faster way to turn down part of a rod?

down about 0.5" of the end of an aluminum rod from

This is a production activity. (Okay, I'm being stupid to use a Sherline for this.) I need to do this for a bunch of products that I will be shipping out the door.

The Sherline lathe has a direct reading dial, so if you want to remove .040" from the diameter, you turn the dial .020". In this case, I meant that I was removing .020" from the diameter per pass--moving the dial in .010" at a time.

Thanks for the suggestion. The Sherline uses a variable speed motor, so I can turn it down to a few dozen RPM if I need to. I'll give that a try, and see if it tolerates a slow but deeper cut.

The product that I sell currently is exactly that. I drill a hole and then put a fully threaded stud into it. It would just be a bit more elegant to look at--and more likely to end up perfectly centered--if I can turn it all out of a single piece of aluminum. (Admittedly, the threads in aluminum won't be as strong as the threads on the steel stud--but then again, the steel stud is being held into a piece of aluminum on the current product, so this probably just moves the potential failure mode from one thread interface to another.)

Excellent idea! But the cutoff tool makes a narrow cut. Are you suggesting using the cutofff tool to make a series of slices?

I've had a Sherline for about 30 years.

Maybe the older ones were different - on mine the cross-feed dial reads depth of cut, not diametral difference. 20 tpi lead screw, with

On mine, the speed control seems to work by sending an intermittent current to the motor. Run it too slow and the spindle does not turn smoothly. The posters telling you to run it slower may be thinking of a pulley or backgear system which gives you more torque at the lower spindle speed. With the Sherline, I'd run it as fast as you can without burning the tool bit.

For that cut, in aluminum, I'd run a HSS bit with a good bit of side relief and top (side) rake, and only a small radius if any on the tip. With a sharp cutter, you should be able to run a lot more than .

It's amazing what work one can do on a small lathe (mill, shaper, surface grinder....) when all one has is a small lathe (mill, .....).

John Martin

So in my stupidity, I actually understood you correctly! Kinda like a stopped clock being right twice a day.

snipped-for-privacy@claytoncramer.com wrote in news: snipped-for-privacy@h3g2000cwc.googlegroups.com:

Yes. Most cut-off tools I use are 3-4mm wide. This would require only 3-4 cuts to get your 1/2" length. Then swap tools and do a finish pass with a normal turning tool.

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Just grind it like the picture, and don't worry about the chip breaker to start till you can get a smooth radius (something you can't see in the picture) and be sure you quench that HSS every few seconds, the moment you see it turn blue you ruined it, and have to grind it off.

down about 0.5" of the end of an aluminum rod from

It's aluminum. Crank that sucker up as fast as it will go, even get a larger pulley. You should be able to knock it all off to spec in two passes. Just put a magnetic dial gauge on the saddle to mark your depth of cut. If it isn't fast enough, you are just wearing out your tool by not taking advantage of shear effect.

Have you considered having this done on a CNC lathe at a job shop? They could do this from bar stock and in a single operation. Costs would be minimal per part.

Id be happy to sell you your very own CNC lathe btw

Gunner

"Liberalism is a philosophy of consolation for Western civilization as it commits suicide"

- James Burnham

Disregard the statement about HSS being ruined by the coloration during grinding. This is bogus information. Quality HSS isn't harmed until it gets beyond the red region.

The damaged-from-heat warning was true of high carbon steel cuting tools, before HSS became readily available and inexpensive. Files, chisels and other high carbon cutting edges will suffer damage from excessive heat.

If you heat a HSS cutting tool to blue, try to file it to see if it's softened from heat (but it won't be).

I frequently grind new HSS lathe tool blanks in the brown and blue color ranges when rough shaping them from the squared-end shapes as they're delivered when new, without damage to the cutting tools. Heating HSS to red by brazing small pieces with a torch doesn't ruin the hardness of the HSS inserts.

Quenching HSS is a bad practice that can create cracks in the tool's cutting edges. Instead of quenching, grind numerous cutting tools, and lay the hot ones aside on a metal plate, while choosing another cool piece to grind. The metal plate will draw heat out of the hot pieces while you're handling/grinding the others.

One of the projects on my metalworking pages shows a very effective tool holder project for grinding lathe tool blanks.

WB metalworking projects

No worries Lloyd (and thank you-) - will give it a try. I was under the impression it was a big NO NO to use the corner (or the side) of a grinding wheel. (Dont know where I got that info, so wont swear to it). Doing tool grinding at school now, getting reasonably consistent on grinding mild steel practice pieces - when I have done enough, they will give me a bit of HSS......

Andrew VK3BFA.

In fact you are citing a method of visually determining a degree of tempering as evidence to the opposite? If you allow your HSS to get that hot while grinding and don't quench frequently you are annealing your HHS. Then you have someone frequently running over to the grinder to resharpen. You can braze carbide inserts but brazing HSS isn't worthwhile, in any case.

No, not in fact, as you contend. You're comments are correct regarding carbon steel, but not HSS. Carbon steel is subjected to softening by excess heat, not HSS.

HSS is much more complicated than carbon steel. You will fracture the cutting edge by quenching hot HSS.

Eli, I've seen in your other post regarding cutting speeds, chip loading and other machining topics where your comments generally indicate that you're very knowledgeable about machining, but you are incorrect about the heat tolerance of HSS.

In industry, nearly everything is done differently than in a home shop, and new HSS cutting tools are most likely shaped and ground with constant coolant, as opposed to grinding dry like a home shop guy would.

Sharpening and shaping quality HSS tooling won't affect the performance of the cutting tool, even if the edge gets into, or beyond the blue color range.

Apparently you haven't tried the test that I recommended, so go ahead and grind a piece of HSS to red, then file it to prove to youself that it's been softened. Let us know how well your tempered HSS can be filed.

WB metalworking projects