Shopsmith Forums

mindpilot wrote: I knew I had passed the point of no return when I had the magnifying glass out so I could see the 1/64ths marks on the ruler.

Your still fine. The point of no return is when you take out the digital caliper to try and measure the distance away from the 1/64th mark while viewing under the magnifying glass.

At the risk of repeating most of what has been said already, I attempt to 'summarize' most of what has been posted.

Precision: Two points of interest:

1) The precision to which the equipment is adjusted/set up.

2) The precision to which work pieces are fabricated.

1 - No one can disagree that the more accurate the equipment is set up, the more likely precision fabrication will result. I think everyone can agree that a reasonable goal is to do it as accurately as one can with the resources at hand and a reasonable amount of effort(fine tweaking within reason). If one has precision measuring instruments it is reasonable for them to utilize them. It is with these devices capable of detecting minute variations that readjusting can become excessive and go beyond the needs of the actual work to be performed.

Penview has demonstrated a simple effective method to check the blade to table and blade to miter gauge using only two pieces of wood. The degree of precision can be increased by increasing the length of those. Within the range of the length of those 'pieces of wood' the procedure is 'good enough'(as accurate as can be done using that procedure).

Just as important(more likely more so) is the ability to perform operations with predictable repeatability.

2 - We know some operations require more precision than others. Those operations requiring more exacting accuracy need to be performed with an understanding of how the methods of handling can adversely affect the final result. One can be less attentive to these issues if the operation being done does not require high accuracy. It is with these operations that 'good enough' becomes more loose. Good enough is an attribute of the task being performed, and is not a measure of sloppiness nor attitude of the 'operator'.

Using precision devices to measure workpieces(wood) is acceptable, if done so with an understanding of the varying nature of the item being measured. Keep in mind that wood can give when an interference fit is encountered. Indeed some joints are better when a small amount of compression takes place when joined. Keep in mind that it will change!

We get carried away with this discussion every time it enters into a thread. As a point of clarification of what I believe I have said:

1) The Mark V needs to be calibrated with great care in order to be safe and effective. I use a dial gauge when doing the miter track to blade adjustments and a Wixey when setting table tilt. I also use a Wixey or a MiterSet when checking the Miter Gauge. I am finding that the new V120 does not need to be checked with an instrument. The V120 protractor is as accurate as I need it to be. Trust it.

Once equipment alignments are completed to the standards that I have adopted for myself (+- .005" and +- .1 degrees) it it time to make sawdust.

2) I now trust my set up. I cut work pieces with the care demanded by what I am attempting to put together. If you are making butt joints, close enough is probably good enough. If you are putting something together using dovetails, you probably want to be extra careful.

A box to throw my cut offs in is not important to me. The jewelry box that I am making for Grandma needs to be dead on. I will likely revert back to calipers on it. I used a Stanley tape measure on the box for cut offs.

When ripping and cross cutting for both of these projects I simply rely on the equipment settings that I have made. The intended precision level being .005" and .1 degrees.

Footnote: I have developed some short cut procedures that have been discussed here that allow me to do these set ups without the calipers and dial indicators but while they work, they are not my primary.

I'm blessed to have a neighbor that is renowned upholster. From time to time he get old pieces to redo. When a piece is couple hundred years old he usually calls me over to examine it. These are usually true quality pieces and people use my neighbor because they know he will maintain the integrity of the piece by using age old upholstery methods to redo their piece. He still often uses horse hair and old jude and uses old methods like hand tied springs.

In any case I love to see the craftsmenship that goes into these pieces, remember to get this far the piece has survived 200 or more years of use.

What I find is few dove tails but of the ones that are there most are flush only on the display surface. On the back side you can slip a piece of paper anywhere in the joint. Mortise and Tendon joints are far more common as is glued paper insert to make the joint tight. Many are pegged which drives my neighbor crazy because at times he must separate the joint.

He did one couch 200+years old that had gone through two floods, at least two separate high water marks. It was made of walnut and the hand carving was excellent. But the behind the scenes work was shocking. Now remember it has survived 200+ years of use so don't think the craftsman was sloppy, he wasn't he just knew what had to be close and what didn't and he made everything close enough.

JPG40504 wrote:No one can disagree that the more accurate the equipment is set up, the more likely precision fabrication will result.

Oh yes I can! As a geeky test lab engineer I'm pretty well versed in things like accuracy and precision. They are NOT the same thing.

Lets do some target shooting with a gun to clarify what I mean.

We take gun #1 and shoot 10 rounds through it. It groups a nice tight pattern. But it's way off to the left of the target bulls-eye. This gun is not accurate, it misses the target. But, it is precise. It kept those misses extremely tightly grouped.

