We are going back to Alaska tomorrow. I am totally relaxed, and ready to go home. Itching to get in the shop. Never did get my router ordered, but that is not critical to make my sled.
Upon reading a review, and commenting, on a digital angle gauge, I started a longer post, but decided it belonged in my blog. The topic of how to measure comes up periodically, but the advent of digital measuring devices adds a new dimension to the discussion. Anybody who has done woodwork for long probably develops his own techniques for measurements.
I am slowly accumlating an array of digital devices. All my devices are made by Wixey:
Wixey Saw Fence Digital Readout
Wixey Angle Gauge
Wixey Digital Caliper
Wixey Digital Protractor
The saw fence readout works well and has been in use a few months, very useful for duplicating cuts, or frequent resetting of the fence in increments.
The digital caliper is in heavy use, and I find it indispensible, and easier to use than an analog caliper, which I also own.
The angle gauge, as noted above, works well, but is not in heavy use.
The protractor has not been put to use yet.
I may buy a height gauge.
Accuracy and Precision
Here is a nice discussion of Accuracy and Precision
It seems easier to me to just read off a number from a device, than measure something as 3/32 and a little, or about 5/64. The mind has to work harder, and the memory process is then subject to errors. Any time I can use a digital device instead of analog with the same work, I do it. To be honest, I am not sure digital devices give me more usable accuracy, but it is easier to be precise. Stated more scientifically, I can get very close to the actual measurement with an analog device such as a ruler, meaning I can be reasonably accurate. Let’s face it, accuracy to the nearest 1/64 is almost always close enough for woodwork. But the digital device allows me to reproduce that measurement over and over, which is the definition of precision. Anytime something is easier to read, easier to remember, and can be reset on the same device or transferred to another device accurately, you increase precision.
I would suspect the most important thing is reproducibility, i.e. precsion. We frequently just need to be consistent to make good looking, nicely fitting furniture and other objects. Using stop blocks, story sticks, cutting everything with the same measurement at once, cutting on the same side of your pencil mark, etc, is more important than a digital device.
Pencil marks are always a source of error, and I remember years ago of falling into the trap of basing measurements on previous measurements recorded as pencil marks, and slowly accumulating significant errors. Now, I never base another pencil mark on a previous pencil mark.
I note that Incra is selling a set of marking rulers, Amazon link
I have a similar ruler made by General that sets on my measurement device tote. However, Incra has upped the ante with a T ruler and bend ruler using the same principle. They have small slots cut in them that exactly fit a 0.5mm mechanical pencil lead. That allows you to be very accurate, because you eliminate parallax errors, pencil width errors, etc. This should increase precision, because you make the exact same pencil mark elsewhere. But your measurement has to be a precise fraction down to 1/32 of an inch.
-- Jim, Anchorage Alaska