How Accurate is Your Work / Project?

[Stone Message]

I think that this is an interesting subject. We are machining wood, not metal, and wood not only changes shape and size (mostly when not wanted or expected) but it is very forgiving and allows a lot of adjustment during final assembly.

I try and work to 0.1 mm most of the time. Not because I expect everything to end up that close but because I want to avoid compound errors. In reality that means that at best I am within 0.4 mm on average and a bit of framing (or whatever) then ends up less than 0.5 - 0.6 mm out.

Now let me put those figures into perspective...

Router depth is measured to 0.1 mm but operator error and other factors will make this at best 0.2 mm.

Router positional accuracy (measured from an edge) is probably no better than 0.25 mm most of the time.

Kapex cut-off (I use an Incra Flip fence setup) is within 0.2 mm but again, rushing/operator error can make this 0.3 mm.

Domino accuracy (I use a pencil line most of the time) is at best 0.4 mm.

Planer (thicknesser) is calibrated to 0.1 mm and accurate to just under 0.15 mm but often better.

The key is to try to get as accurate as you can to reduce the overall error. Measuring diagonals is a good thing to do to check for square. Using an engineer's square is also good. Apart from the super Incra and Woodpeckers squares there are few run of the mill woodworker's squares that are worth the money.

At glue-up Domino joints are very forgiving (or rather the wood is forgiving) and a good knock in the right place can work wonders to achieve square.

Since I moved to Festool, started to use the Incra Precision rule and Flip Fence and stopped using normal woodworking squares (using the engineer's squares instead) I rarely have any issues at glue-up.

The other really useful thing to do is to use a drawing program to ensure that the designs are spot on and the dimensions are correctly calculated.

But the bottom line is the wood itself. It is a wonderful material, just like dear old Dad, it is very forgiving but you have to treat it with the utmost respect. Buy your wood sawn and in as close a thickness to what you want. When you rip it look out for movement and if it is important leave the wood for a week after ripping before planning and final thicknessing.

I hope this helps.

Peter

(corrected a spelling mistake - there may still be others)

 

[roblg3]

3 gem responses in a row! [big grin]  Were all of these good gentlemen from GB?? 

 

[windmill man]

I try and work to 0.1 mm most of the time. Not because I expect everything to end up that close but because I want to avoid compound errors. In reality that means that at best I am within 0.4 mm on average and a bit of framing (or whatever) then ends up less than 0.5 - 0.6 mm out.

So you are making a kitchen base cabinet or a chest of drawers  around the 1 m wide mark.

You got a set of vernier calliper that size to measure that accuracy  Drivel

 

[JayStPeter]

There's a lot of "wood moves so how accurate do you need to be?" responses and some "cave man build with rock and still working" type responses.  Feeler gauges are pretty lightly represented  [big grin].  I will admit to being a little bit of an accuracy geek.  I just like when things come together right.

I think the overall theme of what I've read is efficiency though.  What level of accuracy gives you the results you desire in the quickest way.

I have some beautiful antique furniture.  In all cases, the drawers of those cases are fitted to a specific slot.  Even though the drawers appear to be the same size, they are not.  This isn't a bad thing necessarily, but it is a statement on the accuracy of the original builder.  I also have a couple of Ikea pieces around where CNC accuracy means any drawer fits any slot.  If they look the same, they are.  Not a statement of love for those pieces in the least, but something I think is actually superior to the older stuff.

I strive to create things that are as beautiful as the antiques, while also being more accurate.  Those original builders didn't have machines they could adjust with feeler gauges, Incra, and Woodpeck ... I do.  I don't always achieve the accuracy I desire and will err on the side of making sure it looks and functions well.  My drawers usually require some fitting due to compound errors that Peter did a fantastic job of describing.  But, I learn something each time and my drawers require less fitting each project.  I have to decide when that translates to efficiency.  Fitting can sometimes go quicker than trying to achieve the accuracy I desire and sometimes less fitting saves time.

A lot of posts on woodworking forums are from people who have found the "best way" to do something.  Ultimately I like to see how others build things.  Both "feeler gauge guy" and "cave man build with rock guy" can inspire me to try something different.  Keeps this whole thing interesting.

 

[Gary in Texas]

Peter,

This question will obviously get a lot of varied responses, based solely on the type of work a person does.  General construction would be at the bottom of the scale for accuracy.  Moving up the scale, cabinet construction would be the middle ground.  Finally, making furniture, unique boxes, etc...will typically be the most precise, this simply due to the nature of the beast....and the persons capability along with his/her equipment.

