Sometimes is smart to change approach

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hanermo
Posts: 60
Joined: Tue Oct 01, 2013 5:47 am

Re: Sometimes is smart to change approach

Post by hanermo »

I hate to disagree with Harold_V as I learned so much from him.
And very much appreciate it.

But 15 years ago I started to make a *good* cnc lathe and started with a chicom 7x-14, more or less, here in spain.
After some time I started to use ccmt 21.25 inserts and tools from chronos in the uk.

All my work was on steel, tool steel, typically 1" plus, often 2" plus, goals of 0.01 mm "accuracy" by size and dti and lathe cylindricity.
Pretty good, in fact, plenty good for industrial sales/work/production, I just did not know it at that time, 14 years ago.

So with manual, semi-manual, semi-cnc, lathe work on steels and tool steel I got great results with inserts.
With drill rod or hard steel like 12.9 bolts or blanks I got even better results.
Drill rod turned out great.

I could cut 0.001 mm from a steel workpiece, and it would turn out great.
Always.
Every time.
The surface might be fuzzy, but the "size" was always spot on.

With a bit of experience I knew I could leave 2-10 microns in size, polish it with something, anything, at hand, and end up with a beautiful piece accurate in resolution to about 2 microns, +/-.

I don´t understand the disagreement about carbides,
They are cheap, cut really well.
I have proven for me they cut 1 micron and submicron stuff.

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I spent many years and tens of thousands to learn to cut submicron stuff.

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Em .. I was an executive sales manager for Haas Spain.
All above applies with hundreds of machines sold.

We actually used some ccmt 21.22xinserts on a customer app demo.
These are really critical pieces of industry work - so the guy buys a 150.000€ turning center.
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Harold_V
Posts: 20231
Joined: Fri Dec 20, 2002 11:02 pm
Location: Onalaska, WA USA

Re: Sometimes is smart to change approach

Post by Harold_V »

My question is at what point did you abandon the 7 x 14 and turn to more robust machines? That aside, I tip my hat to you for your exceptional results.

Don't get the idea that I am not a carbide fan. I use it regularly, including brazed types. It's a wonderful step up from HSS when one can take advantage of its qualities, but they are often lost on light duty machines, where the lack of rigidity and spindle speed/power prevent its use, either by poor performance or the damaging of the cutting edge. I just experienced that in the project I'm doing, where there was an interrupted cut. I resorted to HSS while getting through the boring operation, as the interruption was causing premature edge failure of the carbide insert. The HSS performed exceedingly well, and experienced no negative effects. In such a case, HSS will outperform carbide time and again. That's the point I've tried to convey. Carbide is NOT always the answer, so to rely on it alone is a mistake.

H
Wise people talk because they have something to say. Fools talk because they have to say something.
AllenH59
Posts: 479
Joined: Wed Mar 16, 2011 1:26 pm
Location: Prince George BC Canada

Re: Sometimes is smart to change approach

Post by AllenH59 »

I am far from being an expert tool grinder, but I have had great success with tool life cutting hard material by grinding a chip breaker in a quality HSS too with a diamond point in my dremel. This will leave quite aggressive rake at the cutting edge, and a small radius for the chip to work through. I now do this with my cut off blades as well. I am sure you can buy these sets of little diamond bits at Harbor Freight, as I buy them at the similar store in Canada, which is called Princess Auto.
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Harold_V
Posts: 20231
Joined: Fri Dec 20, 2002 11:02 pm
Location: Onalaska, WA USA

Re: Sometimes is smart to change approach

Post by Harold_V »

The cutting edge design you mentioned works wonders when machining tough materials, like stainless. A high shear edge (excessive positive rake) and light feed permits cuts that destroy carbide rapidly, yet they perform flawlessly when ground in HSS. That's a trick I learned as a young man from a slightly older individual who had a few years of experience that I lacked.
My only reservation is that using diamond at high speed on steel isn't good practice, as it is readily dulled by absorption in to the steel. That happens at high temperature, however, so if your application results in relatively low heat, you may not be paying the price. I am in full support of chip breakers such as you've described.

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