Cutting tools questions

Just wondering what other who use these lathes may be using as their cutting tools. When I got my Model C I got with it the original tool holders and square stock tool steel rods some of which were already ground.

Anyone use carbide tips, and if so what tool holders would you suggest... I'm still pretty green at tool grinding, but I Imagine I can make a go of it, just wondering what others have been doing...

Thanks

What you probably have what is refered to as HSS, or high speed steel. These still are widely used as they are cheap, easy to grind, with preferably white AO grinding wheels.

Brazed carbide tips were at one time very popular. But with index-able carbide tip tool holders, their use has shrunk, though still used, these also need to be ground, but with preferably green grinding wheels.

With finishing grinding touches on both HSS and brazed carbide on a diamond wheel if possible.

And there is a whole ton of more modern indexable carbide tip tool holders that the carbide inserts are basically throw aways when wore out. With a whole variety of shapes, geometries, and grades for what type of material to be cut. I recently began a thread on these:
http://www.practicalmachinist.com/vb/south-bend-lathes/recommended-lathe-tooling-insert-type-341711/

There is a whole other mess of choices for tool posts. Those that hold two or four tools, quick change and such are handy. Also what size shank cutting tool do you want to use ? 3/8, 1/2, 5/8, 3/4 and on and on. I think the larger tool can add rigidity, but may depend on size and power of lathe. I have been using 3/4" because my tool holder won't fit a 1". But certain cuts I also need a smaller cutting tool like 3/8".

Lathes like yours are very useful and popular, but they have serious limitations, like speed, power and rigidity. Modern carbide tools are designed for longevity when used with more modern lathes. Carbide is harder and more wear resistant than HSS, but it is much more brittle and are ground with less relief and with more blunt geometries. These carbide geometries require more machine stiffness, rigidities and power than your lathe possesses for optimum performance. Your lathe will perform infinitely better with HSS cutting tools. That said, you can do a lot to improve your lathe's stiffness, by acquiring a modern QC tool post with holders. It makes a HUGE difference. I happen to use a Multi-fix A on my 10k and highly recommend them, but there are others that also work well. Please check the archive. There has been many, many threads on this subject.

There are many HSS tool alloys just like there are many carbide alloy compositions, just understanding the differences can be a minefield for a beginner. In your case, I recommend sticking with HSS. The best performing HSS are the cobalt alloy HSS bits. These are slower grinding, but the edges last very well in all materials. I highly recommend acquiring a good Baldor tool grinder, not a Chinese copy, and learn how to grind your own geometries. I have many HSS tool bits that I have been using for more than 30 years. The skill to grind your own tools is very important and will pay dividends your whole life. Yes, it is possible to grind lathe tools on a bench grinder, I did it for years, but a dedicated Baldor tool grinder with Aluminum Oxide (AO)wheels is much better and easier.

texasgunsmith said:

Brazed carbide tips were at one time very popular. But with index-able carbide tip tool holders, their use has shrunk, though still used, these also need to be ground, but with preferably green grinding wheels.

With finishing grinding touches on both HSS and brazed carbide on a diamond wheel if possible.

Click to expand...

Diamond hand operated hone, NOT a diamond wheel! HSS tools contain iron and have bright sparks when ground.

Anything that contains iron is not to be ground on a diamond wheel.

A hot spark from iron absorbs the carbon from the diamond and dulls the cutting ability very rapidly.

I grind my brazed carbide on a diamond wheel. The steel shank is ground away on a white AO wheel first.


Bill

P.S. The SB HTRL contains good instructions on grinding tool bits.

Can I cut 1/2 x 28 threads with a 5/8 60° cutting tool? I have a BXA tool holder on a 2hp 13x40 engine lathe

Open a very old conversation?
Yes it should work just fine IMO.... but details.
First post Gunguy... I would be remiss without a big handshake and welcome.
Bob

You should be comfortable with both carbide and high speed.
High speed is very inexpensive and OK/Good for many parts. It can quickly be shaped for odd part features like an O-ring groove, a sharp inside shoulder step, turning threads, a certain size radius. most any mild steel, brass, or aluminum parts, and Ok for cast iron, any feature you don't have an insert for.
Carbide tooling is great for repeat parts and harder material, and cast iron.
Understanding how different rake angles and clearance angles affect different materials and cutting forces is very important.
Chatter, poor finish, unable to turn small diameters can be the result of wrong cutting tool geometry (shape), and sharpness.
Most High-speed bits don't need high precision angles, HS turning bits are often just eyeball angles with not even using a protractor.
Thread cutting bits /insert need to be accurate and set to the part accurately.
You can free download How to Run a Lathe by South Bend(better to have your own book).

