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06-09-2006, 12:33 PM #1
Greetings 2 all!
Bought a used chinese lathe that has history of smoking motors.
I am seeking alternate input as to a different motor to put on this lathe...... Unit has had 2 harbor freight motors, both burnt capacitors and or windings. I have looked at putting an american made instant reversing motor with a drum switch on the lathe, cost for baldor 3 hp plus switch is about $600 bux.
Wiring diagram for the dern lathe is a mess!
It costs approximately $400 bux to replace both
the chinese motor and control box........which I am reluctant to do,want to upgrade from a 2hp to a 3hp motor, (230 volt single phase)
ANYBODY??? Have any good input as to other decent possibilities for this near new lathe???
I'd be glad for any good ideas. Oh yeah I already
got the input about using the lathe to anchor my boat! LOL! Thanxx!!
06-09-2006, 12:44 PM #2
Treadmill motor as pictured in the "People throw away the darndest things..." thread.
Surplus Center usually has several varieties listed, along with controllers.
Here is one:
And this might be the controller:
06-09-2006, 12:59 PM #3
Had thought of varaible speed motor to augment
gear selected speeds, BUT did not think DC motor inexspensive enuff to use... Next things I am wondering are: adapting shaft end to appropriate pulley size, and also if that controller is adequate to handle the amps and werk load of lathe???? Like your thinking and input on this problem. Stepper motor GOOD. Chinee motor BAD! Usually bad insulation on windings etc, resulting in motor PREMATURE FAILURES.
I also will have problems adapting all this stuff to make lathe feed etc to werk.........Thank you!
06-09-2006, 01:17 PM #4
06-09-2006, 01:33 PM #5
Those cheapo Cinese motor fail in the windings because it's very likely they didn't go through the final soaking of the whole stator in insulating varnish and subsequent bake. The windings without the dip and bake can move because of the force of their magnetism and chafe on adjacent wire wearing through the insulation and causing a progressive burn-out.
Here's the deal for a minimum cost fix on HF's nickel.
Get a new motor from Harbor Freight, take the stator to a motor shop, and have them dip and bake it. You wll have to clean the motor shells rabbet fits of cured varnish with a screwdriver, scribe, wire brush, etc so the endbells go back on cleanly. You will have to take care the starter switch the motor leads etc are undamaged and go back together as they came apart. If you don't like the new yellow tinge of the insulating varnish, repaint the motor.
Alternatively look at http://www.dealerselectric.com/
They offer a single phase in 3 HP VFD to three phase motor package for $498. This will give you infinite speed control and the smoothness of three phase. Your lathe will run quieter and give you better finishes.
The treadmill motor and control will do the same but they will not gove you the full 3 HP you desire. They best they can do from a wall socket is about 1 1/2 HP regardless of a fraudulent number stenciled on the treadmill.
06-09-2006, 02:42 PM #6
I would shop some ebay before I dropped $600 on a new-in-box Baldor and a drum switch. Good used have many many hours of service left.
06-09-2006, 03:29 PM #7
One caveat about treadmill motors is that their rated HP speed is usually very high relative to general purpose industrial motors. This means you will need to come up with some sort of mechanical speed reduction like a jackshaft or maybe a 2:1 gearbox to get the power in the right dimensions for a lathe.
I recently bought a 1/4 HP permanent magnet DC motor, Boston Gear branded made by Baldor, New In Box for $19.99 on ebay. The guy has more of them. I bouth a new Boston Gear 4 quadrant controller for $19.99 in an earlier auction. With shipping on both item I have about $55 to my door. This was the best add-on I have done to date on my 6" Atlas. The one catch is that the motor is a 'C' face mount only with no foot. I simply clamped the motor housing with 'Adel' style clamps to a wood base with a radius cut-out, then bolted that to the bench the lathe is mounted to. Works perfectly; very rigid.
I'm not saying you can come up with a $60 solution to YOUR problem; you need a much bigger motor than I did. But a motor+controller should only set you back about $200-300 + shipping, should you decide to go that route. But remember that in order to get a great deal, you will have to wait for one to come along. If you must be 'up and running' by next wednesday or something like that, you will just have to buy what's available right now.
Here's a deal on 1 HP, but I have seen many on larger motors, too:
Another thing I'd like to ask is why you want to increase the HP of the motor from 2 to 3? Are you going to use this machine for some kind of production work where you will max it out with deep cuts at high speeds with blue chips flying? I mean if you are only a hobbiest, you will NEVER use up even 2HP, let alone 3.
