Ripping on a slider using fence as bump stop - toe-out

[mark mcfarlane]

Still dialing in my new slider.

My plan is to use the fence as a bump-stop for ripping narrow pieces to the right of the blade.

If I toe-out the fence at all, this seems like it will cause problems.

The ideal setup for this cutting scenario seems to be a perfectly parallel fence and blade, with the fence pulled forward of the blade for such rip cuts.

I can't think of any situation on a slider for having toe-out on the fence, since you would typically pull the fence to the infeed side of the blade, so binding would never be a problem.

What do you all think?

[Mark Bolton]

We keep our fence nearly parallel (it ma y be toed out a few thou. You can always clamp a scrap just ahead of the blade for your bump and that would eliminate any toe. We still rip material longer than the stroke with the fence so a litte toe is essential.

[Dan Friedrichs]

If you have a few thou of toe-out, what problem would that cause? Presumably, you aren't positioning the fence/stop with that much accuracy, so a little error in parallelism shouldn't hurt...

Mine is set for just a few thou of toe-out. Makes it a bit safer when using the full-length fence in the "traditional cabinet saw" mode. But I often pull it back and just use it as a bump stop, too.

[Andy Giddings]

Typically a few thou toe out is plenty - you might need it one day if you ever use the rip fence on its own (as per a US table saw working method) as per Mark's comment. It still works as a bump stop just fine - use the cross cut fence (if the blank is wide enough) to ensure your work is square to the blade and don't try to align it with the rip fence as its a stop, not for alignment. If the blank is narrow use a known square additional blank to give you something to register against the cross cut fence with.

Just try to use roughly the same position on the rip fence as the stop.

[mark mcfarlane]

We keep our fence nearly parallel (it ma y be toed out a few thou. You can always clamp a scrap just ahead of the blade for your bump and that would eliminate any toe. We still rip material longer than the stroke with the fence so a litte toe is essential.

Thanks Mark for the tip on clamping a scrap. I assume you mean ripping longer than the stroke of the slider, but I think you still wouldn't need the toe-out in that scenario if the fence is before the blade, but I guess you need the fence behind the blade to get better support for such a long cut.

As I continue to ponder this, another factor in the narrow rip scenario is the toe-out of the slider/wagon itself.

I have my wagon set so that the outfeed side is slightly further from the blade than the infeed side. So if I set the fence parallel to the blade, it is not parallel to the movement of the slider. If I toe-out the fence, the difference between the slider and fence is even greater since the slider is also toed-out (in the opposite direction relative to the blade).

I have the crosscut fence aligned 'well enough' with an error of 0.5mm over an 8 foot cut, which makes me not want to mess with the wagon alignment .

Now I am trying to dial in the fence to get consistent rips of thin strips using the fence as a bump stop, but am having some problem in getting uniform width strips.

It may be a technique rather than a setup problem, but I am thinking maybe the toe-out of the slider is causing the problem.

[Dan Friedrichs]

I guess I'm not understanding the problem. It's normal to have the fence toe-out (from the blade) a few thou, and have the wagon toe-out (the other direction) a few thou. Yes, that introduces a small error. It seems like a very, very small error, though?

The only alternative would be to set both the fence and wagon perfectly parallel, which seems both impossible and dangerous.

[mark mcfarlane]

... use the cross cut fence (if the blank is wide enough) to ensure your work is square to the blade and don't try to align it with the rip fence as its a stop, not for alignment. If the blank is narrow use a known square additional blank to give you something to register against the cross cut fence with.

Bingo!

Thanks Andy. I used my 5-cut blank against the crosscut fence to register the piece to be cut, and was able to rip a 1" wide strip to within .004" over its 4 foot length.

The saw is officially ready for action after I add in a little toe-out to the fence for safety. Now for the J/P setup.

I also need to cut down the 48" square 3/4" birch blank I used for the 5-cut alignment to something more manageable for use as a future square reference, maybe a 24" square ? Whaddya think?

