Jointer expert – how good is good enough
I just purchased an 8″ jointer, but haven’t ever owned a good jointer so don’t know what I should be looking for as far a specs. I’m planning on having this jointer for quite a while and want to know if the tolerances on this machine are good enough for top notch work (assuming, of course, that I do my part).
Both the infeed and outfeed tables are flat across their width to .0025″ or better. I assume that this is fine.
Both the infeed and outfeed tables have a dip of 6 thousandths over their length (35″ for infeed – 35 1/2 for outfeed). Measured corner to corner each has a dip of about 8 thou.
The fence is dead flat (less and .001″ out) measured over its height. It is concave by about 8 thou. over its length.
Is this a keeper? Can I expect to have any difficulties tuning this jointer with these specs?
Any thoughts would be greatly appreciated!
Replies
BAP
Ha.. ha... ha..ha..ha..
Get a good nights sleep and be on time in the morning at 8 AM. You should have at least 4000 linear feet jointed by "quitting time".
:>)
sarge..jt
Proud member of the : "I Rocked With ToolDoc Club" .... :>)
I think the practical test is to joint two boards as carefully as you can and then put the two jointed edges together. If it looks like you can get a good glue joint out of it you are golden.
I really can't get into micing shavings. The next time the relative humidity changes, the wood movement will far exceed the limitations of the tool.
Frank
In my view, the twist in the tables is too much. They should be parallel in width & length within 2 (+or-.001). For most work it won't matter, however.
If the blades are preferentially worn over the first 2", for example, from edge jointing, the table tilt may frustrate perfect jointing (edge), Face jointing won't matter, even with more error. I'd shim one of the table into parallelism.
A few words of chasing the setup of a jointer at the FAQ link.
Pat, I have to ask: Do you not mean "co-planar" rather than "parallel." Given my spatial challenges, I find it important to keep these two words distinguished from each other and use them appropriately.
Maybe I'm wrong, and you meant parallel........forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)Another proud member of the "I Rocked With ToolDoc Club" .... :>)
In the same plane=parallel=coplaner.
Ahhhhh, nope, I don't think so.
Parallel: extending in the same direction, everywhere equidistant, and not meeting <parallel rows of trees> b : everywhere equally distant <concentric spheres are parallel>
I don't think two lines or surfaces that are set end-to-end can be said to be parallel, as they cannot be "everywhere equidistant." The two surfaces of a jointer table (in- and outfeed) must be set to be coplanar, i.e., existing in the same plane. If they were set to be parallel, they would have to be either one above the other, or one next to the other, not end-to-end.
As most Knotheads can attest, I don't usually get wrapped up in this kind of nit-picking, but in this particular instance, I think it's important that the words be used correctly.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)Another proud member of the "I Rocked With ToolDoc Club" .... :>)
FG,
Excuse me for jumping in here, but...
If the jointer tables are coplanar the machine will not cut. That is, the depth of cut would be 0" As soon as you drop the infeed table to take, for instance, a 1/16" cut, imaginary planes extended from the tables are parallel, and offset by 1/16". I'll grant you, the planes described and limited by the surfaces of the tables are not in themselves parallel, but that is getting pretty picky, since the wood gets pushed from one to the other! :-)
What IS the term that geometry uses to describe two plane surfaces like our jointer tables? "Offset" seems so unspecific...
BTW, congrats on your auction plunder. Stuff always seems better when you get a bargain.
Regards,
Ray
When tuning a jointer, one sets the infeed table to zero, right? That's when the two tables are coplanar. Turning attention to imaginary extensions of the tables and working it that way, the two tables could be parallel and not be coplanar. Imagine that both the infeed table and the outfeed table were slanted slightly from right to left, to the exact same degree. The tables would be parallel to each other but absolutely not coplanar, and they definitely would not joint wood very well.
Thanks for the congrats on the auction stuff. I've decided to keep the JDS air cleaner, I think. $85 is so much better than $300-and-something, and it's "new-in-box!" Now I'm half-way to real honest-to-goodness dust control!forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)Another proud member of the "I Rocked With ToolDoc Club" .... :>)
FG,
"Imagine that both the infeed table and the outfeed table were slanted slightly from right to left, to the exact same degree."
Well, maybe I don't understand what coplanar is. If the two tables share the same plane surface are they not coplanar? whether they are level, slant left or right?
Confusedly,
Ray
A "plane" is a two- (not three-) dimensional concept. Two tables that lie end-to-end (ignore the cutterhead for now) and that are flat and level as a straight-edge is placed across them are "coplanar."
