Table saw question

[Chuck Hoffman]

I'll pose my question again...a little differently this time:

What is the maximum acceptable error for a table saw fence? Mine varies about fifteen thousandths of an inch from front to back. Is that too much, considering that a Forrest Woodworker II blade has a total runout of around

+/- .001 inch?

The problem is not linear, so loosening the T-square bolts, aligning the fence and re-tightening the bolts won't solve it. That's already been done. The problem is that the face is not straight. At about 2 inches from the front edge of the table and at approximately the centerline of the arbor, my dial indicator reads zero. Between those points, the fence runs out .003-.004 inch in one direction. At the ends, it varies from about .007" in one direction to about .008" in the other.

Is this a problem? If so, how can I solve it?

The saw is old but works well and I have no plans to replace it. I'm considering investing in an aftermarket fence but that costs a few bucks and I want to see if the original fence is salvagable first.

[Lew Hodgett]

Why fight it?

Make an aux fence from some 3/4", 13 ply, Birch ply.

I laminated two (2) pieces together to form a 6" high, 1-1/2" thick fence that is straight as an arrow.

Why 6" high?

Seemed like a good idea at the time, especially since I had a piece of ply about 13" wide.

It also simplifies clamping feather boards in place to serve as a hold down.

Why 1-1/2" thick?

Simple.

I'm using a Unifence.

The difference between having the fence extrusion vertical and horizontal is

1-1/2".

Can using existing markings on the scale without having to think too hard.

BTW, make your aux fence 6"-8" longer than your existing fence.

Mount your aux fence with a couple of 1/4-20, stainless steel, flat head bolts, nuts and washers, just snug.

Use some Loctite if your worried about the bolts coming loose.

After all that, get a beer and admire your work.

You're done for the day.

HTH

Lew

[Leon]

First off, What are the results when cutting wood? If they are acceptable continue using the fence. Not acceptable, replace the fence or face of the fence.

[Morris Dovey]

Chuck...

I think it all depends on what you're going to do with the saw. A hundred and twenty-eighth of an inch is 0.0078125". It sounds as if your saw is prepared to deliver ±1/128" accuracy.

Unless what you plan to cut is moisture proof, it'll probably shrink or expand more than that every time the weather changes. If it were me, I wouldn't worry about it until it presents an actual problem...

[Ollie]

Lew,

I have been planning to do suchtype of high auxiliary fence. Could you elaborate the step of using the steel bolts. How do you get all the holes in the right places that you don't need to recalibrate the setting every time you attach your new fence?

Cheers, Ollie

[Lew Hodgett]

I cheat.

I leave the aux fence installed all the time with one exception.

When I need to install a sacrificial fence for use with a dado, I remove the big aux fence to mount it.

Attach the sacrificial fence with the same bolts used for the high fence.

I can make too many mistakes if I have to think too much.

BTW, the only purpose of the bolts is to keep the aux fence attached to the aluminum fence extrusion of the Unifence.

HTH

Lew

[Nate Perkins]

Hi Chuck,

Perhaps I'm just sloppy, but this amount of bow wouldn't concern me too much.

You are talking about a total variation of fifteen thousandths -- about 1/64". Pretty good. And your variation between the front of the fence and your point of cut is half of that.

Cheers, Nate

[mnterpfan]

I agree with the accuracy aspect. However, I preface my question with: I'm pretty new at this. I'm posing a question and not stating advice. Regarding the safety aspect, what amount of runin on the back (behind the front of the blade) of the fence will potentially cause kickback problems?

As a suggestion, you might consider building Jim Tolpin's Ultimate Table Saw Fence with a face that extends down the front of your existing fence. It is in his book Table Saw Magic and also was showcased in a Popular Woodworking (99% Sure it was PW) issue a few months back.

Eric

[Rolling Thunder]

Here's the prior question and response for viewers comments:

snip

If you consider the run out spec for the blade of typically .005", it is likely in tolerance. To improve on it, you'd have to replace the fence. Although, spending several hundred dollars for a fence for this old of a machine is questionable. I would suppose if you're doing precision cutting with very low tolerance, it may be worthwhile to you. Considering most cuts for woodworking is usually OK within 1/16 of an inch (.0625), You're a magnitude better than that. So for weekend projects, I think you're plenty good.

I don't think you have a choice; remove the rust and prevent it from reoccurring. I've used an air compressor driven grinder with a copper brush on the end to remove the rust and then use Top Cote (get this at a wood crafting store) to keep the rust off and the top slick.

If you can't cut a grove into your fingernail with the edge of a blade's tooth (while it isn't running of course), get the blade sharpened or replaced. A combo blade cost to sharpen is around $13, depending on the number of teeth. Harbor Freight has TS blades that are good enough for the weekend woodworker for about half that.

Good to see someone wanting to put an old codger back to work.

Thunder

[Chris Hornberger]

That's within limits by all rules. If you're really worried, make yourself a hardwood auxillary fence and you can finish it to your liking.

The other thing to check is that the variance is the same when the fence is clamped down and when not. You *might* be able to just adjust how tightly the fence clamps and find yourself not worrying about it further. But honestly... that little bit just wouldn't be worth worrying about.

[Chuck Hoffman]

Thanks for all your replies. They've been very helpful.

I haven't actually cut wood with the saw yet. I'm still in the process of restoring it and making all the adjustments. It was purchased used and had been sitting for a long period of time so most surfaces are lightly pitted with rust. I appreciate the suggestions I've gotten on how to protect the metal after I remove the rust.

I've used 220 grit sandpaper to remove the light surface rust but now I need to decide how to approach the pits, the edges of which bulge a little. Perhaps a flat sanding block would work if I'm careful not to remove too much material.

I ordered an owner's manual from Sears along with an arbor wrench (probably didn't need that but I'm a purist) and a spare flex drive (while they're still available) just to have on the shelf in case the one that's on the machine craps out. I suspect this saw was manufactured in the 1980s and may have the original flex drive.

My intent is to make furniture and cabinets so I want as much precision as I can get out of the old girl. I'm considering an aftermarket fence but finances will dictate whether or not that is an option. Making a birch ply or hardwood aux fence certainly is.

Thanks again for the replies...if anyone has any other suggestions please feel free...

[Chris Hornberger]

I bought a Craftsman XR24/12 fence for my Delta table saw, and after some creative mounting, I haven't looked back. It's a nice piece. Might want to give it a look.

[Unisaw A100]

That doesn't sound like pitting. That sounds like someone used the machine top for an anvil in which case yes you'll want to file those down. They are called Vesuvius for good reason.

A hard block wrapped with some sand paper used sparingly should/would do the trick.

UA100

[Silvan]

I recommend a hunk of granite if you can come up with one. I've got some counter backstop off-cuts I scrounged from the trash heap outside a stone counter place. They're great for jobs like this. Wrap tightly with sandpaper, let the weight of the stone do the work, and you don't have to worry about getting things out of whack.

Unfortunately I'm almost out of these. They're surprisingly fragile, and I ruined several of them trying to get glue off the surface. :(