This morning a friend brought over a tool he ordered to setup his table saw. I think it was something like Align or Align-It? Out of curiosity we went out into my shop and had a quick look to see how mine “measured” up.
If I’m reading this correctly, I’m just a hair widths over being 1.5 thousandths of-an-inch out of running parallel in my left miter track.
Seeing as I never build anything really “big” I can’t say I’ve noticed anything ever really coming amiss from this “adjustment.” However…I have toyed with the idea of a project that will be larger that what I normally build.
Math has never been my strong point…at what point does this 1.5 thousandths of-an-inch become a real problem when cutting pieces. Obviously, no variance is the pinnacle adjustment…but am afraid if I start adjusting I may make things only worse and not be able to get back to the tolerance I have now. Is the 1.5 thousandths of-an-inch an acceptable or should I go ahead and try for less… say .5 to 1 thousandth?
E. Sheraton
Replies
IMHO .003 or better is acceptable.
I've been fixing and tuning machines for 25 years and small stuff like Unisaws, PM 66's typically have a tolerance of .015" from the factory. This is table flatness in general and anything less than that in other areas is fine. Woodworking machines typically have a lower tolerance than metal working machines. Jointer tables are a bit tighter. Old Oliver 16" jointers considered .010" flatness on the table to be in tolerance. Setting jointer knives within a few thousandths no one can notice any difference in performance.
I wouldn't be surprised if your saw was off more than you say. You would be hard pressed to find a saw blade that wasn't off by .005" or more. Anyone who says their fence is set within .001" is suspicious in my experience. A warm damp breeze will cause wood to move more than that. Talk to someone who trained as a patternmaker.
While I try for perfection when setting up my machines, I would settle for 0.0015" out of parallel. I just checked my PM2000 again after reading this and it is about equal to yours and I have not had to reset it in a year or so now. With most better saws, once yo get them lined up, they stay there unless you do something big.
I think you are well within tolerance at 0.0015"!
Tom Hintz
Because there is always more to learn!
This is a timely topic for me. I just assembled a new 8" grizzly jointer. My infeed table sags about .006 at the end. that is about the thickness of 3 sheets of paper. It just doesn't seem necessary to start shimming the table to try to fix that. I guesss I would do more damage trying to fix that. Am I wrong about that? Is that out of acceptable tolerance?
Thanks,
Scott
8" jointers generally have pretty long tables which puts that 0.003" out a ways, lessening its effect on the cuts. If I was not seeing any problems with the boards jointed on it, I'd leave it alone, but check it to be sure it is not getting worse. If any problems are seen with the cuts, I'd shim it.Tom Hintz
Because there is always more to learn!
Math has never been my strong point...at what point does this 1.5 thousandths of-an-inch become a real problem when cutting pieces.
That's an easy answer - it's a real problem if you're building a suspension bridge. On any normal woodworking project, 1.5 thousandths is unnoticeable - even if magnified by an 8 foot tall case.
I believe that you can use the jib screws on the machine to tighten up the tolerances on the tables.
We get to soon oldt und to late schmart
I'll take a look at the gib screws. thanks for the tip.
"at what point does this 1.5 thousandths of-an-inch become a real problem when cutting pieces. "
It becomes a problem when you are not able to recognise that 11/2 thou is nothing to worry about (in this context).Laugh it off.
Edited 10/9/2008 12:02 am by philip
E ,
Not sure of what type of work you do or plan to do but the little you are talking will have no effect on your work or results .
Wood workers and machinists don't see eye to eye on much , there is a fundamental difference in the units of measurement we use .
Case in point : many years ago I took a doweling 3/8" bit along with the collar I used in the doweling jig to a local machine shop . The dowel holes no matter what were off a 1/32nd or so , I noticed the bit seemed a tad loose in the collar .
The holes fit the dowels perfect , I asked the man if he could make a collar to fit the bit , ( was that an unreasonable request ? ) he brought out the dreaded micrometer er whatever and measured the bit , he asked me what size the bit was , I said 3/8" he shook his head and asked had the bit ever been sharpened ,why I asked , he said it was 3 thou under size and wanted to know how I expected to do good work .
I asked him to show me the 3 thou on my tape measure , then I left .
your tolerances are tighter then average go to it now!
regards dusty
After reading through the responses to my original post...I think I'll leave well enough alone.
I did enjoy your machine shop story...in the end I guess I'll stop worrying about my 1.5 thousandths when they do put it on a tape measure! Until then...I'll continue on my way and give thanks I have what I do.
