Rip measurements

[Al Sherred]

After ripping a board ,and measuring the width along the length what is an acceptable amount of deviation on the deminsion?

[Peter Aeschliman]

Al,

The answer to your question depends on the intended use of the workpiece. If it will be used for a piece that will be part of intricate joinery, then your tolerance will be different than if it's a solid table top that will be attached with table top fasteners, or trued up after glue-up.

Sorry I'm sure that doesn't help, but we need to know more about your application.

[Al Sherred]

Thanks for the reply. I ask this question because I just went through all the alignment checks, miter slot to blade, blade to fence, and so forth, and I had to adjust my miter slot to the blade, and then the fence to blade. I guess I want to know if .007 in is acceptable after measuring both ends of a ripped board.

[Carl Carew]

I am going to guess that the ripped board must be at least 4 inches wide, and I am assuming you have a good micrometer to make the measurement. That said an difference of .007 could just as soon be mostly measurement error take your plane and plane a couple of fine shavings and measure them, just for perspective. I think you can pat yourself on the back and say you have that saw as good as you will ever need it and go have a beer. Good job

[Wade Lippman]

I've never measured anything I have ripped, but if it came out better than .007" I would be shocked. It will probably move 10 times that during the year.

[Al Sherred]

I measured with a digital caliper. It must be good enough ,it sure seemed to go through the blade very nicely. Thanks for the replies.

[Jebediah Eckert]

After reading this I had to go to the saw and make a test cut and see where I'm at. I couldn't find the .007 on my tape measure so It's going to have to be good enough. :D

[Steve Baumgartner]

Oh come on! It's right there next to the .006! :eek:

[Mort Stevens]

For furniture building 1/16" deviation over 48" length. For home building 1" over 25'.

I know a lot of guys here like to get out the micrometer and boast something like 0.003", but I've yet had the need to measure a piece of wood with metalworking tools.

[Mike Cozad]

For furniture building 1/16" deviation over 48" length. For home building 1" over 25'.

Whoa there.... The builder of my home would argue that rule of thumb.... 1" over 4' is the standard here in Perrysburg, OH....:D

[Brian Hale]

Just for fun, cut a piece 6" or wider and measure it. Then let it sit for a few days and measure it again and see how much it changes.

[Brian W Smith]

Obviously depends on your project requirements.Throw 10 or so,.007 "taper'd" pcs of stock together so that all the wide ends are oriented the same and you have .07".Still not a big deal to some folks.

But reason for post was a suggestion;if you've taken the time(and it appears you have)to dial in your saw........give it a little time.Check your "taper" after running some footage through the setup,say after a cpl hundred feet.And consider the stock....ply vs hdwd...softwood...grain...yadayada.Further,look at the finish of the cut,"off the blade".

Here,I'd say .010 in ten feet would start to get my attention on a nice pce of hdwd and a good blade setup.

[Roger Pozzi]

It depends on the length of your board. .007 in 12" compared to .007 in 60" makes quite a difference.

[Justin Ludwig]

Did you feed the board perfectly? Does your table saw blade "run-out" at fast feed rates? Did the stock have a perfect jointed face to begin with? Is there a gnome in the cabinet of your table saw?

With all things being equal and perfect, no, I wouldn't like .007 difference. I rip my stock an 1/8" fat, plane it to desired width/thickness, then drum sand to near perfection. This is for face frame parts, glue-ups, and door material.

Only be as picky as what you're building needs you to be. Over-stressing things takes the joy out of building - unless you're an engineer.

[Jim Andrew]

In my career of building homes, I ran across these highly recommended framers, with the crappy tolerances. 1" in 25' was probably right, because all 4 corners were out of plumb. So I just quit hiring those losers and framed my own homes. I could get all 4 corners plumb. Sure makes the rest of the job easier.

[Jim Dwight]

It doesn't always take time for wood to move. When you saw one piece off another piece you may relieve tension in the pieces and get some movement - potentially a lot of movement. So a variation doesn't have to be the cutting technique or saw setup. It is inherent in wood. So when we use it in a situation where we need good fit-up, we have to be careful and plan ahead.

0.07 is a little over 1/16. I try for a little better than that and would be concerned if I was off that much and it was me. But on a long board, I would expect it to stay stable within 1/16th. I try for less than 1/32 variation in my cuts. When I need better than that, I use stops and creep up on the desired dimension.

That is for furniture/cabinet construction. If I'm doing a little rough framing, 1/4 inch is OK but I try for 1/8th. If I'm hanging drywall, 1/4 is OK but I like it if I do a little better.

[Jay Jolliffe]

The OP posted .007 not .07.....Big difference...

[Art Mann]

I think some folks need to read the original post more carefully. The OP is talking about rip width, not cut off length. He is seeing the 0.007" variation in the width. I have done exactly what the OP did many times and if I get a width as close as 0.007" across the whole length, it is very unusual. To get that kind of accuracy, you need machine tools, not woodworking tools. On the other hand, some people have mentioned that 0.070" is also good enough. I don't agree with that. That is more than 1/16" of inconsistency and I can't accept that. If that were the error between sides of a keepsake box, I would have to recut the part or sand/plane both pieces to the same width. I shoot for more like 0.020" (1/50") or better ripping consistency and that isn't very difficult.

That thought leads to another observation. It is often much more important that multiple pieces be cut to the exact same dimension than that the dimension on all are exactly right. Using my same box example, it isn't very important whether the width of the sides of a fine keepsake box is built to a width of 3.875" or 4.125" (+/- 1/8) so long as all pieces are the same. However, if the length of the two sides is different by 1/8", then you have big ugly cracks at the joints and an out of square condition that really can't be fixed. That just emphasizes the need for sleds and stop blocks when cutting multiple pieces rather than relying on pencil marks.

