Craftex CX709 motor issue?

[Tom Kitta]

Rare? Not in my experience. For example, the following is an old CGE 1hp utility motor:

Craig

Well not very rare - but most 1ph motors I have are a single direction - many are "cheap" and "farm duty". I would guess, 75% of the motors in 1ph I have are just single direction - I would have to check.

So maybe not rare but a bit less common?

 

[YotaBota]

I know this may sound overly simple but what about taking it in to a motor shop and have it looked at? It will cost a few bucks but it would put to rest the condition of the motor. If it is a problem with the motor and you can live without the high speeds for now all is good. Use the machine until such time as a 3phase/vfd setup becomes viable.
My $.02

 

[Tom Kitta]

I know this may sound overly simple but what about taking it in to a motor shop and have it looked at? It will cost a few bucks but it would put to rest the condition of the motor. If it is a problem with the motor and you can live without the high speeds for now all is good. Use the machine until such time as a 3phase/vfd setup becomes viable.
My $.02

They even have these in Canada for motors under 50hp? Even if they do the rates are probably at least 75/h or more likely 100/h. Much easier and cheaper and 100% sure way is to just get brand new reversing motor from say PA or online from motors website - here you can pick and choose exact name etc. - very competitive prices.

 

[YotaBota]

Couple of years ago I bought new Baldor TEFC 3/4hp motor for $80 and for another $60 had it rewired for reversing. For me it came down to what my time was worth. I could spend a day fiddling around with the motor wiring, hope to get it right and not let the smoke out having to buy another motor or pay the shop $60 to do it correctly the first time.

 

[Bofobo]

I’m going to throw in that I have this lathe as well, I’ve never had it at full power myself, it’s on a power bar and always trips when I try the higher speeds, I’m using factory oil and gear oil mix, Its in a basement so steady temps, I will try the warm up that Tom suggests, then perhaps change the weight if the problem persists. My assumption is that the motor rated as 1.5hp On my placard was simply Op for the 125.v 15a outlet, just like my plasma cutter will work on 110 but only for a few inches ata time

 

[DHHok]

So I've finished working on this problem and the final results are in.
Drum roll please......................Tom, I declare you the winner!......but just by a nose...

It was actually more than just the oil and it still won't run at the top speed, but it now runs on 11 of the 12 speeds.

I have a way of making a short story long, but this is what I did, and what I found.
I ran the motor without belts, because Susquatch was curious, but it ran fine with no load.

The motor & control circuit wiring was suspect, because it didn't match the wiring diagram and it wasn't wired properly. I'm not going to go as far as say it was wired wrong. It just wasn't wired to CEC and accepted standards. I kept losing my train of thought trying to trace the wiring because they kept mixing up the symbols, so it was easier for me to just start from scratch and redo it all.
An example is; the motor tag is U, V, Z and the (internal) motor wires are U, V, W and the control wires are U, O, Z.
Sooo...... O goes to W (which is motor tag Z), but Z control wire goes to V, which is the capacitors.....but Z on the tag is the auxiliary windings so Z should go to Z.......but O goes to W, which is the same as tag Z.....but......ugh.
So after rewiring it all I got 850rpm, but still couldn't run 1100 or 1600. However, I only got 850 once then it was back to not starting. After about 3 tries, it wouldn't start at any speed and just hummed. Sounds like a blown cap, but upon checking they looked good. Out comes the motor and off comes the front plate again. When I was reassembling the motor the 1st time, I guess I didn't tuck the switch wire out of the way and it had snagged on the centrifugal switch and ripped lose. So I soldered it back on and reassembled.
While I was doing all this I noticed there was a tear in the insulating paper for the Run cap and it looked to line up perfectly with one of the terminals. Now I couldn't see any signs of it shorting out, but after I fixed it and put it back on, I could consistently get 850. Still couldn't run 1100 or 1600, but it almost would start at 1100.

So then I went from ISO68 to the lighter weight ISO32 oil and I can consistently get all speeds except 1600. The motor definitely strains to start at 1100, but it does get it up to speed. So I'm stopping there and will just use as is.

