Precision Tools in Woodworking

[Jonathan McCullough]

I generally try to avoid reliance on tight measurements in woodworking, preferring instead to try to match pieces (joints, dadoes) with each other rather than to measurements. I'd like to suggest that the precision of our innate senses are well suited to the precision required of wood working; we are surprisingly accurate when it comes to sensing whether something is level or plumb, parallel or canted, symmetrical or lopsided, and our eyes and hands can sense whether something is fit tight or needs adjustment. Working in metal on moving parts to tight tolerances is admittedly beyond my ability--and probably most peoples' abilities--to do without confirmation of a dial test indicator or those ubiquitous, handy digital calipers. One of the inane things I've seen is the calculation of plane shavings as opposed to the observing the finished surface of the work; No one would think to measure the swarf from a machinist's file. Or feeler gauges to test the flatness on a smoother's sole--a plane either accomplishes the desired result or it doesn't. But one use of precision tools I've seen that actually appears to make a lot of sense is Kevin Drake's incredibly clever use of feeler gauges to offset a dovetail marker for the kerf of a dovetail saw. He demonstrates this in a video available from Glen-Drake Toolworks, where the dovetails he makes pop right in off the saw with no gaps and no pounding. You don't need feeler gauges to do competent dovetail work, but I find that his process, technique, and results are admirable.

[Mark Roderick]

Excellent thread, thank you Stanley.

Woodworking is much easier, especially for the beginner, if your tools are flat and square. So you need a way to check that they're flat and square.

As you do more woodworking, you learn that you don't need any tools to check for flat and square. You can make your own devices - I won't call them tools. To check that an edge is square you can measure the diagonals, etc. To obtain two very straight edges lay them edge to edge and then reverse ends, etc. Given all these devices that can be made in anybody's shop, nobody ever really needs to buy the high-quality tools Stanley is talking about.

The tools that Stanley is talking about are merely shortcuts for those devices. Fine tools have their own aesthetic, more appealing to some than to others. And if you're going to use such tools, of course you want them to be as accurate as possible.

Objectively, Stanley's tolerances are "too high." But there's probably some engineer out there who thinks they are "too low," as a result of an unhappy childhood or something. Doesn't really matter. We all agree that Stanley's tolerances are at least "high enough."

The only thing I'd quarrel with is the assertion that anybody works to within tolerances of a thousandth of an inch. No woodworker works to that tolerance when laying out a cut, if only becuase there is no device capable of measuring that tolerance. I believe all that is meant is that when I am edge-jointing a board to achieve a tight fit I take plane shavings that are a thousandth of an inch thick. But that is totally different in my kind than asserting that I work within a thousandth of an inch "tolerance," which to me implies a measurement of some kind.

[M Manlove]

Gentlemen, Please
I am one of the older folk. I am 66 and a retired postal manager. I've been working wood and pounding metal for over 50 years. We cannot read a response to a post and see the facial expression or body posture of the writer. Those have been throughout history a large part of communication. I see many things here on the creek that I question or just plain don't agree with. However, we are forced to understand the writer based only on what is written. We don't all write as well as we should. We certainly don't all read and interpret as well as we should. We will never all agree on anything, but we need not rise to the level of criticism we sometimes do. Many years ago one of my first jobs was working for an old farmer. I was amazed at his patience with me as I learned the job. He finally told me that he sat down at the end of every day to make sure that he had spent as much time improving himself as he did being critical of others. I think about that often. Obviously I don't do it well or I would be really good at more things than I am. If we all did it we would have legions of masters and that would lead to more confusion. I simply find it a good reminder to stop whenever there is a possibility that I don't understand some one or may have misunderstood them. I respect and admire you all. Keep writing. Be nice.

[Mel Fulks]

Good point from an expert. No better place to learn patience than the post office.

[george wilson]

Mel,was that a joke?

