How close is "close enough"?

I can’t tell you how many thousandths “snug” is. But I can tell you that you are not the first machinist I’ve met who gets frustrated by the imprecise nature of wood.

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

It’s Phildo92027’s fault that I try to hit +- 0.003”. And you better put it together quick before the weather changes!

I use a micrometer that reads to 0.0001”, and going back to a tape measure won’t work for me. Phil emphasizes precision in woodworking, and it’s far more satisfying to me to have a tight slip fit joint rather than one that flops around like the clapper in the Liberty Bell.

-- The days are long and the years are short...

I think snug is in the .003 – .008 range for most furniture joinery applications. So – no more than 1/128th overall…that’s what I’ve read and heard, and tried for…allowing room for the glue you add to the joint. Too tight and you “starve” the joint, by pushing all the glue out of it.

The softer the wood the more snug it can be because of compression of the fibers, but as you get harder, “snug,” is probably in the higher end of the range. Plus in joinery you rarely if ever have a perfectly dimensioned joint so measuring to this level of accuracy isn’t really necessary…even though I’m more than happy entertaining the notion!

You’ll learn to feel what the right “snug” is for the kind of wood and kind of joint you’re working on…

Have fun here!

-- Dorje (pronounced "door-jay"), Seattle, WA

Where do you find $3 a gallon gas???

“Snug” to me is if I do not have to get out the big mallet.

Do not try to fit a joint one day & expect it to fit the next.

Or to cut 4 matching joints in a row & expect them all to fit the same.

Welcome to the sometimes frustrating world of woodworking.

-- http://www.grandprairiewoodworks.com http://www.etsy.com/shop.php?user_id=6453794

Okay, the $3 a gallon gas was LAST month.

You have confirmed what I already suspected. I’ve been using .005 as a ‘target’, and it sounds like I’m in the ballpark. It’s just hard to get away from the machinist’s mindset—“slip fit, no slop” means .002” clearance.

Of course, if wood BEHAVED like metal, it would probably LOOK like metal. And, while metal does (usually) have a ‘grain’, it just isn’t the same. ;)

Thanks to all, for your replies!

-- There is nothing in the world more dangerous, than a woodworker who knows how to read a micrometer...

Oye!....machinists will surely have some “adjustments” to make with woodworking. Wood movement will certainly drive you crazy, so watch out. Just kidding of course…..

Machinists are not nearly as bad to work for as engineers though. I was going to do some basement wood trim for one 3M engineer, but when he hauled out the 8’ level I could see it would not be a pleasant experience so I thanked him for the consideration, and walked away. I couldn’t imagine going through an OCD experience with an engineer.

I started out life as a machinist and still use the tools in woodworking. Mainly just dial calipers. Then I ended
up as an engineer for the last 20 years.

I find that both are a great asset in woodworking. You just have to learn that unlike steel, wood has a mind
of it’s own. It expands, contracts and bends as you cut it. What may be snug one day may be loose
the next.

Snug to me is something you can put together without a hammer and won’t fall apart due to gravity.

-- Gary, East TX -- The longest journey begins with a single step.

Snug to me is if you dry fit something together it stays together with out falling apart. That does not mean that you put it together with a mallet. There should be a drag or friction feeling of the pieces.

I had a neighbor once who always carried a 1/64 ruler with a slide on it in his pocket. He came over one day while I was putting a bay window in my 25 year old house. He started measuring the window in the rough opening. He said, “The window is 5/64 out of square” I said “John, move your ruler or I will nail it to the wall” There is trim going around it. That is called CLOSE ENOUGH!

God Bless

-- Mc Bridge Cabinets, Iowa

tom , you should have nailed it and said there that shim will tighten it a little lol

I know it will be a very difficult thing to do, but the best thing you can do with that micrometer is put it back in the machinist’s tool box. Your best tools in woodworking are your hands and your eyes. If you need to take a thousandth off here and there, then a well-tuned, razor-sharp handplane can satisfy that need for accuracy.

If you’re relatively new to woodworking, may I suggest that you learn about wood movement, moisture content, and grain orientation. These are some of the things that distinguish woodworking from metalworking, and they need to be considered in design, joint making, gluing, and the seasonal stability of your work.

Snug can be a dovetail joint so tight that you can’t pull it apart by hand and need the assist of a deadblow hammer to tap it apart. Snug can also be two pieces that you can push or pull apart by hand, like a sliding box top that fits in a groove. It truly depends upon the situation. Unlike metal (for the most part), wood is always moving to some degree, and one of the skills of woodworking is learning to predict it and plan for it in your work.

Dorje hit the nail on the head when he said, “You’ll learn to feel what the right “snug” is for the kind of wood and kind of joint you’re working on…”

I’m not a machinist, but my engineering background has occasionally collided with the nature of wood to move. But the more I’m around it, the more I appreciate that it’s just another feature like color or grain.

-- Earle Wright, Lenoir City, Tennessee

Earle, you’re right. Sometimes my engineering sphincter is too tight for my common-sense gland.

Rewind, rewind, rewind
I have a little grey C-clamp that won’t stay tight. It has these numbers on it that roll as I turn the handle, but I’m learning to ignore them.. ;)

-- The days are long and the years are short...

Think about how it will look on a trotting horse!! That’s about how observant most people are.

-- Thos. Angle

I’m with Tim, even last month: $3/gal gas? Nowhere near me [giggle].

