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Models for grinding HSS Lathe Tools

mikey

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Thanks so much for your response Mike. I really appreciate the time, effort and knowledge you have put into this thread and with guiding me. I've only been at this hobby machining for a couple of years, on a part time basis and it seems like the more I learn, the more I discover how little I know. I've struggled with finishes and getting to target depth for quite a while. Sometimes it seems to come together but I don't know why and most times I just accept the less than great finish and the close enough size. I have found that with this grind I get a far superior finish and it is waaaay easier to hit the target size. Also, very importantly, it is consistent, even for me. The only way I could get a decent finish with mild steel before was to use a shear tool with a very small DOC (0.001" or 0.002") and the slowest feed rate. Now I get better finishes consistently and I don't have to sneak up on the final size with a bunch of very small shear cuts.

I'm glad to hear the long strings are normal and will not concern myself with that when taking roughing cuts.

I'll take a closer look at my honing, especially the top surface, as that is where I think I may not be getting the finish right.
You're welcome, HB.

One key point I was trying to make about stringers is that they are dangerous. They will cut you but more importantly, if they catch your hand or arm and then they wrap around the work then they can pull you into the lathe. If you have a big nest of stringers, stop the lathe and clear them. Please don't get hurt.

I'm glad the tool is making your work easier and more accurate. I've been criticized before about the angles on my tools. Some experienced guys say the angles are too much. I grind them this way because it works better for me - roughs better, sizes easier and finishes far more accurately. In the end, that is what counts.

Yeah, try to hone until there is no light reflecting off your edges. A sharp tool will cut quite a bit of stock before it needs honing. Hang in there, HB; it will come.
 

bfk

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Bonehead was over again last night - he wanted to catch up on this thread. He was happy to see that some of you have been making progress but he wanted to make a point. He says, "... the real point of altering the geometry of a tool to reduce cutting forces is not so much to enable deep cuts; it is to improve accuracy in small cuts. And it doesn't matter if the lathe is big or small."
Your friend Mr Head is dead right. I got a little time yesterday to play with the RH tool, the one I had used to take deep cuts last week. This time I was seeing just how small a cut I could get. I managed to consistently take .001 off the diameter to a piece of 6061, and get a nice finish. Considering this was the first MikeyModel™ tool I had made, I'm very happy.
One reason I got into this was to learn new things before my brain atrophies, and this whole grinding process has been a great learning experience.
Thanks again.
 

mikey

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Your friend Mr Head is dead right. I got a little time yesterday to play with the RH tool, the one I had used to take deep cuts last week. This time I was seeing just how small a cut I could get. I managed to consistently take .001 off the diameter to a piece of 6061, and get a nice finish. Considering this was the first MikeyModel™ tool I had made, I'm very happy.
One reason I got into this was to learn new things before my brain atrophies, and this whole grinding process has been a great learning experience.
Thanks again.
Like your trademarked name there, bfk! ;)

Yeah, Bonehead is right but I don't want to swell his head with praise - he is already insufferable. Nah, just joking. I will pass along your comments and I'm sure he will happy to hear it. I think its great that you can grind a tool that lets you enjoy your lathe, bfk. Good for you!
 

mikey

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Guys, I meant to tell you but kept forgetting. When you make a turning pass with your tool it is common for guys to just reverse the saddle feed wheel with the tool still in contact with the work to get the tool clear and then dial in a cut for the next pass. Personally, I don't do this because I feel it dulls the tool to drag the tip in reverse. I back up the cross slide a bit to clear the tool of the work and then re-position the saddle before dialing in the next depth of cut.

If you use carbide inserts the same thing applies. Drag an insert out of a cut and it can chip on you.
 

HBilly1022

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Yesterday I was making a little knurled head bolt to replace the set screw on my lathe saddle adjustment collar (sorry didn't get pics) and found the need for a left hand tool but didn't have any except for some of those cheap indexable carbides I got a long time ago. I had to cut the shaft to 6mm diameter and tried the carbide but it left a terrible finish and I was afraid to take too much DOC for fear of breaking the shaft off. So I turned one of your LH cutting tools. Wow, what a difference. I could easily take cuts without fear of breaking the shaft. It was slicing through the steel cleanly and left a great finish. Oh ya, I also got to target size with no difficulty.

Loving these new tools. Thanks Mike.
 

mikey

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Yesterday I was making a little knurled head bolt to replace the set screw on my lathe saddle adjustment collar (sorry didn't get pics) and found the need for a left hand tool but didn't have any except for some of those cheap indexable carbides I got a long time ago. I had to cut the shaft to 6mm diameter and tried the carbide but it left a terrible finish and I was afraid to take too much DOC for fear of breaking the shaft off. So I turned one of your LH cutting tools. Wow, what a difference. I could easily take cuts without fear of breaking the shaft. It was slicing through the steel cleanly and left a great finish. Oh ya, I also got to target size with no difficulty.

Loving these new tools. Thanks Mike.
It's great to hear that you're gaining confidence and experience with your new tools, HB - your experience was a really nice way to start off my day!

