Newbie - Buying first metal lathe

All discussion about lathes including but not limited to: South Bend, Hardinge, Logan, Monarch, Clausing and other HSM lathes, including imports

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pat1027
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Re: Newbie - Buying first metal lathe

Post by pat1027 » Mon Jun 17, 2019 5:36 pm

Harold_V wrote:
Mon Jun 17, 2019 4:00 pm

Is the finish you're getting in keeping with your desire? If not, do you understand why? Do you know what to do to correct the problem? All of those questions are easily answered if you understand tool geometry.

H
The finish I get now is what I desire. It was the tool and knowing when to support the piece with the tail stock. As I cast about for what other people do with grinding I came across this video below. Part way through I said "Huh, can it be that easy?" turned off the tube and ground a tool, then another. After a bit the tool wasn't perfect but there was a nice gleaming surface. Light cuts were repeatable.



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SteveHGraham
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Re: Newbie - Buying first metal lathe

Post by SteveHGraham » Mon Jun 17, 2019 6:25 pm

Most of what I do is aluminum, and I couldn't ask for better results than I get with carbide.

I have no doubt that HSS does some things better, but man, it's nice, just grabbing that same old carbide tool and getting it done.
Every hard-fried egg began life sunny-side up.

John Hasler
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Re: Newbie - Buying first metal lathe

Post by John Hasler » Mon Jun 17, 2019 8:41 pm

Harold_V wrote:
Mon Jun 17, 2019 4:11 pm
Before you, or anyone without a little experience, can judge that they are achieving good results, they must have something with which to compare. Sticking with any given type of tool does NOT provide that experience.

H
Thus my plan to start experimenting with insert tooling as soon as I get around to fabricating a holder.

RSG
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Re: Newbie - Buying first metal lathe

Post by RSG » Wed Jun 19, 2019 7:26 am

To add my two cents to Carbide or HSS, I had no choice but to learn how to grind my own tooling due to the need to solve complex problems I had trying to cut certain profiles. I now have over 20 different profiles dedicated for various needs for the stuff I produce. Everything from steep angled chip breakers to odd shaped round nose form tools. The only thing I use carbide for is facing and turning.
Vision is not seeing things as they are, but as they will be.

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Re: Newbie - Buying first metal lathe

Post by John Hasler » Wed Jun 19, 2019 7:39 am

No back rake visible in the video.

I use a die grinder to add a chipbreaker.

Harold_V
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Re: Newbie - Buying first metal lathe

Post by Harold_V » Wed Jun 19, 2019 4:13 pm

John Hasler wrote:
Wed Jun 19, 2019 7:39 am
No back rake visible in the video.
If you're making reference to the video above, he starts out without back and side rake, but addresses those features later in the video.
I use a die grinder to add a chipbreaker.
Any way you can create the desired chip breaker is more than acceptable, but the chip breaker should be such that the tools aren't limited to shallow depths of cut, as his are. He seems to understand cutting tool geometry well enough, but at his own admission he has had little success with chip breakers, and that's due to his apparent overall lack of understanding of why they work.

In order for a chip to break, all you have to do is steer it in the desired direction (he mentioned that, although in his own words). It need not be forced by things like abrupt walls, or a non-existent radius at the root of the chip breaker. The resulting chip should be free to flow, and will break by the design of the chip breaker. Abrupt wall, or a sharp corner at the root, as he has shown, will yield difficult cutting, as the chip will often stack in the breaker. Not a problem for light depths of cut and light feed, but not at all acceptable for roughing, and that's where a chip breaker is highly desirable.

When you understand chip breakers, you'll also understand that they are the means by which rake is introduced to the tool. In straight ground cutting edges, the side of the wheel on the grinder is generally more than adequate to provide the necessary form, but having a work rest, especially a large table as he uses, pretty much eliminates any possibility that you'll be able to grind the breaker.

