Fence Accuracy - Plastic or Plywood Faces?

[Scott Myers]

I recently bought a SawStop cabinet saw with their stock fence. Got it all tweaked in, but am working on improving the fence. The fence itself is great from an accuracy, tolerance and general use point of view. I'm quite pleased with it now that I have gotten comfortable with it and understand where one can go amiss with this fence design when adjusting it. I had some issues with the fence, but it turned out to be operator error and set-up issues, for the most part. It's good enough at the moment, but when it comes time to replace the fence faces (where the last problem with my tolerance variances lies) I would like to improve the fence face tolerances by going to an aftermarket fence face material that is much more likely to be within +/- .001" (or as close as possible) from one end to the other right from the start.

Here is the post to the saw set-up, including the issues I had getting the fence aligned and repeatable.
http://www.sawmillcreek.org/showthread.php?t=97096

I would like to explore fence face alternative materials from the stock plywood/melamine faces provided by SawStop.

My question is: What has been everyone's experience with fence face materials as far as tolerances goes? I have looked at two possibile popular materials so far.

One is standard 1/2" thick UHMW-PE sheeting, which is the standard material for companies like Jet, Powermatic and Steel City. The specs for such materials doesn't read well, as +/- .030" are typical specs. However that is just the guarantee that the piece is within the thickness that you order, not the true thickness variance for that particular piece. I know any particular piece of 48" long UHMW sheet isn't going to vary .060 total from one end to the other. So what variances are you guys out there seeing throughout your UHMW fence faces if you measure them with mics every 6 inches or so?

The other is the phenolic faced baltic birch found at Woodcraft. I don't know how the tolerances runs on this material. But being wood, I would expect it to not be able to be held to +/- .001", but you never know. I'll have to stop up at my local Woddcraft and measure it. Anyone out there using this material as a fence face? If so, how do the tolerances run on what you have?

I am going to have Sawstop send me some new stock faces that have never been bolted up to a fence. Perhaps I will have better luck on round 2 of the fence faces.

[joe pezza]

Scott,
I had the same problem with a pwr matic saw. There are differences in the fence because of the bolts to the actual fence. After a while I got tired of messing with it and used a piece of 5/4 ipe.

I made the fence a coupe inchs longer on the opperator side and found it very helpful for some rip cuts too.

I would suggest the baltic birch w/pheonolic face or mdf 3/4 or a nice stout piece of stable hardwood.

ps. sold the pwr matic and went to a slider with a unifence type fence.
no deflection with the aluminum fence.

joe p

[Joe Jensen]

I have the Sawstop fence. Having been at this for 30 years, I can't imagine how the Sawstop faces could be out enough to matter. It's easy for me to get bent out of shape over a 0.001" here or there, and then I remember that I'm working with wood.

Have you measured large errors with the SawStop faces?

[Scott Myers]

One of them is thicker in the middle by .010". I think it may be the glue under the laminate. Like I said in the other post, I put the "bad" face on the right side of the fence where it won't be used much, if at all, for ripping. It is just for future replacement. I was curious what others might be using.


I have the Sawstop fence. Having been at this for 30 years, I can't imagine how the Sawstop faces could be out enough to matter. It's easy for me to get bent out of shape over a 0.001" here or there, and then I remember that I'm working with wood.

Have you measured large errors with the SawStop faces?

[Chris Padilla]

I know you just dropped a boatload on this saw but Incra makes a very nice fence system.

[John Thompson]

Even though I don't think .010 is going to make a major difference.. I would shim out between the face and the main fence on each end and call it a day. Pick up a feeler guage and take a close look at .010 and then decide if it matter to you ripping wood which could expand or contract much more than that after being severed.

Sarge..

[Joe Jensen]

One of them is thicker in the middle by .010". I think it may be the glue under the laminate. Like I said in the other post, I put the "bad" face on the right side of the fence where it won't be used much, if at all, for ripping. It is just for future replacement. I was curious what others might be using.

I bet SawStop would send you a replacement face for free. Their service has been great for me....joe

[Mark Singer]

You should be able to shim it with thin aluminum . I think SawStop will replace it. I didn't check my SawStop that carefully.... I just use it and it works great.

