How flat should a tablesaw (for wood) table be?

I have a real late model Powermatic 64A table saw. The table is about .026" warped. Should this bother me?
Tom Rose

0.026"? Nah! Not unless it's dish shaped and abrupt. I don't know waht commercial standards are for saw tables but I submit flat to 0.010 convex is appropiate.

One thing about table saws, they are limber. Have you leveled it and are all four feet bearing about equal weight? Sometimes you have to shim a little to optimise the table's best approximation to flat.

"Does" it bother you? From a work/perfomance perspective?

I would venture that if it does, a PM 64A is probably not the ideal saw for whatever it is you are doing. These saws pack a lot in for the price, but at the expense of a certian amount of refinement. As Forrest notes, they are limber. The castings are not really that heavy, or heavily ribbed/edged, and it seems they blanchard grind the tops about as fast as they are cool enough to handle out of the molds, these days. So a certain amount of movement and settling is almost a forgone assumption. However, they do seem to have things down so that it is a pretty nice saw, given a certain amount of windage allowed in some of the components and systems.

I don't think there is much gain to having one re-ground unless it really bothers you. The tops are already fairly thin, so there is a certain amount of risk that if made thinner, it will continue to settle.

My perspective on tilt arbor variety saws ("tablesaws") has modified over the years. For _many_ years, my primary saw was a mere 12" Rockwell contractors saw. I figured the only use for a tablesaw was to rough rip & cross cut stock, so it could be further processed on other machines. Dimensioning was done with jointer, planer, and shaper. Jointery was done on a tenoner. (A tenoner will do many more joints besides tenons). Plywood jointery was done on a shaper or with routers.

Then I bought a 19-teens R.D Eaglesfield TA variety saw, and began to discover the convenience of having a saw that could be set up accurately, and fence that could be made accurately square. I actually found it convenient to do operations accurately enough on the saw that I would previously have set up the shaper to run. Long angle cuts, jamb rabbeting, long bevel rabbets on the back of window stools, etc. The miter gage was big enough and accurate enough to confidently do repetive miter cuts, and even dados. Sometimes it is faster to cut a lap, or tenon, with high confidence of repeatable accruacy, instead of moving to a tenoner set up.

Funny thing, the Eaglsfield is not a saw I would reccomend, it takes way to many cranks with a full aerobic work out to tilt the blade, and the rise and fall is nearly as bad. The table is dished probably a 1/16". But everything is solid,it stays where it is put, and the throat plate is large, solid, close, and very flat around the blade area.

I've moved on to other saws, and having a solid, truly flat faced, straight, and really square to the table fence is important, Having the saw table flat, or maybe even crowned a little around the blade area with a solid, flat throat plate is very helpful. Having a large cast iron table, say 40" square or larger, is very convenient. If the table is out of flat a 1/32 or so, but every thing else is as above and very solid, you will probably be able to do most anything sensible within good woodworking practice on it. If you make small finicky or technical pieces, optimizing the throat plate area, and the fence, is where to spend your time.

If you still want a really flat, stable, tabletop, Northfield can set you up.

http://www.northfieldwoodworking.com/tablesaws/sawroller.htm

http://www.northfieldwoodworking.com/tablesaws/tablesaws.htm

smt

You might ask yourself "how flat are the boards I intend to saw?"

I bought a new Unisaw in 1982 and it's table was Blanchard ground "flat" within perhaps .015" TIR concave. I eventually shimmed the outboard table extensions to my liking and I've never looked back.

Mike

Tom,

It's hard to find any contractor-type saw with a really flat table. As Forrest & Stephen said, extraordinary flatness isn't critical for most operations.IMO, the most important parts of any saw are the fence & the blade.

The Accu-Fence looks like a dead copy of the Biesemeyer fence, one of the best ever designed. Your owners manual may or may not mention this, but the fence should be adjusted so that you have .005" more clearance at the back of the blade than at the front. This prevents binding as the wood passes by the rear of the blade. If the fence is adjusted exactly parallel with the blade, there's a greater chance of lift & kickback.

There are lots of blades to choose from, but the one that is consistently rated #1 in every magazine test is made by Forrest Manufacturing: http://www.forrestblades.com/sawblades_about.htm Their blades cost twice as much as others, and cut three times as well Their sharpening service is also fast & excellent.

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Barry Milton

I have a real late model Powermatic 64A table saw. The table is about .026" warped. Should this bother me?
Tom Rose

Click to expand...

Good grief, woeeeeeee Nellie and stop the clock

.026 that's a tad much over .001/.003

Tom, use your straight edge and feeler gauges to determine how far out your table really is.
Straight measure across the throat at the lead and aft sections, then do a diag and parellel.
Some saws have 4,6,8 table screws(securing bolts)
for shimming the table true.
If your saw has a little age to it, and it has been out of adjustment as you say, you can see telltail signs at your miter slot and on the slide.
Your miter slot may show a bright wear place where the slide is making irregular wear.
On the slide you may notice this on the underside as well and you may notice a camfered looking edge.
When it comes to just using the saw for general 40T cutting for framing it would work but, when it comes to trimming an interior or cabinet grade work and using a 60/80T and narrow/to wide trim or panels you may not always get the results wanted.
As the slide is moved within the miter slot it may raise and fall depending on how far out your table is and show up when you are jointing/babbiting or trimming.
Let alone without a good adjustment your saw will age and wear faster than you would think. Especially if it is used often.
Check for wear on slide with a 0-1 mic.
Check miter slot with inside mic.
Check table across throat/diags/par's with straight edge and feeler guage.