Thanks,
E. Sheraton
Depends on where that three thou is. I guarantee if you are looking at dovetails cut with that much gap between pins and tails you are NOT going to be happy with them.What if the tenon you just cut is three thou BIGGER than the mortise? It will not fit together no matter how much you chose to ignore that three thou. Then you take off twice that "insignificant" three thou and you have more than the recommended gap for a reasonably strong glue joint !I guess you can pound some nails into your projects to hold them together. Sort of.Good luck with all this.PS: I would rather ignore my damned poor spelling but keep a close eye on my thousandths of an inch (and hundredths of a millimeter).Edited 10/10/2008 2:00 am by rocEdited 10/10/2008 2:01 am by rocEdited 10/10/2008 2:02 am by roc
Edited 10/10/2008 2:06 am by roc
Well I am always going off the subject and this is no exception so I must beg to differ with your statment "What if the tenon you just cut is three thou BIGGER than the mortise? It will not fit togeather no mater how much you chose to ignore that three thou".
Because it will squeeze in quite nicely especially when the wood is soft but strong -examples coming to mind are Makore and Jacaranda.And if you have chamfered the end there will not be a question of glue being wiped either.
3 thou is virtually nothing in woodwork terms but 1/64th may be in some contexts.
But I do get the drift of your message, nontheless.(;)Philip Marcou
unnhuh . . . you must be on a different planet than I am on. If I tried that it would split out. I recommend leaving fruit and flowers on the alter to your guardian angels. Do you lend them out ? I bet the side of your work is bowed out a bit at least in a mortise and tenon.Shameful to lead the new dudes on this way.
Edited 10/10/2008 2:39 am by roc
On the contrary - this is the sort of thing that "the new dudes " should not take for granted but should investigate- 3 thou is three thou, not even a tenth of a millimeter, neither here not there with a lot of woods. Most of the time it would hardly be noticed except as a passing thought along the lines of "dang, that is a nice tight fit". If these "tight fits " were actually measured with instruments rather than rulers etc I guarrantee that the tolerances would be a lot more than 3 thou.
When you push together a typical m&t that gives some resistance it will be due to more than a few thou "oversize", and this especially applies to softer woods.
Enough- no need to split any more hairs.Philip Marcou
philip,
Just so. A good fit in a mortise and tenon joint cut in white pine, will likely be too tight in hard maple. I have seen this in cutting multiples in various species, all dressed at the same time, mortised at the same time, tenons cut at the same time. I always pick a harder wood to adjust the fit in cutting the tenons, knowing softer species will not be too tight. But I have never measured those tenons with a caliper, only against the mortise. Who cares whether the interference is .001 or .0042573, tomorrow it'll be something different anyway.
Most of the circumstances I can think of that I am aiming for a "just right" fit or measurement, are ones that involve making two pieces come flush with one another, or needing multiple parts to be the same exact size. This can be done by either offering one piece to the other and making adjustments (planing, paring, etc), or cutting them at the same setting using jigs or stop blocks. Seldom, if ever it is hypercritical that the dimensions of a furniture component be precisely anything. Moreover, it is frequently easier and faster to get things "close enough", then flush up after assembly, dealing with those errant thousandths by planing or scraping, rather than endlessly nudging and adjusting a fence or depth stop to only make a single cut.
Ray
I think it's reasonable to say that a swipe or two with a plane can make the difference between a joint that fits well and one that doesn't. So, one way to quantify what that means would be to simply measure the thickness of a plane shaving. I don't happen to own a micrometer, so I can't do this myself. It might be useful if someone who does have a micrometer would set up a plane to take a thinnish shaving, measure how thick it is, and then report back here.My bet is that it will be closer to .005" than to .0015".-- Russ
RC,I've taken a .002 lick on a 24" x 3/4" cherry edge, measured with a dial caliper marked in .001 increments. My weapon was a Lie Nielsen low angle block plane. Two applications for the .002 shaving- the freshly planed wood was wonderfully smooth to the touch, and that shaving joined with others to start my charcoal grill.Cheers,Seth
Seth , You have taken the use of hand tools to a new level , but there was mention of food maybe .
dusty, who also uses shavings for tinder
Ol' Dusty,The brag on the .002 shaving was to a buddy, one of those sorts of tempest/teapot competitions that might spin wildly out of control and become a Darwin award if left unchecked. (A SF Bay Area man strapped 3 JATO engines to a hand plane...) About 30 minutes from me is Japan Woodworker in Alameda, where a chap working there told a tale of a visiting Japanese crafter who was demonstrating a wood body plane. The crafter asked the small crowd gathered around him to move back several steps, because the humidity from the collective exhalations were causing the plane to not consistently cut sub .001 shavings. If that's true, that's amazing.Clearly, a well tuned hand tool can take the wispiest of shavings, but those shavings burn too quickly in the cauldron BBQ to do much good. That's why I've hereby reduced the tolerance of all my woodworking, to better promote larger bits of wood for burning.
