First lathe, tool bits

Highsider said:
You don't mention if you have a good coolant system on your 15", but if you do and your set up is rigid, you will be missing a bet if you don't learn how to grind lipped cutting tools from HSS. For brute metal removal rates with the RPM range you state, they can't be beat, and they produce an acceptable finish with coolant. They are all we used before carbide and high RPM gigahorsepower lathes were common. The difference is that the removed metal comes off as a tightly coiled ribbon rather than as a chip that's breaking up and coolant flow is essential. The depth of cut can be 3/8" to 1/2" per pass depending on horsepower.
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Can I ask what kind of lathe you used to take those depths of cut?
 
Jmanb13 said:
Thanks for all the suggestions!

I would like to learn to grind my own bits. I enjoy the learning process as much as actually making stuff, its kind of in my DNA. Also, I'm pretty sure old my lathe tops out at 500rpm in the top gear with the motor at 60hz. Even if I run the motor faster than rated i'm still barely breaking into carbide speeds. I think this really limits me to HSS.

I dug out all the bits in the box of stuff I got with the lathe. Here is what I currently have to work with that came with the lathe. Most of the bits look like they were either ground for a specific profile or were broken in use. The labels I can read on them suggest that some of them branded REX.

The majority of the bits are 3/4" or 1/2". The tool holder I have can hold up to 3/4 bits.

Most of the 1/2" bits are generally between 1.5" and 2" long as is. The 3/4" bits are similar lengths as you can see. I'm not sure what the usable length of the bits needs to be, but to be held by 2 set screws on the tool holder they need to be at least 1" long plus whatever stick out amount is needed. I would think that leaves me very little wiggle room on regrinding the profiles.

I have close up pictures of each size of bit if it helps.

View attachment 228706
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I didn't see any recommendations or I read over them. Watch the Tubalcain lathe tool grinding video(s) and you can use the old HSS for practice. I'm not sure what's on the tools you have shown so a quick cleanup would make a big difference along with being able to see if they have any markings as to what you have.
gheumann said:
I will go out on a limb here. I tried this with my first lathe. It was a mistake. I really didn't know enough, even after reading up on it a bit. Grinding your own tool bits is a skill and an art. Are you sure you want to try to learn that before you know how to machine with a lathe in the 1st place? If something doesn't go right, how will you know if it is the tool or one of countless other variables you might not be familiar with? Me? I really wanted to learn to make things FIRST. It really helps to have actually experienced using various tools to understand why this angle is that, and that angle is this, and so on. You say this is your first lathe. If I were you, I'd buy a tool holder set with indexable inserts. They work great and even to this day I do 95% of my work with them. They last long, they're a time saver, they're not expensive - and they just WORK so you can get to the business of learning how to make things. About the only cutting tool I take to the grinder on a regular basis are my parting blades.
A set like http://www.grizzly.com/products/7-pc-Deluxe-Tool-Holder-Set/G8787.

If you really want to grind your own, this looks like a nice compromise. Seeing a properly ground tool will really help! https://www.littlemachineshop.com/products/product_view.php?ProductID=4516&category=

I know the old timers all say "learn to grind your own tools". THEIR teachers HAD TO. I don't think it is a bad idea if it interests you in and of itself. It just isn't necessary to learn RIGHT AWAY to start really enjoying your new lathe. Old timers used to tell me I should learn to use a slide rule - but I grew up in the calculator age. The analogy applies. They were tied to the way THEY were taught but they were wrong. I've never, ever needed a slide rule.
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.....and then your battery died. Were they really wrong? Learning how to do something isn't the same as saying you must always use the old way. Not learning how to grind and taking the shortcut is good up to a point, as long as your supplier keeps the inserts coming. Knowledge and the educational process to attain is something that can't be taken away. Bottom line; Do you want to be a machinist or a machine operator?

From the position of an apprentice in training, there's a lot more being taught when you grind a 60 deg. tool to cut a thread, or a Lt. & Rt. hand cutting tool.
 
Highsider said:
You don't mention if you have a good coolant system on your 15", but if you do and your set up is rigid, you will be missing a bet if you don't learn how to grind lipped cutting tools from HSS. For brute metal removal rates with the RPM range you state, they can't be beat, and they produce an acceptable finish with coolant. They are all we used before carbide and high RPM gigahorsepower lathes were common. The difference is that the removed metal comes off as a tightly coiled ribbon rather than as a chip that's breaking up and coolant flow is essential. The depth of cut can be 3/8" to 1/2" per pass depending on horsepower.
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That's why a chip breaker was ground into the tool which is something someone doesn't learn if they never grind a cutting tool. Okay, they may learn why inserts are designed to break chips and they may even learn to look for color if that's the shop environment they work in.
 
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mikey said:
Thanks, Highsider. Them is some mighty cuts, that's for sure!
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I was fascinated by the process. I just happened to walk into a shop looking for someone to repair the die on my punch press. The owner felt the need to show me why they didn't do work that size. They were turning a shaft that was in the 12" x 20'+ range and they were breaking the spiraled cuts (serious weapons) at 5'-6' and collecting them in a trough/bin that followed the cutter.
 
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Buy a few but also buy some blank HHS and grind your own. It is amazing how ugly a bit can look and still work fine! All IMO; Don
 
Eremius said:
I'm guessing with a 15" LeBlond it's not going to be an issue.
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A 1946 LeBlond wasn't really designed for carbide so the high speed and the horsepower rating is for HSS, and back then, they were using CS. The high speeds devolped would be on tall gears so pushing a carbide cutter into the work surface would be based on HP. Working in reverse, the SFPM would slow and the quality of cut would go downhill also. Without knowing what horsepower the lathe has or the SFPM it can maintain, I was simply stating that HP comes into play.

I have a vintage Lodge & Shipley that I don't as yet know the age so I've spent a lot of time looking at the old machines. My father-in-law who gave me the lathe, purchased it sometime in the early 1950's. His 40+ year machinist career started in the early 1930's. When he gave me the 2-gal. can of misc. HSS and carbide cutters he explained the pros and cons. The cons for the carbide cutters are primarily the speed and feed rates required. At slow speeds the heat isn't transfered to the chip so it builds up in the work. The carbide inserts work better than the brazed tooling because they have a smaller surface and a built in chip breaker.

I'm not comparing my lathe to the LeBlonde because they are two diffrent machines with decades between their production. I think you know everything is relative, especially in the machinist trade. In regards to may comment, we can start with the quality of the carbide cutter. In 1946 the LeBlond operators manual was mentioning carbide as a cutter with minimum instructions on material-speed-feed etc. -Russ
 
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