I've commented a few times on grinding without a rest. It's not easy to make the transition to grinding that way, but it is the chief reason why I was able to fashion tools that worked well. Give that some thought.

H
Wise people talk because they have something to say. Fools talk because they have to say something.

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Re: Newbie - Buying first metal lathe

Post by John Hasler » Wed Jun 19, 2019 9:58 pm

I had watched only the tail end. I went to Youtube and watched the whole thing. He talks about back rake and grinds it in, but it looks like his (odd looking to me) chipbreaker eliminates it.

I've never gotten around to building a rest for my bench grinder.

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Re: Newbie - Buying first metal lathe

Post by Harold_V » Thu Jun 20, 2019 1:46 am

John Hasler wrote:
Wed Jun 19, 2019 9:58 pm
I've never gotten around to building a rest for my bench grinder.
If your experiences parallel mine, you should end up quite talented.
I've told the story before, but long ago.
I was introduced to no rest grinding when I took the last job I held. By then, I had about 8½ years in the (commercial) shop.
Their idea of a pedestal grinder was, literally, a small grinder mounted on a post in the shop. It was quite high, so you could stand erect to grind. I hated it, and struggled at first. However, once I figured out that the wheel will act as a guide, I changed my attitude and quickly realized how much more convenient the grinder was. When I started my humble shop, the first thing I did was build one very similar, although on a stand, and with a wet side, for carbide. I haven't used a rest to grind (HSS) tools for well over 50 years now. I have no desire to look back.

I should mention, I do use a rest for carbide (wet, with a diamond wheel). I've done it freehand, too, but the results leave a little to be desired.

H
Wise people talk because they have something to say. Fools talk because they have to say something.

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Re: Newbie - Buying first metal lathe

Post by John Hasler » Thu Jun 20, 2019 9:56 am

Harold writes:
Their idea of a pedestal grinder was, literally, a small grinder mounted on a post in the shop.

I recently picked up a pedestal-mounted Wissota for $20 at a yard sale. Pedestal is still too short, but it's already better than bending over to use a bench grinder. Much quieter and smoother, too.

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SteveM
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Re: Newbie - Buying first metal lathe

Post by SteveM » Thu Jun 20, 2019 2:34 pm

Harold_V wrote:
Thu Jun 20, 2019 1:46 am
It was quite high, so you could stand erect to grind.
I'm redesigning my shop and I'm going to have a spot on the end of a bench for grinders. Each grinder will be on a plywood base that will lock onto the bench, so that I can have different grinders for different purposes and not have to constantly change wheels.

I'm thinking of mounting them up higher because between my back and my eyes, neither is interested in having the grinder at waist level anymore.

Steve

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Re: Newbie - Buying first metal lathe

Post by Harold_V » Fri Jun 21, 2019 3:50 am

Fact. If grinding tools is uncomfortable, you're likely to never master the technique. Raising the height of a grinder is a reasonable start. Mine is taller than those found on a bench.

I learned as much from working in a job shop as I did working in the missile industry. In a job shop, you make do with what you have at your disposal. It makes a better machinist of most guys. It was a job shop, started by nine guys, where I was introduced to the taller (post mounted) grinder, the one without a rest. For that experience I will always be grateful.

H
Wise people talk because they have something to say. Fools talk because they have to say something.

LIALLEGHENY
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Re: Newbie - Buying first metal lathe

Post by LIALLEGHENY » Fri Jun 21, 2019 8:20 am

Never mind the pedestal grinder being to short....I've decided to raise the majority of the machines in my shop by 4 to 6 inches. I'm 6'4" and I'm tired of being bent over the lathe or mill, and my back doesn't like it either. I thought about it the other day, the average male is about 5'10" So I have 6" on that, and many machines were designed way back in the day when people were even shorter....I highly doubt todays machine tool builders have ever thought much about each generation getting a little taller when they build new machines today.....makes you wonder...

Nyle

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