Long Range Hunting Online Magazine


Go Back   Long Range Hunting Online Magazine > Rifles, Reloading, Optics, Equipment > Gunsmithing


Reply

Looking at some lathes and mills on auction

 
LinkBack Thread Tools Display Modes
  #8  
Old 12-01-2012, 09:38 AM
Platinum Member
 
Join Date: Dec 2011
Location: S.E. Michigan
Posts: 3,464
Re: Looking at some lathes and mills on auction

Quote:
Originally Posted by westcliffe01 View Post
Don't worry about the 3 phase requirement. All you do is run 220V single phase to you garage, then use a variable speed AC drive. I bought one from Hitachi for about $300. Go to driveswarehouse.com You want single phase in, variable 3 phase out. You end up starting and stopping the machine using the drive and the speed is controlled with a dial. The drive will even decelerate the spindle and can do it more sharply if you add an external load for braking.
Amazing the information gleaned from publically viewed websites and forums....

I own and operated a commercial machine shop for a living ad I can tell you without malice that vector drives only work with lightly loaded motors and lathes are not considered soft start or lightly loaded.

You know more so keep talk'in. I'll be on th side soaking it all up........
__________________
'It's not about me, it's about we'..........
Reply With Quote
  #9  
Old 12-01-2012, 01:53 PM
SPONSOR
 
Join Date: Mar 2010
Location: on the Southern Plains
Posts: 1,205
Re: Looking at some lathes and mills on auction

'Bout the only way to get true 3 phase, if you don't have power company supplied, is to use a rotory phase converter. They are, in simplist terms, a single phase motor driving a 3 phase generator. I wouldn't buy one for each machine. I'd buy a large enough one and feed a three phase panel and wire my machines from there. Flip's right about the "hard start". Lathes without a clutch, air compressors, 3ph welders all fall under that heading. That VFD from e-bay might look good, but, check e-bay for "rotory phase converters". Not much difference in price and it makes "the real thing". Electronic "variable speed" isn't a 'gotta' have' for gunsmithing tasks. Simple gear changes work just fine.
__________________
"Shoots real good!": definition; it didn't blow-up in my face. Not everything can be fixed on an internet forum!
Reply With Quote
  #10  
Old 12-01-2012, 04:07 PM
Platinum Member
 
Join Date: Dec 2011
Location: S.E. Michigan
Posts: 3,464
Re: Looking at some lathes and mills on auction

Adding to Shortgrass's post (I'm no 'lectrician by any means as a disclaimer...) but, 3 phase motors are most Wye wound. That means the T3 leg (the one you don't have with 220/1, is stackable.

It simplest terms, size your rotary convertor (I happen to have a Gerhardt-Werner btw) for the median horsepowr requirement you have, say a lathe with a 3 horsepower motor, keep in mind the inrush amperage is 3 times running amperage, so size the convertor for 9 horsepower to be safe.

I run the GH on the Servo-shift and the CNC machining center because I want to insure I don't smoke the electronics.

Leg all the 3 phase motors on one circuit and start and idle a couple notors before starting the bigger ones. The T3 windings on the idling motors will exite and provide starting amperage for the big motor to start.

If the machine is frequency drive (my LeBlond Servo Shift is), it's imprative that the T3 leg is pure sine wave 60hz power or you'll fry the frequency drive.

Also keep in mind that 3phase motors running on artificially excited (static conversion) single phase, produce less than nameplate rated power and more residual heat.

BTW, I wired my shop myself, 400 incoming amps and I live to tell about it.....

Never put both hands in a breaker box at one time, make sure the mains are pulled when fiddling around and be sure to discharge any capacitors (all motors of size have start capacitors that can kill you, right now and most motors don't have dropping resistors across the capacitors.
__________________
'It's not about me, it's about we'..........
Reply With Quote
  #11  
Old 12-01-2012, 04:25 PM
Platinum Member
 
Join Date: Nov 2008
Location: SW Montana
Posts: 4,568
Re: Looking at some lathes and mills on auction

Quote:
Originally Posted by SidecarFlip View Post
Amazing the information gleaned from publically viewed websites and forums....

I own and operated a commercial machine shop for a living ad I can tell you without malice that vector drives only work with lightly loaded motors and lathes are not considered soft start or lightly loaded.