My opinion: The OP will not have problems under any circumstances with +/- 0.007" of inconsistency when cutting wood.

[glenn bradley]

I think your saw setup is fine and your rips should be fine as well. Very few parts that I make for furniture go directly from any machine into the finished piece. You may be able to up your game with the addition of featherboards for material control is you are not already using them but, that would just be for grins in my book.

It is interesting that people get so excited about the question of accuracy. Nearly every thread that is started on it rapidly brings responses from the .001" camp (my camp) and the 1/32" camp. Neither are wrong for their intended work. I like my machines to give me as accurate a result as is reasonable for the effort required to yield it. In short, I like to start as close to my intended measurement as possible because it makes less work for me later and that's what I use machines to do; make less work ;-)

Certainly "close enough" and "good enough" are fine for a lot of things. I'm building a Drill Press cabinet right now out of plywood that deviates a fat 1/64" over its thickness. I'm using stopped dados that will be hidden and they are "about" the same length and that's fine. A deviation of .007" on both surfaces of some visible mating joinery is pushing 1/64" which could make for some ugly dovetails or glue-lines in your bridle joints.

Right tool for the job. Right joint for the job. Right accuracy requirement for the job.

[lowell holmes]

Sounds to me like a stealth brag. That is 1/147". Who can see it?:)

[Al Sherred]

Sounds to me like a stealth brag. That is 1/147". Who can see it?:)
This post has nothing to do with bragging, or stroking my ego , it was intended strictly for a safety concern. Since I hear all the time about such things as kickback and the damage caused by such an accurance. I know that ZERO deviation is probally unacheviable, I,m more concerned with how much deviation would it take to make a rip cut more risky, than it would normally be. This is the first time that I have ever moved the table on my cabinet saw to align the blade and miter slot so I am a little on the cautious side.

[Chris Padilla]

7 mil...you're doing fine. Nice job on the tune up and alignment. Go measure that board right now and see if that 7 mil is still true. :)

[Wade Lippman]

This post has nothing to do with bragging, or stroking my ego , it was intended strictly for a safety concern. Since I hear all the time about such things as kickback and the damage caused by such an accurance. I know that ZERO deviation is probally unacheviable, I,m more concerned with how much deviation would it take to make a rip cut more risky, than it would normally be. This is the first time that I have ever moved the table on my cabinet saw to align the blade and miter slot so I am a little on the cautious side.

If you use a splitter and a pushblock you would trouble getting kickback no matter how badly aligned your saw was. Without them it can/will happen no matter how perfect you are.

Worry more about that than .007 or .07.

[Pat Barry]

I'd say that you should be rip cutting something stable like MDF to take the measurements, not a pine 1x6 for example. Stress relief ina real board can make a huge difference. In something like MDF you don't need to worry about that and can get a much better idea of the truth.

[Eric Anderson]

Just for perspective, a piece of 20 lb paper is 0.004" (approximately 0.1 mm) thick. So 0.007" is less than two sheets of 20 lb copy paper. +/- 0.007 is not significant and probably within the range of measurement error for a dial or digital caliper (particularly if it isn't a extremely high quality and expensive unit).

[Art Mann]

+/- 0.001" measurements are easy even with a $15 Harbor Freight digital caliper, but the vast majority of all the world's most exquisite fine furniture was built without anything but a stick ruler and a story stick. How did they do it?

I am concerned with thousandths of inches mainly with my CNC router. Sometimes, very uniform thickness is necessary for certain types of carving. Even there, 0.007" of inconsistency isn't that big a deal.

[Patrick Walsh]

I took a job a few months ago working on a crew doing carpentry. We do most everything from frame to finish. However often the framing is subbed out.

We make corrections to the framing as the architects and designers call for them on bigger project and do the framing on smaller projects. I started trimming out and siding the exterior of a 8000 square foot uner custom home with these guys for the first time a couple weeks ago now.

I cant believe what they call good enough. Its crazy id be mad if they where building my house and i was paying the going square footage rate. Being the crazy custom home it is im sure the Sq ft rate is much more than the average adding further insult to injury.

Im not quite sure how any tradesman does not get that if you frame something not plum and square it will carry through all the way to the last coat of paint. I guess you cant even pay someone to care or take pride in what they do. You either do or you don't.

[Martin Wasner]

I guess I want to know if .007 in is acceptable after measuring both ends of a ripped board.

What's it like working for NASA?

[Brian Tymchak]

Whoa there.... The builder of my home would argue that rule of thumb.... 1" over 4' is the standard here in Perrysburg, OH....:D

Wonder if we had the same builder... I've got a few walls that are out of plumb by ~1.5" from ceiling to floor...

[lowell holmes]

I wasn't meaning to belittle your post. It was meant to be in good humor. I operate with a splitter and push stick on all rips. I should add feather boards are used when needed to hold the board against the fence.

I also stand out of the path a kickback would take and wear a canvass shop apron with double layers of canvass on my chest and stomach.

If you rip enough, kickback will happen regardless of alignment, and it probably will be a result of something you did because of carelessness or fatigue.

I also wear safety glasses and hearing protection when running the table saw.

Sorry that I offended you.

[Prashun Patel]

Hi Al,
I'm positive Lowell was joking.

It's common round these parts to call something a 'stealth brag'. It's always said tongue in cheek as a compliment, not a jab.

It's SMC's inside-joke equivalent of, "Man, I wish I could get my own saw that accurate."

[Mel Fulks]

I don't see anything about what blade you are using. Some jobs require a rough rip before dressing then a jointing and
finer rip with a "combination " rip. Seems ripping with the larger teeth has some variance .

[Jim Dwight]

Thanks for the correction. .007 is plenty good enough for anything I do. That is less than 1/64th and as good as I expect to see. Wood movement alone is often bigger than that.