Tool Height

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Well, there is nothing inherently dangerous about that method. It is simply a method of obtaining an high positive top rake. This is a skiving cut. I will say that on the majority of materials, it wouldn't work really well. The knife-like edge would probably be too fragile to last very long. It's the same as a wood lathe cut where you hold the skew chisel on the top of the work and draw it back towards you until you achieve a controlled cut. I've turned many a print roll with a similar cut. They were a hard rubber. I'd say that for aluminum and brass, etc., that tool would do just fine. Of course, the further from center you get, the less accurate the dial graduations and/or indicator reading the DOC would be.


Now to the flavor of this thread. It is a difficult thing to express one's opinion with zeal without chancing alienating someone, but there are some people who speak their mind freely without regard for how it may be received. If that is left unchecked, hurt feelings can result, and friends become enemies. If this were a face to face conversation with a group of good, beer drinking buddies, then you can probably get away with nearly anything. It doesn't mean anything if the tone of voice is kept good natured and a friendly poke is given. On the Internet, all you get is black and white text. No face, no voice. In all this, care must be taken on both sides of the "conversation" not to make someone think it is a personal attack. I'd like to think we are all well-mannered adults and would never make a personal attack on who, in reality is a perfect stranger. We are above that, correct? This is all a part of what we want this place to be like: Different. Different from other places where you may be afraid to post something that others may think is stupid.....and say so. We're supposed to be comfortable here.

So I'm not picking on anyone in particular. I'm saying this for the general population. If this will help adjust your thinking a little, then great. We just want the place to stay peaceful. For everyone.
 
sssfox said:
1200rpm,

I used to belong to a woodworking forum and had to quit because of a situation that started similar to this.
Someone asked a question and I responded with a perfectly valid response. Another member attacked me in a similar fashion because he didn't like my answer.
He then started attacking me every time I responded to anything. After a week or so, I quit responding to questions and he started sending me emails questioning my experiences and qualifications to answer any questions posted by others.

I finally had to quit and haven't been back since. It was just a forum and I didn't need the grief. What made it worse was that he was a moderator.

On one hand, there is valid discussion and on the other, there is someone who wants to be right by any means.
I'm not accusing anyone of anything. It's just that I have seen this before and it doesn't always have a happy ending.

I hope we don't have the same issues here.
Click to expand...


Ain't gonna happen here, because we have moderators and an admin who won't let things go too far to where someone is hurt.
We don't let grudge-holding occur, like what you describe in your thread. We don't let people who do that become moderators, or admins.
Even as owner, I have to set aside my feelings for people who haven't treated me so nicely in the past.

I have read over the thread, and I believe I understand what is going on.

Gordon is concerned about safety, which I applaud.
But let's remember that (a) reasonable minds can differ as to what is safe, (b) warnings only go so far, and (c) when your warning is delivered in a way the other person finds harsh, they will feel slighted and won't learn anything.

In this case, the warning has been delivered. You guys have to "agree to disagree." What happens from here on is in the hands of the end-user.
I am reposting what Tony said, because it bears repeating:

"It is a difficult thing to express one's opinion with zeal without chancing alienating someone, but there are some people who speak their mind freely without regard for how it may be received. If that is left unchecked, hurt feelings can result, and friends become enemies. If this were a face to face conversation with a group of good, beer drinking buddies, then you can probably get away with nearly anything. It doesn't mean anything if the tone of voice is kept good natured and a friendly poke is given. On the Internet, all you get is black and white text. No face, no voice. In all this, care must be taken on both sides of the "conversation" not to make someone think it is a personal attack. I'd like to think we are all well-mannered adults and would never make a personal attack on who, in reality is a perfect stranger. We are above that, correct? This is all a part of what we want this place to be like: Different. Different from other places where you may be afraid to post something that others may think is stupid.....and say so. We're supposed to be comfortable here.

So I'm not picking on anyone in particular. I'm saying this for the general population. If this will help adjust your thinking a little, then great. We just want the place to stay peaceful. For everyone. "

I don't want anyone to feel picked on in this place. Or to leave, or feel they have to. We have reached an impass here and have to agree to disagree. One day I will tell you guys the story of how I ended up going back to college. (http://www.hobby-machinist.com/show...-on-taking-criticism-wisely?p=50372#post50372)

I'm locking the thread for a bit to let everything cool a bit.
Peace.

Nelson
 
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Well, I think we can continue this discussion. It does seem that not everyone agrees on the subject, and that's fine. I'd request that all the comments made here are thoughtful, considerate and not intended to provoke anyone. Of course, this thread can be locked again, or deleted. Try to keep that in mind, please!
 
For clarity, my understanding of the term "on center" in lathe work involves a plane parallel with the ways of the cross slide and compound. The center of the spindle axis is a set distance from the ways. Therefore, any tools can be said to be above, on, or below center as they relate to the plane that contains the spindle axis center. Above or below that plane refers to the tool lying not on that plane, yet moving in another plane, parallel with that plane, because the tool moves on the ways.

That was clear as mud....but then, I've not had coffee yet.
 
1200rpm said:
since i threw a curve ball into the discussion...to avoid confusion, i figured i should try to clear it up. :)

this is a very sharp tool with tons of front clearance and has a slight hollow grind from the bench grinder- even though it`s way above center it will still cut.

it`s great for finishing cuts on difficult materials- if this doesn`t work, it`s time to break out the carbide! :)

admittedly, a professional would never do this today, you have to use a very slow speed and it takes a long time.

1200
Click to expand...

Thanks 1200

I didn't get it from the book but your picture actually clears it up for me. Its kind of like you are moving the tangent point higher. So even though the tool appears to high from the perspective of the tool holder if you look at it from the perspective of the cutting edge is it right. I can see how this would be better for this kind of setup. From the cutting edges perspective the line of force is going more down the length of the holder instead of 90 degrees to the holder. Giving those old style holders effectively more rigidity. Its also funny your tool looks like how I grind tools (ie the way I was taught) which tends to be to great an angle. I wounder if the person that taught me had this in mind but never got around to showing me this part or I just didn't get it at the time. Of course now I just use my QCTP and the grinds are totally different. This is my cool fact for the day.

Thanks
Jeff
 
Gordon Clarke said:
Back to the picture :)

That tool might cut but the smaller the diameter of the piece the tougher things would get and end with "Mission Impossible". I wouldn't personally use a tool with that angle for cutting anything much harder than perhaps brass. For cutting steel it'd have to be ground often.

Gordon
Click to expand...


You are spot on with that. One of the dangers of learning on AL is having to relearn so many things on steel. My angles are much steeper for steels and other such. (I do a lot of SS work) But I still have some tools with what I think of now as crazy angles for plastics, brass, and other soft materials. My regular HSS tools are probably still ground at to much of an angle but I am getting better.

Jeff
 
I'm willing to bet that this section of "How to Run a Lathe" is part of what is causing the current "confusion":





Of course this was printed before the development of the QCTP which hold the bit at a different angle.

-Ron
 
Thanks Bill, never to old to learn now I know what HTRAL means. Still got a 100 more to figure out.
And I do have a SB book but never clicked my brain. Not caught up with the 20th century yet.
And I am one more to vote for, get it close with a pinched ruler, face the end, now reset tool height to
perfect center, center drill it- go to work. I always use my dead/live center just about for everything.
 
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