Shim table true.
Insure throat plate is below table.
If you have wings for the saw, straight edge across them as well after truing the table.
Square up your arbor using the miter slot as your
P.O.B.
Check and square the fence to the P.O.B.
(note)Tho you can square it as you go with the sawblade after the arbor is true, getting into the practice of checking the arbored sawblade to the miterslot on a regular basis is good habit.

With good practice and adjustment you actually can get your machine within .001/.003

Hope this helps a little,

Patch

I've got a 20+ year-old Craftsman table saw with a cast iron table. The saw's been moved several times, and I've never paid much attention to setting it up level or treating it nicely.

I just checked it with my best straightedge, and it's out-of-flat only a couple thousandths or less in any direction.

However, I doubt that 0.026" over that distance is going to matter much for woodworking.

Roger

Thank you guys very much for your input. I haven't been able to shim the table flat due to the lack of ridgidity of the cabinet it sits on. The wings have a bow of .012" on one of them and the other is within .003". The fence is nice and adjustable, it just needs it almost every time I use the saw.I have put a Forrest blade on it, it smoothed it out but high lighted the flex and movement in the trunnion. I think I got a lemon.
The Northfield saws are beautiful, I had no idea such a thing was being made in this country anymore.
Tom Rose

It depends on what you're doing. If you're making furniture or the like, most workpieces are going to have a finished edge machined on the jointer after ripping on the tablesaw.
If you need the saw for a nice crosscut, you can build yourself a particleboard sled with two nice hardwood strips on one side that ride in the saw's machined table slots. On the top side you've got a nice wooden fence that backs up the piece to be crosscut at whatever angle you choose. Since the sled bridges any gaps in the table, the table is not as important in this case either.
I tend not to like miter gauges. Some of my friends won't even use them, preferring to keep a collection of sled-like jigs preset at different angles.
The Biesmeyer type of fence is terrific in its simplicity. I like to build myself a box that fits right over it which you can subsequently cut into or add things to (edge for catching plastic laminiate, production crosscut stop, high fence, etc.)
Bottom line is that there are many workarounds for a saw of this type and the condition of the table not nearly so important as it might at first seem.
If you'd like something better, Tannewitz, Oliver, and a number of other american companies made some really nice smaller sliding table saws (compared to today's European sliders) that can be had for not too much money and are sometimes in pretty good shape. Northfield still makes one like this and it looks like you've already got their url.
Northfield's a neat little company. I wish they would update some of their stuff (shapers) but I guess that's part of the charm. Last I knew they were still family owned and their machines beautifully finished. Standard disclaimer...
Just my two cents.

As Steve said, one place to put effort is your fence. I have a fence that I think is better than a Biesemeyer fence, but sadly they are no longer made. It is a Paralock fence - it uses a drafting table mechanism to keep the fence parallel when you move the fence back and forth on the table. It is easily adjustable to 0.001" And it locks down on both the front and back rail. I set it to have about 0.002" more clearance at the back of the blade than the front and I get cuts that are very clean. Opinions on saw fences are many - others will give you a different story. Whatever fence you use, a well adjusted fence and a good blade make more difference than most other things you could change

Trade that Model 64 in for a 66 and I think you'll sleep much better at night

After my interactions with Powermatic, the last thing I want to do is give them more money however Matt I think probably a different saw would suit me better. I have figured out how to fix the flex of the cabinet useing steel tubing and then could get the table reground. Basically I would be fabricating a cabinet saw.

tkrot, I think the "stuff" under the table in a cabinet saw is on a different scale of beefiness than the contractor saws...

This is just an estimation from my experience, I've owned a Craftsman cast-iron contractor saw with the Biesemeyer, and now the PM 66 as data points.

Adding, a quick check of "shipping weight" from a couple websites yielded this: PM 64A = 258 lbs, PM 66 = 600 lbs, which probably isn't a 100% apples-to-apples comparison, but hopefully this lends some "weight" to this theory I am proposing

Haven't looked under the skirts of a PM 64, but I'd assume it's like most others, with all it's guts hung from the bottom of the table. And the tables isn't exactly a monster.

I've rebuilt about 2 dozen table saws over the psat decade, for personal use and resale. I've gone as far as having the tops blanchard ground with the extensions attached. This can help to flatten out your average PM66, Unisaw, whatever. Just keep the table at the same temperature as when it was ground, it may stay put. New, used, reground, I've gotten to where .032" is about the acceptable level. Can't seem to hope for much better. Some are better, but if you have a dust collection line backfeeding cold air in the winter, that's enough to tweak it. Big hole for the throat plate, not real heavy on the ribbing, whatcha gonna do.

The big table saws seem better; I have one well loved Oliver 260D that probably isn't worse out than .005", and while I've never tested my favorite, a Tannewitz XJS with feeler gages, a quick going over with the straight edge suggests you're wasting time looking closer. After my experience with garden variety 10" saws, I've been amazed with the real sized ones.

In short, table saw tops are not a surface plate, don't sweat it, cut something.

Rob,(pretend machinist but fully qualified wood whacker)

Stephen Thomas wrote:
The castings are not really that heavy, or heavily ribbed/edged, and it seems they blanchard grind the tops about as fast as they are cool enough to handle out of the molds, these days.

Things must have changed recently at Powermatic. As of 2002 they aged their castings for tablesaws in a lot out back, letting them rust for months before they milled them. I agree they are nothing close to flat, but they use to be aged castings with a fair amount of ribbing and mass. As recently as 2003 I worked in a retail woodworking store selling PM. Having moved more than a few I can say they make Delta Unisaws look like rather light duty.

These comments apply to the model 66.
Michael