Kent vs Victor lathe

Typically the limitation to metal removal in a manual lathe of this size would be more the inert size and DOC, the other factor is that in order to get the speed range for a 2 speed or 3 speed VFD model lathe they will run the motor in the range of 20-180 or 200 Hz, above the base speed the torque will fall off in a non linear fashion but you gain the mechanical advantage, below the base speed the motor torque is flat but you loose the multiplication factor due to the gearing. Most VFD machines will compensate for this by using a larger motor, so in 14-16"swing models they typically will go with a 5 Hp, 17" is usually 7.5-10Hp. The additional 3rd gear range in the Sunmaster lathes mentioned goes a long way to covering the 200-600 RPM range where torque would fall off in a 2 speed. Above 600 RPM, the work diameter gets smaller and thus less applied torque at the radius of the cut is needed. There are cases where one can stall a VFD model, but typically it is due more to a cost cutting compromise in smaller lathes and mills, I would not expect those limitations in a light industrial lathe. It is all a trade-off, but if VFD system is designed properly, something else will break before one reaches the power limitations of the drive system.

I also find that when using a VFD for speed control I can dial in a more ideal cutting conditions dynamically when turning and boring/drilling, as I can adjust the speed until I get the chips coming off the way I want without chatter or vibration. Also when using my larger MT drills that there is an ideal speed range typically +/-10% for that size drill and the material/feed rate.

There are several nice features when you get into the 17" range of lathes mentioned, the larger spindle bore and also the mechanical stop system that kicks out the carriage feed. Controlled acceleration and braking is also a plus on the VFD models if the lathe is not equipped with a clutch system, but as the lathes get bigger so does everything else, which means increased tooling costs as well as needing assisting lifting devices for the chucks and for moving other parts of the lathe. I also indicated that the headstock width can be a factor, depending on the type of work being done.
 
Can anyone speak to the finish quality differences between a geared head and a vfd controlled lathe? While the geared head can remove more metal in certain applications, removing at least some of the gears can also improve the finish. The tool room machines like 10EE, Rivett, Smart Brown, Schaublin, Leinen and Hendey T and G went to great efforts to take gearing out of the equation. The large lathes tended towards metal removal but the vfd control lathes might deliver some of the same benefits. Again, i don't know how important that is to the OP and I suspect there are a million other factors at play but someone considering a lifetime lathe ( rather than the next one to rehab ) should know the benefits and trade offs of all types.

Dave
 
@Beckerkumm The manual lathes I saw from Taiwan that *theoretically* I could order that used a large spindle motor built right around the spindle with an ELS for turning/threading. I saw these in the 1990s, but they wouldn't export to Canada at that time, so I bought a LeBlond. Those lathes take all the mechanical noise out of the equation and you are left with considerably less noise from the field and the cogging.

I've never been a fan of surface finish minutia. I turn it down to larger than spec and either lap or wet and dry to the number.

From the previous discussion - I've done this for 45 years now. I've never bogged down a lathe larger than 1.5 HP. My little 12X36 is 1.5 and I do bog it down from time to time. I've used about a dozen lathes over the years enough to say that pattern holds. Guys like 'certain youtubers' who pride themselves on deep DOC aren't doing anything practical. Overly fast removal rates just end up heating up the part, and then you have to wait waaay too long for it too cool evenly to make your dimension in tolerance. And for a hobby use, the heavy removal rate is far less applicable. So no it is really not important whether he buys a 7.5 or a 10 HP, or even a 5HP lathe. With a VFD on my 7.5 HP Leblond, I can still take a .100 DOC (.200 on diameter) in a 4" bar of steel. But it would be stupid to remove metal faster than that, for the above reason.

If you are in a rush, taking a lesser DOC with a higher feed rate puts far less pressure on the ways and carriage, and gets you there faster with less heat build up. And less HP is required as well. There are many ways to skin that cat.
 
I put together this spread sheet with what I could find on the Sunmaster, Victor and Acra-Sharp lathes. By Acra-sharp, I mean the Acra lathes that look to be rebadged Sharp lathes, similar to Acra's rebadging of Sunmaster lathes.
BTW, The PM1440GT appears to be a Victor 1440GLV (without evs and only a 1.56" spindle bore.

One that I came across that peeks my interest is the Acra 1700ACE-v (or FHL 1740V) wich appears to be a 17" version of the Sharp 1640LV. Anyone familiar with this lathe?
 

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The Sharp is a big bore version with a D-8 spindle and 3.1" bore so a different league than other 16" with D1-6. Dave
 
Beckerkumm said:
The Sharp is a big bore version with a D-8 spindle and 3.1" bore so a different league than other 16" with D1-6. Dave
Click to expand...
yes, but the Acra ACE 1740v appears to be a 2 1/4" bore version built on the same frame... At least the specs are very similar.
www.penntoolco.com

Acra Precision Engine Lathe 17" x 40" - ACE-1740V

Offering a huge selection of industrial tool sales online. Find over 100,000 metalworking products, precision measuring tools, power tools & accessories.
www.penntoolco.com www.penntoolco.com
www.penntoolco.com

Sharp Industries 16" x 40" Vari Speed Precision Lathe - 1640LV

Offering a huge selection of industrial tool sales online. Find over 100,000 metalworking products, precision measuring tools, power tools & accessories.
www.penntoolco.com www.penntoolco.com

In anycase, is anyone familiar with the Acra ACE 1740v? It seems very reasonably priced.
 
The specs are not the same. Although they look similar I think they're not produced by the same manufacturer.
Although the ACE looks Taiwan made so far I've seen nothing that states made in Taiwan.
 
Given that Acra has a 17" series that are listed as made in Taiwan, the fact that the ACE series doesn't say where made isn't a good sign.

Dave
 
Apples and oranges, many of the machine designs are copies of other companies lathes. They may look somewhat similar, but that is where it ends. Some of the lathes are sold by different vendors in slightly different build specs. for the same models like the Sunmaster's. I would be very wary of buying a machine at this level, and not knowing all the details, and have some feedback from someone that owns one. On some close up pictures of these lathes, you can see some major differences in the fit and finish. If one lathe is twice as expensive, it is very likely to be better built and have higher quality components. That being said, the Sharp brand name machines are usually about 25% higher in price then the same machine with a different distributor badge. As I outlined elsewhere in this thread, if you are spending this level of money and only going on pictures and specs. on paper, it may be worthwhile to take a trip to the distributor to check out the lathe before one ends up with a boat anchor.

Other big issue for me when buying newish machine, is parts availability and service/warranty if needed. I would rate PM/QMT and Eisen near the top in this respect. This is based on my personal dealings as well as others that have bought machines from these distributors.
 
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