In my previous post, I started working on the scale. In this post, I finish the woodworking, and painfully re-learn the woodworker’s adage: “Measure twice; cut once”. Continue reading Dog Water Bowl Scale, Part 2: Measure Twice; Cut Once
In my previous post, I designed and printed a Centering Guide to line up the top and bottom pieces of the scale. In this post, I finish assembling the scale.
Now that I have the Load Sensor Holders that I designed and printed, I drilled mounting holes in the blocks that will hold the Load Sensors.
In my previous post, I 3D-printed parts to hold down the Load Sensors. In this post, I fix the counterbored holes that keep the nuts from protruding below the bottom of the bottom piece of plywood.
In the woodworking post, I used a router to cut counterbore holes on the bottom side of the bottom piece of plywood. These holes hold the nuts that hold the circuit boards.
In my previous post I described how to calibrate a load sensor. This post shows how to measure center of gravity, and shows a failed attempt to mount the load sensors to the scale.
Now that I’m using 4 load cell amplifiers rather than 1, I can calibrate each load sensor separately. This in turn will let the Arduino calculate Pippa’s real weight accurately regardless of what part of her bed/scale she’s lying on.
In my previous post I described the electronics of the Dog Bed Weight Scale. In this post, I’m doing the final woodworking and assembly – at least enough assembly to test the thing.
First I needed to design some sort of support for the load sensors. Because of the design of the sensor – a “T” bar surrounded by a “C” shaped bar – I needed to make blocks that were 1) tall enough to keep the top piece of plywood from resting on or crushing the electronics and 2) cut out to allow the “T bar to bend below the “C” shaped part as weight was added. You can find plenty of videos of people trying to use load sensors by mounting them on a flat surface; that won’t work.
I want to learn how to use Load Sensors to continuously weigh stuff with an Arduino, so I thought it would be fun to continuously weigh our dog, Pippa, while she sleeps in her bed each night. The project is a little like Nate Seidle’s Beehive scale, but simpler.
The idea is to turn Pippa’s bed into a scale. Pippa’s in fine shape right now, but it’s always good to keep an eye on your dog’s weight, and a custom-made scale is a great way to do it.
After completing my drill press table, I decided my next step would be to make a fence for it – so I can drill vertical holes in the sides of short boards.
First I cut a 3 1/2″ board of 3/4″ MDF, of a width to match the drill press table. This first piece will be the face of the fence.
I started cutting the X-axis pieces for the Build Your Own CNC Machine. At first things went well, then they went downhill quickly.
First, I clamped together the two roughly 2’x4′ pieces of 3/4″ MDF that would become the X-axis table, clamping together the best square corner of each.
As multiple woodworkers have mentioned, a drill press as-is is poorly suited to doing woodworking: the cast iron table can transfer grease to the wood; the table is small; the table has limited places to fasten clamps to hold the wood down.
So here I am making a drill press table.
The drill press arrived this evening!
I’ve never assembled a machine tool before, so I was put off by the rust-preventive coating that needs to be cleaned off, through mysterious and inadequately-explained means.
The manual says to remove the gunk with kerosene or some other solvent, and assumes that the reader is a seasoned machinist who knows what in the world they’re talking about.
After much searching, I found that they’re saying basically “it’s covered in grease; use a grease-cutting goo to clean it, then protect it with something”. The most benign thing I found recommended online was oven cleaner or 409. Many folks swore by kerosene (which is highly flammable) or mineral spirits.
So my plan is to clean the parts with 409 then, for the parts that need protection, use the (non-silicone!) wax I bought for the scrollsaw table.