Shop Tips #16

By Dick Raczuk

Loupes

TT wrote in an interesting way to determine the hardness of a particular piece of metal you may be working with. It's pretty simple (always the best). First, you need to come up with some kind of standard. A piece of CRS 1018 will be around 150 on the Brinell Hardness scale. Really for this type of testing we are just trying to get a feel for how hard a piece of metal might be. Another piece of a known hardness will be your other standard. Then you need too place a couple of punch marks. One in each piece. You will also need a good loupe to determine the difference in punch marks.

This will give you an idea on how the punch marks will look. #1 is harder than #2. For illustration purposes I used one piece of metal.

Here is the standard the PTC kit comes with. It is covered with a know hardness. Using it checks your calibration.

There are several different models of loupes available. Choose one that has graduations on the lenses.

This way you can measure the differences in the diameter of the punch mark. The smaller the mark, the harder the material. You will need the references to realize any benefit of the procedure. I happened to pick up a PAC portable steel-hardness tester at a swap meet for $25 .

It didn't take very long for me to make up my mind to buy it. It' s not something a homeshop fabricator has laying around in his toolbox, but at that price, who can pass it up. The automatic center punch it comes with has a round point. This is a more accurate way of establishing a mark to measure. It's accurate to 1-1/2 points RC. You may have to play with this a bit, but the benefits may be of value someday. If you can find someone with a RC tester to calibrate your automatic centerpunch marks, that would be the ultimate. If you could radius the tip of your punch, that would work even better.

While we are on the subject of Loupes, I always use mine to check the sharpness of a toolbit. You won't believe the difference you will see under a 10 power Loupe.

Magnets by Ian Griffith

This photo shows what looks like a battery for a wrist watch. It is actually a "rare earth magnet".

I have no idea what they are made from, but they are VERY powerful, and not too expensive. I got the magnets from a local woodworking supply place, Lee Valley Tools. They come in a variety of sizes, and I'm sure they are available online.

This photo shows one on the side of my drill press holding the chuck key. Much easier than trying to use a chain or cable,or any other type of holder. Usually it goes on the right side of the head, because I'm right handed.

This shows the magnetic mount task light on the same drill press. If I need it, it's there, but not in the way.

Scribes by Ken Le Masurier

I made this scribe from a 1/2" diam bolt, nut and deck screw. The nut can be adjusted to set the scribe line where you need it, and the tool follows curves etc nicely as well as marking straight lines. I have found it really handy for marking metal for trimming.

Bandsawing Small Parts

If the need arises to saw some small pieces, use a holder. I use the vise pictured whenever possible when handling the little buggers. When sawing a piece as pictured, start slow with slight pressure. Once you get started you can put some pressure to it. This is all relative to your machine and HP. The blade in the picture is a 6 tooth and very dangerous. Stay away from it with push sticks or a solid holder.

Cutting Small Pieces on a Bandsaw

If you are going to make a thru saw cut in a small piece, the vise will pinch the blade. I just cut a piece of scrape to hold the part with a snug fit and cut away. By all means, make yourself a promise not to hold a small piece similar to the one pictured with you fingers. Not even one time because your in a hurry.

-- Dick