Any steel rules with graduations in 128ths?

[Mini Me]

As I pointed out before, I use a tape measure and steel rule like a story stick. If a measurement falls between two engraved lines, and it's a write-able tape, I can use a pencil to mark it. Then I take the tape (or rule) the table saw to set the fence. If it's a steel rule, and the cutline is between two graduations, I'll see if the metric scale will help. I know this method works very well for me...until the day my eye sight says otherwise. [big grin]

Now, with the 1/100ths, there's a higher probability that a measurement will fall on one of the graduations. And anyone looking to buy such fine rules, I highly recommend the General for its design and prices.

Just use a storey stick, why do you need a measurement at all, it just complicates things.

 

[ChuckM]

I explained it earlier already. A story stick is not fool-proof, and every time you need to find a clean story stick (of the proper length). I find the rule or tape measure handy and accurate as the engraved lines are straight, uniform unlike a tick mark or pencil mark.

 

[jimbo51]

Years ago, Bridge City Tools founder John Economaki wrote a piece in support of the precision fence they were selling. I think he stated that differences in widths of pieces over 0.004 in/0.1 mm could make a difference in how pieces fit together.

Also years ago, there was an article in Fine Woodworking by a fellow who used precision metal working tools to set up his saw for cutting parts for small drawers for small tool chests. He claimed that his drawers could be made with very fine fit and never bind. I do not recall how he compensated for wood movement.

Also many years ago, I bought a used 48 in Starrett vernier caliper. Inside the vernier it says Outside 0.001. I suppose that means it can measure to 0.001 in. I bought it for fun and haver only used it a few times to check other tools. The vernier scale can be adjusted, but I have never bothered to check calibration down to 0.001 in.

In practical terms, I have to use magnification to set measurements down in the 1/32 range. I use rules with holes when possible. Setting the table saw fence can also but an issue since my old Unisaw fence moves a little bit when clamped down. Since I do not have to work on a set schedule, I can spend extra time making small adjustments with an already cut piece as a guide if I have to repeat cuts after the fence has been moved. Sadly, getting pieces to fit exactly is a source of happiness more than just a routine expectation.

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[Packard]

Early in my career, I was an independent sales rep, representing several manufacturers. I represented two machine shops.  One that did conventional level machining and one that did machining to extremely tight tolerances.

The shop that did the tight tolerance work had to have material in stock at least 1 week in advance of any final machining operations.

The “rough” machining was done in a conventional machine shop environment.  But when it came to the final machining, the steel (some of it partially machined) had to sit in a temperature controlled room held to very close temperature tolerance.  This, because steel (brass, copper & aluminum) all expand in warmer temperatures and shrink in colder temperatures. 

I don’t recall the exact temperature it was held at, but about 70 degrees.

My other shop, even equipped with the same machinery and measuring equipment, could not work to the tolerances of tenths of a thousandth.  They did neither had the mindset nor the environmental controls to do so.

Now onto woodworking:

I was told, when I started working in wood that expansion/contraction across the width of a board could be as 1/8” for a 12” wide board.  I just googled that, and apparently that number is still being bandied around.
https://workshopcompanion.com/KnowHow/Design/Nature_of_Wood/2_Wood_Movement/2_Wood_Movement.htm#

So, you can measure more closely.  What’s the point?

 

[ChuckM]

Snip
I use rules with holes when possible. Setting the table saw fence can also but an issue since my old Unisaw fence moves a little bit when clamped down.
Snip

That's not uncommon, and even with my PCS, the fence moves a tad if it is set by moving it to the right (i.e. away from the blade) and clamped down. That's why I set the fence by pushing it towards the blade so nothing is moved when the fence is clamped down.

Now, many people say their eye sight isn't good enough for working with anything finer than 1/32th. Is lighting a factor? I have had no issues with 1/64ths (I'm not young by any definition), and I have good lighting where needed (one directly above my table saw). And I'll be using 1/100ths where needed -- not every cut needs that kind of precision!

 

[ChuckM]

Snip.

Now onto woodworking:

I was told, when I started working in wood that expansion/contraction across the width of a board could be as 1/8” for a 12” wide board.  I just googled that, and apparently that number is still being bandied around.

So, you can measure more closely.  What’s the point?
Snip.

We can achieve piston fit drawers, but whether they can stay that way will depend on how they are maintained relative to their environment.

In fine woodworking, we prepare the stock, cut the joints and the best practice is to finish the relevant parts within a practical period of time. During that period of time, wood movement shouldn't be a factor. I say "shouldn't" because wood can behave wildly despite what we can control in the shop. But my overall experience has been that wood movement isn't relevant to my using a finer rule to do my machine settings (on the PCS or Kapex).

 

[ChuckM]

As I pointed out before, I use a tape measure and steel rule like a story stick.

Maybe the Lee Valley Story Tape will work then. Surly a Canadian checked that first  [cool]

My Fastcap tape measure from Lee Valley Tools is "write-able."

 

[Cheese]

The “rough” machining was done in a conventional machine shop environment.  But when it came to the final machining, the steel (some of it partially machined) had to sit in a temperature controlled room held to very close temperature tolerance.  This, because steel (brass, copper & aluminum) all expand in warmer temperatures and shrink in colder temperatures. 

I don’t recall the exact temperature it was held at, but about 70 degrees.

My other shop, even equipped with the same machinery and measuring equipment, could not work to the tolerances of tenths of a thousandth.  They did neither had the mindset nor the environmental controls to do so.

Because of the coefficient of linear thermal expansion that you mention, that's the reason some manufacturers place thermal insulating pads on their micrometers and measuring standards like these. Just the heat from your hand alone can give you inaccurate readings.

