20 HP Lathe

This lathe is advertised as 20 HP:

I do not doubt that the ad is true, but I have to wonder why any lathe would need a 20 HP motor. I have hard times imagining how even a fraction of that could be expended cutting metal with a single point lathe bit.

Single point bits are not the only type used in a lathe, and heavy lathes often take heavy roughing cuts.

Check out the lowest RPM rating... Tells me maybe someone would turn a huge diameter part in that machine as it can go down to 6 RPM. That could require HP if the gearing were just "right" to need it.

Regards, Joe Agro, Jr. (800) 871-5022

01.908.542.0244 Automatic / Pneumatic Drills: Spindle Drills: V8013-R

Material removal rate-- there are various tables, and, as always, it depends on various factors, but by one rule of thumb 20HP would remove about 30 in^3 per minute of steel or maybe 100 in^3 of aluminum.

If you want to turn something 12" in diameter down to 3" over an 8" length, that's um.. around 850 in^3 if I did the math right, so it would take almost half an hour for steel and 10 minutes for aluminum if HP was the limiting factor.

Best regards, Spehro Pefhany

Perhaps you need to pick up a book or 2 on the theory of turning? It's all about metal removal/time. You'd really be gobsmacked if you come across a series 80 Monarch lathe of the same swing. It will have a 60 hp motor.

Tom

Which reminds me of a cartoon we ran in _American Machinist_ in the mid-'70s. The caption was, "Why productivity is so low in the Soviet Union."

-- Ed Huntress

I am gobsmacked. Just found this page

weighs 10 tons

Our cast iron pulley cells (cnc) have 35 hp spindles and most parts are 12" dia or smaller. Even the machines turning aluminum castings have 15 hp spindles and sometimes our gang roughing groovers get the belts to slip. Plastic muli-vee belts suck.

That thing has a 25" swing. 20HP seems reasonable to light depending.

Wes

So, what did the cartoon show? Best regards, Spehro Pefhany

Imagine what moving that thing would cost... Best regards, Spehro Pefhany

A lathe operator turning a piece of stock around 12" diameter down to maybe

3" diameter, over an 8" length. Then he held the part up with pride.

-- Ed Huntress

I worked at a shop years back that had a lathe with a motor that was rated

40 HP continuous duty, and 50 HP intermittent use. We would run it at the full 50 HP fairly often. Physically it was not a very large machine, but it sure would make chips!! Greg

I guess it depends on your hobby. I have a 20 hp. Mazak M4 CNC lathe. Nice machine and useful. But not a watchmakers lathe.

Karl

On Tue, 10 Jun 2008 14:43:26 -0500, with neither quill nor qualm, Ignoramus13673 quickly quoth:

Go look at pics taken in some of the machine shops during WWII, Ig. They turned prop shafts for battleships, cruisers, and carriers with 'em. Here is one from more recent years:

-- Besides the noble art of getting things done, there is a nobler art of leaving things undone. The wisdom of life consists in the elimination of nonessentials. -- Lin Yutang

On Tue, 10 Jun 2008 17:45:50 -0400, with neither quill nor qualm, "Ed Huntress" quickly quoth:

That's an expensive practice, wot? It's amazing that the USSR was unionized, though. That sounds like union practices.

-- Besides the noble art of getting things done, there is a nobler art of leaving things undone. The wisdom of life consists in the elimination of nonessentials. -- Lin Yutang

That's "planned economy" practices. They never got it right. Some planning, eh?

-- Ed Huntress

Can you post a proper URL Larry>?

I suppose he means this:

Tom