Now we'll take gun #2 and shoot 10 rounds through it. The shots are all over the target paper, but they are beautifully centered around the bulls-eye. This gun is not precise at all. But it is accurate. The shot group is perfectly centered on the bulls-eye.



Start to see the difference?

By no means is an accurate but sloppy saw going to give precise cuts.

foxtrapper wrote:Oh yes I can! As a geeky test lab engineer I'm pretty well versed in things like accuracy and precision. They are NOT the same thing.

Lets do some target shooting with a gun to clarify what I mean.

We take gun #1 and shoot 10 rounds through it. It groups a nice tight pattern. But it's way off to the left of the target bulls-eye. This gun is not accurate, it misses the target. But, it is precise. It kept those misses extremely tightly grouped.

Now we'll take gun #2 and shoot 10 rounds through it. The shots are all over the target paper, but they are beautifully centered around the bulls-eye. This gun is not precise at all. But it is accurate. The shot group is perfectly centered on the bulls-eye.



Start to see the difference?

By no means is an accurate but sloppy saw going to give precise cuts.

I agree withj your accuracy/precision difference and analogy. However the analogy is being applied to the same 'operation'(firing at a target including sloppy aiming[or whatever causes the splatter]).

I was referring to the accuracy of setting up the saw and precision of cuts made with it. I also used the word 'likely'. Likely in the context that without an accurate setup, precision cuts are 'unlikely'.(indeed more 'likely' impossible)

FWIW I consider a 'sloppy' saw to be impossible to set up accurately.

Another interesting word that has some relevance is 'resolution', a close relative of 'precision'. A digital measuring device may have 4 digit resolution, but if its accuracy is only within 1% than the fourth digit of 'resolution' is worthless.

The v120 has a 'resolution' equal to the notch spacing(ignoring vernier). Fortunately they are machined precisely so that the vernier does provide additional 'resolution' with accuracy. If however the pivot becomes worn(sloppy) it cannot(not likely) yield accurate angle cuts. Proper use of the 'sloppy' device may yield accuracy if operator takes action to minimize the effects of the sloppiness. i.e. A machinist always advances a cutting tool by adjusting the lead screw the same direction.(this removes the effect of the slop in the threads[backlash]).

Beauty is in the eyes of the beholder just as precision is in the hands of the craftsman.

Precision and accuracy have different interpretations by both the scientific world vs. the general public. In a woodworking forum, assume them BOTH to mean the same thing.....how well you hit the "bulls-eye". Look up the technical definition vs. a public definition and you'll see what I mean.

This subject will always be up for debate. The way each of us use the tools in our shops is a personal matter. Some like to fine tune, some like to build fixtures and some like to build new projects and test ones skills, to each his own.

A fine tuned machine does not make the operator a craftsman, and a craftsman does not need a fine tuned machine.

efmaron wrote:This subject will always be up for debate. The way each of us use the tools in our shops is a personal matter. Some like to fine tune, some like to build fixtures and some like to build new projects and test ones skills, to each his own.

A fine tuned machine does not make the operator a craftsman, and a craftsman does not need a fine tuned machine.

Oops, a craftsman I shall never be
for to me
a fine tuned machine is a necessity.!

efmaron wrote:This subject will always be up for debate. The way each of us use the tools in our shops is a personal matter. Some like to fine tune, some like to build fixtures and some like to build new projects and test ones skills, to each his own.

A fine tuned machine does not make the operator a craftsman, and a craftsman does not need a fine tuned machine.

An old school friend of mine became a steady customer in our shoe repair shop. One day he got to talking about a shoe shop his grandfather had owned when he was growing up. He had spent a lot of time with his grandfather in the shop and at one time wanted to own a shop of his own but he told me that he just could not master the work. Almost everything in rebuilding a pair of boots or shoes is free-hand work. Pretty much all eye-hand coordination. He said that he just could not make the heels come out round and smooth and he couldn't make the heel on one shoe come out looking like the heel of its mate. While he was (and is) a "very" successful businessman he often made friendly expressions of envy about what I could do with his high priced shoes. He has always wished that he could have mastered the art.
Like most things including woodworking, shoemakers fall into about 4 general categories. There are some that are truly remarkable to a spooky level. Some are quite good. Some are functional but not very polished in their daily work. Then there some that should just close the door and go home. The last ones hurt everybody in the occupation... That also applies to woodworkers that are in it to sell stuff to the public.
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There is room for everybody in woodworking as a hobby and we all work differently. My personal choice is to be more of an artisan instead of a technician. As much as I love the machinery and its speed (especially Shopsmiths) in many cases I tend to look at them as something to get me quickly past the rough cut stage and ready for my hand tools to do the finish work.
I don't do huge amounts of lathe work but I think one reason it is so popular is that it is one place where the machine still allows the artisan to be in near complete control of his craftsmanship.