[Mel Fulks]

Would I joke about something like that ? I understand they are in trouble financially and have made some suggestions to help. They could rent out little cubicles to those in line ,so that their families could visit them while they're "away".

[David Weaver]

excellent

[Stanley Covington]

Dale,I trust OLD Starrett stuff. And then,I still check them against my known standards,like my granite squares,granite straight edge,or granite surface plate.

Now that is the attitude of a serious professional worth emulating. The cap is doffed once again.

Stan

[Patrick McCarthy]

Stanley, having now read all 173 responses, I can say I have enjoyed the discussion. I have been surprised by some of the assumptions others made about what your original post meant, but overall a thoughtful discussion.

My take-away: I think it is important FOR ME to get better reference tools to check my standard working tools to make sure they are as accurate as I hope them to be.

Thank you for starting the discussion and fielding the responses. Patrick

[Stanley Covington]

Patrick:

Thank you for wading through it all. Your kind words have made it all worth while for me.

Stan

[george wilson]

Thank you,Stanley. I had bought a brand new Starrett USA made dial caliper. This was before they went Chinese. To make the story short,I found out the inside measuring jaw was .008" off. Messed up a job due to it. I had been using my Mitutoyo calipers instead,I suppose. Anyway,I sent it back to Starrett for repair. It came back with the repair woman's tag,only out .004" this time!! I got hold of a VP somehow,and he had me return the caliper for a new one. HOW this caliper was STILL off .004" after special attention"By one of their best technicians" was never explained. I should have just fixed it myself and saved the waiting and aggravation.

So,no,I never trust any new product. I test it,and prefer OLD Starrett stuff. When I was in college,back in the good old days when we made fine machinery,a student kept getting a thin gear tooth when he cut the last tooth on a gear. He did this a few times. The teacher examined the Brown and Sharpe index plate. It had the wrong number stamped on the circle of holes the student was using. B&S was one of the very best brands.

Like in the X files,TRUST NO ONE!!

[Ed Looney]

George

I like a phrase Ronald Reagan used with the Russians. "Trust but verify". As Stanley has steadfastly pointed out it makes sense to have standards used only for verification of one's measurement and layout tools.


Ed

[george wilson]

Machine shops with decent standards regularly have their instruments re certified. I have used measuring equipment that has the re certification tag still pasted on.

Shops that have 9000 series manufacturing standards get their tools checked. Now,9000 series doesn't mean a THING!!! It only means that the shop has established precision standards which every product must pass. HOWEVER,what those standards ARE may not be that precise. You will see Grizzly and other catalogs mention:"Made in a 90XX series shop". Take it with a grain of salt!! My NASA machine shop manager friend told me what the 9000 series means,and it may not mean much,but sounds impressive.

Besides,anything made in China is perfectly capable of being a dud,whereas its other "brothers" may be o.k.. Quality control over there is still very iffy. Look at the poison baby formula,for example. I don't think the manufacturer meant to make a shoddy product,but some supplier likely sold him contaminated ingredients(this is an assumption on my part),but the guy committed suicide over it,which makes me think he was sorry.(Or maybe afraid of Chinese prisons).

[Bruce Haugen]

Shops that have 9000 series manufacturing standards get their tools checked. Now,9000 series doesn't mean a THING!!! It only means that the shop has established precision standards which every product must pass. HOWEVER,what those standards ARE may not be that precise. You will see Grizzly and other catalogs mention:"Made in a 90XX series shop". Take it with a grain of salt!! My NASA machine shop manager friend told me what the 9000 series means,and it may not mean much,but sounds impressive.

I have a friend who used to work in an ISO 9000 certified company, say 20 years ago. (This company made products that are used world-wide, and everyone on this site would recognize the name.) When the certification team was brought through, they always went to one process machinist who rigorously adhered to the standard. The company always passed inspection. Not one other machinist in the company followed those standards. So much for standards. They only work if everyone follows them.

