How Accurate is Your Work / Project?

[peter halle]

There has been recently a flood of posts referring to the use of feeler gauges and digital calipers for determining the accuracy of work.

I know for a fact that since 1983 I haven't used a feeler gauge for anything other than an automotive situation.  Am I behind the times?  Has wood movement changed to be more stable in the past 30 years?  Am I behind in the times and also techniques?

So my question to all is:  What is the degree of accuracy you expect in your projects?

I expect that this will be a controversial thread if anyone posts.  I will remind ahead of time that is ok to debate but not ok to attack.  Also this is just a thread on an internet forum so please don't take comments personally.

Peter

 

[jacko9]

OK Peter, I'll go first.

I use solid hardwood to build furniture which I buy in the rough sawn state.  I store my lumber in a post and spar lumber rack with spacers between and the ends seal coated.

When I build a project I select the lumber, rough cut it to length and width and run it over my jointer and through my planer to rough dimensions.  I sticker the stock for at least one week (and sometimes more).  I do have precision Starrett (and Woodpeckers) straight edges and squares and since I started my career as a machinist I tend to be continuously watching for wood movement (unlike metal).

While I "sneak up" on the final dimensions and correct as I go I do not expect to be sanding joints after they are glued together.  My rails and stiles and my leg to apron joints fit to the accuracy of the Domino Joiner (and previously my horizontal slot mortiser) which is within a few thousands.  When I cut stock or panels square on my table saw I don't expect to see light across the edge (or I re-calibrate my machines, fences, etc until I get there).  I should mention that when I purchased my Powermatic 66 Table Saw the table I received was concave in the center by more than 0.030" so I rejected it and they sent me a new table that was ground flat to within a few thousands ( I still have that large chunk of cast iron around if anybody wants it).  I have replaced my pipe clamps and bar clamps with Bessey K-Bar up to 60" long and I pay careful attention while gluing up a project correcting as I go.

The biggest use I have for my sanders is the ripple that comes from my Shelix cutter head on my planer and I can't adjust that out.

My older DeWalt miter saw was out of square in the machined casting and while I could have made a bed/fence to get to square I chose to buy a Kapex.

You might notice that I have refrained from using accuracy numbers because I don't have to measure them and (I'm not doing this for a living).

Jack

 

[jmarkflesher]

1/16 or 1/32 or 1/64 is the best I get in my wood projects. But for set up of the machines that cut the wood I strive for .001 inches. Every been hit in the chest with a piece that comes off a table saw with a fence not tuned properly? I just spent 8 hrs on a sled for a table saw to cut picture frame material. I used all wood for the sled. I checked and rechecked all while making it. All within .001 inch. Eight cuts and I still see a paper thin line at the last corner. I try not to use filler. Just my way. MARK

 

[nclemmons]

It depends but I do go for accuracy.  Rough carpentry is at one extreme.  Fine furniture or museum pieces are at the other extreme in terms of precision.  Cabinetry is somewhere in the middle depending on the species and finish.

The chess set that I did was executed to 1/100th of an inch partly because the board was all press fit.  Two night stands I am currently working on are executed to 1/64 of an inch in general but the mortise and tenons are routed to hundredths of an inch for proper fit on small details. 

I frequently will use digital calipers for furniture work - wanting to thickness a piece to consistent size to match others for a glue up or to to route a dado to a consistent width or depth. 

In general, I always push accuracy in the work that I do on furniture and that requires more precision.  If a piece is going to be painted, I think you have a lot more leeway on the precision than if the piece is going to be left natural with an oil or wax finish.  Same for sanding versus hand planing.  You can definitely tell the difference in the surface between the two under a natural finish.  One is more precise, the other is faster.

I can tell a difference in a gap or reveal on a cabinet door or an offset in a leg and a side frame.  And with digital read outs on planers, table saws, drill presses and router tables now, the opportunity for improving accuracy is there.

With accuracy you have to be mindful of wood selection, considerations on expansion / contraction and movement.  Precision won't make up for wood movement.

I also do machining as a hobby, which always is to the 1/100th or even 1/1000th of an inch on some press-fit piece clearances. 

neil

 

[Jason Kehl]

On foundation work we square and level the forms to 1/16" before pouring concrete. After pouring the concrete we accept about 1/8" or so on average over the foundation, there always some slight undualations with concrete.

