Buying a metal lathe, anyone have some tips? or know of a cheap used one?

[MotorMaster]

I've been looking at getting a lathe to be able to work on motors among many other things, and I was wondering if anyone on here knows of some good brands or other tips about lathe buying. I've been looking at those chinese mini lathes, but I need something that I can turn down things up to 5" and their swing over carriage is only like 4". I've also heard it is better to buy a used higher quality lathe from a machine shop closing down or another situation where lathes are being liquidated.

[Ramcatlarry]

try here: http://www.blueridgeshoponline.com/

or Harbor Freight has reasonable cheap chinese tools. www.harborfreightusa.com

[zaprp]

ebay is a good place to look around and see what's out there.

Not sure if the "Emco Unimat" is made anymore, but that used to be the machine of choice since it would convert into a milling machine as well as a precision lathe. Good luck!

metal lathe:
http://search.ebay.com/metal-lathe_W0QQssPageNameZWLRS

mini lathe:http://search.ebay.com/search/search.dll?sofocus=bs&sbrftog=1&from=R10&satitle=mini+lathe&sacat=-1%26catref%3DC6&sargn=-1%26saslc%3D2&sadis=200&fpos=77035&ftrt=1&ftrv=1&saprclo=&saprchi=&fsop=1%26fsoo%3D1&coaction=compare&copagenum=1&coentrypage=search&fgtp=

[Slapshot]

Most new Mini lathes today run in the range of $475-$700. Sorry in bidding wars even on E-bay they go for close to that range give or take $100. I few times I have seen a older Sherline and Unimats go for $450 (A prisine old Unimat will often go for the price of a new unit almost what you can buy for new from the factory). Weird. So beware.

Be aware of the motor that is connected to an older unit that you may purchace as not many are replaceable or have parts such as brushes anymore. You can pay as much as $35 a pair for motor brushes for these puppies. Or $100 or more for a universal replacement Dayton motor which most have to be modified to change direction (to CW for the shaft rotation) by flipping over the interal motor brush PCB brush carrier assembly.

On a good note....

Harbour freight has a multipurpose lathe at a reasonable price. A copy of the old Unimat III.

Mini Multipurpose machine (http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=39743)

http://www.harborfreight.com/cpi/photos/39700-39799/39743.gif

Then there is Rejon machnery in Europe who have the revamped modern Unimat IV...
http://www.rejon.co.uk/emco_hobbyist.html

http://www.rejon.co.uk/images/unimat4_main2.jpg
http://www.rejon.co.uk/images/unimat4_pro_2.jpg

Then there is Sherline about the only US based hobby late around right now at $575 for the basic unit and $850-1200 for the acessorie package which includes a chuck and a few other things ....

http://www.sherline.com/

http://www.sherlinedirect.com/

http://www.sherlinedirect.com/prodimg/ACFx9UAJB.jpg http://www.sherlinedirect.com/prodimg/4000Bpicm.jpg

Don't forget most of thes lathes come as basic units only, and accesories are added such as adjustable collets or chucks...


Raymond

[triggerman]

These websites were helpful when I was looking for a Mini Lathe a few years ago. Email me if you want some more info.

This site is a wealth of knowledge on the Harbor Freight model and other Chinese Machine Tools:
http://www.mini-lathe.com/

Here's another one:
varmental.com (http://www.varmintal.com/alath.htm)


This site has all the replacement parts and accessories to get you started.
Littlemachineshop.com (http://www.littlemachineshop.com/)

[fastslotracer]

I have a mini multipurpose lathe. I bought for under $300. Works great. If I were you I would shop around. They do come in useful at times. I've used it for making my own zapping slug, can tools and to keeping my set-up block flat. It was worth every penny. Good Luck.

[MotorMaster]

I'm going to get a 9"x20" (or larger) lathe, I just need to find a good (read cheap) one. The true limitation of the lathe is the swing over the carriage and I need atleast 5". The 7x lathes only get to 4". The 8x12 I'm assuming is about 4.5" but it only comes with a 4" chuck, so even if it did have a 5" swing over the carriage the cost of a new 5" chuck would make it more expensive than just buying a 9x lathe that comes with atleast a 5" chuck. I think there will be more used quality 9x lathes also.

[Monty @ B.O.W.]

MM,

Among my 5 mini lathes, the most versitile is my Micro-Mark 7x14. It is variable speed, only about $500, and has a wide variety of attachments made for it including a tool post grinder.

Lets make sure you understand the term "swing". Thats the measurement of vertical height from turning centerline down to whatever might interfere, usually the bed or the carriage. Note, this is a RADIUS. You can actually turn a diameter of up to double the 'swing'. Your first post mentioned turning a 5" object, which I would take to be its diameter. You could do this with a 3" swing lathe. The other consideration is a chuck, as you've noted, but depending on what the object is, you may be able to hold it with centers and drive with a dog, or run a shaft through and drive the shaft, or grip some minor dia. on the part in either chuck or collett, etc. 3 jaw chucks, incidentally, are often rather poor for holding runout to a minimum. For high concentricity requirements, collets are better, but a hard bearing/shaft interface, like on a comm lathe, is best.