There are times when carbide is the best choice, and you might consider buying an SCLCR tool holder and try some CCMT and CCGT inserts; they work much better than the older style triangular inserts. If you do this, go for the smaller nose radius inserts to keep deflection to a minimum.

There are also times when roughing and sizing with carbide but finishing with HSS is the best approach. I sometimes do this when working with hard materials and need to hold tight tolerances. A carbide insert will not allow micro-cuts but a HSS tool will. It works.

Bottom line: know your materials and know your tools, then use the best tool for the job at hand.

You're doing great, HB!!!
 

Metal

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@mikey:

As this thread expands can you move your excellent tutorial posts and edit them into the first post?

At 11 pages and no sign of slowing down its going to become a bear to page through this thing to find the meat eventually :)
 

mikey

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I don't know - which posts do you guys think are important? I also don't know if the new software will transfer images and stuff so I'll probably need to contact one of the Mods to discuss it. Can you guys make a note of which posts you think should be consolidated and I can try to create a .pdf file and post that; might be easier. There is now a number in the upper right hand corner of each post.
 

Z2V

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I'm thinking that someone mentioned doing that sometime back. Of course I'd have to read all 11 pages to find the post.
LOL
 

mikey

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I suspect that the guys who really want this info will read the whole thing, mine it for the stuff that matters to them and then create their own document.
 

DHarris

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Ok, I just checked it and it seems to work for me.
Now, if a moderator can figure out how to "stick" it to a start post or someplace else easy to access we are home free!
 

mikey

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Ok, I just checked it and it seems to work for me.
Now, if a moderator can figure out how to "stick" it to a start post or someplace else easy to access we are home free!
Thanks, Dave - that saved some work. You weren't kidding; 23 pages!
 

DHarris

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I have the MS word document that I can e-mail to anyone who wants it in case you want to add your own inputs / references for one package (can't attach it to a post - says not allowed file type?).

Dave

p.s. Glad to help in some small way Mikey!
 

mikey

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You did help, Dave - thank you!

I was just thinking - if Bonehead wrote this, it would be maybe 2 pages and by the time you were done reading it you would know more but you would have a headache and also be pissed off!
 

mikey

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I've never used a shear tool, mostly because I never felt the need for one. My tools finish well enough for me.

If you and anyone else would like to make a model or discuss grinding one, please feel free.
 

brino

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okay I wanted to play too!

I have always used a bench grinder to shape and sharpen my lathe tools in the past.
But I wanted to try this MikeyModel™ too.

The problem was my current bench sander would not allow access to the edge of the belt.
I fixed that here:
http://www.hobby-machinist.com/thre...-sander-to-access-the-edge-of-the-belt.63436/

and then proceeded to create this tool following @mikey's instructions:
oblique.jpg

the end:
end.jpg

the side:
side.jpg

the top:
top.jpg

I still need to hone it and try it.

-brino
 

mikey

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Wow, that came out really nice, Brino! Geometry looks good and the finish is really nice, with no heat-related color changes. It looks like your very cool sander mod worked well because the rake angles came out great.

How do you like grinding tools on the belt sander vs the bench grinder?

Let us know how the tool works for you. I really hope it meets your expectations but if it doesn't then change it until it does.

I have to say that you guys have been grinding some really nice tools, really nice.
 

brino

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How do you like grinding tools on the belt sander vs the bench grinder?
You already mentioned one of the biggest differences -HEAT!
The belt sander seems to keep the tool bit cooler.
I was using a push stick and dipping in water frequently.

I hope to get the honing done and the tool tested one evening this week.

-brino
 

mikey

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I think the shear tool is a good addition to the arsenal because it does produce really nice finishes. I do not know anything about the geometry though, so if you or someone else would like to discuss how to grind one and how the geometry works I think it would be really interesting.
 

Doubleeboy

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Shear tool, face rake 15 to 20 degree, end clearance rake 7+ degrees. very easy to grind. Depth of cut should be limited to a thou or two max. Works great even with M2 from China. Machinist workshop did an article by gunsmith editor Steve Acker a few years back, good stuff.
 

cascao

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Shear tool is good for finish, everybody agree. But it is great too when you need to remove a very small amount of material. Conventional tool sometimes have a grab-no grab behavior.
 

mikey

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I will need to grind one of these vertical shear tools one day and compare it to my general purpose tool for finish potential and accuracy with small cuts. My oldest square tool will take a tenth depth of cut and produces a really fine finish but that doesn't mean the shear tool can't beat it. We'll see. I'll report it here when I compare the two tools.
 

Ken from ontario

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My oldest square tool will take a tenth depth of cut and produces a really fine finish
I affirm that statement to be true, I do have one of Mike's square tool that he personally ground and honed . I know he calls it a "general purpose"tool but IMO it is a perfect tool for dimensioning, when I need to take off the last few thou, and also to get the best possible finish, this square tool hasn't let me down yet and based on the way I use it , it never will.
It will be a good challenge for you Mike to grind a shear tool that can outperform your square tool but I am looking forward to seeing what you'll come up with.
 
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