When framing we work to the 1/16.

For interior finish everything must be tight and crisp looking with no visible gaps. Exterior finish we shoot for the same quality but will accept small spaces, less than 1/16", unless it is an area that will be caulked for weather proofing then 1/8" is easily filled with caulk and often speced by manufacturers anyway.

Cabinetry is tight, feels smooth and looks pretty.

j

 

[roblg3]

I'll go Peter...I was praised for very good and accurate work prior to Festool making it easier for me to do the same level.  I now have better and tighter work to within fractions of a mm (thanks to Festool).  It depends on the wood you have, where it is going to live and how well controlled the final resting spot of the piece goes.  Wood LIVES!  It moves waaaayyy more than fractions of milimeters depending on species, width and the aforementioned reasons.  I just don't bother paying attention to the "machinist" woodworkers.  If you understand how your material will respond based on what I continue to learn from books and experience you'll realize feeler gauges are intended for metalworking and you can save time by not using them in woodworking.

 

[junk731]

Peter good question and personally if anything the quality and characteristics of certain woods is getting worse, more movement allowance needed. I think you should also define a length for accuracy. For instance I try to keep 20 lineal feet of cabinets within an 1/8" to 3/16" overall of the measured distance, no feeler gauge needed. On small tables and furniture pieces cuts are made to be within 1/32" with no gaps when assembled. Doors and inset pieces are made with a consistent 1/8" gap. The only place I get the feeler gauges out is for certain machine setups like jointer outfeed table height to blade height and even that doesn't really need complicated measurement unless there is a problem.

 

[rizzoa13]

I've come to the conclusion that wood is a bullsh*t medium to be working with anyway since it moves so much! Expansion and contraction happens and it's really frustrating when you have a passion for your craft to see the end result change so much. I'm always very impressed to see peoples work stay tight through the seasons and want to bring my finishing and planning skills up to snuff so that I can achieve those kind of results.

Rant off: I don't feel that such extremes in measuring are necessary for the reason you stated, wood moves. On the other hand laying out curves and making things level/ plumb and perfectly parallel are really important. My eye can pick up my slight mistakes in a straight or curved line when free handing so the use of precise techniques and tools for those applications is important to me.

 

[#Tee]

the feeler gauges i use just to get a sense of calibration on specific tooling. i think building is all about covering up your mistakes. rough frame>drywall>taping>mudding>prime>spackle>painting. so for basic furniture joinery if its being pianted .5mm is acceptable to me.

 

[peter halle]

Thank you to the Brave who have posted so far.  This isn't about right or wrong.  Just about helping me understand better - so I can be better as a moderator and also as someone who sells his time as a carpenter.

Peter

 

[charley1968]

I (try to) work to the mm on furniture or interior; to the cm when building something for the garden or house (roof for the porch etc.) But i don't mind adapting my building plan if i cut an 'half inch shy'. [wink]
Digital instruments i use for adjusting or set-up of machinry, mainly router.

 

[Jeffonebuck]

Heavy sixteenths, Light sixteenths, if making furniture I'll cut shy and fit with chisel or plane

 

[jbasen]

As accurate as I can make it [wink]. Here are some examples:

I use a Wixey digital gauge on my table saw.  When I zero the Wixey gauge I rip a piece of wood and double check the cut with a micrometer. If it isn't dead on accurate I start over again and re-zero the fence.

When cutting longer work pieces I have no choice but to use a tape measure.  I trust the accuracy of tape measures about as far as I can throw my table saw. I have a handful of tape measures around my shop. When I'm working on a project I make sure I use the same tape measure throghout the project so the measurements are at least all consistent

When I dimension rough lumber I first run it through my thickness planer.  Then I finish it taking shallow passes with my drum sander, measuring the thickness with a micrometer as I go.

These are some of the things that I can control so I do the best I can to take advantage of that.

When using tools where I can't dial in the accuracy, like jacko9, I also sneak up on cuts. 

To some people all this may seem a little bit crazy. Fortunately, as a hoobyist building A&C furniture I don't have to include time or income in the equation when I'm working on a project. 