If you buy a lathe, better get used to the idea of grinding your own toolbits as well. Its not hard to do, but a decent grinder is indicated, and if you will be using carbide bits, the appropriate stone is mandatory.

[MotorMaster]

so if the swing over the carriage is 3.9", will I be able to cut o-ring grooves in something that is 5" in diameter??

[Bill from NH]

What are you making now?:)

[MotorMaster]

large, high flow, fast acting pneumatic valve for the purposes of supersonic (with helium) starch acceleration.

of course that would be only one of the many uses of me having a lathe.

[Zippity]

large, high flow, fast acting pneumatic valve for the purposes of supersonic (with helium) starch acceleration.

:D :cool: :rolleyes:

[MotorMaster]

Originally posted by Monty @ B.O.W.
MM,

Among my 5 mini lathes, the most versitile is my Micro-Mark 7x14. It is variable speed, only about $500, and has a wide variety of attachments made for it including a tool post grinder.

Lets make sure you understand the term "swing". Thats the measurement of vertical height from turning centerline down to whatever might interfere, usually the bed or the carriage. Note, this is a RADIUS. You can actually turn a diameter of up to double the 'swing'. Your first post mentioned turning a 5" object, which I would take to be its diameter. You could do this with a 3" swing lathe. The other consideration is a chuck, as you've noted, but depending on what the object is, you may be able to hold it with centers and drive with a dog, or run a shaft through and drive the shaft, or grip some minor dia. on the part in either chuck or collett, etc. 3 jaw chucks, incidentally, are often rather poor for holding runout to a minimum. For high concentricity requirements, collets are better, but a hard bearing/shaft interface, like on a comm lathe, is best.

If you buy a lathe, better get used to the idea of grinding your own toolbits as well. Its not hard to do, but a decent grinder is indicated, and if you will be using carbide bits, the appropriate stone is mandatory.

I just checked mini-lathe.com to see if that was true and they say swing is a measurement of diameter?

[RocketRod]

it has been standard practice for a long time to list the radius as the swing --- double it for the total size a lathe can handle ---

a 7" swing should equate to a piece that is 14" diameter

[Bill from NH]

"large, high flow, fast acting pneumatic valve for the purposes of supersonic (with helium) starch acceleration."

It might be cheaper to just farm out the machining work.:) I bought a Unimat SL1000 in 1969 & have never regretted it. It does come in handy at times.:cool:

[MotorMaster]

well, there happen to be a lot of other people wanting this size valve as it has been advertised by the main spudgun people "spudtech", but has had no time to test it and his orders for stuff that he has tested and are in stock have arrived up to 6 months after the order was placed! he's losing a ton of customers and he obviously has no time to test it since he cant een keep up with his current orders! I on the other hand get off school at 2pm and have plenty of time to test a valve, so I'm going to start a small ebusiness selling pneumatic valves. I need money for more slot car stuff!

[MotorMaster]

"Swing A dimension representing the largest diameter workpiece that a lathe can rotate. The 7x10 or 7x12 mini-lathe has a 7" swing, meaning that the maximum size workpiece that can rotate without hitting the bed is 7" in diameter."-minilathe.com

is it different on minilathes???

[Monty @ B.O.W.]

over some dumbsh*t copy writer...

Nick, I was an aerospace machinist for years. The swing of a lathe is supposed to be the largest RADIUS it can handle. That being said, I read the nameplate on my Micro-Mark and it says "7 inch swing diameter" - and it is. The actual swing, as I would define it, is 3 1/2". By that logic, my Unimat 3 is a 4" lathe, since I actually measure the swing at 2". I guess the makers of mini lathes were afraid to make them sound too puny... The phrase used in advertisements for commercial lathes is "swing over bed' or "swing over carriage" - refers to the linear clearance over the named structure.

For the job you're describing, you had best pay attention to the horsepower as well as the overall size of the lathe, however. While some mini lathes could FIT a 5" dia. valve body between centers, it would be rather easy to stall a typical 1/3 horse motor carving a groove on something that size. With patience, and a light cut, I think the Micro-Mark could do it, while I'm certain that my Sherline could not - even though the Sherline has a riser attachment that can increase the swing. Buying a larger lathe than you actually need is not a bad idea given the circumstances. Larger lathes with any real capability of doing precision work could get a bit pricey though ... be careful with your money.

[MotorMaster]

I was able to make a design change that saved me money, decreases ineffecieny due to "scrap"/leftover materials that are too small to use, and will allow me to make the valve on a 8x12 lathe.

So, anyone here use ever use the Harbor Freight 8x12 lathe? The shear weight increase from 100lbs to 280lbs makes it seem a lot more rugged than the 7x10s