I haven't seen any threads wherein people are measuring their projects to the ummphh degree, or with feeler gauges, etc.  I have seen a number of posts, particularly with regard to the Kapex, where people are going to the extreme using feeler gauges to determine if the saw has a level surface and so on.

As some others have mentioned here, I too set up my equipment to function as accurately as it can, within its limits/specs. Yes, I pull out the micrometer and ensure the blade is parellel to the miter slot on my cabinet saw, and the fence is set up as perfect as can be expected.  As such, I can produce accurate cuts, but no, I will not go to the extreme of trying to ensure the side of a box is accurate down to .001...  What is crucial is that all both sides of my box for example, are equal in length, same applies to the box ends.  In that regard, you really don't need to measure at all, as long as you can ensure the parts are cut equally for proper make up....

 

[tbellemare]

What is crucial is that all both sides of my box for example, are equal in length, same applies to the box ends.  In that regard, you really don't need to measure at all, as long as you can ensure the parts are cut equally for proper make up....

Bingo, Baremeg!

Process is as important as, or more important than, equipment.

With excellent process and approach, stellar results can be achieved. With fantastic equipment, stellar results can be achieved some times.

To achieve stellar results efficiently and consistently, process and equipment are key.

Tom

 

[Tinker]

What is crucial is that all both sides of my box for example, are equal in length, same applies to the box ends.  In that regard, you really don't need to measure at all, as long as you can ensure the parts are cut equally for proper make up....

Bingo, Baremeg!

Process is as important as, or more important than, equipment.

With excellent process and approach, stellar results can be achieved. With fantastic equipment, stellar results can be achieved some times.

To achieve stellar results efficiently and consistently, process and equipment are key.

Tom

Tom, a great observation and better reply.
Tinker

 

[roblg3]

I may be hogging this thread, but oh well.  I remember being told by a famous and very successful cabinetmaker " that I'll take consistency over accuracy all day everyday!"  That's what I shoot for more than anything.

 

[tigger]

I like to keep my life and job simple. I always work as accurately as possible, regardless of what I'm building. The repetition of this practice has allowed me to work faster with accuracy over the years.
I have only one standard. The best of my ability.
Festool helps me achieve that because the tools are so accurate in what they were designed to do. It is the sole reason I started using Festool in the first place.

 

[jacko9]

Good reply tigger.

 

[tigger]

Good reply tigger.

Thanks  [big grin]

 

[Brent Taylor]

Architect draws it to a 64th, blue prints are good to 32, the first rain changes it to 16th, you mark it with a pencil that's an 1/8" thich and cut it with a chain saw. Can't get any closer ;D. But for real 1/2 a mil, until the temp or humidity changes, it's wood, not metal.

 

[jacko9]

Architect draws it to a 64th, blue prints are good to 32, the first rain changes it to 16th, you mark it with a pencil that's an 1/8" thich and cut it with a chain saw. Can't get any closer ;D. But for real 1/2 a mil, until the temp or humidity changes, it's wood, not metal.

Good for concrete forms!

Jack

 

[sancho57]

Ok, I know I'm going to get some of you guys jumping out of your skin like a Dilbert cartoon.
To me, accuracy is a illusion or perception.

As long as it's square and functional to its means it's good enough for me. For example, I've been building tool racks w/ bread cubbies lately. Does the bread or the paper towel roll know I'm 5 mm-15 mm short of longer then the desired dim? As long as the bread and paper towel fit and its square it's all good.

On a discussion here once about how accurate are the parallel guides, I mentioned that I can rip a cut a that will be out 1-1.5 mm over the length of a 2438 (8 FT) sheet of ply.

One guy went nuts saying how inaccurate it was. I let him rant rant. As I always do. 
However I'd like to see him or anyone rip me some ply 2438 mm long that was out only 1.5 mm that accurate then that without using  a $30K sliding  panel saw.
So as I said, it's a illusion or perception.

 

[Tinker]

As I have often mentioned, my HS shop teacher used to say, "There ain't no such thing as guddenuf, its gotta be purfic."  At other end of the spectrum, my algebra teacher said "There is no such thing as a straight line.  We can only see a representation of a straight line." I am still in a place with my own skills where, 'if it fits, I'm happy.'  My fits are improving.  The less work it takes to make it fit, it seems the better it fits.  In days gone by, I used to marvel at some of my mentors, as well as competitors, at how well they could put stonework together.  It seemed the better the workmanship, the faster it had gone together.  there were some masons who were extremely quick to arrive at the finished project.  They were not fast because they were sloppy.  They were fast because they could size up each stone and with minimum of hammering, chiseling or whatever they had to do, they were able to work with complete accuracy.  They knew that each stone would fit perfectly before they put it into place. 

