How flat is flat? (Newbie question)
I’m attaching the wings to my new Grizzly 1023SL, following the instruction manual as exactly as possible. Right off the bat, I run into a problem — the manual says the wings are not symmetrical, but they are (I’ll address this with Grizzly). Anyway, after getting them both on and flush, I’m working on shimming to get them flat with reference to the main table. I then realize I’m not positive I know how much to tweak this. I’ve got them both flat to the point that I can get a .004 feeler gauge under the straightedge but not the .005 gauge. Is this good enough? (And from a nomenclature perspective, is that “flat to .004” or “flat to .005” ?)
It also turns out that one of the wings is bowed (ends are higher than the center — that’s a “bow”, right?) very slightly at the point where it attaches to the main table, but not out near the edge of the wing. The bow is also about .004 (I can get a .004 feeler gauge under, but not a .005). Is this a problem?
Thanks,
-M.
Replies
Mark,
I believe there was a thread several months ago that spoke about acceptable tolerances in the .008 range from the factory.
Mark
At .004 or .005 you shouldn't lose any sleep. ha..ha.. You be good to go.
Good luck...
sarge..jt
Mark -
I pee'd & moaned over the horrible warp in the wings of my Unisaw after struggling to get them aligned with the main table, too. Then it was pointed out to me that cast iron, within limits, is somewhat ductile - that is it will bend some. The trick is to get the front or back, one or the other, aligned as perfectly as possible, Then get the middle bolt in and align it as perfectly as possible. Then, clamp a couple pieces of heavy angle iron top and bottom across the last edge of the wing and the main table and force it into submission.
My main table is over .005 out of flat. Now, mind you, that's measured with the straightest instrument I have which happens to be a 30" aluminum level. Not the most precision instrument in the book by any means. None the less, I'm also rather positive that any piece of wood I cut (and you as well perhaps) will end up distorting by one or more orders of magnitude as a result of relieving the stresses inherent in a natural product like a piece of timber.
The bottom line - we're talking about such minor degrees of measurement that I'd risk invoking the wrath of the tolerance gods by saying it's somewhat irrelavent. I say this after agonizing over the same sort of dissapointments you appear to be experiencing after paying big bux for a nice new machine. If this were a metal working forum and we were talking about a new engine lathe, that would be another issue, of course.
Get your saw as close as you possibly can then start building things. I think you'll find it will serve its purpose quite well. I'm only a weekend woodbutcher myself and perhaps I'm not being sufficiently anal about things.
Dennis in Bellevue WA
[email protected]
Thanks for your reply!
I'm actually not agonizing over the measurements -- I'm just so new to this I didn't know any better and decided to ask. After yours and Sarge's posts, I'm done fiddling with it.
Now if only I had 220V power I could make some sawdust. The electrician won't be here until weekend after next. Sigh.
Ah well. Still gotta install ducting for my dust collector anyway.
-M.
Sorry - hope I didn't come on too strong. But as another post implied - few of us have the necessary precision type straight edges to make checking something as big as the top of a table saw top for flatness.
I know exactly how you feel,though. I saved long time and spent some serious money (for me) in rising to the level of a real cabinet saw. Then when it wasn't perfect like some kind of NASA equipment OEM thing I felt really dejected. But I got over it and focused on not cutting my fingers off at some not-so-perfect angle (grin)
Have fun with your new saw. I went from an aged 1hp Craftsman contractor's saw to a 3HP machine and I'm still somewhat intimidated by it. But I guess as long as I stay at least a little that way, respecting what that machine could do to me if I weren't always mindful of it's potential for disaster, then I'll keep all my body parts intact.
Think safety, my friend!!!
...........
Dennis in Bellevue WA
[email protected]
Safety? Oh, I'm not planning on actually turning it on. I just like the green color.
:-) :-) :-)
Mark, the most important thing is what are you using as a straight edge? Your tables could be perfectly flat and your straight edge could be out 5 thou, or your tables could be way out along with your straight edge, making the error seem less. If your using a real machinists straight edge than I'd say that that is an acceptable tolerance, but if your not, who knows how much your tables are out by.
As you may know, grizzly and all the other taiwanese companies (as far as I know) machine their castings "green" which means that they don't stress releive them, so there is a chance they will warp after machining. I would make sure that your tables are resonalbly flat before your warranty is up so you don't get stuck with warped tables. With that being said, woodworking relies more on relative than absolute precison, so if your tablesaw is working well then don't worry too much if your tables aren't perfect, as long as it cuts well. You can always do fine tuning with handtools.
hope this helps
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