My final conclusion to all this is that the motor is in no way whatsoever 1.5hp. I doubt it's even 1hp.
Going to a lighter weight oil is a must because the motor is simply underpowered.
That being said, I am still clinging to the belief that there is an issue with the centrifugal switch. The switch itself is ok, but I don't think it's weighted properly for how this motor is used.
If the motor was just underpowered, it would bog down, not be able to turn the load, and end up tripping the breaker. This motor bucks and heaves as if the power is quickly being turned on/off.
The contactor is staying engaged, so there is no lose of power. The only thing I can think of is my original thought. The centrifugal switch is opening too soon. That causes the motor to slow down and switch re-engages. That sends a big inrush of current to the motor and causes the "bucking". Then it speeds up and the switch opens.....repeat.

 

[Tom Kitta]

Yeah I like to win! I was worried when the label said 1.5hp and amps 14 - with more power I was worried maybe its not oil... But it looks like they just changed the label on the motor to say 1.5hp and its just old 1hp. Maybe you can put clamp meter on the wire and see how many amps it really draws. Make it work hard and start to slow down and see how many amps it is taking.

I also was surprised when they increased power by 50% and did not even change belt size up. Who would have thought they put false label on the motor?

My old 089 would start with old oil at the 850 (or one down 740?) consistently when warmed up. Since yours is in warm environment already it is warmed up. I guess wires were messed up & hence this batch had more speed starting problems then "usual".

I have no clue why after 10 years they simply did not change to correct oil.

 

[Susquatch]

What a sad indictment of Busy Bee....

Thanks for humouring me and running the motor without belts.

I'm satisfied that the issue is an underpowered motor and a lot of things designed to make sure it can never live up to what is expected of it.

I am of the view that the centrifugal switch would work fine on a properly powered motor. But when the motor is underpowered the motor doesn't provide enough oomph to get through the switch limit so it stalls and the cycle repeats.

If I were you, I'd both change the motor AND reduce the loads.

Good on you for persevering.

 

[gerritv]

What a sad indictment of Busy Bee....

Why? they said there was a problem, and significantly reduced the price. And fixed/resolved the issue on new stock.

 

[Susquatch]

Why? they said there was a problem, and significantly reduced the price. And fixed/resolved the issue on new stock.

Unless I have totally misread this thread, there has always been a problem, and they still have a problem. They just sold a few with an even bigger problem at a discount.

It's a bit like selling a car that won't run in 4th gear but only giving a discount to those that won't run in 3rd either and never even acknowledging or fixing the 4th gear problem.

Sad, just plain sad. But I do sincerely hope that I am wrong.

 

[trlvn]

I only have enough electrical knowledge and experience to be dangerous. Could someone who understands motor theory lend a hand? I believe the motor being discussed here has a start capacitor and and a run capacitor. If one or both are somewhat below their design spec, could that explain the performance problems described in this thread?

If the centrifuge switch is also poorly designed or badly constructed, that could compound the issues.

I take it as a given that Chinese motors are cheap. Designed to use the least possible amount of copper, etc. Assembled with the lowest cost components available of which the capacitors would be a non-trivial element. Nonetheless, they would not be saleable if they wouldn't run at all.

What if there was a batch of capacitors that produced the low end of the range of capacitance that they are specified for? They might still be "within spec" but when coupled with a marginal design of the rest of the motor, they don't have enough oomph to get up to running RPM when faced with a somewhat higher starting load.

This is where I'm well out in the weeds, though. I seem to recall that measuring capacitance isn't that straightforward. But I think if the OP took the caps to a motor shop, they could probably check them. New capacitors are pretty inexpensive--$15 to $20 range--so maybe just buying new ones is something to consider.

Craig

 

[Susquatch]

I only have enough electrical knowledge and experience to be dangerous. Could someone who understands motor theory lend a hand? I believe the motor being discussed here has a start capacitor and and a run capacitor. If one or both are somewhat below their design spec, could that explain the performance problems described in this thread?

If the centrifuge switch is also poorly designed or badly constructed, that could compound the issues.

I take it as a given that Chinese motors are cheap. Designed to use the least possible amount of copper, etc. Assembled with the lowest cost components available of which the capacitors would be a non-trivial element. Nonetheless, they would not be saleable if they wouldn't run at all.

What if there was a batch of capacitors that produced the low end of the range of capacitance that they are specified for? They might still be "within spec" but when coupled with a marginal design of the rest of the motor, they don't have enough oomph to get up to running RPM when faced with a somewhat higher starting load.

This is where I'm well out in the weeds, though. I seem to recall that measuring capacitance isn't that straightforward. But I think if the OP took the caps to a motor shop, they could probably check them. New capacitors are pretty inexpensive--$15 to $20 range--so maybe just buying new ones is something to consider.