However, If we magically slant the left end of each table down a bit, they are no longer co-planar because they aren't in the same two-dimensional (by definition) plane. If we give them imaginary extensions, they may be parallel, but they aren't co-planar.
OK, take a look at the following attachment. I did a little "paint" with Microsoft. Pretend the lines aren't jagged, please.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)Another proud member of the "I Rocked With ToolDoc Club" .... :>)
FG,
Ok I gotcha now. Problem was, I was visualizing the tables from the rear of the jointer,BOTH tables slanting from left to right. Now I see that you were standing beside the machine, and EACH table has its own slant, from end to end. It's hard to communicate visual concepts verbally isn't it?
Have a good day,
Ray
Hurrrrrraaaaaay!
Back atcha, Ray. Have a great one. forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)Another proud member of the "I Rocked With ToolDoc Club" .... :>)
Thanks for the responses. Sorry for my delay in replying, but we had a large storm come through and no power or phone for about 14 hours.
FG - I don't mind the detour. Can always learn more.
George R. - I didn't mean to get your hackles up. I don't know much about jointers (hence the question posed in the thread), but somehow you seem to have extrapolated that to a general lack of knowledge of engineering and measuring procedures with the following:
" "The fence is dead flat (less and .001" out) measured over its height."
Having been a tool maker I will tell you he lacks the skill and tools to make that claim. He having made that claim puts the rest of the claims in doubt.
He also lacks the ability to determine if the tables remain parallel when they are out of plane."
Not knowing my skills and tools it seems that perhaps you have overplayed it just a wee bit, but the question of measuring procedure is a fair one, so here is a brief description how I arrived at my numbers. Being a tool maker, and I assume a fairly bright guy at that, you will be familiar with most of this.
The measurements across the width for both the fence and the tables were done with a lab grade precision 12" straight edge spec'd at .0005" across its length. It is handled with kid gloves and regularly checked against a lab grade AA granite surface plate spec'd at a unilateral tolerance of .000050" to make sure it hasn't been dinged. Using proper measuring techniques which, given your background and experience, you are no doubt familiar with (gauges, straight edge, tool at the same temperature, etc., etc.,) and taking a measurement every one inch along the entire length of the fence similar to what Uncle Dunc described, at no point would a .0005" gauge pass. While this may not guarantee that it is EXACTLY within .001, given quality equipment and a reasonable level of experience in measuring, the claim that it is within .001 is not as outlandish as you make it out to be.
The measurements across the length of the tables were taken with a 36" machinists edge spec'd at .0006 across its length. As stated by the poster above, such tools are certainly pricey and not all woodworkers have access to them and I certainly didn't get them to do woodworking, but I really don't understand the point of trying to jump down someone's throat without being remotely informed about their skills or background.
However, you are certainly correct that I don't have the ability to determine if the tables remain parallel when they are out of plane (wish I did), but I never made any claim that I could.
While none of this proves that the measurements are accurate, for the sake of the original question, can we just assume that the measurements are reasonably accurate?
Nicely done, BAP.
Regards,Jamie "Leave the driving to us" forestgirl LOL!forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)Another proud member of the "I Rocked With ToolDoc Club" .... :>)
What you describe will provide the right answer some of the time.
It is very hard to measure the geometry of any surface within .001".
A proper method to do the measurement would be to place the surface plate on the fence. Place a indicator base gage with a dial indicator on the surface plate and run the dial indicator point over the fence. (I ignored the details of aligning the surface of the surface plate with the surface of the fence. And most shops would have a large suface plate 4'x6' or so and place the fance and the indicator base on this larger plate, but you do what you can with the tools you have.)
In any case .010" is close enough for the fence.
FG, parallel described it well enough for me. Assuming the two tables of a jointer (surface planer) are each a perfect plane (which they may or may not be) and set so that the front and back edge of each table forms a perfect tangent with the circle desribed by the knife tips across the width of the cutterhead, then if the infeed table is set below the top of the arc described by the cutters by 3 mm to establish the depth of cut, and the outfeed table is set level with the arc of the cutters (or near enough for practical purposes) then the two tables are parallel.
Quite likely it's impossible to guarantee such accurate engineering in mere woodworking kit unlike perhaps something like the Hubble telescope, and we all know what happened there, ha, ha, but something close to that perfect state usually works well enough for us wood whackers. There's always a bit of movement in wood that we have to live with anyway. Slainte.RJFurniture
>>"Assuming the two tables of a jointer (surface planer) are each a perfect plane...." Part of inspecting and tuning the jointer is to determe that this is the case, hence my preferred use of the more specific term coplanar.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)Another proud member of the "I Rocked With ToolDoc Club" .... :>)
FG, only if you have two flat surfaces in the same plane are they coplanar, i.e., if a theoretical third flat plane stretching to infinity is used as a testing device can be laid across the surface of two planes thousands of miles apart, or just three or four inches apart with no gaps appearing then the two original planes are coplanar.
