Difference between 7x, 8x or 9x Chinese Lathes

[ShagDog]

Sounds like a real fine machine. Would like to see some pictures.

Here you go. https://www.hobby-machinist.com/threads/select-lathe-model-816b.85227/#post-765245

Also, some pictures in the above link that you quoted.

 

[silence dogood]

Nice lathe, Mine has lots of iron in it like yours. but it does not have the quick change gears like yours does. The thing about going from a 7" to a 8" is like going from a Vespa to a Harley.

 

[addertooth]

I realize you made your choice, but let me give a perspective on the 7 inch lathes for people who will be reading this much later. I was a machinist for a living about 40 years ago. I operated some seriously large pro-grade lathes. They had massive 3 phase 480 50+ HP motors. The vertical lathe I used had a 6 foot chuck on it. I get it, BIG lathes are cool. Even now, I see anything with a chuck smaller than 24 inches as petite.

The question of size often boils down to:
1. What kind of physical space do I have for a lathe: Desktop, free standing, room-consuming.
2. What kind of electrical power do I have available in my space: 110v, 220 single phase, 220 multi-phase, etc.
3. What is the largest item I will want to machine: Be realistic about this one. With skill, ambition frequently grows.
4. What features are most important to me: (Digital read out, metric and standard threads, variable speed, gear box with levers or changing physical gears, power feed for longitudinal and cross feed, horse power, variable speed brushed, variable speed brushless, etc.

In my case, I had little space, only 110V readily available, I was going to be working on air rifle mechanisms, antique pens, and tiny gizmos for additional hobbies. Long term upgradeability and available parts were also VERY important to me. I plan on using it for a couple decades. The important thing to remember is: over time, everything eventually breaks and needs parts. Say what you will about the tiny 7 by X lathes, but they are pretty much everywhere, and have a well defined support mechanism for parts and upgrades. There are endless sources of how-to articles on upgrades for these tiny machines.

Now for the harsh reality, most small Chinese lathes (7/8/9 inch) kind of suck from the factory. Almost all of them need a full disassembly, deburring, polishing, bearings and gibs enhanced, gibs adjusted, gear trains aligned, a lot of them need headstock and tailstock aligned to do precise work. Not everyone is up to the task, and will simply choose to use them out of the box. They may experience challenges in their use. Usually those who buy the bigger ones have a bit more experience, they may have bought a smaller lathe and "outgrown" it. As such, with their previous experience, they often get great results on larger lathes. Newbies tend to gravitate to whatever lathe is inexpensive, as such it is difficult to rate their experiences (their lack of experience colors their outcomes). It is uncommon for an old salt to say "all they need is a 7 by X lathe", the pool of very experienced people buying the smallest lathes is quite small. Many of the trouble reports come from inexperienced machinists, who frequently haven't tuned/upgraded their 7 inch lathes. Even worse, some have purchased someone's ancient/early troubled lathe for a song and a dance, not realizing that current manufacturing techniques on these lathes has improved. I too have seen some of the older ones which had rough-milled ways. Many of the new ones now have nicely ground way surfaces; they are a different animal today.

Now let me bag a bit on 7 by X inch lathes. If you are imagining you will be machining items which are 7 inches around... it is not likely to happen without an upgraded longer cross slide (and retracting the compound feed to gain more distance from your center line), AND a bigger chuck (which may require an adapter plate to mount it at additional cost). If the motor is not 600 watts plus, you will be taking very tiny cuts on large diameters. Quite frankly, these smaller lathes are happiest with items that are about 2.5 inches around or smaller. As for length, remember the measurement is sold as "center to center". What it means in the practical sense, is a 16 inch lathe can't really machine (normally) a 16 inch long item. With the tailstock pulled all the way back, and the quill retracted to the point that it is about to eject my live center, I get about 13.5 inches of space between the jaws of the chuck and the point of the live center. I get even less distance if I need to drill the end of round stock (a drill chuck with a bit in it is MUCH longer than a live center). For items which are smaller than 3/4 inches in diameter, those will pass through the chuck and spindle, with a good spider on the backside of the spindle (to support it so it does not slap in the inside of the spindle), longer parts can be worked, such as a tube or the outer diameter of a barrel. Small lathes don't come with a spider, but you can buy them (or make them with a lathe and a drill press). Summary: If you plan on working parts that are 4 to 7 inches in diameter, it is not practical on a 7 by X lathe. If you are planning on doing long items which are larger in diameter than the hole in the spindle, it is not practical to do long parts, (get a bigger lathe, and be aware they may have a reduction in working diameter and length as well; plan accordingly).

But, if you are only working petite parts, it may fit the bill nicely, once you have put in some sweat equity to make that tiny lathe hum.

Please note, my opinion is from practical use of a 7 by 16 Lathe. It is bolstered from using much larger lathes in the past.