Refering to the Asian 7X12 lathes, some have a low speed of zero and
others begin at 100+ rpm.

Is this a significant consideration regarding a purchasing decision?

wrote in message
...
Refering to the Asian 7X12 lathes, some have a low speed of zero and
others begin at 100+ rpm.

Is this a significant consideration regarding a purchasing decision?

No. Just marketing hype. Every lathe has a low speed of zero, by just not
engaging the drive. The statement is about as meaningful as saying a car
has a low speed of zero. So while this is not a significant consideration,
I would keep away from a comapny whose brochures are so misleading and
confusing to a newbie.

Boris

--

-------------------------------------
Boris Beizer Ph.D. Seminars and Consulting
1232 Glenbrook Road on Software Testing and
Huntingdon Valley, PA 19006 Quality Assurance

TEL: 215-572-5580
FAX: 215-886-0144
Email bsquare "at" sprintmail.com

------------------------------------------

"Boris Beizer" wrote in message
nk.net...

wrote in message
...
Refering to the Asian 7X12 lathes, some have a low speed of zero and
others begin at 100+ rpm.

Is this a significant consideration regarding a purchasing decision?

No. Just marketing hype. Every lathe has a low speed of zero, by just
not
engaging the drive. The statement is about as meaningful as saying a car
has a low speed of zero. So while this is not a significant
consideration,
I would keep away from a comapny whose brochures are so misleading and
confusing to a newbie.

I would add that the legitimate lowest speed and the highest speed are
important considerations. The smaller the lathe the more important the
higher speed and the less important the lowest speed. It's all about
getting the surface speed correct for the work you're doing. The smaller
the diameter of the work the lower the surface speed for a given rpm. Let's
take some typical cutting speeds in feet-per-minute for several materials
you're likely to turn:

steel 150
brass 300
Aluminum 500
wood 1000

Now consider various diameters of what you are about to turn: 1/4", 1/2",
1", 3", 7" .
You can looks these up in a handbook, such as the Machinery handbook with
the following results:


1/4 1/2" 1"
3" 7"
steel 2140 1224 535 185
76
brass 4585 2290 1450 380
180
aluminum 7639 3440 1720 640 270
wood 15,000 6880 3440 1270 544


Now you are very unlikely to turn something 7" in diameter on a 7"
lathe. It could be a bowl, or a plate, but not a shaft because there isn't
enough room over the cross slide to turn something that big. Also,
something that diameter will be pushing beyond the power limits of the
lathe, its rigidity, not to mention the size chucks you have. Practically
speaking, a 3" diameter is a working maximum for typical work on a 7" lathe.
So the lowest speed you're likely to use (except for cut off tools and
threading) will be about 185 to 200 rpm. Note however, the high speeds
you're likely to use - most lathes won't go that high -- even wood working
lathes.
The lowest speed is important for using a cut-off tool and for
threading. By and large, there you want to go as slow as possible.
Certainly while you're learning.
It's not enough to have a high high speed-- it has to be a good high
speed, meaning the bearings are good and there's no wobble in the spindle at
high speeds.
Okay, that's lesson 001 in the selection of a lathe.
A while back, someone in this newsgroup posted an article entitled
"Advice on buying a clunker." or something like that. As I recall, that
was an excellent introduction to get you to level 002. Suggest you let the
group know what you intend to do with the lathe, which ones you have in
mind, and get a sharper answer to your question.

Boris

--

-------------------------------------
Boris Beizer Ph.D. Seminars and Consulting
1232 Glenbrook Road on Software Testing and
Huntingdon Valley, PA 19006 Quality Assurance

TEL: 215-572-5580
FAX: 215-886-0144
Email bsquare "at" sprintmail.com

------------------------------------------

On 2005-02-17, wrote:
Refering to the Asian 7X12 lathes, some have a low speed of zero and
others begin at 100+ rpm.

I don't think any of the currently shipping models have the older motor
controller. I just got one from Homier (who in the past shipped a model
with a different controller) and it will turn very very slowly.

--
Ben Jackson

http://www.ben.com/