But my definition of snug is “doesn’t need a mallet”.

The other thing to remember about wood is not only does it change size as you breathe on it, different woods compress in different ways. That’s the only reason I can see for a dovetail jig to be adjustable…

-- Dan Lyke, Petaluma California, http://www.flutterby.net/User:DanLyke

I’m a ole machinist myself. when I make a mortice and tennon joint, I aim for a .005 to .010 slip fit. I use a mortice machine or horizonal router for the mortices. with calipers the tennons are .005 to .010 under the nominal size in the mortice. I find this to be a good fit and allows for any squareness or parallelism variations.
However if the tennon is .025 undersize I still use it as is. Any more then that and I repair the tennon by gluing a piece on the side and recutting it. probably overkill.

-- work from your heart and your spirit will live forever

You’re right, MyronW. Those fancy “little gray C-clamps” that I have, don’t hold worth a darn either. They also limit the size of my projects. Have you ever priced the 24” model? ;)

-- There is nothing in the world more dangerous, than a woodworker who knows how to read a micrometer...

For those that aren’t into fine measurement, Gary K has the right approach. It should go together smoothly and not come apart by gravity alone. This is not always true. Sometimes a tighter or looser fit is useful.

Being one of the measuring type I tell my classes to aim for .003” clearance. this is the thickness of a dollar bill. I think a “C note” might be thicker (All those zeros :-)

-- Phil, Near San Diego, CA

Just be thankful that you weren’t a nuclear engineer. Then you’d be dealing in milimicrons. Or nanobits.

I don;t know how small they are but they are less than 0.00001.

Lee

P.S> 1/64th is usually good enuff for me.

-- No piece is cut too short. It was meant for a smaller project.

Nice thread. I would guess that this thought has crossed all woodworkers at one point or another. What are the right expectations for tolerances, who knows. . . I like some of the comments though. I agree in general that a joint should not require a mallet and should not seperate by gravity. Glue is not a filler, so I aim for the joint to slide together easily and also have enough dry friction to stay that way. There are many tips for different joints. Chamfer tenons for example. Allows for tight joint as well as a place for excess glue to migrate.

Machinist are a tough to please group though. Quite the opposite of construction workers gone fine woodworkers.

-- Jeff, South Carolina

USCJeff: Imagine my friend the carpenter’s frustration with me, when we built my deck. I learned very quickly, not to say “It’s off at least a sixteenth.” I don’t ever want to duck that flyin’ hammer again!

Angst level reduced. Thanks to all!

Can we get started on GD&T standards for wood, next? [insert evil grin here]

-- There is nothing in the world more dangerous, than a woodworker who knows how to read a micrometer...

This is an interesting thread. I think I am glad I was never a machinist.

Well if this kind of reply is an average response to a question at ljs then I know I am going to like it here. (already decided that anyway). You guys rock.

So… Let me put my two cents in…I am finding it a difficult thing because I grew up with a general contractor (my Father) and worked with him for years in res. carpentry. Anyway, I am finding it very difficult in getting things precise enough. We learned to measure once not twice and nail the board down and grab another, and hurry up your getting behind. SO…I am learning to S L O W down and finesse the wood. Still not really delighted with some of my results because I find small imperfections that ruin the final results. So all this talk about 0003 tolerance is still something I’m getting use to. I can imagine that an engineer’s learning curve is smaller than a rough carpenters learning curve. That’s my humble opinion.

-- JJohn

Interesting question.

Yes to all the answers. Go together easily, where you don’t split the wood if you use a mallet to tap the pieces together, and so tight that when gluing, it hangs up before it gets all the way in and it requires a clamp to pull it together.

-- What happens in the workshop stays in the workshop. No wait that doesn't sound right. Karson Southern Delaware karson_morrison@bigfoot.com †

JJohn hit a corollary issue….Are we sometimes too focused on the outcome to enjoy the journey? I have always looked at woodwoking as a journey. Each step along the way is something to be savored and enjoyed. This approach doesn’t work for everyone, but to me it makes the process much more enjoyable. There is a kind of zen side of woodworking that you can tap in on. Wood has it’s own personality. It does what it will do. We can work with it; understand it; appreciate what the wood will share with us…or…we can fight it. Trying to make wood do something that it isn’t suited to do (because of defect, warp, or internal tensions in the wood) is a very frustrating process; not usually sucessful I might add.

Think of resawing a board….You use a bandsaw to “split” or resaw wood into two new thicknessed pieces. Upon completing the cut you open the “book” and see something that has NEVER been seen by human eyes before! This can be a very moving experience. You just have to slow down to notice.

May you find peace and tranquility in your saw dust. May you hands, heart and soul bond with the wood to create something beautiful.

-- Phil, Near San Diego, CA

One must also think about the type of glue that will be used on the joint. The viscosity and holding strength varies. For example, blind tenons, floating tenons, through tenons, and wedge tenons will seat differently depending on the type of wood and sizes one is working with. John

-- Oldworld, Fair Oaks, Ca

I’ve always considered “snug” as having a toasty fire, warm blanket, bottle of wine and the Swedish Bikini Team.

But with woodworking you need to take into account that wood expands and contracts. So if you can get it “prit-near” true, then that will be snug enough.

*Gotta get back to my dreams now! Bye! Oh and nice meetin ya! Have fun here at LumberJocks!

-- Bob Vila would be so proud of you!