Low speeds - any disadvantages?

I use what I have. I'm not in a hurry, production is not an issue. I could get up to 2K RPM just by finding a 10HP idler, but I've not been motivated to do it.

ever use the higher

to some good articles

No articles needed, Bob. The lathe is 3 HP in "low range", 5HP in "high range". The 5 HP idler works fine in low range but can't wind up the lathe in high range before the circuit breaker in the lathe pops.

How you could help: rather than articles, send me a 10 HP idler and someone to move the hundreds of lb of raw stock and rack that's in front of the present idler, intall the new idler (next to the old one), check it all out and put everything back.

That doesn't bother me a bit, Jon. I often back up even when cutting inch threads. The threads I cut are usually short, often fine, and it's as easy to change speeds (gear head lathe) as it is to hit the right spot on the threading dial. I cut slow so I can stop in time, back up fast. I've found it works best for me to do it once slowly rather than thrice quickly get it right third try, since I very seldom make more than two or three of anything.

Carbide cutters work best at higher speeds, HSS works well at lower speeds. HSS can take a keener edge than most carbide. I can take finish cuts of tenths with HSS that produce fuzz or dust rather than chips. Carbide won't do that, at least not for me. I don't understand a preference for carbide in a home shop where production isn't an issue. It's useful when working with hard or abrasive materials, but for ally, brass, bronze, delrin, nylon, mild steel and some stainless I much prefer HSS. I often run it dry or with just a few drops of cutting fluid, still get good surface finish with sharp, carefully-ground bits.

I have never made anything thatcouldn't be made on a 9 or 10 inch Logan or South Bend or even a Myford Super 7, but what I have is a

I'm retired now, but these attitudes were formed when my shop time was as limited as that of most guys with a full-time job and a family. Shop time was relaxation, a respite from the competitive race and daily grind of bidness. Production efficiency has never been an objective in my shop. On my time, having fun is job 1.

My Student has a top speed of 1200 I think it is but because I run it off a phase converter it's not too happy at starting up on the highest speeds. 900 is ok but I actually rarely run it at more than 650 and don't find that to be any sort of restriction. In high volume production you want the optimum speed for maximum metal removal but for odd jobs and home shop work most things will cut just as happily at lower speeds with sharp tooling for the sake of a few more seconds per job.

I always find the key is the right tooling. I use razor edged non ferrous carbide tips even for ferrous work because they cut better on small machines. Maybe for the occasional roughing job I'll use an actual ferrous tip but you can't get any sort of finish with them.

If the lathe is suitable otherwise I wouldn't give the top speed a second thought.

ever use the higher

to some good articles

No articles needed, Bob. The lathe is 3 HP in "low range", 5HP in "high range". The 5 HP idler works fine in low range but can't wind up the lathe in high range before the circuit breaker in the lathe pops.

How you could help: rather than articles, send me a 10 HP idler and someone to move the hundreds of lb of raw stock and rack that's in front of the present idler, intall the new idler (next to the old one), check it all out and put everything back.

Don sez:

"No articles needed, Bob. The lathe is 3 HP in "low range", 5HP in "high range". The 5 HP idler works fine in low range but can't wind up the lathe in high range before the circuit breaker in the lathe pops.

How you could help: rather than articles, send me a 10 HP idler and someone to move the hundreds of lb of raw stock and rack that's in front of the present idler, intall the new idler (next to the old one), check it all out and put everything back."

Point well taken, Don. Hey! I still plan on coming up to see you when the Delta Queen gets running again. At that time I will be happy to help you move all the raw stock, rack and etc. that's in front of your idler. In the mean time, your under powered idler's performance could possibly be improved by the judcious addition of some capacitors. Remember all the discussions re. idler, load motor, and interconnections comprising a network?

Resp,

Bob Swinney

This thread has been interesting for the number of posters who have lathes with modest high speeds and who don't feel it's a problem.

I have a 10 x 24 Jet with a max speed of 2200 rpm +-. I have a controller for it that takes the FPM desired and the diam, and drives the VFD to give the right speed. I often find the the controller wants the spindle to go faster than 2200. In ordinary circumstances, e.g., mild steel & 1/2" diam. Such that I was considering re-pulleying it to get higher speeds (if the spindle bearings would be OK with it).

My assumption has been that the FPM is not just a matter of efficiency (i.e., production speed), but of surface finish. That too low FPM will produce a worse finish than a higher "right" value. Am I wrong? Is FPM just a max value to keep production up without destroying the tool?

As always I'm sure that the vast collective knowledge here will have the answer, Bob

Delta Queen gets running

and etc. that's in

could possibly be

discussions re. idler, load

When you get here, let's just enjoy the day. Winter is shop season.

Man, I must have things all messed up. I think winter is fishin' season. Shop days are rainy days or too hot days or any day I need something.

Karl