Tool bits:
https://littlemachineshop.com/images/gallery/instructions/grindingtoolbits.pdf

You can likely practice turning a straight to the size part, turning to a step length, tuning a screw thread. repairing a thread, turning a small diameter part, end facing, putting in a center with a center drill, going to between centers, parting off, tail adjust to make an angle, drilling and screw thread tapping, restoring the tail angle to straight, indicating the OD of a held part, adjusting a 4jaw held part to center, better center a 3jaw part with using shim at one jaw, with the tooling you have.

books:
how to run a lathe book - Search

I too have a 9C lathe. I am also in Canada. This is where I buy most of my lathe tools: INSERTS. Contact Curtis, the owner, directly by email [email protected] and he will ship to you in Canada. You will love the aluminum carbide inserts as they are sharp and leave beautiful finish. All of the carbide tools and inserts are awesome. I use the 1/2 inch bar size as recommended for this size lathe. I just placed another order with Curtis last Friday.

Oh man...should have read whole thread first and looked at posting dates. Oh well, my information is good for those interested.

Engmaxx said:

I too have a 9C lathe. I am also in Canada. This is where I buy most of my lathe tools: INSERTS. Contact Curtis, ....

Click to expand...

Old thread or not I second the vote for Curtis.

good that he posts things like this:

POLISHED & GROUND SHARP EDGES
FOR ALUMINUM, BRASS, PLASTICS, ETC
MIRROR POLISH TO PREVENT CHIP WELDING
.015 NOSE RADIUS

Using any old tool/cutter/insert/bit for any/every thing is not the way to go.

Old thread or not, Michiganbuck's and others comments about using HSS instead of carbide are correct. A lot just don't fully understand even why those bigger, heavier and much more rigid lathes everyone say's it really takes make the carbide work so much better. Abom 79's recent post on Youtube and his build of a missing 3 jaw chuck wrench shows it more than well if your paying attention. A higher HP, rigid, heavy lathe that can take those .010" feeds and fairly large depths of cut per revolution (and more) helps to heat the material to plasticize it as it's coming off as a chip. Compare his surface finishes right off the tool and what most carbide tips produce on the much smaller lathes. There's your visual proof. Note I didn't say carbide can't work, and yes it will also work better with those honed and meant mostly for aluminum inserts. It will even cut metal on almost any lathes including a tiny watch makers, but in general those surface finishes certainly won't be optimal. If we then have to spend a whole lot of time to sand and polish trying to get that smooth shiny surface finish that might well be far less accurate, then you haven't gained anything over just using well sharpened and honed HSS that lathe was designed to use. Carbide might be the only real choice with chilled castings (maybe) or a whole lot harder material than the average mild steel just as Michiganbuck mentioned as well. But expecting carbide to do everything that shows up and never needing to learn how to sharpen HSS just ain't going to happen.

For the most part Hitandmiss's post about grinding steel or HSS back in 2017 is generally correct and the diamond will burn. But it needs to be mentioned for any that don't already know it. That's simply due to the heat generated from the high rpm to start that burning. So it's not quite the blanket and correct statement as it seems. Diamond wheels can still be used under power though. The much slower Glendo Accu-Finish or any other slower machines that run a few hundred rpm or a bit less are fully capable of grinding steels and HSS with no problems using those same diamond wheels. But they were also designed more as a final finish honing method. To be efficient, you'd still rough shape the tool on a more conventional bench grinder first. And using the correct wheel type for the cutting tool material your grinding. I even hand hone my HSS on a Diamond plate most times without an issue. It stays flat and remains sharp to where any stone, oil or water are just about more trouble than there worth. A few things have changed since that HTRAL book was written. And if your buying braised carbide, then so far I haven't used anything better than what Micro 100 produces. The dirt cheap off shore braised carbide is garbage simply because the profit margin isn't there to even halfway duplicate what the better manufactures do every day. With any tool making using more modern than maybe 1960's technology, actual labor cost's have almost zero effect to the out the door costs for any cutting tool. Cheap cutting tools are only cheap because a whole lot of steps, material quality and even methods get ignored or left out on purpose. And yes I tried and failed to use those cheap sets of braised carbide for far longer than I should have before I finally got a bit less stupid.