Category Archives: Construction

I regularly encounter interesting math, particularly geometry, in my woodworking and remodeling projects.

Budgeting for an Air Conditioner

Posted on 20-August-2014 by mathscinotes

I just recently added 20 kW of capacity electrical capacity to the lab. Other lab users have probably added another 20 kW of electrical capacity to the lab. Since I am conservative by nature, I will assume that all this electrical power is going to be used and will end up as heat dissipated in the lab. So I am estimating that we have added 40 kW of heat load to the lab, which means I should provide sufficient air conditioning capacity to cool that load (Figure 1 shows a common type of commercial, roof-top, air conditioner Continue reading →

Posted in Construction, General Science | 1 Comment

Compound Miter Cuts Without Any Formulas

Posted on 15-August-2014 by mathscinotes

Quote of the Day I refer to that time as their second bottle phase. — My mother on the teenage years of her children. My brothers did down one or two beers 🙂 You will find many carpentry web sites … Continue reading →

Posted in Construction | 7 Comments

Calibrating My Chop Saw to Make a Perpendicular Cut Using a Bit of Geometry

Posted on 2-August-2014 by mathscinotes

I have a similar saw (12 inch version) and I am very happy with mine. I thought for a moment and asked my co-worker "Have you calibrated your saw?" He told me no and he did not know it could be calibrated. Time for a little geometry -- construction always presents me with the best classical geometry exercises. Continue reading →

Posted in Construction, Geometry | Comments Off on Calibrating My Chop Saw to Make a Perpendicular Cut Using a Bit of Geometry

Interesting Folding Bed

Posted on 22-June-2014 by mathscinotes

I am an amateur woodworker and I find clever, geometric constructions in wood very interesting. Here is an interesting collapsible bed design. Check out their web page. Continue reading →

Posted in Construction, Geometry | 1 Comment

It's Warm Out and the PVC is Getting Longer ...

Posted on 20-June-2014 by mathscinotes

I live in Minnesota -- where winter temperatures can be as low as -36 °C (-33 °F) and summer temperatures can be as hot as 38 °C (100 °F). Because most things expand when our days get hotter, we occasionally have things like doors and windows that are too tight in the summer and too loose in the winter. Today, I encountered a PVC pipe that was installed during the heat of last summer and it had ripped itself free of its mounting brackets during the cold of winter. Of course, it is summer now and the pipe is back to its installed length. I was asked by an electrical equipment installer today how much length variation should he plan for when using PVC pipe outdoors. It turns out the National Electrical Code (NEC) actually has a table that addresses this question and I will discuss in this post how that table was generated. Let's discuss the answer I gave this installer. Continue reading →

Posted in Construction, General Science | 2 Comments

Bisecting an Outside Wall Corner Angle

Posted on 5-May-2014 by mathscinotes

I have just returned from putting up crown molding at brother's house. It is always fun working with my brothers. In many ways, we are little different today than we were 40 years ago. During this task, I encountered a wall corner that was not square. Let's talk about how you can measure and bisect this angle. You need to bisect the angle when you want to cut the molding to fit around the corner (Figure 1). Continue reading →

Posted in Construction, Geometry | Comments Off on Bisecting an Outside Wall Corner Angle

Frost Depth Deeper Than Normal This Winter

Posted on 16-March-2014 by mathscinotes

Quote of the Day Maybe not today..., maybe not tomorrow..., but someday... soon; ... and for the rest of your life ... - Rick Blaine, Casablanca. I was in my home town of Osseo this weekend to do some computer … Continue reading →

Posted in Construction | 1 Comment

Heating a Room with People

Posted on 28-August-2012 by mathscinotes

I am currently sitting in a really boring meeting that is being held in a very small room. The room is packed full of people and it is hot in here. Of course, there is a part of me that … Continue reading →

Posted in Construction | 3 Comments

Lighting My House Number and Designing with Phototransistors

Posted on 11-July-2012 by mathscinotes

Introduction I have had several people say that my house number is difficult to read at night. The number consists of four digits mounted on a structural column that holds up a section of my roof. In response to these … Continue reading →

Posted in Construction, Electronics | Tagged | 5 Comments

Cost of Cooling Electronics

Posted on 26-June-2012 by mathscinotes

Introduction One of my favorite physicists stopped by today and wanted to talk about the cost of cooling electronics like fans and air conditioners. The talk was somewhat mathematical and worth discussing here because the basic math is what a … Continue reading →

Posted in Construction, Electronics | Comments Off on Cost of Cooling Electronics