First lathe, tool bits

[Bob Korves]

I like the older HSS and brazed carbide bits better than the new ones. They seem to be higher quality. In HSS I like the MoMax best, and the Rex (Crucible), Morse, and Ludlum as well.

 

[Glenn Brooks]

looks like a good price for a bunch of bits. Actually, with your original collection of bits, Polish them up with a wire wheel in your grinder if you have one to remove the oxidation on the surface. Then you will know better which you might be able to use. The short 1"-2" bits can be mounted back to back in one tool holder. One end does facing cuts, switch around, the other end does turning cuts. Very efficient use of short cutters.

Any of the long bits you can't use because of shape, just grind the ends off into a right or left handed turning bit, or whatever you need. Really doesn't take much time to do, and gives them a new life. Same with the thread turning bits.(60* angle, pointy end in the center of the bit). Looks like you have several. Probably you will only ever really use one of them. Convert the long ones into roughing and finishing tools- they each have different shapes- and see what you can do to tweak finishes etc... that's more or less what I have been doing to learn how to use the various types of HSS geometries, and develop a feel for proper cutting edges and shapes.

BTW, I mounted a small 3" diameter grinder on the bench beside my smaller bench lathe, where I store the bits I use. At the slightest sign of not cutting properly, I can just reach over and put a fresh edge on the bit - sometimes without removing it from the tool holder.

Good luck.
Glenn

 

[ThunderDog]

I agree with Reeltor in post #25. Those import mystery meat a.k.a. brazed carbide are terrible. I bought a small set when I first got started. On the very first cut it broke the tip right off. So, I put in another one and thought it was operator/beginner error and backed off on my depth of cut only to see the same thing. Mind you, I had a bunch of HSS bits that I bought at a yard sale for $10. It was then that I decided to force myself to learn how to grind. I took a methodical approach and actually did what worked for me. I made a very basic jig out of wood and learned with a 1"x 30" belt sander. I know what you're thinking, "This Thunderdog guy must be dumb!!". It worked, it was slow, I didn't own a bench grinder at the time, and I made some decent chips with that first knife edge bit. Over time I kept revisiting the topic through my L.H. Sparey book(my favorite to this point); knowing that I wanted to learn and should learn how to make proper HSS bits on a bench grinder. I bought a grinder and started learning and made mistakes along the way. Only now have I just started to get into carbide inserts. I agree with BOTH sides of the table when it comes to just making stuff vs. learn to grind first. I can see the validity for both camps of thinking.
Regardless, have fun and get out there with that machine!! Just don't be tempted to purchase those horrible import brazed carbide things. Let it be known that I'm not against brazed carbide bits of higher quality.

 

[Eremius]

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.

It really depends on how big what you're turning is. SFPM is king. It doesn't take much diameter to make up for your lack of RPM.

 

[Jmanb13]

It really depends on how big what you're turning is. SFPM is king. It doesn't take much diameter to make up for your lack of RPM.

That is a good point. I looked up recommended SFM specs for different materials. At 500 RPM It looks like anything above around 2.5" gets me in the carbide range for steel, but i'd have to be in the 6 or 7" range for aluminum.

 

[whitmore]

Thanks for all the suggestions!

I would like to learn to grind my own bits....

I dug out all the bits in the box of stuff I got with the lathe. Here is what I currently have...

Well, that's LOTS of tool steel, you won't have to buy blanks for a while. It's
a good thing you want to do the grinding.

If you don't have a project in mind yet, this would be a good time to wire-brush the bits
you have, and examine the edges. Chuck up some scrap and see how they
cut, make a few washers, wedges, or widgets.

And, try truing up and sharpening bits that don't cut well. I find that
a stereo microscope is a great help in edge examination, but even a jeweler's loupe is good.

Tuning up the lathe was good, now for sharpening you'll want to tune up the grinder, too.
A flat stone, or (better) a selection of hones, does the fine tuning on a ground tip.

 

[Downunder Bob]

I finally got my 1946 15" Leblond lathe cleaned up and running. I have added a CXA QCTP with holders.

I'm planning to buy a set of HSS bits to grind to shape. How many and what size would you recommend as a starting amount for the different profiles.

I was thinking of 3/8 by 3/8 Grade M2 bits.

What would be a good starting set of bit profiles to have on hand?

I finally got my 1946 15" Leblond lathe cleaned up and running. I have added a CXA QCTP with holders.

I'm planning to buy a set of HSS bits to grind to shape. How many and what size would you recommend as a starting amount for the different profiles.

I was thinking of 3/8 by 3/8 Grade M2 bits.

What would be a good starting set of bit profiles to have on hand?

Congratulations on getting the lathe cleaned up and running. I'm not sure how much previous experience you've had, but your question suggests not much. I'm not familiar with the Leblond brand of machines, but the age 1946, that's getting old, and "the size 15", getting big, would suggest to me that it would not be a very high speed machine, and therefore carbide inserts would not be very useful at the smaller diameters. By all means use them on larger dia's, and very hard materials, they are very good.

Back to your own thinking of 3/8 HSS, probably the most universal size for medium to large machines and certainly the right size for a 15" lathe, unless you're going to only be doing fairly small work. you might want to get a couple of 1/2"bits for the heavier jobs, but otherwise I'd stay with 3/8.

Certainly learning to grind your own tools is quite a challenge, although not as difficult as drills, although all the same rules apply. But it is well worth the effort, and skill to b e proud of. There are plenty of discussions on angles on this site as well as others, so I won't get into that, other than to say there is no absolutely correct way to grind a tool as long as your relief angles are reasonable, and it works, remember that not enough relief will not cut, and too much weakens the bit and reduces the ability to get the heat away, it also takes longer to grind. If the tool you grind works well then it is near enough to correct.

I would start by enquiring at what quantity of bits do you get a good price break, for instance a packet of 10 or 12 , then buy that quantity. If there is no advantage then buy 5 or 6. I'd start with a general purpose turning, facing bit, 1 for RH and 1 for LH, I'd add a 60deg thread cutting tool, regular right hand threads only, I'd leave the LH tool until you need it, maybe never. I'd also leave the 55 deg thread tool until you need it. For parting off I'd go with a specialised parting tool with holder I prefer the wedge type.

A couple of boring bars with holders will get you started. Remember save all your broken drill bits, including center drills and tool bit stubs the are very useful for making boring bars.

Have fun,

Bob.

 

[intjonmiller]

Remember save all your broken drill bits, including center drills and tool bit stubs the are very useful for making boring bars.

Yes! I have a box labeled "dull/broken bits" where I toss anything carbon steel or better. Even an old spade style wood drill bit can become a useful tool of some other kind down the road. If you have family or friends in woodworking, construction, manufacturing, etc. you can ask them to save their "junk" bits as well. SDS-type hammer drill bits are particularly good as the shanks are very tough and the tips are often carbide. Once they round off that carbide a little they often get tossed. I've picked up several off of the ground at job sites (when I used to work in construction) so I can sharpen them into something else when needed. Tiny drill bits can become the knives in a shop-made wire stripper or the tip of a new scribe.

 

[Highsider]

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.

 

[Al 1]

Go for the E-b-- lots. You can get a pile for a good price. Practice your sharpening with different types of cutters.
(HHS and carbide). I got into metalworking in 2010 and have many cutting tools, probably more than I will ever use.
None were purchased at new product prices.
Al.