First lathe, tool bits

Don't get rid of them until you are certain you understand them! They may be very useful forms. Post pictures so we can help identify if you like.

Best case scenario your bimetal bandsaw blade's teeth are only very slightly harder than what you're cutting. That's not going to happen. Abrasive, plasma, torch, waterjet, or wire EDM are the usual methods for cutting tool steel like this, as this is the steel that is used to cut other steel.
 
I'd like to encourage you to learn to grind your own tooling. Sure, carbide inserts are swell and easy to use. However they have two significant draw backs. They break and shatter in no time with interrupted cuts. Also they require high lathe speeds (RPM) to operate properly. Most old lathes are not made with the kind of high RPM's that carbide inserts are designed to work with. OK, Three drawbacks - they are also expensive to buy. As a rule of thumb HSS works at RPMs ranging from 36 to 250. Generally, carbide inserts work at speeds from 400 RPM to 2000rpm, depending on the diameter of your work. Another way to think about it is: HSS speeds should be slow enuf to produce yellowish - straw colored chips. Carbide bits should work at higher speeds that produce hot blue chips. So a lot depends on what your lathe can turn for RPM's. A 1947 15" Leblond is definitely a HSS machine -super slow and powerful.

OK! So also, It's just not that difficult to learn to grind HSS tool bits. Plenty of examples on YOu tube. Plus your local live steam (miniature railroad) club will have someone , or many someone's, who would likely be happy to help you learn how. After a few tries, you will be touching them up all the time. Sometimes just a few seconds on the grinder to apply a keen edge, makes all the difference in the world for producing fine finishes.

Second the advice from Bob and others to use 1/2" bits. Cheap on eBay, particularity the used ones, and more rigid than 1/4" or 3/8".

Good luck and have fun!

Glenn
 
Glenn I respectfully disagree. That may be what the book says. I turn wood, aluminum, brass, delrin and steel almost exclusively with carbide inserts. I DO increase my speed over the recommended IPS for HSS, but unless you're turning really tiny diameters material you won't have any trouble getting these tools to perform, even on a lathe that maxes out at 1200RPM. I get great surface finishes. I've never broken a tool bit. I don't do a lot of interrupted-cut work, particularly on steel, but I do do it occasionally.
I am not against learning to grind your own tools. I'm against doing it before you've learned how to use your lathe. I am proof you don't have to.
 
gheumann said:
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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Hey, who you calling an old timer? ;)

It's good to have a choice. Many guys cannot grind a good HSS tool and there is a difference between choosing and not being able to choose. One day you'll be turning a piece that has a lot of work already in it and you'll have to take 0.0005" off the diameter. That's about the time you learn about nose radii, deflection, cutting forces and the benefits of predictability.

In my opinion, the best idea is to learn to grind good tools and also try some carbide. Then compare them on your lathe, doing the kind of work YOU do, and make your own choices.
 
gheumann said:
I am not against learning to grind your own tools. I'm against doing it before you've learned how to use your lathe. I am proof you don't have to.
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I agree with you, Greg, to a point. If I understand your position, you're saying that you don't have to learn to grind tools just so you can use your lathe and its true, you don't. But what if the OP chooses to do so? Is that not okay, too? Many of us have a lot of experience with both carbide and HSS and many of us choose HSS because it works better for us, not because someone told us to do it or because its the party line.
 
I got a 1/2 gallon pail of tool bits of all shapes and sizes, some new with my lathe. I might be able to put together an assortment for you very cheap if your interested. 75% are cemented carbide, balance HSS.
Aaron
PM me
 
mikey said:
Hey, who you calling an old timer? ;)

It's good to have a choice. Many guys cannot grind a good HSS tool and there is a difference between choosing and not being able to choose. One day you'll be turning a piece that has a lot of work already in it and you'll have to take 0.0005" off the diameter. That's about the time you learn about nose radii, deflection, cutting forces and the benefits of predictability.

In my opinion, the best idea is to learn to grind good tools and also try some carbide. Then compare them on your lathe, doing the kind of work YOU do, and make your own choices.
Click to expand...

Can't argue with that!
 
Go with hi speed. Half inch bits are fine, but you'll use the 3/8 too. Less grinding with smaller bits. Make your inevitable mistakes with tools that you can fix.

Indexable carbide is great stuff, and I use it to save time or machine things that hss won't cut, but the inserts are expensive and unforgiving. The tool holders are also easily damaged, insert seats are hard to come by, and expensive too.

Grinding advice...

A slower grinder is better. Use a quart container of cold water to dip tool bits in. If the tool is getting temper colors, you're spoiling it. Keep it cool. Keep your grinding wheels dressed flat and free of metal embeds.

The tool isn't finished when you're done grinding. The little burr that's left will break off and blunt the edge. This leads to metal buildup on top of the tool and early failure. Take a fine stone and rub the faces carefully. It will more than double the life of the edge.

In common steels, your chips should not have temper colors darker than straw yellow. (You won't see temper colors in stainless unless you are cutting with ceramic tools).

Sent from my Moto G Play using Tapatalk
 
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