Cheers,Seth
>My bet is that it will be closer to .005" than to .0015". After reading the accuracy of tools used:Bubinga or purple heart using a block plane with a straight across blade edge. A decent shaving is .0015" to .002" Thicker shavings in these two woods is difficult without going to a radiused edge.Mitutoyo digital mic (the good stuff) $150 for a one inch mic.It re-calibrates every time you turn it on with anvils touched together (there is a friction thimble that controls how much pressure the anvils are set to. You turn in the anvils and the knob slips and you can not apply any more force. (Most/all mics are made this way)It has plastic pads where you grip it so the heat of your hand does not change the accuracy It comes with a 25 mm test standard accurate to +/- 0 microns at 20 c room temp>more digits than the other guy. Some of these wonderful tools read to four digits accuracy, but it may not mean a whole lotFor the sake of, as my family member would say, "boosht and conversation" the read out on this mic is:.00005 inch = five one hundred thousands inch (fifty millionths)
.001 mm = one thousandth millimeterDoesn't mean anything but hey; I am "sharing"Edited 10/11/2008 5:12 am by rocEdited 10/11/2008 5:15 am by roc
Edited 10/11/2008 5:23 am by roc
My.. my.. hasn't WW come a long way over 5000 years that we can be disturbed about .0015 of an inch off.. or that we have machines that can cut tenons to exact. I'm sure there are engine builders that would love to have one of our machines to put a race piston to those tolerances.
I just cut over 40 tenons for a Mission coffee table and intentionally made all a tad over-size. I have opted to not have a digital read-put but chose a should plane.. rasp.. file instead. How crude I must be even though the dry fit sitting in the shop seems to be quite good. Perhaps I got lucky but then again... it could come back to haunt me in years to come.
BTW... IMO..... it would be-hoove every Joe WW to buy a $5 feeler gauge and take a look at .001 - .002 - .003 daily. That might give you the significance in just how important that is. Frankly... you couldn't force a gnat under .003 even by attaching C-4 plastic explosives to his *ss.
Back to the low-tech shop where finesse is the order of the day when attempting to build "using a rightful manner" as told to me by Ian Kirby a while back.
Perhaps I just don't get it?
Sarge..
Edited 10/11/2008 9:03 am ET by SARGEgrinder47
No Sarge , you got it .
d
I had a hunch I did too! :>)
Sarge..
Yeah, Sarge, you got it. The problem is that a lot of Woodworkers have been schooled in the "manufacturing" mindset by their jobs, society as a whole, or the vendors of woodworking machine tools, or all three.
In manufacturing, it's critical to have close tolerances so that parts are interchangeable both in relative position and with each other.
However, woodworking for the last 5000 years didn't conform to that expectation - each joint was individually fitted. Tenon A does not fit in mortise B, it fits in mortise A. This sort of fitting is the key to high craftsmanship in a small shop, and is why a guy in a very dimly candle-lit room with nothing other than relatively crude (by today's manufacturing tolerances) tools and working with wood that was in no way delivered to him with flat faces or square edges was able to produce some of the greatest masterpieces in furniture that the world has ever known.
That said, it's very much easier to put a digital readout on a power planer, and dial in a table saw set-up with machinist's tools. I used to work this way, I can categorically state that it leads to frustration - even very precisely calibrated power tools will still produce parts that don't quite fit, because cutting off a little bit of wood off of a solid board often causes the board to move a bit.
I strongly suspect this is why small kitchen cabinet shops typically deal with veneered plywood and mdf panels; it's not about stability or durability after the product is completed, it's about dimensional stability during the manufacturing process. That's certainly the way I would go if I was running one.