[Jim Becker]

Mark, there are a number of ways to make these narrow rips and a tiny amount of toe for the method you're asking about isn't going to affect much unless you're going to be doing really long pieces. You might also consider making the "Fritz and Franz" jig that there's a major thread dedicated to for doing narrow rips safely of reasonable length. My feeling on toe is it should be minimal on a slider. Having a 'thou or two is fine because there are those times when we rip "traditionally", although even then if you only extend the fence to the back of the blade, it's almost immaterial. My personal preference is pretty much close to parallel with my slider. (I actually need an adjustment for that as I think I somehow knocked it out a hair more than it needs to be)

[mark mcfarlane]

I guess I'm not understanding the problem. It's normal to have the fence toe-out (from the blade) a few thou, and have the wagon toe-out (the other direction) a few thou. Yes, that introduces a small error. It seems like a very, very small error, though?

The only alternative would be to set both the fence and wagon perfectly parallel, which seems both impossible and dangerous.

Imagine the toe-out on the wagon is 12" over the length of the cut (for an extreme illustration).

It seems to me that if you clamp a board to the wagon the right side cutoff is going to be 12" narrower at the end of the cut when compared to the start of the cut, because the wagon is moving away from the blade through the entire cut.

If the wagon toe-out is .1" over the length of the cut, the error would be .1"

That's what my brain is telling me.

[mark mcfarlane]

Mark, there are a number of ways to make these narrow rips and a tiny amount of toe for the method you're asking about isn't going to affect much unless you're going to be doing really long pieces. You might also consider making the "Fritz and Franz" jig that there's a major thread dedicated to for doing narrow rips safely of reasonable length. My feeling on toe is it should be minimal on a slider. Having a 'thou or two is fine because there are those times when we rip "traditionally", although even then if you only extend the fence to the back of the blade, it's almost immaterial. My personal preference is pretty much close to parallel with my slider. (I actually need an adjustment for that as I think I somehow knocked it out a hair more than it needs to be)

Jim, Building a Fritz and Franz jig is in the plans.

When people talk about toe-out measurements, are they usually talking about a measurement over the circumference of the blade? That is what I suspect. So .002 over 12" means .016 over the length of an 8' slider.

[Jim Becker]

Yes, over the width of the blade...

[David Kumm]

My toe out is measured over a longer range. I set my crosscut fence to as square as I can get it. When happy, I cut a fresh edge on mdf at least 2' and maybe 3'. Pull the slider back and set my rip fence against the fresh edge and adjust it to match. Maybe a couple thou over the 2-3' range but maybe less. I then run the mdf against the rip fence just beyound the blade but not all the way through. Stop the saw and look that the blade is centered in the kerf at both the leading and trailing ends. Typically my 16-18" blades produce a kerf that is .004-.006 wider than the blade tooth so I have some room. Dave

[mark mcfarlane]

My toe out is measured over a longer range. I set my crosscut fence to as square as I can get it. When happy, I cut a fresh edge on mdf at least 2' and maybe 3'. Pull the slider back and set my rip fence against the fresh edge and adjust it to match. Maybe a couple thou over the 2-3' range but maybe less.

Looks like a great way to adjust the toe-out on the fence, thanks David.

I then run the mdf against the rip fence just beyound the blade but not all the way through. Stop the saw and look that the blade is centered in the kerf at both the leading and trailing ends. Typically my 16-18" blades produce a kerf that is .004-.006 wider than the blade tooth so I have some room. Dave

So I guess that 'extra kerf width' beyond the width of the blade is the sum of your wagon toe-out and the fence toe-out, over the length of the blade, so if you toe-out on the fence is only .002 over 3 feet, than you must have a significant toe-out on the wagon.

Assuming I am following all this correctly.

[Warren Lake]

does the tow out you guys are talking affect your square cutting? or its a seperate setting, I would assume for cutting squaring a panel you want it dead nuts square with no tow at all?

[mark mcfarlane]

does the tow out you guys are talking affect your square cutting? or its a seperate setting, I would assume for cutting squaring a panel you want it dead nuts square with no tow at all?

Warren, It can have some effect on square cuts depending on how you use the slider (technique for a particular kind of cut). For example, Andy Gibbings tip above basically eliminates the effect of fence toe-out by using a square reference set against the crosscut fence.

The toe-out is essentially a measure of the angle between the blade and the slider wagon or the fence. Toe-out is added for safety purpose.

If the fence toes into the blade then it increases the chance of kickback when ripping to the right of the blade, particularly if a lively piece of wood expands as it is cut and stresses are released.

In a perfect world, dead-nuts as you propose would be fine. In the real world of blade wobble, wood movement, non-perfect fence repositioning,... a small amount of toe-out is considered by many to be preferable due to the added safety benefit.