drawer slide adjustment

If you mark one part of a joint from another, what's the error associated with that procedure? Isn't this what determines the accuracy of a joint rather than the ability to measure anything? (I'm assuming here that you cut the joint by hand.)

I started wondering about tolerances when I started trying to face joint wood. If I aimed for "perfect", meaning that I couldn't detect any deviation from my Starrett, then I'd still be jointing. And I concluded that seeking that level of accuracy doesn't make sense because of the changeable nature of wood. (I plane the other side and it bends 0.1" anyway.) So if perfect isn't the goal...then what is? I picked 0.004", but I don't know if that's the right answer.

Reply to
adrian
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They're quoting an absolute accuracy--you can do much better than that w/ repeatability using the same tape and good technique where you don't care if the measurement is off relative to the reference NIST but simply need to reproduce multiple pieces or partition the total length, etc., etc., but all w/ the same measuring device most absolute error cancels.

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Reply to
dpb

CONSISTENCY in dimension is oftentimes more important than precision in measuring the dimension.

Recall the "batch cutting" references ...

Reply to
Swingman

sigh...

Regards,

Tom Watson

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Reply to
Tom Watson

It only took me once, to learn to use the same tape throughout a project.

Reply to
-MIKE-

:)

Reply to
Swingman

Depends on which way the error goes. If the cabinets end up 5/16 too short you can fudge it any number of ways. If they end up 5/16 too long then you've got a royal pain in the butt.

Reply to
J. Clarke

Also, a woodworkers delight is finding that his project tape measure coincides precisely with the tape measure on his table saw fence!!

Reply to
Swingman

This has only happened to me once, when the framers moved a kitchen sink window rough opening in the stud wall 4" closer to the only perpendicular wall I had too worry about; then, to compound the problem, mounted the window in the RO closer to one side than the other.

In order to center the sink base cabinet on that kitchen window (something that is ABSOLUTELY required in most installations where a kitchen window is involved over a sink), I ended up having to completely rebuild the last of four base cabinet in the run to fit the now too small space.

... amazing how little time a one off, angled, base cabinet takes to build when it's urgent.

Three years later I still have that right hand, angled base cabinet in storage, and still looking for a place to install it ... the houses I've been since have been mirror images in layout. :(

Reply to
Swingman

Yep, I went to school. And I already admitted to being prone to excessive analysis. :)

And no matter how much people talk about "equal" and refuse to acknowledge that there' s a tolerance, there's really still an underlying tolerance determined by your measurement process, or whatnot. Just like you can't measure (as noted by Tom Watson), there's also no such thing as "equal". I think I've gotten a good answer from people's posts despite their aversion to the word "tolerance". Maybe a better way to pose the question is to ask about practice rather than about tolerance, since there seems to be some sort of objection to the term. In other words, suppose you're gluing up a drawer. You've got it all together and it's time to check if it's square. What's the process? Is it slap a measuring tape on it and measure the diagonals from the outside corner? If a difference can be detected by this procedure then fix it. Using some sort of rod gauge would be more accurate. Is it necessary, or is the tape measure procedure adequate?

A picture of the piece in question can be seen here:

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Reply to
adrian

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Watson
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Reply to
Tom Watson

"Practice/practical" is what we've been talking about, your insistence on "tolerance" is theoretical. :)

In other words, suppose you're gluing

Along with Tom Watson's link (incidentally, Tom being a master cabinetmaker, in the finest sense of the word, so pay particular attention to any tips you get from that quarter), try the following, either which will increase your "tolerance" when using a tape measure for measuring diagonals in pursuit of the holy grail of square:

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said, a simple stick of sufficient length will also to the job.

to give you a hand as it looks like something that is doable with enough experience ... keep on trying to you get it, each brick wall broken is another step closer to mastering the situation.