As often as I see the scenario... you gave about as good an explanation of "why" as I have heard. It seems to come up quite often and I have to bite my tongue each time it does as I suppose I must be "old school". Several months ago now there was a thread on another forum that went like this:
I just got a digital read-out. I checked a piece of 36" stock I ripped and there was a .0046 variance on the side I ripped over the length of the piece. What should I do?
Seven people posted an answer on that question suggesting ways to fine tune the blade.. fence.. etc. etc.. I basically gave the eighth answer which was try to get your money back for the digital thingy and get back to work. Then the sane crowd followed suit and chimed in to re-enforce that it is of total in-significance.
The OP came back with he had a Wood-rat which is a very precise machine and it "required" exact tolerances. I did not reply as I did not want to be rude and tell him he was full of manure. I just feel that the mind-set I see on some of these supposed WW forums just gets under my skin a bit. Some of these people are afraid to start a project unless they have their machines tuned the to specs of a NASA rocket.
I will now go back to the shop as I have to put down a layer of de-waxed shellac on end grain of a table top before I apply stain. Now... my question is: the Zinser de-waxed shellac lays a coat around .0024 according to my digital reader. How do I dilute it to get it to lay a .0020 coat which has been "time tested" to be the best thickness for that particular application?
If your answer is: ha.. ha... ha..ha..ha.. I will scrap the idea and just deal with the .0024 come h*ll or high water.
Regards...
Sarge..
Sarge - Yeah, my reaction is definitely ha, ha, ha. The really interesting thing about this subject is that many people have a reaction to a true antique that could be summarized by "charm".
Often, that charm isn't really about the inherent design of the piece, it's about missing paint, worn molding, inconsistencies in the dovetails, crooked doors and a lot of other defects that scream "made for a utilitarian purpose by a craftsman unconcerned with square edges".
In some sense, this is what I think is often missing on so-called "contemporary" or "studio" furniture. A lot of the pieces I see are perfect in every detail, right down to the surface finish, and very obviously made to be manufactured with as little food-powered tools as possible. There are certainly exceptions (the latest back cover of FWW is a good example), but it's rare to find any carving or surface ornamentation that requires hand work. Amusingly enough, the ones that do contain well-done hand marquetry, carved elements, and other design features that are difficult or impossible to adapt to machine production are lauded as being the exceptional pieces in the genre. How very odd.
Probably nothing "charming" about any of my work so... can we call it "ruggedly handsome"? hee....
Sarge..
I make all of my adjustments at 0° Kelvin to avoid fluctuations in the measurements due to those pesky molecules rattling around. ;-)
And that's a great idea, Ralph. Once upon a time in a land far away I ran a 6 man Hunter-Killer team. I attempted a 1700 meter shot one day that missed by a hair high. I highly suspect there was someone somewhere along the bullet trajectory line that was looking up. Their breath probably lifted the trajectory slightly causing the miss as I just don't miss under normal circumstances. ha.. ha... ha.. ha..ha...
Did I tell you about that monster bass that got away? :>)
Regards...
Sarge..
Edited 10/12/2008 2:25 pm ET by SARGEgrinder47
rcooper,
My point is this: Why bother trying to quantify the thickness of that shaving, or the tenon itself for that matter. The goal is to achieve an acceptable fit, not measure what it takes to achieve the fir. No one I know is measuring the tenon thickness. calculating the amt needed to remove, then setting the plane to remove that amt.
Now if you are trying to gain some bragging rights, posting the thin-ness of your shaving will work. But telling the crowd to move back to reduce the humidity...that is priceless, gotta remember that one.
Ray
Hi Ray,I must not have done a very good job of making myself clear. I agree with everything you are saying!What I was trying to get at was the question: "Is 0.0015 inches a big deal in woodworking?" by relating that 0.0015 to the thickness of a plane shaving. If the thickness of a plane shaving is somewhere in the neighborhood of that 0.0015, then yeah, those thousanths are important because a swipe or two with a plane can make the difference between a joint that fits well and one that doesn't. On the other hand, if a plane shaving is more like .005 or .010, then there's probably no point in worrying about a thousanth or two.As it turns out, this is all quite academic for me personally. I'm lucky if I can get all the grooves for a drawer bottom on the inside of the drawer!-- Russ
My gawd I agree with you. It appears that a lot of people get on their high horse just to argue and appear superior. End of rant.Cheers,Peter
Better life through Zoodles and poutine...
