BT3 Methods for setting fence

[Bill in Buena Park]

I was just curious to know if anyone actually sets the front rails on their BT3 so the scale is accurate enough to set the fence by for rip cuts. I have a 21829, which has miter slots in the accessory tables (and I have two of these), but have been thinking about adding the narrow little miter slot accessories on each side of the main table. This would cause me to move the rails to the left a bit to accommodate the SMT, and would mess with the rail scale alignment. Turns out this may not be that big of an issue, since I rarely use the rail scale (unless critical accuracy is not an issue), preferring instead to measure the distance from the fence to the edge of the carbide on my blade when setting up for a rip cut. Left me wondering if anyone else also measures by tape for every cut instead of using the rail scale.

[LCHIEN]

I find the rails, when set, are very accurate and don't need recalibration unless moved. I always check the results and they are DNO. (Dead nuts on). I feel like I can get within .01" (better than 1/64th) of the desired rip width consistently just using the scale.

[LinuxRandal]

With the 21829 being portable, your rails are more apt to be moved. I would set them to where you are happy with them and use a piece of scrap of whatever size, to reset them (known scrap size). Label its size and what it is, and keep with the saw.

[poolhound]

I move the rails too much to ever bother to set the scale. This evening as I was finishing the cutting for a project I moved them 3 times. I do have an extra set of half rails which one day I will permanently attach as part of a new base but even then I doubt I will set the scale.

[RodKirby]

Steel rule - no mistakes - Darkside or BT3x

[eccentrictinkerer]

I use the Wixey Digital Fence Readout. I can set the fence to 0.001" even if it's not necessary.

[LarryG]

I find the rails, when set, are very accurate and don't need recalibration unless moved. I always check the results and they are DNO. (Dead nuts on). I feel like I can get within .01" (better than 1/64th) of the desired rip width consistently just using the scale.

I voted "Dark Side" because that's the current situation, but when I was still using my BT, Loring's answer perfectly describes my method and results.

[leehljp]

Steel rule for me too, Always - 1 ft, 50cm and 100 cm and 4 ft rules. And I use the movable rails quite often.

I don't think I have ever used the tape on the rails for measurement.

[cgallery]

For normal use, I find the rail tape MORE accurate than using a steel rule. That is because when unlocked, the fence isn't perfectly parallel to the blade. If you measure from the blade to the fence, lock the fence (and measure again), you'll find the fence has shifted a little.

Not a problem when you use the front rail tape.

I did use a rule with my old contractor saw. But on that saw the fence parallelism was impossible to keep aligned. I had to measure at the blade, then measure from the fence to the miter slot at the front and back of the saw to make sure the fence was square.

I will admit, however, that when I'm looking for accuracy better than 1/64", I sometimes do use a rule at the Ryobi. But if the line graduations on the rail tape were a little finer, it probably wouldn't be necessary.

[dkerfoot]

I too find that the rails are very accurate when set. But, I have the 21829 and often slide the rails right or left, depending on the cut. Rather than taking the time to set the rails to the blade each time, in actual practice I use a steel rule more often than the rails.

If I ever get a sliding miter saw, it will replace many of the wide cross-cuts I currently do and I'll be more likely to set the rails and leave them there.

I also have the Craftsman micro-adjuster http://www.sears.com/shc/s/p_10153_12605_00922214000P? and use it frequently. One of the advantages of this handy little tool is that makes me think in terms of 1/64ths rather than "smidgens". Most often, I set the fence a bit wide and make the first cut. Then I adjust the micro-adjuster and make the final cut.

This is fairly inefficient and largely due to my just not getting enough shop time to be as proficient as I'd like. Right now though, it is slower for me to measure twice and cut once than it is to measure once and cut twice.

[RAFlorida]

Steel tape.

I know when I lock down the fence it usually shifts maybe a 64th of an inch, but that's why you always measure TWICE. When it shifts, I just unlock and nudge it over till it lines up with the tape. BTW, I've never once used the rail measurements. Like some of the other posters, I move the rails left or right for necessary cuts......

[LCHIEN]

one thing is, that on the BT3, the rail is the pivot point for the fence. When you set the position by the rail tape, then lock the handle, the cursor stays put but the back end swings around to line up properly parallel with the blade, after which it locks in place. The part near the blade won't move as much as the back end, but may still move some. If you are measuring at the blade with a tape, you need to measure before you lock it down (to get it close) then may have to iterate a couple of times until the sideways movement is out.

[steve-norrell]

I have calibrated the scale on the front rail, but I almost always use either a tape or carpenter square to set the fence -- a good habit that I am reluctant to break.

I have to add that I have been impressed with the accuracy of the scale on the rail and would be comfortable with using it for all but the most precise measurement.

The only issue I have encountered is the slight movement of the tip of the tape measure, depending on whether you are doing "push" or "pull" measurement -- hence the use of the carpenter square.

Regards, Steve

[LCHIEN]

I have calibrated the scale on the front rail, but I almost always use either a tape or carpenter square to set the fence -- a good habit that I am reluctant to break.

I have to add that I have been impressed with the accuracy of the scale on the rail and would be comfortable with using it for all but the most precise measurement.

The only issue I have encountered is the slight movement of the tip of the tape measure, depending on whether you are doing "push" or "pull" measurement -- hence the use of the carpenter square.

Regards, Steve

You do of course know that the movement of the tip hook of most tape measures is an automatic correction for inside and outside measurements.
If you hook the tip on an object and pull the tape then the inside of the hook is at zero. and will measure (for example) the width of an object the tape is over.

If you push the tip hook against the inside of a box for example, then the outside of the tip will be at zero and the tape will accurately measure the inside dimension of the box.

In the case of rip fence, you should push the tip against the inside of the fence or blade and then the tape reading at the other inside point will be correct.

[steve-norrell]

Loring:

Thanks for the input. I actually knew that but when it comes to actually measuring my old addled brain gets confused and can't seem to remember which is which. Someone needs to come up with a fix for "brain addle". My current work-around is a carpenter square or straight edge.

Regards, Steve