You know more so keep talk'in. I'll be on th side soaking it all up........
Interesting!!! I have a Leblond lathe on a rotary phase converter, works OK but would work better if I balanced the legs better. Next week a new lathe will be here and the outfit I bought from recommended a VFD for my application and has been using them with lathes for some time, it seems like a lot of guys are using the VFD vs the Rotary so I guess I'm going to find out first hand. I figured I can just build another rotary if I let the smoke out the VFD
__________________
"Pain is weakness leaving your body"
Reply With Quote
  #12  
Old 12-01-2012, 05:01 PM
Platinum Member
 
Join Date: Dec 2011
Location: S.E. Michigan
Posts: 3,464
Re: Looking at some lathes and mills on auction

But is it a frequency drive? The LeBlond's used vacuum tube drives not IC's on the servo shifts. Big difference between them and a conventional chang gear drive. Most engine lates aren't speed controlled like the Servo Shift is....

My Haas is also speed controlled but it's IC plus it has direct computer (convrsational programming). It's sensitive to input voltage and frequncy stabilization.

The real impetus for stabilization is constant speed/torque delivery. My Kent surface grinder demands pure 60hz 3 phase for its stabilization electronics to deliver a true 3600 rpm spincle speed regardlss of wheel loading.

Anyting is possibe but longevity wise, I tend to err on the side of reliability. All my machines cost big bucks so I'm partial I guess. I make my fun money with them.

He could get by with static conversion/repowering to 220/1, rotary conversion but I have doubts that any VFD, unless rated properly will stand up to the high torque starts thar most lathes encounter... You got to get her spinning and thats where the runner meets the road.

I've seen guys start 3 phase motors with a rope pull.... You get it spinning and the T3 leg self excites (if wye wound). Not ideal but doable.
__________________
'It's not about me, it's about we'..........
Reply With Quote
  #13  
Old 12-02-2012, 04:10 PM
Platinum Member
 
Join Date: Jun 2010
Location: greenwood, IN
Posts: 3,645
Re: Looking at some lathes and mills on auction

Quote:
Originally Posted by SidecarFlip View Post
Proper nonenclature is 'swarf' not chips btw. Chips are what the English eat with their fish.

Have 3 phase at home? Lathes especially don't like static phase conversion because the start loads are high and repowering to 220/1 can be expensive and not practible if the machine is frequency drive.

Your prime concern will be bed length and spindle through hole internal diameter. The bigger the through hole the better and the longer the bed is (to a point) the better. You won't need anything longer than a 45" useable bed length *between centers". Make sure the machine is D1 camlock spindle, preferrably D1-4 or better and even better would b a diametrical thread cutting gearbox. All the manufactirers you listed are tits up so gtting parts can be a hassle...except B'Port that is now Hardridge.Make sure the machines are tooled and have taper attachments is possible. The nore hard tooling the better, Hard tooling can b 2-3 tims the cost of a machine and make sure the tool posts have Aloris or Aloris style wedge lock toolposts with corresponding toolholders.

Mills are mills. All vertical mills, unless CNC machining centers with tool changers are just fancy drill presses with power downfeed. get a B'Port, parts are available anywhere. Cincinatti is a good machine but parts can be a PITA. If any of the mills are BT40 or CAT40 spindles, get that. Unlike R8, Cat 40 and BT 40 are more versitale, locate more accurately when doing tool changes and offer through spindle coolant flow.

I've bought some great machine tools at school sales and some really bad ones too.
keep in mind that the American lathe parts are near impossible to come by these days. Those LeBlonds are probably in the same catagory as well. Not sure about the Southbends. On any of them you can get a new lead screw from a shop up in Traverse City Michigan. Clausings are still being built last time I heard, and are pretty good lathes. The condition of the equipment is what you must check out (I wrote a long post on how to look over a lathe and a mill a while back). The issue with the tubes can be hit or miss, but you can often still buy them. Avoid any thoughts about converting one to solid state. I've yet to ever see one work well. Bridgeport parts are fairly common, and if it's a step pulley head you got a good one. They still have a lot of trouble with the variable speed heads. If the slides are hard chromed, they are very hard to rebuild, and seem to wear rapidly. The best lathe for gunsmith work is a Monarch EE with a 10" or larger chuck. They made them with tubes and also solid state. Parts are hard to come by, but a good one is a Cadillac (pretty much any Monarch)

You pretty much figure that if it's a used lathe you need to rescrape in the compound at the least. That will set you back anywhere from $400 to a thousand dollars or more (gibs being shot). Make sure that the spindle is free of dings and hickys where the chuck mates to it. Clutch parts are out there, and the designs are fairly simple. A motor rebuild can be expensive. Bearing packs will vary on spindles, and can be anywhere from $300 to $3500. Tail stocks seem to catch a lot of abuse, so check the quill very closely and expect to shim the tail stock into proper alignment after the bed of the lathe is properly leveled (90% are never done right). The cross slide can be a real animal, and the only good way to check it is to pull it. If the apron has hardened ways your ahead of the game. But if they are messed up you can do nothing but send the complete apron out to somebody like Viking for a complete regrind ($$$). If the bed ways are showing a lot of wear you have a real problem that's not an easy fix. You could be looking at $4.5K for a complete regring of the apron and ways plus shipping. By the way Viking is the absolute best I've ever seen and used. Normally somebody that knows what they are doing will charge about 45% of the cost of the machine when new for a complete rebuild. Some are higher and some are lower, but you usually get what you paid for here.

