A36 is a tough steel to machine on a mini and can also have really hard spots throughout, it’s primarily used in structural steel construction.

the short spring is for when you move arms to other set of hole

I only use HSS lathe tooling for nonferrous metals anymore. Carbide insert tooling is just to darn handy to fuss with regrinding HSS bits.

Nice knurl tool should made one , I made one years ago i got plans some where and works great ty for the great video. oh that spring i would say if you clamp to knurl small parts its a replacment take out the longer one use the smaller one i would say!

At around minute 5:30 look at the leavers of your tool post - the seem to come loose. On the other hand your band saw cut that steel like butter, so it can't be that hard.

For someone getting into milling and what a cheap reasonable set of both 2 and 4 flute cutters try the set from harbor freight for a beginner they work

ER collets have a larger range, since they are often used for work holding. ER40 collets have a full 1mm range, so a set of metric ER40 collets will cover the full range with fewer collets than the imperial 1/32 set. R8 and 5C and DA collets all have a smaller range, and pretty much need to be on size. I have 5C collets by 64ths and frequently find scavenged stock that I cannot hold in my lathe. This explains the popularity of 5C "emergency" collets, if you need to hold a non standard size you just bore out an appropriate collet. R8 and DA collets are pretty much used only for tool holding, so you don't need very many sizes unless you want to use them to hold drills. I have DA200 collets by 64ths, so I can hold small fractional drills, but not most number drills or metric. A DA200 collet holder is a lot smaller than a drill chuck so it can be used close to other features where a drill chuck would hit. A set of ER16 collets would probably be comparable for that, but would cover the entire range with a set of metrics collets, including the in between sizes. R8s in both imperial and metric is not an unreasonable number of collets, a "full" set of each is still a lot fewer collets than my 5C 64ths set. For R8s I only have imperial, because I tend to buy my end mills used on eBay, and most of them in that market are imperial. Now that I have the ER40 collet chuck for my lathe I will probably never buy metric 5C collets, but before that I was eyeing them because there is an increasing amount of metric stock in the hobby market. So I guess the tldr is for a hobbiest, ER collets are the most economical. You can get a 3/4 shank ER16 collet holder that will hold all your tools up to 3/8 or 10mm and it will fit in your 3/4 R8 collet and take less Z height than a drill chuck. You can also get an ER20 with a 3/4 shank, that will hold up to 1/2 inch, or 13mm, but the nut is bigger if fitting in tight spaces matters. For tiny stuff, like using those carbide circuit board drills and mills you can get fairly cheap ER11 is big enough, but most mini mills don't spin fast enough to make those things effective. I have milled with them, running my mill flat out at 3000 RPM, but you really need 10k+ for those tiny things. They do look pretty funny though, sticking out of a 1/8 inch R8 collet. At 3000 RPM it is really easy to break them with a twitch of the hand wheel.

I went all metric for everything. For me it is easier as everything i do is for powersports and it is all metric. Yea that metal is tuff stuff! I have gone all carbon inserts on my setup so i can work on any kind that comes across.

I ended up just cutting off the wheel end of my push knurler so I wouldn't be tempted to ever use it on my lathe. I've had very good results with my scissor type knurler. Little machine shop sells different type of knurl pattern wheels that fit that type of knurler.

If it wasn't for cheap end mills I wouldn't be playing! I'd suggest Er16 collet holders in both R8 and MT2 (tail stock) shanks. Then get a set of er16 collets (they are inexpensive) in both IMP and Metric. The longer you play the more likely it is you'll end up doing metric stuff anyway. Yep that head stock seems a bit loud! YMMV

Unless machining some really tough material or semi-hardened steel, I wouldn't bother with carbide end mills in a hobby shop. They are too expensive and too easy to break compared to a high-speed steel end mill. Remember that when you end up with a box of dull endmills, go to a tool and grinder shop and they can sharpen end mills 3/8" and larger for a few bucks apiece. They will want a number to sharpen to make the set-up worth their time. They will usually want to run them with endmills from other shops so you might have to wait a week or two to get them back. Smaller sizes are just cheaper to replace. Don't throw small dull or broken endmills away as you can grind them into special tools for the lathe and fly cutters on the mill.

3% Carbide?

Perhaps for future videos: either put yourself completely into the video or not at all.

It looks to me like you are running *WAY* too fast, and the angles on your tool don't look right. Using HSS, and if that is A36, you should not be running more than 80 surface feet per minute. That bar looks to be about 3" in diameter, so your spindle should only be running about 320 RPM at most, with lubricant. Use a positive rake with a generous radius. A36 is not all that easily machined, but HSS is fine for machining it. The blade on your band saw is at best HSS, you know, and maybe not even that. Be sure to get underneath the mill scale with the first cut, or grind it off prior to turning.