How To Grind A Hss Turning Tool

[mikey]

Brino and llhots, thank you! Just basic info but hopefully it will help someone.

 

[Christian Poulsen]

I guess I'm not

Chris, this thread is intended to help our newer members learn to grind a HSS tool. It is a skill well worth learning because it is a skill that is being lost. The industry has moved almost entirely to carbide tooling and almost nobody in a modern shop grinds HSS tools anymore. Who, then, will keep this skill going? Us hobby guys, that's who. For whatever reason we choose to use these tools, we have to grind them to use them and I wanted to give the newer guys a start.

Why not start a thread of your own? I promise not to come in and label something you said as BS.

Sorry Mikey but I am just answering in rebuttal to what seems as anti carbide/misinformation on threads I read ...
...and I also agree and like to see the grinding (sharpening) skill of cutters going onward;
...Sharpening carbide also does just that (Again; I'm not talking about insert tooling in the home, hobby setting (But grabbing a handful from a bucket of dull or chipped throw aways can also be silver soldered to prehard or boring bars and sharpened...(and IMO; My take (experience) with carbide is also good for the beginner/novice and home machinist to know and consider...

...Again and granted; A diamond wheel (I prefer a 220 "face wheel") is the way to sharpen carbide (with a coarser (around 100) diamond wheel on a regular old 8" "snag grinder is the way to rough form one (if needed)...
...But then, with all the same info around here (for instance like you have also posted) on HSS cutter angles and experimentation as applied to different materials, one ends up with a superior cutter (many times longer lasting edge) for most materials (steels,...especially the tool steels) on any lathe (that isn't "slop city" lol)...
....Again; Some carbides aren't much better(**) for wear than HSS and some it behooves one to put a little more nose radius (chipping) for heavy and interupted cuts...
....(**)= again depending on grades (thangs' such as cobalt content, grain size, tonnage of press, hot (or not lol) isostatically pressed...and yada yada

...so with all that, I'll post this link again and notice the braised carbide cutter pics and illustrations (ground forms and angles) are very much the same as HSS:
https://www.google.com/search?q=car...X&ved=0ahUKEwjyqf3oydTQAhWhxVQKHZIDAyIQsAQIGg

 

[Hukshawn]

I honestly find I actually have better luck with ground tools over my carbide bits. I'm really going to use this post!
I have a bunch of 3/8" hss tool blanks coming for Christmas with a bunch more qctp tool holders.
I bought an old Kennedy style tool box off a retired machinist a while back and I've been using all his tooling. Resharpening the right tools to use. I want to grind a bunch of my own nice tools and get them set in dedicated tool holders for the qctp. Gonna be sweeeet. *bookmarked*

 

[mikey]

Chris, my intent was to help a new guy learn to grind a good tool, that's all. As near as I can tell, I provided no misinformation. Instead, I tried to provide information as simply and accurately as I could.

If you're somehow construing that this post is a debate that somehow warranted a "rebuttal" from you, tell me what I said that justified such a vigorous response from you. Maybe instead of pushing your own agenda here, why not start a new thread that states your position and then teach the guys how to do what you think they should do? I may not agree with your views but I'll be damned if I don't respect your right to have them. And as I said before, I will not come into your thread and disrespect you.

I am not a pro machinist like you. I am a lowly hobby guy with only 25 years messing with metal so I'm still learning every day. I am also a Professional in my own field, with over 35 years of experience. In my world, professional conduct is somewhat different.

 

[mikey]

I honestly find I actually have better luck with ground tools over my carbide bits. I'm really going to use this post!
I have a bunch of 3/8" hss tool blanks coming for Christmas with a bunch more qctp tool holders.
I bought an old Kennedy style tool box off a retired machinist a while back and I've been using all his tooling. Resharpening the right tools to use. I want to grind a bunch of my own nice tools and get them set in dedicated tool holders for the qctp. Gonna be sweeeet. *bookmarked*

Like you and Sandan, I have a drawer full of those HSS tools ground by some old school machinist, too. Some of them have some really interesting shapes that I haven't seen before, including some negative rake tools with chipbreakers on them that cut surprisingly well.

Hukshawn, good luck with your grinding. No pressure but if you care to share how they went, I'm sure the guys would enjoy seeing them.

 

[Hukshawn]

Well Christmas is still a couple weeks away, but if I remember, I'd be more then happy to share.

