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How flat is flat enough - Table saw

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Forum topic by petergdenmark posted 04-04-2012 02:02 PM 3268 views 0 times favorited 9 replies Add to Favorites Watch
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petergdenmark

55 posts in 1880 days


04-04-2012 02:02 PM

Hello.

I’ve spent 500+ hours on a renovation of an old Wadkin AGS table saw. Had i known, I would have put it outside with a small roof over it and used it for rough sawing lumber.

But I thought “nothing more can go wrong now” and continued.

Now i’ve finally put it together, and it runs ok. One thing i havn’t been able to fix is the table top. It has a small, not abrupt, dip in the middle of about 0,015”, and the wings dips the same amount. but not uniformally (they are very slightly warped), so this is the point i arrived at, as a compromise

Now – i could try to get it milled flat, at a cost of about $500 (taxes here are severe). Further more – it would require me to take the saw apart again, which would again take a lot of time (pretty tricky procedure on this saw).
Shimming is not possible – i’ve tried.

It’s an old saw, and i paid $250 for it, and the rise and fall isn’t totally smooth, but the blade stay square when rising the blade, and it has other small faults, that isn’t a deal breaker, but just makes it impossible to get it to “good as new” condition.

So now i’m thinking that i might hunt for perfection, that isn’t possible for those of us on a budget. I watch Norm, The Wood Whisperer and video podcasts on other websites, and maybe this has brain washed me into thinking you can’t do fine furniture if your tools isn’t up to NASA specs.

I havn’t used the saw for anything serious yet, since i wanted to get the saw ready, and didn’t want to start woodworking (which was the original point), only to have to stop, and start messing with the saw again.

So honestly – how flat are your tables? How flat is flat enough? Are there any “official” flatness tolerances?

-- I'm from Denmark, but live in Sweden.


9 replies so far

View Fred Hargis's profile

Fred Hargis

3932 posts in 1955 days


#1 posted 04-04-2012 02:17 PM

I’d bet there area plenty of opinions on how flat it should be, and I’d also bet they area all less than .015”. But I think I’d try cutting some wood on it first…..then carefully check all dimensions to see if it’s cut accurately…if it is no more anything is needed.

-- Our village hasn't lost it's idiot, he was elected to congress.

View CharlieM1958's profile

CharlieM1958

16241 posts in 3680 days


#2 posted 04-04-2012 03:16 PM

I sure wouldn’t put another $500 into it, but I totally agree with Fred. The proof is in the pudding, so go ahead and saw some lumber and see what happens. Rip a couple of boards of the same thickness, then line up the freshly cut joints with each other like you were making a panel glue-up. If you’ve got a satisfactory joint, you should be good to go.

-- Charlie M. "Woodworking - patience = firewood"

View GregD's profile

GregD

783 posts in 2598 days


#3 posted 04-04-2012 03:17 PM

I suggest you move forward and build a few wood projects with the saw. I suspect that at first your inexperience will limit your results, and as your skills improve you will probably find ways around the dip in the top if indeed you ever find that it is causing a problem in some particular instance. Most plywood, for example, is probably warped more than that anyway. It won’t be an issue for the performance of many jigs and sleds.

You might be able to mitigate the problem by adjusting the throat plate a bit high.

IMHO, it is more important that the work slide smoothly over the top, and onto good outfeed support, that you reduce vibration as much as practical, that it holds the blade alignment fairly well, and the bevel and depth of cut controls work smoothly, consistently, and don’t slip once set.

If the saw is the best you can afford, and you’ve tuned it as best you can, by all means use it, and proudly. Both you and the saw will get better with experience.

-- Greg D.

View Dallas's profile

Dallas

3599 posts in 1949 days


#4 posted 04-04-2012 03:58 PM

Now, to begin with I want you to know that I’m not advising that you use this method.

About 35 years ago I worked at a car lot in Las Vegas where the owner also had a small hobby wood working shop to use when he wasn’t busy.