[Scott Myers]

Points taken gentlemen. Thanks to all!

[Josiah Bartlett]

If you want something that's really flat, bolt up some hardwood to the fence with well countersunk fasteners, and then run the whole thing across a jointer, presuming that there is enough clearance to clear the T square part of the fence (or remove that, if you can). Then the face will be about as flat as you can make it, and not suffer deflection from the backbone or fasteners.

[Chip Lindley]

As you already allow, there is no guarantee the steel tube of your T-fence itself is made to such tolerances as you acribe to. There is no material which will be "out-of-the-box" ready to simply install flat to within .001" . Perhaps .500" thick slabs of aluminum milled flat by a machine shop?? Even these may require slight shimming, and woe be unto you if you should KISS them with the saw blade and ruin their looks and your consderable investment. Any material you choose will give you good service once you afix it by shimming where necessary to within a hairline of a known straight edge. All of these fence parts degrade over time and need replacement, and the process begins again....

[Joe McCormick]

I would like to explore fence face alternative materials

Have you thought of a metal fence face? I am referring to the one made by Grip- Tite. You have probably seen their magnetic featherboards. http://www.grip-tite.com/
You can buy the metal fence face at http://www.mesavistadesign.com/griptite-fenceplate.html
They have lengths from 24" to 42".

[Scott Myers]

Chip - The fence itself actually does measure +/- .001" down it's length on the sides. The sides also measure better than +/- .001 within parallel of each other in both the horizontal and vertical axis. The sides have been fly cut by SawStop in Taiwan, as you can still see the machining marks. (Their technical support guy I was speaking to about my issues didn't even realize this fact. I'd put this in my marketing literature if it were me! Powermatic does.) So the base you start with in mounting the faces to is VERY good. Really couldn't ask for better within reason. (See original post http://www.sawmillcreek.org/showthread.php?t=97096)

So the problems came in in two areas.

1- One of the faces is not right. It has some various thickness issues. But I figure this is just a fluke on that particular face.

2 - The second, and what seems to be the bigger issue, is how the fence faces were over-tightened from the manufacturer overseas. It would appear that when they mount these faces, they REALLY bear down on the screw heads. So you get dips at each screw. There are 11 screws on each face, as opposed to the 5 or so on a typical fence. So there really is no need to bear down on the screws with that many screws holding the face. It even says so in the manual! Apperently production never read this. I found that just lightly snugging them with a couple fingers on the T-handle is enough to keep you from moving the fence face, unless you were to whack it with a hammer. They have been bore down on so hard that they actually imprinted the keyhole shape of the hole into the plastic surface out up to 1/2" away from the keyhole on the back of the face. This not only caused the dips, be put some warp into the face in spots. The screwdriver tool that I received with the saw (cheap ball end 5mm hex screwdriver, chrome plated), wasn't good enough to get out the screws as it just slipped due to the screws being so tight. I had to go buy a set of decent metric T-handles with ball ends to budge the screws. (Didn't own ball-end metric.) They were in that tight. So it may just be a matter of getting new faces from SawStop that have not been overtightened if I want to get rid of the dips and valleys.

Side note - SawStop uses an unusual method for getting to the screw heads on the fence face. They use slots in the underside of the fence and you have to take off the left fence face before you can even work on the right fence face. At least they allow you access first to the face that is used the most! I whined about this at first, but it's not so bad once you get used to it. And you have good ball end metric T-handle hexes of course.

As far as both Chip and Joe's suggestion on a METAL FACE FENCE; Guys, I think you missed this detail; it's a SawStop saw. So I won't do that for two reasons. First, I don't like a metal fence face for safety reasons and ease of attaching aux fences where I want them. But the more important reason is; Large metal surface near blade on SawStop saw = BAD! You wouldn't even need to touch the blade with the metal fence to set off the saw. Just get it within a few millimeters and the saw can fire the brake. The saw works by putting a slight charge on the blade, like an touch lamp. When you touch it, it senses the change in voltage and fires the brake circuit. BUT, when you put a large area of metal up near the flat surface of the spinning blade, contact doesn't even have to be made. A capacitive effect can occur and the voltage be tranferred to the fence through the small air gap (or wood) and fire the brake also! There was one guy here on the Creek who experienced this very thing with the Incra fence system. Bummer.

