Sliding Table Saw - Why Slider Above Table?

[Matt Culik]

Hi. I have a Grizzly G0623X sliding table saw. I use the slider side 90% of the time, and I've got it pretty well dialed in thinks to the folks on this forum and YouTube. One of the things mentioned by a variety of folks is that the sliding table should be planar to but ~0.010" ABOVE the table saw table.

Can someone explain why? And more importantly, how do you rip thin pieces where some sits on the slider without it "un-squaring" the cut?

As I said, I use the slider side 90% of the time and use a "Fritz and Franz" jig for ripping when the board to rip is wide enough to fit nicely on the slider and shorter than the slider's range of motion. This works perfectly. However, tonight I had to rip some pieces that were too narrow for "Fritz and Franz." So I ripped them the normal way, along the rip fence with my Micro Jig. My test cut was perfect, EXCEPT that because about 1/2" was sitting ~0.010" higher on the slider side, I ended up with a piece that wasn't square.

This wouldn't have been an issue if the slider were level with the table, but again, the recommendations seem to be the slider should be just slightly above the table.

So, if the recommendations are correct, how do you rip conventionally on a sliding table saw in situations where your off-cut extends onto the slider?

Thanks!

[Ned Otter]

Matt,

I believe the main reason that the "wagon" of a slider is above the cast iron is to reduce friction.

Can't see how that in and of itself would make a cut "un-square", as that would be more a function of setting things up properly to be 90* to the saw blade.

Apologies if I'm missing something in what you described.

Ned

[Jacques Gagnon]

Matt,

A couple of thoughts:

- is there a reason why you cannot produce your narrow piece with a wide piece sitting in the Fritz and Franz? The narrow piece would fall to the right of the blade and be square.

- if you absolutely need to work on the right side of the blade and using the rip fence as the reference would it be possible (while working safely) to start with a piece that is narrower than the distance between the fence and the sliding table? The blade would remove the waste and the cut would be square to the table (sorry, I have difficulty visualizing how the desired piece can fit between the blade and the rip fence and yet not being able to process it with the F&F - a picture would help).

Regards,

J.

[Kevin Jenness]

"Can't see how that in and of itself would make a cut "un-square", as that would be more a function of setting things up properly to be 90* to the saw blade"

A narrow workpiece spanning the gap will not be quite parallel to either table, thus not square to the blade. I set my sliding and fixed tables flush so I don't have to think about this issue. I have never noticed a problem with excess friction.

Jacque offers good solutions to the problem. One instance where I would use the rip fence traditionally is with a long narrow strip that is bowed or may bow when held by Fritz and Franz. The planer can help in this situation down to a certain thickness. The bandsaw is another option for narrow pieces.

[Bobby Robbinett]

I have always assumed the reason for the sliding carriage to be slightly above the cast iron table top is so that pieces don’t get hung on the edges of the cast iron top and either move your piece while cutting causing a kick back or (assuming your cross cut fence is in the front) if your cross cut fence is behind it would stop the workpiece from going through the motion of the cut.

My saw is a Griggio sc3200b which has a different blade orientation than your Grizzly, I believe. My sliding carriage is above the cast iron top top and I don’t like it. I have not yet figured out where the adjustment is for that on my saw. If anyone happens to know please let me know.

[Dan Friedrichs]

If the sliding table isn't just slightly higher than the cast iron, work will catch on the front edge of the cast iron and/or drag on it. 0.010" is not a magic number - I suppose ideally it would be nearly 0, but because of variations, 0.010" is probably reasonable. According to David Best (author of this excellent site on aligning sliders: http://davidpbest.com/VA/StonehorseS...ng%20Table.htm), sliding shapers often target 0.003".

As others said, it seems like there are other ways to make this cut to avoid the problem. However, I'm not sure why it's even a problem. Say you're cutting a 6" wide board to the right of the blade and it's slightly overhanging onto the slider, which is 0.01" higher than the cast iron. This results in a cut at 89.9 degrees. Or for a board that is 1" thick, the top side is 0.002" wider than the bottom. (It's early - someone feel free to check my math )

[Eric Shimp]

Matt

I have a slider and never use the fence unless the board I am ripping is longer than the 6.5 feet stroke of the slider. The way I cut thin strips is start with a known width board on the slider, using my parallel cutting guides I subtract the width of the thin strip I want and subtract the blade width, clamp it to the slider then make the cut. It takes a while because each strip has to be calculated but I have gotten pretty good at it. Hope this helps.IMG_0578.jpg

[Erik Loza]

In case anyone is curious as to “why” the slider is generally installed a little proud of the cast iron table, the formal explanation is to avoid marring finished panels or to avoid any suction effect in the offcut piece. This is why you see a finger divot in the cast iron table of some of the Italian machines. Personally, the only time I would want the slider truly flush with the saw table is on a combined saw/shaper (or dedicated shaper).

Erik

[Jim Becker]

The explanations have been made and I agree with them. I'll also say that I never ever found it to be an actual issue in my work.

[Derek Cohen]

As I said, I use the slider side 90% of the time and use a "Fritz and Franz" jig for ripping when the board to rip is wide enough to fit nicely on the slider and shorter than the slider's range of motion. This works perfectly. However, tonight I had to rip some pieces that were too narrow for "Fritz and Franz." So I ripped them the normal way, along the rip fence with my Micro Jig. My test cut was perfect, EXCEPT that because about 1/2" was sitting ~0.010" higher on the slider side, I ended up with a piece that wasn't square.

Matt, did you measure how much out-of-square the edge was? I very much doubt that it would be evident. My slider wagon lies 0.5mm high, and I have long just ignored this concern off the rip fence. All crosscuts are done on the wagon. These count.

Regards from Perth

Derek

[Richard Coers]

One of the things mentioned by a variety of folks is that the sliding table should be planar to but ~0.010" ABOVE the table saw table. How did guys my age ever get woodworking done without Youtube and friends? Set the table like you want it (I have mine set to even with the table and keep the table waxed) and change it latter if you don't like it.

[Kevin Jenness]

How did guys my age ever get woodworking done without Youtube and friends?


Clearly you were doing it wrong.

I have never noticed any of the problems mentioned due to the carriage being high or level with the main table. I would say that an aluminum extrusion flat within .006" over 9' or 10' (+/- .003") is darned good. I have worked with several sliders that were considerably worse and as long as the carriage was not lower than the table there were no issues except on long bevel cuts.

[Wes Grass]

Considering a sliding tablesaw is a step 'above' a conventional tablesaw, you'd expect the slider itself to be 'above' the table...

Personally, a piece dragging on the table is the equivalent of fingernails on a blackboard...

;-)

[Rick Potter]

I fought with this also, and finally decided that I will build a small sled that extends past the blade about a foot on both sides. I will use it for cutting small parts, and leave the slider as is.

As far as ripping narrow pieces, I can hear a click every time the cut is completed and the wood snaps down on the table, and THAT is what grated on my nerves. Keeping my table saw solved that problem. In reality it wasn't a problem, but it did bug me.

[Mark e Kessler]

The most important setting on a slider in my opinion is as follows 1. Adjust twist if any out of cast top 2. set blade stop 90 to cast 3. Adjust slide coplanar with cast, while setting height with coplaner taking priority. I have a 9’ slider, i think i am 0.008-0.009 over about 7’-8’ and at the end it jumps to like 0.015 but it doesn’t matter as I won’t ever need to cut to a specific height at the far end of the slide (think dado)