Accuracy & Precision in Woodworking

[sehast]

There have been numerous discussions here from time to time concerning accuracy required in woodworking and woodworking tools. I thought I would share this article on that matter. It was written some time ago before a lot of modern tools and aids we now take for granted were in use but I think the focus is still very valid. Its a little bit long but a very worthwhile read.

PreciseWood.pdf

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[dusty]

This is a very good article. Thanks for the post.

I think that it is necessary, however, to distinguish between accuracy when doing alignments and accuracy when doing wood working. I strive for near perfection during alignments but I readily accept accuracy to within 1/64" when doing "fine "wood working. For most tasks 1/32" is good enough.

[Dansmith]

Thanks for sharing. Good read.

[Ed in Tampa]

I believe real accuracy is only achieved after the Wood was processed by a machine.

Machine accuracy should produce results that insure when completed by the machine the wood can be easily fine tuned by hand. That means the cut is not too short or too small of an angle.

To me any machine that produces a cut that can be easily touched up by hand is accurate.

Let me add;
To me a tablesaw, any tablesaw, is a rough cut machine.

[dusty]

Sarcastic, rude and uncalled for comment removed by author.

I came back just to remove this post but a follow-on post had already been made. This eliminates the ability to remove a post completely.

[sehast]

Let me add;
To me a tablesaw, any tablesaw, is a rough cut machine.

Wow, that is quite a statement. Just the kind of discussion I was hoping to promote.

[Gene Howe]

With excellent blades on accurately aligned Shopsmith, rip cuts and cross cuts will easily produce surfaces ready to glue. My jointers are only used to prepare an edge to ride against the fence. Quality tooling, properly used, will produce quality results.

[jsburger]

With excellent blades on accurately aligned Shopsmith, rip cuts and cross cuts will easily produce surfaces ready to glue. My jointers are only used to prepare an edge to ride against the fence. Quality tooling, properly used, will produce quality results.

I agree Gene. I use mostly rough sawn stock. Before I cut anything to width the edge takes a trip to the jointer to make sure it is straight when it is put against the table saw fence.

However if the stock is not too wide for my 6" jointer then the face gets flattened first and then the edge to insure they are 90 degrees.

[Ed in Tampa]

With excellent blades on accurately aligned Shopsmith, rip cuts and cross cuts will easily produce surfaces ready to glue. My jointers are only used to prepare an edge to ride against the fence. Quality tooling, properly used, will produce quality results.

My intent was not to cause anger or to challenge anyone's craftsmanship or suggest I possessed exceptional skill or produced work that exceeded hobbiest skill level. But I do know precision and expert craftsmanship.

That said do not misunderstand what I said. I said a tablesaw produces rough cuts. Can tablesaw produce useable results absolutely. But I contend they probably will not compare equally with a precision hand fitted joint. One where a craftsman used razor sharp knives, chisels and careful use of sandpaper and trial and error fitting.

I use glue ready blades and my results suit me but compared to hand prepared surfaces of a skilled craftsman they are rough. Skilled hand preparation of cuts and joints don't just fit but produce joints that are molded to each other.

Let me also say a Pefectly aligned and setup,machine will only produce the accuracy and percision that the skill of the user has acquired. Jig, hold downs, sleds, etc. will minimize sloppy handling of operator but they will never replace acquired skill.

If this angers anyone please forgive me that was not my intent.

[BuckeyeDennis]

“Rough” and “precise” are both relative terms. Compared to a chainsaw, a tablesaw is quite a precise tool!

In metalworking, people use numerical tolerances to specify the required level of accuracy, both for dimensions and for surface finish. And numbers pretty much take emotion out of the equation.

But even in metalworking, hand finishing may be required in order to achieve the required precision. The ways on many high-end CNC machining centers are still hand scraped, both to get the best fit to the tool slides, and to create the ideal texture for retaining lubricant. Injection molds are still polished by hand to remove the machining scratches.

A bit closer to home, new handplanes and bench chisels need to be hand-fettled to reach their full potential. And of course, that process basically consists of removing imperfections from the machining processes. Even Lie Nielson chisels need their machining cleaned up, by the way ... they are hand-polished at the factory.