Also, after reading this, i got thinking, and tinkering. I have a bench top 4x21 belt/disc sander in my wood shop I don't ever use with an adjustable compound table.... guess what's going to turn into a dedicated tool grinding machine...

 

[Ozwelder]

Mikey,
you wrote

<This is a discussion about tool grinding, which can be a dangerous business. I highly recommend safety glasses, leather gloves, dust mask and hearing protection. I also use an apron in case something comes apart and hits me. Please be careful and wear your safety gear>

While I agree with most of what you say I would feel wrong to let this go unchallenged.
Gloves of any type on rotating Machinery- A BIG NO NO

After nearly 50 years in the trade I have had to assist injured fools that wore gloves on grinders just too many times.

This is from your own American OHSA.

https://pmpaspeakingofprecision.com/2014/08/13/gloves-and-grinders-unsafe-osha/

I would look at reducing the belt grit size as its far too coarse for anything but roughing.

Ideally a 8'' wheel of about 120 grit gives a near razor finish to the cutting tool. Great for hand grinding drill bits-no drill doctor required.

Safety first for sure

Regards
Ozwelder

 

[Dan_S]

Mikey,
you wrote

<This is a discussion about tool grinding, which can be a dangerous business. I highly recommend safety glasses, leather gloves, dust mask and hearing protection. I also use an apron in case something comes apart and hits me. Please be careful and wear your safety gear>

While I agree with most of what you say I would feel wrong to let this go unchallenged.
Gloves of any type on rotating Machinery- A BIG NO NO

After nearly 50 years in the trade I have had to assist injured fools that wore gloves on grinders just too many times.

I'd add that if the wheel comes apart, an apron isn't going to do anything to protect you.

 

[mikey]

Mikey,
you wrote

<This is a discussion about tool grinding, which can be a dangerous business. I highly recommend safety glasses, leather gloves, dust mask and hearing protection. I also use an apron in case something comes apart and hits me. Please be careful and wear your safety gear>

While I agree with most of what you say I would feel wrong to let this go unchallenged.
Gloves of any type on rotating Machinery- A BIG NO NO

After nearly 50 years in the trade I have had to assist injured fools that wore gloves on grinders just too many times.

This is from your own American OHSA.

https://pmpaspeakingofprecision.com/2014/08/13/gloves-and-grinders-unsafe-osha/

I would look at reducing the belt grit size as its far too coarse for anything but roughing.

Ideally a 8'' wheel of about 120 grit gives a near razor finish to the cutting tool. Great for hand grinding drill bits-no drill doctor required.

Safety first for sure

Regards
Ozwelder

Thank you for your input, Oz. Yes, I recognize the danger of using gloves around rotating machinery. I don't use gloves when working on a bench grinder but I do when using my belt sander. The reason is that when, not if, a belt snaps the tag end can cut you in an instant. I have a scar that taught me this lesson. I am careful to leave only a 1/16" gap between the belt and the table and I use a push block to distance my hands from the belt. When weighing the danger, I feel that doing it this way is an acceptable risk. You are correct, however, in raising this red flag and again, I thank you for making us all aware of it.

I also agree that a 24 grit belt is too coarse for anything but roughing but that is what I use it for, roughing the shape before refining it with an 80 grit belt. The 24 grit shapes the tool fast without requiring excess pressure while also keeping grinding temps down. I tried every grit before I settled on this one and found it to be the best compromise. If you note the straw brown color of the tool bit after a face is ground; that tells me the tool is only getting to somewhere in the high 400 degree range. This is very cool when shaping a bit. Moreover, it only takes me about 2 minutes to grind the side, about 10 seconds to grind the end and maybe 1-1/2 minutes to grind the top of the tool so the belt cuts fast and cool without requiring excess pressure that might bog down the little 1/2HP motor I have.

You spotted the inherent danger of my approach and the fact that the belt I use is quite coarse. First time anyone has pointed these things out and I appreciate you doing so. While I accept those risks we need to be sure others are cognizant of them so again, thank you.

 

[mikey]

I'd add that if the wheel comes apart, an apron isn't going to do anything to protect you.

Yup, that's one of the reasons why I don't use a wheel. The apron works great for catching a fragment of belt that slams into your chest, of that I'm sure. For those using a bench grinder, use your wheel guards and make sure your wheels are sound. An exploding wheel is not an experience I wish to ever have again.

Thanks, Dan.