Reply to
Swingman

I'll try to go slower next time: I'll see if I can take 15 years on my next project. :)

But more seriously, I prefer to be slow are careful and I think I mostly do work that way. But being rushed by the glue is one problem that I didn't see a way around until I was forced to really look for different glue. (There is no way I ever could have put the case together in the 15 minutes or so that PVA allows. I enlisted my wife's help in glue application and assembly and it still took 45 minutes to get everything together.) So when I glued up the drawers I was always rushed. By the time I would get to the point where I'm supposed to check if the assembly is square I've already been fighting against the glue and I'm at the end of my open time and probably tired and drained from the stress of it all. I'd much prefer it if I could come back tomorrow and double check the assembly for square. But I haven't found any 48 hour glues. At least the next time I do something like this I'll have an hour instead of 15 minutes---that should cut down on the rush factor. (The next project is a table which seems like it should be a lot easier to put together than 27" long dovetails.)

You're right. I did respond in a defensive way and I can see this now that it was not what I should have done.

Reply to
adrian

I found the remark about using the straight edge with the bevel down to cast a shadow interesting. My straight edges are all unbeveled and I never saw the point of the bevel.

Reply to
adrian

I'll try to go slower next time: I'll see if I can take 15 years on my next project. :)

But more seriously, I prefer to be slow are careful and I think I mostly do work that way. But being rushed by the glue is one problem that I didn't see a way around until I was forced to really look for different glue. (There is no way I ever could have put the case together in the 15 minutes or so that PVA allows. I enlisted my wife's help in glue application and assembly and it still took 45 minutes to get everything together.) So when I glued up the drawers I was always rushed. By the time I would get to the point where I'm supposed to check if the assembly is square I've already been fighting against the glue and I'm at the end of my open time and probably tired and drained from the stress of it all. I'd much prefer it if I could come back tomorrow and double check the assembly for square. But I haven't found any 48 hour glues. At least the next time I do something like this I'll have an hour instead of 15 minutes---that should cut down on the rush factor. (The next project is a table which seems like it should be a lot easier to put together than 27" long dovetails.)

========

try epoxies. the open time can vary from seconds to weeks for different products. the one i use for glass takes approx 1 week to set up.

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course, it would be hard to undo it if you did make a mistake.

regards, charlie cave creek, az

Reply to
charlie

Did you read down to where it talks about using them as bar gauges?

Regards,

Tom Watson

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Reply to
Tom Watson

Simple solution: Don't glue-up the whole piece at once!! Break it into two, or more, glue-ups! Rare is the component that you can't break down into multiple glue-ups if need be.

CAVEAT: when doing partial glue-ups, it's a good practice (actually imperative) to go ahead and clamp up the full assembly, both glued joint, and unglued joints, and check for square.

Use some common sense with multiple glue-ups, think it through so that you don't glue yourself into a corner; practice the steps first before each glue-up, with clamps at ready; and your project will thank you ...

Reply to
Swingman

I didn't find that part so interesting because it seemed like getting the clamp on without the parts slipping would be annoying. And I have this already:

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Reply to
adrian

Do you have any idea what the working time of this stuff is? They say it takes a week to cure. I have an epoxy that takes 2 weeks to cure. But the working time is only 80 minutes.

I haven't had much luck with undoing "reversible" glues. I experimented with hide glue. Turns out my shop is too cold for it, and even though I warmed the Old Brown Glue to 130 degrees I only got about 5 minutes of working time. But when I tried to reverse the glue because of large unsightly glue lines I ended up giving up and sawing the pieces apart.

The fish glue I used is supposedly reversible, like hide glue. I haven't tried to reverse it. But they claim a 60-90 minute working time which is as long as the epoxies I'm familiar with.

Reply to
adrian

On Wed, 02 Dec 2009 14:41:12 -0600, the infamous Swingman scrawled the following:

Bwahahahahaha! Two points for each of you.

-- Follow the path of the unsafe, independent thinker. Expose your ideas to the dangers of controversy. Speak your mind and fear less the label of 'crackpot' than the stigma of conformity. And on issues that seem important to you, stand up and be counted at any cost. -- Thomas J. Watson

Reply to
Larry Jaques

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