I few years back I rebuilt a couple Bridgeports (42" tables with chromed ways). I ended up sending the tables and saddles out to Viking for about $1700 each. Had them grind all the way surfaces and table top and sides for installation of optical scales. Dovetails came in at about .0002" or maybe slightly less measured off gauge pins. The saddle came in at about one tenth, and were pretty much done when I got them. The knee was in pretty good shape, and simply had the chrome stripped and a minor rescrape (about two days work on each knee). I used the ball screw setup from Lead Screw International. The variable speed heads had to have a complete rebuild with new quills and one new frame ( bearings had spun in the quill, and the bore on one frame was worn out). Been cheaper to buy a complete head from Bridgeport in the end! I ended up with two machines that had less than .0005" compound error in 16" compaired to Bridgeports normal .001" in 12". Not really worth my time, but that's what they wanted. Could have bought new machines for that kinda money, and I tried to tell them that at the start.

You also might want to look for a Southwest Trac vertical mill that uses a similar head to the Bridgeport. I think they are a better mill, and are easilly rebuildable. My favorite is the one built by Willis Machine. It uses #40 tool holders and has a much better way design that's very easy to rebuild. Spindle is similar to a Bridgeport but built a lot heavier. Ways work off Turcite, so they should show much if any wear. It's easy to change the Turcite or simply Moglice it and forget it.

Lastly none of the machines you listed will work very well with a three phase convertor. You need the real deal here!
gary
Reply With Quote
  #14  
Old 12-02-2012, 04:16 PM
Platinum Member
 
Join Date: Jun 2010
Location: greenwood, IN
Posts: 3,645
Re: Looking at some lathes and mills on auction

Quote:
Originally Posted by SidecarFlip View Post
Adding to Shortgrass's post (I'm no 'lectrician by any means as a disclaimer...) but, 3 phase motors are most Wye wound. That means the T3 leg (the one you don't have with 220/1, is stackable.

It simplest terms, size your rotary convertor (I happen to have a Gerhardt-Werner btw) for the median horsepowr requirement you have, say a lathe with a 3 horsepower motor, keep in mind the inrush amperage is 3 times running amperage, so size the convertor for 9 horsepower to be safe.

I run the GH on the Servo-shift and the CNC machining center because I want to insure I don't smoke the electronics.

Leg all the 3 phase motors on one circuit and start and idle a couple notors before starting the bigger ones. The T3 windings on the idling motors will exite and provide starting amperage for the big motor to start.

If the machine is frequency drive (my LeBlond Servo Shift is), it's imprative that the T3 leg is pure sine wave 60hz power or you'll fry the frequency drive.

Also keep in mind that 3phase motors running on artificially excited (static conversion) single phase, produce less than nameplate rated power and more residual heat.

BTW, I wired my shop myself, 400 incoming amps and I live to tell about it.....

Never put both hands in a breaker box at one time, make sure the mains are pulled when fiddling around and be sure to discharge any capacitors (all motors of size have start capacitors that can kill you, right now and most motors don't have dropping resistors across the capacitors.
being as you working off the sine wave generator setup with the LeBlond, you really need to have the whole system balanced out (electrically) with a scope. Makes a big difference down the road. In the end you money ahead with a three phase installation (plus it's normally cheaper to operate on)
gary
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes


Similar Threads for: Looking at some lathes and mills on auction
Thread Thread Starter Forum Replies Last Post
Is this a good first lathes. jeff 300 Gunsmithing 7 03-26-2012 10:36 PM
Gunsmithing lathes, mill for sale sakotrg308 Reloading Equipment and Components 6 11-12-2011 12:32 AM
MOA/Mills??? ShooterMedic The Basics, Starting Out 11 03-14-2010 03:37 PM
mills vs moa Young_Sniper The Basics, Starting Out 3 03-25-2009 09:31 AM
AFM lathes any good? 458win General Discussion 0 10-30-2005 11:47 AM


All times are GMT -5. The time now is 08:27 AM.


Powered by vBulletin ©2000 - 2014, Jelsoft Enterprises Ltd.
Content Management Powered by vBadvanced CMPS
All content ©2010-2014 Long Range Hunting, LLC