Models for grinding HSS Lathe Tools

Per mikey's request on another thread, I'm posting my left and right hand HSS lathe tool bits here. Here's one that I think is properly formed.IMG_5766.jpgIMG_5765.jpg

IMG_5764.jpg
 
This one I'm embarrassed to post. I know I messed up with the side angle is way too great, but I'm waiting until my belt grinder is done to fix. To fix on my bench grinder, will be tedious.

IMG_5767.jpgIMG_5768.jpgIMG_5769.jpg
 
devils4ever said:
Per mikey's request on another thread, I'm posting my left and right hand HSS lathe tool bits here. Here's one that I think is properly formed.View attachment 363113
Click to expand...


Is this being held at an angle to the work? It looks like it might rub a little if straight on.

The cutting corner looks worn, or perhaps has material built up on it? Honing should be able clean that up. Try to keep them sharp. It makes a bigger difference than I expected.

Consider trying the square tool. It works great for most work.
 
Yes, it is angled relative to the lathe axis.

I tried to put a radius on the cutting corner with a diamond hone. There may be some material built up on it as well. But, even after re-sharpening them on the grinder, they don't seem to cut any better.

Square tool? I'm not sure what you mean.
 
devils4ever said:
Yes, it is angled relative to the lathe axis.

I tried to put a radius on the cutting corner with a diamond hone. There may be some material built up on it as well. But, even after re-sharpening them on the grinder, they don't seem to cut any better.

Square tool? I'm not sure what you mean.
Click to expand...


One of the tools we discuss in the thread is called the square tool. There is some detailed information on how to grind one toward the beginning of the thread.
 
devils4ever said:
Per mikey's request on another thread, I'm posting my left and right hand HSS lathe tool bits here.
Click to expand...

Thanks for posting pics. Here is what I see:
  • The tool in post #1581 is a LH tool. It has decent relief angles, some side rake but no back rake. The nose radius is only on the very top of the tool and does not extend below that. The end cutting edge angle is very small so this tool will create a lot of deflection as the end edge contacts the work. This tool, as currently ground, will cut but it takes a big lathe to use a tool like this and it will be okayish for roughing but will not take very light cuts accurately.
  • The tool in post #1582 is a RH turning tool. It has what looks to be about 8 deg of relief, some side rake, no real back rake and the nose radius is only at the very top of the tool. The end cutting edge angle is large so it will access shoulders okay but this tool will not finish well except when taking very light cuts because there is no end edge to produce a finish.
For those of you who don't know what this is about, devils4ever stated that he can only take a max depth of cut of 0.010" on his 7X lathe and I asked him to post pics of his tool because his lathe should be capable of much better performance. As you can see, he has kindly done that.

@devils4ever, after seeing your tools I can say that we can fix the LH tool but we'll tackle that later, after you learn to grind a RH tool. The RH tool you showed us cannot be fixed; there isn't enough material left. I suggest you grind a new tool and as @ttabbal suggested, I would grind a Square Tool. Detailed instructions on how to do that can be found here. Grind that new tool and then show us pics and we'll take it from there.

The thread I linked to tells you how a turning tool is ground. It does not tell you why each tool angle is ground that way. The why is contained within this thread. Yes, it's a monster at this point but everything that I know about this subject has been poured into this thread. After you read through this thread I am totally willing to answer questions about HSS tool geometry you may have, although my answers qualify as just my opinion on the subject.

Your lathe is capable of performing vastly better that you might think. Your tools are what is limiting you right now and luckily, that is easy to fix. Grind that Square tool and we'll take it from there.
 
I’m beyond amazed. My 2x72 belt grinder build is finally complete and it was time for a quick test run before dinner. I slapped on a 36grit Norton ceramic belt and grabbed a junk 3/4 inch piece of Chinese HSS. Ground a 35 angle about .250 wide. It took maybe 15 seconds to grind and the bit was barely warm to the touch.


Sent from my iPhone using Tapatalk
 
Yup. A 2x72 with ceramic belts eats even HSS for breakfast. Cobalt makes it work a little bit... :)

Congrats on the build! Always nice to see a tool you build work for the first time.
 
Yep, welcome to the 2x72 club. I’ve lost count of how many belt grinders have been built as a result of this thread alone. I’m pretty sure mine is the most often used tool I have in my garage.
Thanks Mikey
 
I'm in the process of doing my 2X72 belt grinder build. I should have everything done in the next day or two except the tool rest. I'm working on the platen currently, but I can run a belt on it now. So, I might wait until this is completed before trying to create a square tool. The bench grinder is so slow.

I bought 36, 60, 100 grit ceramic belts for it along with 220 AO belts. I can't wait to try it on HSS. This is was the main reason for building it: HSS lathe tooling. I have a fine diamond hone. Do I need other grits? The square thread claims to need coarse, fine, and extra fine ones.
 
You must log in or register to reply here.
Back
Top