C, I'll start this off and the other guys can correct me or chime in.
There is a lot more to knurling than what you asked so I'm going to try to give you an overview. Knurling does not cut a pattern; it deforms it into a pattern so it is a high pressure process. For a little machine like a Compact 5, this means a scissors knurler is probably your best bet because there is no significant side loading of your spindle. All power goes to apply torque. The scissors knurlers you linked to above will work. Here is a similar one with 6 knurls for a decent price:
https://littlemachineshop.com/products/product_view.php?ProductID=3770. The only problem is that I do not know if these are Circular or Diametral Pitch knurls and you should clarify with LMS which they are before purchasing them.
You should know that these knurlers are cheap. While they will probably work (I don't know; I've never used one of these), you can make a better one but it requires a mill and some knowledge. Probably the best commercial knurlers come from Eagle Rock but they are way big for your lathe so maybe go with a cheap Chinese one for now and make a better one later when your tools and knowledge allow for it.
There are two general kinds of knurls: Circular Pitch and Diametral Pitch. The latter, which we'll call DP, are intended for use with nominal stock. That means you can take a piece of stock and knurl it without having to turn it to a specific diameter. To be clear, if you bought a piece of 1/2" or 3/4" mild steel rod then you should be able to use a DP knurl to knurl that rod without having to turn it down. No calculations are needed.
CP knurls work with stock of any size. Many folks use formulas to calculate a diameter that is supposed to greatly reduce mistracking (multiple imprints of the pattern) of the knurls. Those of us who have been knurling for many years have found that these calculations are usually not necessary. What is necessary is to use enough pressure to allow the pattern to form before running the knurl. The beauty of a scissors knurler is that it allows you to easily apply that pressure with the turn of the top knob. You will find that there is a good deal of controversy regarding the need to calculate a diameter before knurling but personally, I don't bother calculating most of the time.
Assuming you decide to go with CP knurls, here is what I recommend:
- Prepare the work. Get it round and chamfer the end of the work piece. This allows the knurl wheels to climb onto the end of the work if you need to make more than one pass.
- Position the knurling tool so that the work is roughly centered height wise and the center of the pins are in the center of the work piece.
- Move the wheels onto the end of the work so that about 1/2 the width of the wheel is resting on the work, just past the chamfer. Apply some pressure and rotate the work by hand several revolutions. This will leave an imprint in the work and you can see if the pattern tracks well. If it does not then you will see multiple patterns forming, not the nice diamond or straight knurl pattern you want. If this occurs, increase pressure and turn it again until you begin to see the desired pattern form. Once you get the desired pattern forming by hand then you know that you have the minimal pressure required to knurl that piece.
- The depth of the knurl pattern can be done in one or more passes. Ideally, you are looking for a pattern that is about 90% of full depth. This means that the peaks of the pattern are almost sharp but not quite. Form Roll, a maker of good knurls, considers greater than 90% depth to be abuse and will result in premature wear. Besides, if you take it to 100% you will likely file the tops off anyway. Note that in materials that don't work harden - Aluminum, brass, mild steel, plastics - you can make multiple passes, going deeper each pass until you get to the depth you want. On materials that do work harden easily, like stainless of titanium or tool steels, it is better to start at a 90% pattern and run the knurl in one go. This how I knurl most of the time, regardless of the material.
- Okay, so you have a nicely tracking pattern and are ready to run the knurl. Now you need to set up your speed. Theoretically, you can knurl at normal turning speeds for your material. However, you will find that your knurls and pins will live longer if you slow down. Over the years, I have come to use 50-60 sfm for just about everything and find it works well for me. I tend to feed manually because I want to go as fast as the knurls will allow me to go. You have to try it and get a feel for this but you will also find that if you go too slow, you'll have a lot of debris and flaking. I also come out even faster than I went in, although this is not as important.
- Before you run the knurl, apply cutting oil to the work and the knurls. I use sulfur-bearing cutting oils because this is an extreme pressure operation. You can buy this at any hardware store.
- Now, run the knurl and then check with a magnifier to see if you have the depth of pattern that you want. If not, tighten the knob a little and make another pass. It is wise to use a nylon or brass brush and maybe a little compressed air to blow off debris before each pass. When you get the depth you want, you're done.
You should also know that knurls for axial running, where the knurl is longer than the wheels are wide, the knurl wheels should either have a bevel on the sides of the wheels or it should be convex. Accu-Trak sells good convex knurls. Form Roll will grind a bevel on the wheels for you (at no extra cost the last time I ordered) if you call and ask them for it. Wheels without bevels or convex shape will also work for axial running but the pattern will not be nearly as clean.
Okay, that should get you up and running. I'm sure the other guys will be along to add to this.