06-09-2006, 04:06 PM #8
I have this lathe in a clone (Birmingham), and while my motor didnt fail, I did convert it to variable speed DC. The motor and controller is from Surplus center.....
Motor #10-1723 $89.95, controller #11-2102 $145.00.....
This set-up is working VERY well for me in my home shop,---- have just been learning to thread, and being able to slow down to maybe 20-30 revs min has really helped.
I've also got 5 other machines with DC conversions, mostly various treadmill adaptions, coming from ebay, so that IS a very viable source for motors. A search under 'DC motors' will usually bring up around 150 choices----
The shaft will have to be addressed....I made a collar/adapter, the motor shaft was 5/8" and pully was somethin MM?? (around 7/8", I forget) and had to cut a key slot
I cant figure why you would need a larger HP motor either, are you maybe gonna use it in a production setting?? I was experimenting with my DC set-up and when I got up to taking a .120-130 cut in mild steel with out a strain, I decided that 1 1/2 hp was PLENTY.
We may be neighbors,--- I'm right on the Tex/La border, if you need additional info on the set-up I used give me a holler
06-09-2006, 08:39 PM #9I would shop some ebay before I dropped $600
However, it's near impossible to find an inexpensive 3HP, 1750 single phase, TEFC. Email or PM if you have one for sale, it's to replace the 1.5HP on the belt/disc sander.
06-09-2006, 10:22 PM #10
Greetings again folks!
Just back on line, hot as HADES here near Deberry, Texas!
Lotsa great input from all!! Really like the idea of variable speed in addition to geared speed changes. Especially like the $$AVINGS on motors,I have little familiarity with larger DC motors....Do they run as hot as AC types? Any input as to average motor life? I.E. [no. of hours of usability???] Thanxx to all!
06-09-2006, 10:35 PM #11
Good point Barry, I was thinking 3 phase motors.
I still believe I could get a 3hp - 3phase motor and a VFD for less than $600.
Then you have a nice industrial strength anti-cogging motor, single-phase input, and variable speed.
06-09-2006, 10:51 PM #12
Jimbo 1490, reply to your Q.......Would only cost me 33 bux more to upgrade from 2hp to a 3hp.
seems money well spent were I to have gone this route, secondly small lathe I have is way underpowered.............thanxx!
06-09-2006, 11:09 PM #13
I have one of the same HF lathes right now. Not bad but not anywhere near great. The chicom motor they put on them is way over rated in the HP dept (guess the horses in china are a lot smaller and lazier). My last lathe was a South Bend 10L (the heavy ten) and I put a GE 1.5HP 1725 RPM motor on it and was very happy with the smoothness and power. I got mine from Tractor Supply for about $175 and it has to put out at least a half horse more than the chinese one. Another big plus is the frame size and output shaft should match the one you have.
06-10-2006, 01:26 AM #14
Concerning treadmill motor ratings, one of the high priced treadmil manufacturers advertises one of their machines as having a 5 hp motor. It does produce 5 Hp, at 380 volts and 120 Hz. The vfd that powers the motor has 120V input, stepped up to 240. Output is rated 4/6 amps. FLA of the motor at 208V is 6.6 amps. At full load on 208 volts and 60 Hz, the motor actually produces 2.5 hp. Of course, the vfd in the treadmill will not provide FLA. The motor manufacturer tests the motor at 208V, the torque produced at FLA and 60 Hz is how the 2.5 hp was calculated. Testing determined that the motor could run at 380 volts max and at 120 Hz could provide a continuous 5 hp. The treadmill manufacturer then advertises a 5 hp motor but does not explain that it will not approach that in their machine.
06-11-2006, 01:36 PM #15The chicom motor they put on them is way over rated in the HP dept </font><blockquote>quote:</font><hr />
seems money well spent were I to have gone this route, secondly small lathe I have is way underpowered.............thanxx! </font>[/QUOTE]I think I get it now. The motors in these tools do not really make the power they are advertised to make. I recall noticing this on a HF mini drill press a few years back. The motor plate said it was 1/4 HP, which is OK for a small DP, but the thing is you could STALL the motor with a 1/4 inch bit if you got aggressive with the feed 1/4 HP my a$$!