Admitting to spending most of my time with wood in the hardness range of 2000 pounds plus (Nick Engler's Woodworking Wisdom p 8) I must demure to your knowledge of the ones in the Makore and Jacaranda range. ~1300 lbs : Wood Explorer Databasehttp://www.thewoodexplorer.com/maindata/we1183.htmlWood working is such a big world. Sounds like there are some pleasant surprises awaiting my future explorations. Thanks !
roc,
In this case the OP said the left miter track was out 1.5 thou , not that there was runout in the arbor or the fence and blade were not right , I suppose if you only used the miter track to make your joints it would be possible to make something out of perfection , but how would you know ?
I can say I do not use the miter track to make joinery, the fence yes .
As far as the example you are using of a too tight fitting mortise , a swipe or two with a sharp chisel has worked awful good for the last 30 years for me .The wood may swell more than the .003 whence the glue is applied anyways .
As was said use the mic on almost any wood part and it will change from seasons and perhaps day to day . Perhaps you are really a machinist talking up like a wood worker , but your insistence on a unit of measurement that can't be found on a tape measure , is critical is a waste of worry for wood working .
regards dusty
I have been following this thread and the one question that comes to mind is whether or not the device the OP was using is certified for these tolerances? Some ingenious sales people realize they can sell more if they have more digits that the other guy. Some of these wonderful tools read to four digits accuracy, but it may not mean a whole lot.
Just a thought.
Brad
Hi Brad,
I'm the OP of the thread.
The product my friend had purchased was by a company called In-Line Industries. I've not ever purchased anything from them myself so I don't know a whole lot about their work or how well these are suited to track in those increments...I will have to say that this kit my friend order seemed to contain about anything you would want to track on a table saw (or just about any other woodworking piece of equipment)...that doesn't account for how accurate it is obviously, just an observation.
If anybody knows about the accuracy and quality of product(s) from this company I would be interested in finding out more from others who have used it or can comment on the accuracy or in-accuracy of their instruments.
Until you posted your post Brad, I hadn't considered your point. Quite an important one when you think about it.
E. Sheraton
Hello E ,
You know being accurate is for me very important , keeping machines set up square and knives just right all help to contribute to overall accuracy , errors often compound from one end to the other if left out of adjustment .
We do have to remember that our medium of choice is a less than perfect one at best . The few thou in question to put this question in balance can be found from one side of a board to the other , use a mic or a vernier caliper or any other measuring device and see for your self . Just soft and hard grain in some woods can vary from area to area .
dusty
Most of the certified tools have provide the accuracy level with the tool. If you can find the manual online it will probaly have a spec such as a percentage of the measurement. I think you have proven that your setup is very reasonable and much more may be a waste of time unless you are building projects that demand such accuracy. I would ask if you have been having fit problems with your projects? If not, why worry?
Brad
If I understand you correctly you're talking about how parallel the blade is to the mitre slot. And also to your fence. For the benefit of newer woodworkers I would say the following:
This will not effect the SQUARNESS of your cut. IE it will not run out, your cut will be square and parallel. (You can't cut a taper by having the fence at an angle to the blade.)
I can't think of an instance where a work piece would be taken from the table saw and not further refined or finished by planing or paring.
All that will happen with the kind of tolerance (I don't even want to call it mis-alignment) you are talking about is the width of the kerf will be 0.003 more than it's theoretical width.
If a work piece passes both the front and back of the blade then the resulting dimension will be the distance between the fence and the point on the blade nearest the fence. For your mitre fence it will similarly be the distance between the stop on the fence and the nearest point on the blade.
So I would say don't worry about this and bring your comonents down to correct fit with a well tuned plane rather than worrying about your tablesaw.
Just my two penneth from Yorkshire England.
Spot on.. woodbender. A bit of a different angle is having the tail of a full fence toed too much toward the rear rising teeth of the blade which can cause the stock to pinch.. touch the dangerous rear rising teeth and potential kick-back.
Keep in mind that most here in the U.S. use full fences contrary to the half fence you run in England. I run a half fence to help avoid that very issue. But.. very good job of clarification on why the slight variance won't make a difference.
Regards...
Sarge..
Just me so take it for what it is worth..
My saw is a so called Junker.. Works for me! AND then some!
No matter how close your measuring tool tells you.. Wood does it's own thing.. My Junk saw CAN saw straight! Period!
Sometimes I see the wood go off the end of the fence a bit... (As in the back end of the blade)..
No Science expert here.. BUT forces equal each other as I remember from College.
First thing to give in is the spinning blade! It is way less ridgid than your fence!
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