measurements. This reference mark would indicate the apex or top dead center position of my saw blade. Unfortunately, it does not appear to be that easy on my Delta contractor saw because the apex of the saw blade is not located in a fixed position. The saw blade apex moves from front to rear of the saw table as the blade is raised or lowered to a new height. Any suggestions?
Replies
I've used a simple attachment to a small combo square for years (1st pic), which works reasonably well. More recently I purchased a Wixey digital height gauge (2nd pic), which is more accurate.
I'm sure there are many more approaches like setup blocks at known heights etc. that others may suggest.
Hope this helps.
I take it you mean for non-through cuts, such as slots, dados, rabbets?
They sell all kinds of gizmos, but I've never used one. I make a tick mark on the end of the board, and adjust the blade to that position. I make a test cut in scrap, and check the depth. It takes less time than using a gadget.
The apex doesn't change. If you think it is, you are measuring the teeth too far forward. For any blade height, their can only be one apex.
I keep one of these in my jean's pocket while working. It is fast, practical and convenient. The edge graduations are particularly useful for rabbits and grooves. Being always on hand it has many other uses throughout a build.
https://www.highlandwoodworking.com/starrettprecisionrulewithendgrads6.aspx
I've given up trying to measure so always run test pieces (for non-through cuts). It seems like no matter what I used to measure, there would be some mechanical movement that changed the depth of cut.
Agreed. Regardless of how you setup or measure, failure to do a test cut is a suckers bet.
I use Veritas setup blocks. Just lay them next to the blade and when the top of the block is aligned with the top of the tooth you can feel it. No rulers. But I do a test cut anyway.
John c2 of course the apex is the apex ,what else could it be?...but part of what the op wants to do is put an index mark on the top of the table saw that marks where the apex is. On his contractor saw the blade apparently doesn't go straight up and down at height adjustments but moves forward or back somewhat in relation to the tablesaw top. I guess sort of like a hinged circular saw base. Alot of those portable jobsite saws don't use an actual trunnion to raise the blade but something else that they make up that is cheaper to do. If that's the case then I guess he can scratch, so to speak, that plan.
I made a set of blocks for various height adjustments. I made them for router bit adjustments actually. They seem to me to be pretty accurate. Between 0 and an inch or so I can pretty much do it by eye anyway and be accurate to less than 1/64 th. Then I make a test cut and measure, or I make a mark on the wood ,set the height and then make a test cut.
Pantalones868 - you have described my blade height adjustment situation perfectly. My saw blade does not go straight up and down with height adjustments but moves forward or back somewhat in relation to the tablesaw top.
Based on the various responses I have received, I think I'll be using set-up blocks to get my blade height close and will fine tune the height with inevitable test cuts.
The apex on my Powermatic model 65 moves forward and back with height adjustment.
I make a test cut, as my throat plate is not always perfectly the same height as the table top, or can flex, or gremlins can screw things up. I start with a router gauge that goes from 1/8' to 1" in 16ths, or a 6" rule with 32nd and 64th gradations. Then the test cut. Set-up blocks would be nice.
JHarveyB - thanks! You indicated some very practical issues that can complicate setting exact blade heights. I now think set-up blocks followed by test cuts to fine tune the blade height are the way to go for me.
There are two kinds of setup blocks: those accurate to 1/32 and those only accurate to 1/16. My blocks came from Infiniti and are of the first kind.
The gradations going up start at 1/16, then 3/32, then 1/8th. The 3/32 block enables every 1/32 from 3/32-32/32, or one inch. The set also includes a 1-2-3 block so you can go from 3/32 to 4 inches in 1/32nd of an inch gradations.
StevieRay - Thanks for the detailed set-up block information. I now know what to look for.
I always reference a test cut as final. As previously noted there can be discrepancies in throat plates and there are in some of mine even though phenolic. To get to the rough measure usually the end of a Starrett rule or sometimes set-up blocks whichever is handy. For set up blocks you can place the block to run next to/along side blade then lightly press a small scrap of wood on top of block and also overhanging blade teeth. Bring blade up until the teeth just touch the underside of scrap.
Great suggestion about placing a small scrap of wood on top of the set-up bar. If the scrap piece is an inch or so wide it can cover not only the apex point of the saw blade but also the blade slightly in front of or behind the apex point. This gives you some leeway in placing the set-up block and will ensure you are measuring the exact apex of the blade.
I've used rulers, set up blocks, etc. They always require a test cut, or twelve, to get it just right.
I have begun marking my saw blades with a straight line between opposite teeth, through the center. This gives me a reference point to always measure against. Once the line is plumb, I know where the highest point of my blade is all the time. (I have also slathered the plate surrounding that tooth with black sharpie to make it easy to see as well).
Another good suggestion. I will try this for situations when the saw blade is raised enough to make the line between opposite saw teeth visible. I can see this working well, for example, when cutting tenon checks with a table saw tenoning jig. I'm not sure this is practical, however, for cutting shallow dados and groves where little more than the saw tooth is protruding above the throat plate. In these situations the line marked on the saw blade would not be visible.
Set up blocks come in all sizes if you make them yourself. I mean, if the ones you buy aren't dead on accurate then what are you buying? Buying I'd expect them to be something like a 1 with a dot and a whole bunch of 0's in front of it! A machinist would laugh himself silly at only being accurate to a 32nt, or out of a job!
I think you misunderstood the reference to a 32nd of an inch. It's not referring to the tolerance of the blocks, it's referring to the sizes of the setup blocks. Some sets only come in 16ths of inch and you can usually get a companion set that accommodates 32nds as well.
Certainly a ruler or combo square can be used. Your angle of view can mess with you depending on the measuring device. If you are after sub-32nd accuracy a height gauge can be your friend. I made this . . .
. . . out of a device that measured in 128ths that I found annoying. As a height gauge it has found new life in my shop for many years. Some thing similar can be made in many versions, digital or analog, you will find on the web. I find a leg radius of about 6" to work well on the tablesaw and the router table.
Excellent suggestion! I have a similar (but less precise) version of the height gage in your picture. I made this originally for use on the router table but with a few modifications that I made based on your suggestion, I think this will work effectively for the table saw too. See attached photo.
I added a removable MDF "foot" to the ruler section of the gauge that adjusts up and down. The "foot" provides a large surface for locating the apex of the saw blade in case the gauge is placed too far in front or behind the apex of the blade. I also added rare-earth magnets to bottom surface of the support legs that allow the gauge to straddle the saw blade. The magnets are countersunk and glued in place. They prevent the gauge from falling over as I incrementally increase the blade height and slowly turn the saw blade back and forth by hand until I can hear or see the blade barely skim the bottom surface of the "foot".
The height of the "foot" is initially set using a set-up block or blocks that equal my desired blade height or depth of cut. A few test cuts are then used to confirm if the setting is correct.
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