[Stanley Covington]

Shops that have 9000 series manufacturing standards get their tools checked. Now,9000 series doesn't mean a THING!!! It only means that the shop has established precision standards which every product must pass. HOWEVER,what those standards ARE may not be that precise. You will see Grizzly and other catalogs mention:"Made in a 90XX series shop". Take it with a grain of salt!! My NASA machine shop manager friend told me what the 9000 series means,and it may not mean much,but sounds impressive.

Besides,anything made in China is perfectly capable of being a dud,whereas its other "brothers" may be o.k.. Quality control over there is still very iffy. Look at the poison baby formula,for example. I don't think the manufacturer meant to make a shoddy product,but some supplier likely sold him contaminated ingredients(this is an assumption on my part),but the guy committed suicide over it,which makes me think he was sorry.(Or maybe afraid of Chinese prisons).

There was a time when Plain Jane ISO9000 meant something. But not now. I succeeded in obtaining ISO9000 certification for a company simply by writing documentation, but I know the procedures required in the docs were never implemented. That said, at the level of horsepower of the construction industry where I am employed (my current employer has 9000+ employees and does US$15 -16 Billion in sales annually) there are ISO certifications that are meaningful, so I will not condemn them in general.

There was a time when I was in charge of having products made in China. A few interesting things I learned.

1. A Taiwanese owned/managed factory in mainland China is far far superior to a Chinese-owned factory (Japanese factories did not make the product we required).

2. While there are responsible and conscientious mainland Chinese people in charge of quality control and inspection at many factories in China, the probability is high that the trained QC person you approved last month will probably not be overseeing the QC for your product next year.

3. If quality is important to you at all, you must hire your own man in China or Hong Kong or Taiwan to oversea QC compliance. Another option is to hire a certified inspection company, but this can get pricey and they are not as effective at motivating the factory.

One scenario goes like this: The QC guy you interviewed and approved at the mainland China factory does good work for 14 months. Product quality is acceptable in light of the low price. In month 15, he leaves the factory to go work for Uncle Hwa, and is replaced by a teenage girl from the countryside. She likes the big city, but misses her Mom and cousins. Her job, as explained to her, will be to ensure the labeling is attached properly and serial numbers are entered into the product verification log, occasionally. Magnaflux testing? What's that? Dimension confirmation? "Yea, use those jigs over there, close is good enough," her manager tells her.

The factory you contracted with to manufacture the product, after serious value-engineering efforts, will receive three shipments of materials from the supplier you approved, enough to keep production going for 18 months. But for the fourth shipment, the supplier sends defective materials, and splits the cost difference with the shipping manager at the factory you contracted with. The shipping manager resigns, returns to Fujian Province, builds a new house, and every day enjoys a nice bottle of beer kept cool in his new Toshiba-knock-off refrigerator. Trusting the designs and specs you created, and the QC procedures you have agreed upon in writing with the Owners of the factory, you will not realize the product that just arrived at the port of Long Beach or Yokohama is dangerous garbage for some time.

Three months later, after the initial customer complaints, you were successful in snatching back the defective product already shipped prior to any deaths or lawsuits. Sadly, the two customers that realized the product was defective swear they will never buy your product again. But after the defect is corrected, your company's (still-high-for-now) name value, combined with the 37% lower price of your Chinese-made product brings them back for more. Greed and short-term memory solves all.

Because Murphy is in his heaven, an end-user buys one of the defective products that reached market before you could grab it back. He complains to the retailer that sold it to him, and the retailer exchanges it for one made from materials compliant with the approved specs. Out of the 3,000 defective products sold to end-users, 30 are returned within the warranty period as defective. While the whole episode has been embarrassing, the company has not only retained all its customers, but gained a few more in the DIY market. Profits have increased steadily over the last two years, and in perspective, 1% warranty loss is less than the "shrinkage" that walks off the loading dock in the same time period. Tee time is 4:15, Big Bertha is awaitin, and its your turn to buy the first round of drinks at the clubhouse.