10-18-2006, 12:50 PM #16
Me too. I've got a little mini drill press that I couldn't resist for 44 dollars at Menards. Motor said 1/3 hp. Yeah, I could almost stall it with a 1/4 bit. I put a 1/3 hp Dayton from my spare motor pile on it and whammo! I noticed that the amperage draw listed on the dayton nameplate was double that of the china unit. The Dayton was also three times the size and four times the weight. I suspect that the amperage rating is at least a little better indication of what these motors will achieve.
Which brings me to ask. What exactly is the relationship between hp and amp draw? Amp specs are commonly touted by manufacturers to describe the power of their handtools - less so for heavy machines. I know that you must compare same voltages when comparing amps. But otherwise, how useful are they when evaluating engine performance?
10-18-2006, 12:57 PM #17
My favorite one is the hp rating commonly seen on shop-vacs. "6.5 peak hp" I'm not an engineer, but I have vague idea of just how this might be measured. Spin the little motor up to top scream, thrust a good sturdy screwdriver into the windings with sufficient force to bring the experiment to an instant halt - presto.. for a millisecond you have applied approximately 6.5 brake hp to the tip of now mangled screwdriver.
10-19-2006, 03:14 AM #18
1 horsepower is 746 watts
You need to get your head around the power usage factor here- a formula where P(ower) is equal to I(amperage) X E (voltage) X Eff (motor effeciency) X PF (power factor) divided by 746
This is for single phase motors
For 3-phase, multiply the top line by 1.73.
Sounds complicated, but it's really not.
Let's say you've got a motor that draws 6 amps at 120 volts. The efficiency and power factor vary, but are stamped on the motor nameplate. Just for ****s and giggles, let's say the efficiency rating is 1, and the power factor is 2.
So this gives us 6 X 120 X 1 X 2= 1440, and divide that by 746, giving us a motor just under 2 horse.
What works about this formula is that if you don't have one of the values, you can just plug in what you do have to find what you need, like if you know the (american) horsepower rating and know what voltage you're ging to run it on, you can figure what size circuit breaker you're going to need to keep it running under load.
Chinese horsepower and construction quality? Well, the reason our recycling industry is doing so well (seen what you can get for aluminum lately?) is that there's a lot of old Budweiser cans and '76 Monte Carlo bumpers in them there electric motors, pulleys and bed ways.
Peak horsepower is a myth, obtainable through foggy glasses and aforementioned Budweiser. Hmmm, I'll have a "peak" at the amp meter right before the motor goes "Puff"
I'll personally stick with the older quality american stuff, thanks.
But what does an old faht like me know?
10-19-2006, 03:42 AM #19
DC motors that are industrial quality, TEFC are the only ones to consider and one of these with controller is going to be at least $300, used.
New will be a lot more. They have strange form factors also in addition to smaller shafts. I think a much better bet would be a 3ph motor and VFD, which would allow you to discard essentially everything in the control box. You would most likely have to buy a new pulley but that is not much, even for a two speed pulley. A friend bought the www.dealerselectric.com combo pack for his mill drill, 2hp. It was about $350 then now about $425. The motor was chinese with a Marathon label. It has done well so far in home use. OTOH, www.surpluscenter.com has 3 or 4 different 1750rpm 230/460vac 3ph motors in stock (2 to 3Hp) for between $30-80. A TECO FM100 controller for $200 or so would get you in business for well under $400 even if you throw in a replacement pulley. You would have to fab up a new motor mount, but that would likely apply to any replacement. All the switches on the apron and front of the lathe terminate in the terminal strip at the bottom of the control box so rewiring would be childs play. All the contactors and transformer are not used with a vfd unless you want to power up the lights.
10-19-2006, 05:03 AM #20
Billy your figures don't reflect the everyday reality of induction motors. 746 Watts/HP presumes a perfect 100% efficient motor. Here we are talking about commercial induction motors and a few examples of DC motors. All are much less than perfect and suffer from the expected losses. For example, 5 HP induction motors demand 1000 VA per HP and up as the nameplate HP decreases.
A 3 HP single phase motor is typically nameplate rated at 230 Volts at 14 Amps more or less. A 3 HP three phase motor connected for 230 Volts will be rated at about 8.6 Amps.
Further, Power Factor is equal to 100 times the cosine of the phase angle between the voltage and the current. It's typically 55 for a lightly loaded induction motor and as high as 85 for an integral HP indction motor at full load. It's never equal to 2 except under the rarest of laboratory conditions.