This guy was a first generation Cubano and probably met Noah on Mt. Ararat when he landed. Seriously… His idea of body work was to pour lead and smooth it by hand. I know his 1958 Buick weighed over 9,000 lbs because I had to have 16” wheels made for it to put truck tires on.

Anyway, one night while the lot was closed some drunk tourist decided to ram his pick up truck through the coke machine sitting outside the shop because it wouldn’t give him his change.
In so doing, the machine didn’t give and he slammed the machine and the front end of his truck through the cinder block wall which collapsed down onto the saw siting inside.

When I got there in the morning the boss was happily layering Bondo onto his dented and warped saw table and lovingly flattening it with his body tools.
When he was happy with that he cut a piece of aluminum plate and layed it on top of the table using bevel head rivets, (Aircraft rivets), to make it stationary.

I saw him about 12 years ago and he’s still using that same old saw although it’s had at least two different motors and a new arbor since the accident.

-- Improvise.... Adapt...... Overcome!

View knotscott's profile

knotscott

7210 posts in 2837 days


#5 posted 04-04-2012 04:04 PM

I agree with Fred. Measure the cuts, not the saw, and see how it’s doing. It’d take a fairly sizable deviation from flatness in an unfortunate location before you’d see a meaningful deviation in the cuts.

-- Happiness is like wetting your pants...everyone can see it, but only you can feel the warmth....

View DamnYankee's profile

DamnYankee

3297 posts in 2024 days


#6 posted 04-04-2012 04:08 PM

to me the key is does it cut square, or any other angle you are after. For cross cut you could fix any issue with the use of a cross cut sled. For ripping…haven’t a clue.

Again, it’s the final cut that matters most.

-- Shameless - Winner of two Stumpy Nubs Awards

View petergdenmark's profile

petergdenmark

55 posts in 1880 days


#7 posted 04-04-2012 04:53 PM

Thank you guys for the input.

Guess i will start bulsing some shop furniture to start with, and see how i fare.

Since the concave dip runs pretty uniformally along the lengt of the saw around the mouth, i do have the option to put a chunky piece of oak under the table, and then put some stout peices across the table on some blocks, and connect the oak to the cross pieces with some clamps through the insert hole, and try to take the dip out by force. Cast iron is pretty soft, and 0,015” shouldn’t put it anywhere near it’s breaking point.

Just though there would be a lot of people out there with smal dips and bumps, who wasn’t bothered by it, but that doesn’t seem to be the case.

I have built my own house from the ground up, and i’m glad i didn’t get into furniture before that, since this kind of fussyness has no place in that king of construction :).

-- I'm from Denmark, but live in Sweden.

View Loren's profile

Loren

8301 posts in 3110 days


#8 posted 04-04-2012 05:38 PM

You can grind it by hand if you want to invest several dozen
more hours in it. Lots of fun.

Seriously though, cast iron is soft enough to be scraped
and certainly filed. You can glue a sanding belt or other
large piece of sanding cloth to a flat man-made board,
piece of metal or whatever is flat and move that over
the high spots. Just like a plane, that sanding board
will take off the high spots and leave the low spots.

The warpage may not throw off your work in any significant
way so unless the warped table is keeping you awake
at night thinking about it, you might want to try to
live with it.

Your idea about straightening the table with a bending
jig is a good one. Cast iron jointer fences for example
are sometimes bent and are not hard to straighten using
a similar method.

View mcase's profile

mcase

446 posts in 2591 days


#9 posted 04-05-2012 05:36 AM

Are we talking 0.015? 1.5 hundredths. All better manufacturers I have ever seen publish a tolerance for a table saw top guarantee 0.01 So by the current standard you are off. But this is one old saw and may hail from a day when 0.15 was all they aimed for. Its not good news that its out by 0.005 more than a new quality saw, but on a table saw its probably not that critical. If it was a jointer you would have a problem, but its not, its a saw. So I agree with the folks above who suggest you just run it and see. It may very well have no effect of your cuts. Try some rips of different lengths and widths and a variety of crosscuts and see. If its ok then great just leave it alone.

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