If you think steel is an issue, you have to be very careful with aluminum & plastic. The coefficient of linear thermal expansion for aluminum is twice that of steel and "plastic" is 8-10 times that of steel, while wood is 1/2 of the steel value.

As luck would have it, for construction of houses...concrete & wood move at approximately the same rate.

[attachimg=1]
.

 

[ChuckM]

Years ago, Bridge City Tools founder John Economaki wrote a piece in support of the precision fence they were selling. I think he stated that differences in widths of pieces over 0.004 in/0.1 mm could make a difference in how pieces fit together. Snip.

This reminds me of his kerfmaker (which was slightly revised later):


Like many woodworkers, I've made a wooden version of his first design. A little over a decade ago, a few woodworkers and I dropped by his office unannounced, and he happened to be there, and he did a few demos for us. The only tool I own from BCT is a (24"?) stainless steel straight edge.

[attachimg=1]

 

[Mini Me]

I explained it earlier already. A story stick is not fool-proof, and every time you need to find a clean story stick (of the proper length). I find the rule or tape measure handy and accurate as the engraved lines are straight, uniform unlike a tick mark or pencil mark.

I still don't get it. You use a tape but if that does not give you the answer you want you then mark it as you would a story stick.

 

[ChuckM]

I might not have made it clear enough in my earlier post(s). Normally, the steel rule or tape measure with its graduations can handle most of the measurements, but when it doesn't and if it's a Fastcap tape, I use a pencil mark.

Now, with 1/100ths, it is even more likely that the steel rule can give me an engraved line that matches the measurement required.

 

[ChuckM]

Finer graduations indeed matter!

I needed to cut a spacer to an exact length. The 16ths/mm rule gave me this measurement, which was hard to transfer to a saw:

[attachimg=1]

The 32ths rule did the job:

[attachimg=2]

The spacer was spot on:

[attachimg=3]

My 1/100ths rules (6" & 12") can handle any precision requirements!

 

[Mini Me]

A hand plane and a shooting board is an excellent tool to get very fine tolerances, way better than any power saw and no fiddling with shims and spacers.

 

[ChuckM]

Yes, I do use the shooting board and the Veritas shooting plane where needed.

In mass production projects like the one I'm working on where I need to repeat something a dozen times, I try to get the set-up right and as precise as possible. Each saw is different, but I've been so familiar with my SawStop PCS that in most cases, I can really dial in a cut that gives me a perfect, or close to a perfect, result in the first attempt. I almost can say the same for my Kapex, if using the blade teeth rather than the laser lines to set up a cut.

 

[Cheese]

Finer graduations indeed matter!

Ya, if I need an exact measurement and the dial caliper doesn't work, I'll grab a handful of stainless scales with different measurement scales. There's usually at least one that will accurately measure the item so that I don't have to interpolate between markings.

[attachimg=1]

 

[ChuckM]

Snip.

Ya, if I need an exact measurement and the dial caliper doesn't work, I'll grab a handful of stainless scales with different measurement scales.
snip.

I even mix units, using, for example, the imperial for the width and the metric for the length of a certain thing and make cuts based on those units. It has its risks, but I'm used to doing it. I use a story stick when it's suitable.

 

[woodbutcherbower]

I just re-read this entire thread from the beginning. Absolutely no disrespect intended to the OP - but I figured that this thread needed some reality and common sense injected into it. Precision metalworking - racing-car engine interference-fit piston bore sizes, aerospace jet engine tolerances - fair enough. But wood? Absolutely ridiculous. I converted 1/128th to the metric I'm familiar with, and it's 0.2mm. My steel rules are calibrated in 0.5mm - and I struggle to see those tiny lines, even with a headband-mounted magnifying glass. My thinnest-possible marking pencil draws a line 0.35mm wide. I have a marking knife with an 0.1mm blade - but the uncontrollable heartbeat-induced shake on my hand (which none of us can control) is 3-4-times wider than that. The thermal expansion/contraction/moisture level/warping/cupping/bowing/shaking/splitting of the material we all work with is maybe ten times that on even a relatively small piece. And at what ambient temperature is the 1/128th measured on the wood? Has it been sitting in the hot Arizona sunshine for a few hours? Or is it being used in an Alaska shop in the wintertime?

I could continue - but you get my point. Three and a half decades as a pro - and I never came across a single job where measurement to that degree was even remotely necessary. Attempting to measure and cut wood to this level of accuracy is absolute nonsense. And even if you manage it - by the time you come back from your coffee and restroom break, it maybe won't be exactly the same.

As I said - absolutely no disrespect intended.

 

[Crazyraceguy]

Totally agreed. Actual measurements that close are just not necessary. Wood will swell, shrink and even compress to some degree, depending on the species.

 

[rvieceli]

Hey [member=44099]Cheese[/member] sre all those tiles like online weather forecasts? Keep searching until you find one you like?  [tongue] [tongue]

Ron

 

[ChuckM]

snip.

As I said - absolutely no disrespect intended.

To be clear upfront: No offense taken. We all work differently and/or to different degrees of tolerance.

I achieve tight tolerances with hand tools, but constantly checking the progress is part of the process. What I have been trying to do -- with much success -- is to achieve that kind of precision result when using power tools through careful machine set-ups, which often call for the use of finer instruments such as 0.3mm pencils, 1/64ths or finer rules, story sticks and what not.

For example, in the batch production of the phone stands below, I relied on consistent and precise set-ups in marking, drilling and cutting to achieve the kind of efficiency I aimed for:

[attachimg=1]

That kind of efficiency could be easy to obtain if I had a CNC machine.

These are the finest rules in my shop (100ths):

[attachimg=2]