No matter how hard I try I still make plenty of mistakes and can point each and every one out in my finished pieces.  All I strive for is that they are small enough that nobody else can notice them

 

[WarnerConstCo.]

Blonde, brown or red    hairs......

Fine to course in that order.

 

[Jesse Cloud]

Good thread Peter.

My answer would be Hopefully, as accurate as it needs to be.

So, for instance, if I am building doors or drawers, on cabinets I want doors to line up at the top and bottom with other drawers.  With Euro hinges, this is for the most part just an adjustment you make once they are all hung.

On fine furniture i want a consistent gap between door/drawer fronts and the carcass they sit in.  So I first cut it for a friction fit, then plane it down to fit my standard shim which is two playing cards.  The drawer is done when I have sets of shims two playing cards thick on all edges.  Never bothered to measure how thick two playing cards are, don't really care.

When setting up machinery or making a jig, which will affect all the cuts made on it in the future, I try to be anal.  Dial indicator to get table saws, jointers, planers to within a thousandth or two.

I like feeler gauges for "sneaking up on a cut"  But not exactly sneaking.  Make a cut on your tablesaw, say and see how it fits.  If the fit is loose, stick feeler gauges in the gap until you find one thats snug, but still comes out easily.  Take that feeler to the saw.  put the feeler on the blade side of the fence, clamp a stick against the fence, then remove the feeler and move the fence against the stick.  Your next cut should be dead on.

For dimensions that don't matter, I don't even measure.  I have no idea how wide my table saw sled is, but I know that its within one thousandth of square.

 

[elfick]

Accurate enough to be strong and look good. If I'm not even that worries about it then I describe my accuracy as "good enough for government work"  [eek] [big grin]

 

[jacko9]

Peter,

As you can see from the responses so far accuracy is in the eyes of the taskmaster; foundation framers, rough carpenters, finish carpenters, cabinet makers, and furniture makers of different task levels, etc. There is no one standard for accuracy unless you talk about task specific job requirements.  For me I just don't care to use a belt sander to even out my furniture projects and most professional contractors don't care to waste their time fiddeling with digital calibers for rough layout work.

Good responses so far with the diversity of work being accomplished.

Jack 

 

[Stephen B]

[size=14pt]Thankyou Peter for raising this.

I too have wondered about the degree of accuracy discussed by some in their posts in other threads.

Accuracy is indeed in the eye of the beholder. I know a builder who will say when looking at a spirit level, "that's fine, a blind man would be pleased to see it". Well actually, no, often he wouldn't!

My context - I am currently restoring (not rebuilding!) a 120 year old house and am near to completion of our main house.

In the older house nothing is level or straight to start with, so for example; new skirting boards have to look rather than be accurately levelled. In the new house I aim for single or near mm accuracy in most tasks ( but do not always achieve it! ).

When machining timber I do check dimensional accuracy with a steel ruler, digital callipers and a high quality square. Depending on the tasks I aim for accuracy in my cutting using a steel ruler, builders ruler, Festool Folding Ruler or tape measure. Occasionally I even get out the family heirloom marking gauges!

The discussion here and at other recent threads is really Festool's fault [eek]. It is a brand that psychologically instills in us an attitude that demands higher quality and skill in our work. Or is it the reverse, that those who strive to improve the quality of their work each time, go out and seek Festool and other high quality tools?

Edit: Some further thoughts.
Is the Leaning Tower of Pissa perfect in level and dimension? No, so what is character vs clinical precision?! Can you have both? Place and context?

 

[rst]

I set up my machinery, tools, and measuring devices to be as accurate as possible.  My machinery and tool set-ups I check with micrometers and machinist squares as I am comfortable using metal working machinery.  I check all my measuring devices against each other to be sure the graduations are the same.  There are already enough variables in materials and processes to throw off results.  After 35 years building and fixing every thing from rough carpentry to aluminum store fronts to automatic entry door systems and plastics fabrication, I have learned that preparation is everything for great results.  I only became aware of Festool in the last two years and now I work in metric as much as imperial.

 

[mouppe]

It depends on the project. If it's inlay work then it has to be very accurate perhaps to a couple of thousands of an inch because you can see and feel any gaps. Glued joinery less so and screw and nailed stuff even less.