Craig

Measuring a capacitor isn't straightforward as you say, but it isn't difficult either. Many multimeters come with a range for testing capacitance. If yours doesn't have that, maybe you know someone with one that does. Or you can go to a tool place and borrow one or even just "evaluate" one ostensibly before buying.

If not, here is link to how you can test one using the time constant method without the required range on your multimeter. It's actually pretty easy to do too. You just need a good stop watch, a decent battery, and a resistor. You can use the formulas at this link and the capacitance you think you have to select a decent size of resistor for the job that will make measuring the time doable.

Basically you charge the capacitor with a known voltage through a known resistor and measure the time it takes for the voltage on the cap to reach 63% of the battery voltage.

Edit - I know the link says "invalid request" but click on it anyway.

Resistor-Capacitor (RC) Time Constant Calculator | DigiKey Electronics

Calculate resistor-capacitor (RC) time constant of a resistor-capacitor circuit by entering voltage, capacitance, and load resistance values.

www.digikey.ca

 

[DHHok]

If I were you, I'd both change the motor AND reduce the loads.

And reduce the load?? Geez, for the most part I'm only turning 1" stock.

In regards to the caps, I believe they are ok. I tested with a multimeter and although I didn't calculate the capacitance, my gut (which is often smarter than my brain), feels they are good.
I could take the motor to a shop and have it fully tested, but with how the machine is running now, I have no real need to.
Besides, if it ended up that something was wrong with the motor, that would mean the oil weight was not a problem. I just don't have it in me to take the win back from Tom.

 

[RobinHood]

Geez, for the most part I'm only turning 1" stock.

And that is exactly why you’d want the 1600 rpm working -> the smaller the diameter, the higher the spindle speed you need.

Kudos for persevering and trying to get to work what you have. I think your analysis was very methodical and you found some issues which you corrected. If the BB discount was big enough, I would turf that motor and get a decent quality one (or at least replace the caps - I would even go one size up on the start cap).

By putting on a motor that actually works for this lathe, you increase the value of the machine. It solves all the headaches and you will enjoy it more.

 

[Susquatch]

And reduce the load?? Geez, for the most part I'm only turning 1" stock.

I meant to use lighter weight oil. Besides, for small stuff you need high rpm.

In regards to the caps, I believe they are ok. I tested with a multimeter and although I didn't calculate the capacitance, my gut (which is often smarter than my brain), feels they are good.

The soft gut is easy to fool because it likes to be right. Best to trust cold hard logic and evidence and keep your gut happy with Christmas baking.... Ho ho ho.....

 

[DHHok]

If the BB discount was big enough, I would turf that motor and get a decent quality one (or at least replace the caps - I would even go one size up on the start cap).
By putting on a motor that actually works for this lathe, you increase the value of the machine. It solves all the headaches and you will enjoy it more.

I'll probably install a VFD. I can pick up a good 3ph motor for about $100, so along with a cheap chinese VFD, I'd be into it for under $300

Best to trust cold hard logic....

I never let logic interfere with my train of thought.

 

[Susquatch]

I never let logic interfere with my train of thought.

Can't say I blame you, but I try very hard to do the opposite.

 

[combustable herbage]

Logic always solves the problem but is not always the most efficient way, intuition/gut can be a big benefit but you can get burned as well and sometimes cost you more but you have to be willing to accept the outcome. I like to do things logically till I can see an opportunity for an efficiency, I guess we could call that experience.

 

[Susquatch]

Logic always solves the problem but is not always the most efficient way, intuition/gut can be a big benefit but you can get burned as well and sometimes cost you more but you have to be willing to accept the outcome. I like to do things logically till I can see an opportunity for an efficiency, I guess we could call that experience.

They say that experience is the toughest teacher of all because she gives the test BEFORE the lesson.

I prefer to learn from the mistakes that others make, but somehow or another I seem to make plenty of my own anyway.

 

[ThirtyOneDriver]

Sweet @DHHok

I also have one of those heavily discounted CX709"x"s... I have zero experience w/ electrical motors, etc. (@Tom Kitta's oil change is on my list of things to do). Where would I start to source a replacement motor? I expected the machine to be 220v 1ph before buying and would still be open to that as a possibility. (devil on my shoulder says "sell it" for whoever is going to say that next) Anyone in Ontario willing to do a motor swap (as in replace mine)?