Metrology for the cabinetmaker

[Brian Holcombe]

Thanks, gents. Appreciate the comments. It is time consuming, it took me a month’s worth of early morning writing and documentation to create the post because I can usually only spare about 15min at a time.

[Brian Holcombe]

Glad this thread is back! I’ve enjoyed it and absolutely think it belongs here. Some recent machine restorations have peaked my interest in metalworking.


My business is millwork and joinery and the thread has me thinking about how my measuring process has evolved over 40 years. No doubt it’s possible to do first class work with minimal measuring methods. In my early days precision measuring was done by pulling a inch on the tape. Advanced and more precise measuring can make machine repeatability- setup quicker and more accurate. The days of producing large quantities of woodwork are gone, now it’s more about small batch sizes and one off work in the custom sector. And also for the home shop that wants to work more efficiently.


No machinist skills here but I have some thoughts on how woodworking machines can be adjusted and maintained for accuracy with a few tools. For machine setup it think the essentials are a couple good squares, ( the Lamb square is my favorite) a good straight edge, feeler gauges, digital height gauge, dial indicator, digital calipers and a protractor. The protractor and cheap dial indicator are marginal and on the list to upgrade. The long measuring stick in the photo is for site measuring and should not be in the picture for machine setup.

Attachment 414020


For checking wood parts for accuracy the digital calipers, small Starrett square, tape, folding rule and 10 mm square bar are my go to. Last picture shows how the square bar is used.
I work in millimeters and find 0.1 or 0.2mm is close enough for most joinery. That’s about .004-.007 inch.


Attachment 414021
Attachment 414022

Joe, thanks for sharing your approach. I had a feeling you'd be using height gages as well, it was a game changer for me. I used to hang a double bevel off the tool and set the height that way. It was accurate but the height gauge is always spot on.

At the machine shop we used precision levels to setup machinery and also for setting up rough cuts. I'm not sure how useful it will be in the woodshop but I decided to add one for aiding in machine setup. A little easier than using a carpenters level or a cast iron level.

[mreza Salav]

Very interesting thread. I always strive to be as precise and as good as possible but I mostly work/build for myself. I hope those of you who woodwork/cabinet making to 0.001" get paid enough.
When I was building our house and various things for it a few builder in the area stopped by and asked if I was willing to build them similar things. My response was you can't afford me. I don't do this for a living and I am sure if I was doing it the way I work for myself I won't be paid enough.

[Donn Ward]

Very interesting, informative, and well-written; thank you!

[David Buchhauser]

Brian,
Lots of good information here. I have reread your column (more closely) and I do see the merit of your application with these instruments. I feel bad about some of my previous comments. Heat of the moment - if you know what I mean.
I will look forward to part 2. Glad you were able to get it back on the forum.
David

[Ole Anderson]

Thank you for the write-up Brian. Very well done sir!

I have a small granite surface plate, but it is only used as a base for sticky back abrasives in my scary sharp system. I recently acquired a few measuring instruments, but none of them are intended for use with a surface plate.

[Brian Holcombe]

Thanks, gents!

David, very much appreciate your comment, that means a lot to me.

Second post in this series should be coming up shortly.

[Donn Ward]

Very informative thread, I am enjoying it immensely. Thank you to those who are taking the time to put this information together for the rest of us, I am very appreciative.

[Pat Barry]

Brian, where is Page 2? The link in the original post is just refreshes the page as far as I can tell. Thanks

[Brian Holcombe]

Pat, it's on pages 4 and 5.

[Jeff Bartley]

Thanks for this Brian, I've thoroughly enjoyed the deep dive into metrology!

[Pat Barry]

This is where you really get to know people.

Pat, it's on pages 4 and 5.

Thanks. I see its under Lee's name. I was just skimming for yours.

Ps: maybe Lee can fix the link to redirect to the content on page 4?

[Brian Holcombe]

Thanks, Jeff!

Pat, happy to help. May be worth bringing this to his attention directly.