It is interesting to know people still use metal fence faces though. That's good info.

I am really not trying to be a big weenie about the accuracy of the fence. It's good. Very, very good. I have things adjusted well now. It is just a small issue with fence face warp as supplied by the factory so I am exploring options for the future.


As you already allow, there is no guarantee the steel tube of your T-fence itself is made to such tolerances as you acribe to. There is no material which will be "out-of-the-box" ready to simply install flat to within .001" . Perhaps .500" thick slabs of aluminum milled flat by a machine shop?? Even these may require slight shimming, and woe be unto you if you should KISS them with the saw blade and ruin their looks and your consderable investment. Any material you choose will give you good service once you afix it by shimming where necessary to within a hairline of a known straight edge. All of these fence parts degrade over time and need replacement, and the process begins again....

[Jim Becker]

I had the UMHW faces on the Jet saw I used to own...and longed for laminate covered BB plywood. I never got to that change before selling the saw when I bought my slider, but would have if it was still in my shop. The high density plastic was not accurate at all and varied considerably across the length of the fence face.

[Sonny Edmonds]

I had the UMHW faces on the Jet saw I used to own...and longed for laminate covered BB plywood. I never got to that change before selling the saw when I bought my slider, but would have if it was still in my shop. The high density plastic was not accurate at all and varied considerably across the length of the fence face.

What Jim sez, and to add in my experience plastics crawl a LOT with temperature swings.
I'd take the issues up with SawStop.
But then, you get a reply from a Lawyer.... :mad:

[Scott Myers]

ROFL! Let's keep the lawyers out of this, shall we? :rolleyes:

But point taken with you guys on the plastic "crawling", as Sonny says. (Love the picture of yourself Sonny. Too bad you don't have any personality at all! LOL)

I'll probably try the phenolic covered Baltic birch when/if I try to make my own fence faces. Seems like a reasonable choice.




What Jim sez, and to add in my experience plastics crawl a LOT with temperature swings.
I'd take the issues up with SawStop.
But then, you get a reply from a Lawyer.... :mad:

[Chip Lindley]

Sorry Scott, the fact this is a SawStop eluded me for a moment.
I was shooting for exact tolerances, thus my suggestion of machined aluminum faces, altho (IMHO) some in these forums do overly obsess, wishing to apply metal working tolerances to an unstable, vegetable material called WOOD.

You do have valid issues with a brand new, expensive machine. SawStop seems a very customer-oriented enterprise, and I am sure your saw fence faces will be replaced if you complain as to their agressive assembly methods. You can mount the new fence pieces as you desire.

As you document, the SawStop is a well designed machine! The first true innovation in table saws since the Unisaw was invented about 70ish years ago! It seems to have all the Bang For The Buck that a saw of its caliber (and price tag) should offer! The SawStop fills a very real need to protect consumers/students/workers from themselves and minimize liability of businesses and institutions.

That being said, I won't be trading off my PM66 for a SawStop. Its paid for and I will accept the calculated risk of walking into the workshop as my own sole responsibility, with Every Tool, not just the table saw.

[Wayne Cannon]

I, too, would expect a laminate-faced plywood fence face much flatter than HDPE. My current fence has HDPE faces and there is 5-10 mil of variation between the locations of the fasteners and the area in between fasteners. 1 mil is probably unreasonable for wood, since anything you cut will expand and/or contract significantly more than that anyway. However, I would expect to be able to do better than 10 mil.

[Rob Blaustein]

I replaced the UHMW face of my Grizz 1023 fence with the 3/4" phenolic covered BB from Woodcraft. As you pointed out, the UHMW is milled to a spec that is less than that of BB and it is a bit soft so there were dips where the face was screwed to the fence. Now I WAS able to mostly shim it out with blue painters tape strategically placed but it was a pain. And I can't recall the tolerance I was able to achieve. But I liked the phenolic BB better, and it was easier to attach a metal face to that (for using the magnetic grip-tites). But now I have a SS, though haven't checked the fence yet...