Clearly for a surface planer (jointer) to work the infeed table has to be set in a lower parallel plane to the outfeed table otherwise the depth of cut can't be set, therefore the tables are not coplanar. They can be set coplanar (or near enough for woodworkers needs) but the machine won't function if they are.
Whether or not the machine is set up correctly or the tables are flat is a different story. Slainte.RJFurniture
Poor BAP (original poster) -- hope he doesn't mind this side-discussion.
"Whether or not the machine is set up correctly or the tables are flat is a different story." Richard, Richard -- that's the part we're discussing here, my friend. I'm starting to get a case of the giggles.
To reiterate what I wrote in my 2nd post back, this discussion about coplanar relates to when we set the infeed table at zero in order to inspect and tune the jointer. Obviously (even to me, LOL) when we adjust the infeed table for a cut, the tables aren't coplanar any longer. I'm not talking about during cutting! I'm talking about during the inspection process.
forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)Another proud member of the "I Rocked With ToolDoc Club" .... :>)
Okay, FG, I see what you're talking about. I'm going to let it go. I'm sort of replying to your post 19 in this thread, but in your second drawing in that post the set up you drew would work perfectly well as a jointer--- or surface planer as I know the tool. True, it's not go two tables parallel to the ground, but it would work as long as the boards being flattened weren't too long, ha, ha.
Actually there's never any need to get the infeed table and outfeed table co-planar to check the set-up. A straight edge and a couple of shims of a known and constant thickness will do the job just fine-- a couple of pound coins can work as a matching pair of shims-- I imagine a couple of quarters in the US are reasonably similar in thickness too, ha, ha-- ha, ha, ha. You only have to know that the tables are parallel at any given setting of depth of cut, and in woodworking that setting doesn't need to be too accurate. Slainte. RJFurniture
There is no way that you can make the measurements you claim.
>> There is no way that you can make the measurements you claim.
Why do you say that? None of those measurements look tricky or impossible to me. They would only require a good straight edge and a set of feeler gauges. A third hand might help of some of them, like the horizontal bow on the fence.
On the one he reported as .0025", I agree that measuring to .0005" doesn't seem likely, but if the .002" leaf is loose under the straight edge, and the .003" leaf won't go, .0025" is a perfectly reasonable interpolation.
I agree with Uncle Dunc about being able to measure those types of tolerances. I do it all the time when I'm setting up jointers. I have a 6' straight edge for this kind of work.
I think the question is whether the measuring device - the straightedge itself - is that accurate over its length.
I have no idea whether it is, but I figure that must have been the implication.
"There is no way that you can make the measurements you claim."
Sounded more like he didn't know how one could make these measurements. It can be measured within a few thousandths. For woodworking the tolerances are very forgiving. For precise metalwork it get trickier.
One of his claims is:
"The fence is dead flat (less and .001" out) measured over its height."
Having been a tool maker I will tell you he lacks the skill and tools to make that claim. He having made that claim puts the rest of the claims in doubt.
He also lacks the ability to determine if the tables remain parallel when they are out of plane.
But we are cutting wood here, the jointer need not be very accurate.
George is right on the measuring.
One looks at a straight edge and it "looks" straight. You can slide a .001 feeler under one end and not the other so you think one end is .001 off.
Few woodworkers keep a precision (not polished import crap) straight edge to measure with. There is a difference between a "rule" and a "straight edge" and when your trying to measure thousands, you have to use a precision straight edge.
In order to see if it is off .001 at a distance of one foot, the straight edge can't vary more than a .001 itself over that distance. Unless your using a precision straight edge, you can't "measure" that accurately because of potential inacuraccy introduced by using a non precision straight edge.
A 24" precision straight edge is $40 and up, and a 36" one is $90+. Most woodworkers don't have one of those lying around. While I am not a tool maker (artists in metal) I do work on guns. Few guns keep things within a .001 as an example.
Hi,
Your original question "Is this a keeper?" was lost somewhere in the discussion, I think.
.008" is the maximum allowed for deviation from flatness for my Delta DJ 15.
Using a straight edge on the out feed table, they set the table above the cutter head by .015", every where the same, and then adjust the infeed table parallel to the straight edge using a .015" feeler guage, again everywhere the same. No tolerance is given, except that the measurements are "critical"
My jointer never worked well until I could measure no error, and that took awhile. I used a dial indicator to set the table to the cutter head, and I use it to set the knives.
Ken
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