I had a young man working for me who was getting pretty good at brick, block and concrete.  He was getting better and better, until we would get onto a stone job.  He would try to fit a stone into a specific spot.  I would tell him it did not fit.  He would go for another stone, work on it for awhile and place.  It still did not fit just right in some way.  He would try another stone with same end problem.  I would finally go to the pile of stones on the ground, pick one up immediately, tap on it to maybe knock of a tiny knob or to just change the shape minutely and place into the wall.  My friend would blow up and go storming off into the woods to cool down and come back in 10 or 15 minutes and go back to work.  As time went on, he did get better. He could fit a stone to near perfection.  He was getting faster.  His work showed he was getting faster. It showed his speed in its perfection.

I think I am slowly finding that out with woodworking.  My work is getting a little faster.  Partly because i am getting better with this accuracy thing.  So far, it is "guddenuf".  Some day, it might get to be "purfic". 
Tinker

 

[tigger]

Ok, I know I'm going to get some of you guys jumping out of your skin like a Dilbert cartoon.
To me, accuracy is a illusion or perception.

As long as it's square and functional to its means it's good enough for me. For example, I've been building tool racks w/ bread cubbies lately. Does the bread or the paper towel roll know I'm 5 mm-15 mm short of longer then the desired dim? As long as the bread and paper towel fit and its square it's all good.

On a discussion here once about how accurate are the parallel guides, I mentioned that I can rip a cut a that will be out 1-1.5 mm over the length of a 2438 (8 FT) sheet of ply.

One guy went nuts saying how inaccurate it was. I let him rant rant. As I always do. 
However I'd like to see him or anyone rip me some ply 2438 mm long that was out only 1.5 mm that accurate then that without using  a $30K sliding  panel saw.
So as I said, it's a illusion or perception.

Well I suppose you could be right about the perception part if you a refering to a paper towel. Working accurately generally means a better finished product. Joins are a good example. If you are accurate with your mitre cuts then the overall "look" is professional and pleasing to the eye and makes for square joins, so practical too.
I do however get what you're saying. But to say it is an illusion is, in my opinion, too broad a brush stroke.

Am I making any sense ?  [huh]

 

[Stone Message]

Now this is a nice mitre - but not my work. It was constructed by Steve Applin using my pedestal desk plans and is far superior to anything that I have ever made.

[attachimg=1]

Peter

Edited to include the maker's name  [smile]

 

[charley1968]

Why? Mine look all like this... [wink]

 

[Paul G]

Ok, I know I'm going to get some of you guys jumping out of your skin like a Dilbert cartoon.
To me, accuracy is a illusion or perception.

As long as it's square and functional to its means it's good enough for me. For example, I've been building tool racks w/ bread cubbies lately. Does the bread or the paper towel roll know I'm 5 mm-15 mm short of longer then the desired dim? As long as the bread and paper towel fit and its square it's all good.

On a discussion here once about how accurate are the parallel guides, I mentioned that I can rip a cut a that will be out 1-1.5 mm over the length of a 2438 (8 FT) sheet of ply.

One guy went nuts saying how inaccurate it was. I let him rant rant. As I always do. 
However I'd like to see him or anyone rip me some ply 2438 mm long that was out only 1.5 mm that accurate then that without using  a $30K sliding  panel saw.
So as I said, it's a illusion or perception.

IIRC I was that guy, and the illusion here is your recollection LOL. Speaking in inches you're saying being out about 1/16" over 8' is acceptable to you and of course you are completely entitled to your own QC standards. However I had to meet the QC standards of my boss, the owner of the cabinet making business, and any employee would have been fired if our work was that inconsistent. Not a rant, just reality. The main shop tools used were jointer, planer, and plain old large heavy cabinet saws with large feed tables and long fences. The only saw that slid was the radial arm saw. So while your bread may not care how accurate something is, my boss and more importantly his customers cared a great deal.

BTW, are you missing some decimals when saying "Does the bread or the paper towel roll know I'm 5 mm-15 mm short ..."?

 

[sancho57]

Nope no decimals. I add in enough to en sure if im off that much the roll would still fit. No worries.