HSS or Carbide inserts fot lathe turning????

[pipehack]

I picked up a tooling package from "Little Machine Shop" includes the 3/8" carbide tool inserts. TCMT 21.51 style inserts. I've watched videos, read several chapters on HSS tool grinding and I just can't seem to do it right. I've also broke several carbide inserts or chipped them I should say. What am I doing wrong? Am I trying to take too big of a bite? Embarrassed about the HSS tool grinding. Using a bench grinder and am dressing the wheel. I also have a belt/disc sander. Most if not all my cuts look like Ray Charles was using a beaver to turn down the steel. I've only really made 2 weld in bungs for mounting a gas tank on my motorcycle. I've had this a little over 6 weeks and obviously getting frustrated and somewhat discouraged. HELP! HELP!! HELP!!!

 

[wwunder]

Hi, I'm a rookie too, but have been grinding some of my own HSS bits. To start what lathe are you using and what type of steel are you cutting? It could be that your bits are ok, but you have a lack of rigidity or are taking too much depth of cut. How is your work being held and are you using the tailstock center?

FWIW, I started out with a little 6" dunlap lathe (not too stiff) and bought a set of Taig preground 1/4" HSS bits. I had more issues due to improper work holding and too much cut than with the grind of the tool itself. Now I have sharpened the bits many times and started grinding some of my own modelled after the first set and everything seems ok. I can't help with the carbide as I don't use it.

 

[Codered741]

First things first, DON'T GIVE UP!! We have all been there, been frustrated at our machines, the tools, and the parts that we are trying to make! You have taken the first step, reach out for help, now help us help you!

The best way that we can help you in this case, is to first see photos of your setups, tools (carbide or otherwise), and as detailed information as you can provide on the type of material, diameter of the material, speed of the lathe, and depth of cut.

There are many opinions on HSS vs Carbide, but I personally think that carbide (or pre-ground HSS) is a good place to start for the newbie. It gives you a known good cutting tool, so you can make swarf without first burning all your fingers grinding HSS. Then later on, when you are comfortable with the machine, you can work on grinding your own tools. If you were in a class or had a mentor, it would go the other way, learn to make tools first, then the machine, but going solo as a newbie, I like a tool that I know SHOULD work.

As far as chipping carbide inserts, well, it happens, especially when first starting out. Carbide is very hard, and therefore brittle. Taking heavy or interrupted cuts on less than rigid equipment can make chipping worse. Carbide requires a very rigid setup to work efficiently, which is why information about your machine and setup will help us determine what the problem is.

Lets start with some photos of your equipment, setup and cutters, and go from there. Don't get discouraged, we are here to help!

-Cody

 

[Splat]

FWIW, this is why I went with the tangential holder. Only one face is needed to be ground and you're good to go. I had tried some practice grinds using old pieces I found at a flea market. The results were not good after many tries. Yes, anyone can do it but it does take practice. Like anything else, some guys get it faster than others. For me, I knew I didn't want to be taking hours to grind my tools. You can make your own tangential holder if you have a mill and others have rigged up their own even using old Anderson style holders. I just wanted to give you another option though grinding your own tools is great feather to have in your cap if you can do it.

 

[itsme_Bernie]

Hey Pipehack-

First- I would stay away from the carbide until you get some other things nailed down. You have a lot of variables here, so staying "safe" on a few of them will help you.

I am not sure what is happening with your HSS, but as was stated above, you can get cheap pre-grinds to get past the hump, and see a good grind in person. Sherline sells them too if I recall. This also eliminates that variable if you are doubting your grinding.

Are you attempting to cut welded places on the metal? Or just cutting something that WILL be welded? Also, I am curious of the kind of steel you are cutting.

Definitely pics of your setups and your grinds would help us help you. I'm sure your machine is great, just gotta set you up right.


Bernie

 

[DMS]

What type/size is your lathe? The reason I ask is that carbide is tricky on smaller lathes, and you have to run it differently to get the best out of it. On my Monarch, I can take a pretty decent cut, and the machine is rigid enough and powerful enough to handle it. I get pretty good finishes like this too. On my little 7x14, It took me a while to get carbide to "work". It took as much speed as I could throw at it, and a fairly light cut (10-20 thousands on the radius IIRC) before I got things working right. Even then, I never got very good results with aluminum.

Chipping carbide is usually due to manhandling it, or interrupted cuts. Carbide is very hard, and also very brittle. It can run hotter and logger than HSS, but it can also fail in an instant if something shifts.

If you post some pictures of the tools you have ground, we can probably give you some hints. There are also some decent videos on youtube that walk you through the process. Check out MrPete and Ox Tools on Youtube. One thing to keep in mind is that you may be doing just fine; some materials are just darn near impossible to get a good finish on (such as cold rolled mild steel).

 

[pipehack]

Thanks guys.. It's an Atlas/Cman 6" lathe. Some of the pieces are unknown because I got them off a jobsite. I think the piece I'm messing around with may be hardened to an extent. It's part of a link to an escalator from the airport I used to work at. 1" in diameter about 2 1/2" long. I'm working close to the chuck so I'm not using a steady rest, which I think could be a pain in the rear to set up anyway. Most of my other steel is from one of the big box stores. Either CRS or HRS. I'll post up some pics in a little while. I'm off on a work injury right now. 3000+ pound scissor lift driven by an apprentice I was working with rolled on top of my foot. I can stand for a short time them it's time to chill. Fractured a couple of bones in my foot. Trying to steer clear of the pain meds till I really need them or at bedtime. When I got this lathe I thought it would be east peasy. WRONG-O! I was surprised at the amount of set-up time that's needed. I would like to start using HSS because of the cost and ability of sharpening them.

 

[davidh]

then there is the tubal cain videos that will knock your socks off. he make its look pretty dang easy. I started out using both. bought some cheap carbides, some lived,, some didn't. I chalked it up to practice.
actually sharpening tools to cut is simple, making them do a nice clean cut is experience and more experience.
as been said, cutting a weld is a *****, but so is just trying to cut a diameter on a shaft.
don't give up. watch some videos. they will tell you how. . . . . to sharpen.

 

[stupoty]

If your recouperating your foot then some grinding practice can be done sitting down

Having pre ground hss cutters as somone suggested is a good idea, i luckily got a lot of used quite well ground tools with my first 2nd hand lathe its come in very handy to look at them from time to time when im grinding a cutter.


my bench grinders not very good and has got a lot of vibration so lately ive been ruffing with the grinder and finishing on an oil stone, especially adding the radius as thats where i mess up on a grinder quickest, i generally sit outside in the sun so i can look at the tool real good when im doing that.

Stuart

 

[itsme_Bernie]

Hey Pipehack-

That's the lathe I learned on! I will be happy to help you tune it up and get you going.
I would stay away from the carbide up until you get things nailed down with HSS.

If the part you are working on is hardened, it may be a little beyond your abilities at this point. But keep it around. You will be able to work it shortly. I worked with every type of metal, all different sizes, diameters with my 618 with great success. I could part 3 inch steel with no problems. CAREFULLY, but no problems.

Is it easy for you to take pics with your phone or camera and post them to us? Pics of the pieces you cut (and don't like the finish), your HSS bits that you ground.

How does the spindle feel when you grab it with your hand, from the thread? Besides turning, does there feel like any movement up or down?

There are ways to easily tighten up the whole machine in ways that will make machining a joy.


Bernie