Thread: Huanyang VFD issue when engaging lathe clutch

My 5hp home built RFC works fine with my Boley5LZ.

Phil

Here's a 5LZ threading with 4 speed reverse

http://youtu.be/HRvZlJcA75k

Phil

Originally Posted by philbur

The flip of a switch 4 speed reverse with the integral brake is a hugely important and convenient feature for manual threading, at least if you don't have a threading dial.

Phil

Thanks for the clip. It certainly is a conveniant feature. In the old mechanical days, it could only be had with such upper class machines. At the expense of added drivetrain complexity, and the associated cost not only to buy, but also to maintain it.

The good news is, that after a VFD variable speed upgrade, everyone can now have this feature too. It comes so to speak for free with the VFD. I do it all the time when threading, on my low cost hobbylathes fitted with VFD. I just have to turn the speed pot to max speed during the return pass. Well,
- the VFD cannot brake as fast as the mechanical brake, but much faster than just coasting. And all but the cheapest VFD's can be fitted with an external brake resistor. It is not a problem anyway, because one can simpy reduce the speed with the speed pot as one approaches the end of the return pass.
- with the VFD you may not always have a 1:4 speed increase on return available. The possible speed increase is variable as it depends on several factors. Like if its a cheap V/Hz VFD or a Vector VFD. Like what frequency you select to begin with for the forward cut. But a 1:2 speed increase will always be available if you do the forward cut with no more than50Hz, and 3:1 and up to 4:1 speed increases are certainly possible with some thinking ahead when setting up the task and using a frequency of 25Hz or less for the forward pass.

That still leaves the OP with the choice whether to keep the original clutches/brakes/1:4gearbox for threading. Or to ditch it all in favor of a simpler VFD and drive setup, with slightly less perfect threading functions. It is not an easy choice to make, but the choice is hopefully easier after knowing the above.

Originally Posted by cba_melbourne

Thanks for the clip. It certainly is a conveniant feature. In the old mechanical days, it could only be had with such upper class machines. At the expense of added drivetrain complexity, and the associated cost not only to buy, but also to maintain it.

The good news is, that after a VFD variable speed upgrade, everyone can now have this feature too. It comes so to speak for free with the VFD. I do it all the time when threading, on my low cost hobbylathes fitted with VFD. I just have to turn the speed pot to max speed during the return pass. Well,
- the VFD cannot brake as fast as the mechanical brake, but much faster than just coasting. And all but the cheapest VFD's can be fitted with an external brake resistor. It is not a problem anyway, because one can simpy reduce the speed with the speed pot as one approaches the end of the return pass.
- with the VFD you may not always have a 1:4 speed increase on return available. The possible speed increase is variable as it depends on several factors. Like if its a cheap V/Hz VFD or a Vector VFD. Like what frequency you select to begin with for the forward cut. But a 1:2 speed increase will always be available if you do the forward cut with no more than50Hz, and 3:1 and up to 4:1 speed increases are certainly possible with some thinking ahead when setting up the task and using a frequency of 25Hz or less for the forward pass.

That still leaves the OP with the choice whether to keep the original clutches/brakes/1:4gearbox for threading. Or to ditch it all in favor of a simpler VFD and drive setup, with slightly less perfect threading functions. It is not an easy choice to make, but the choice is hopefully easier after knowing the above.

Thing is the braking happens in maybe a quarter of a turn so you can thread to a shoulder and it's all in one switch so it's quick. If he wants the auto threading to work he will need to keep the mechanical system.

PS: Also during the reverse the motor remains running, in the same direction.

The ultimate goal is to keep the 5LZ as it was from the factory. There is no chance I am going to stop using the clutch. It is an integral part of the machine. My aim is to give it my best shot before accepting a compromise. At this point the only electrical gremlin is the high speed reverse.

I did some more investigation today with the 5LZ and VFD. I rewired the whole setup to use much heavier gauge wire. It made no difference at all. On that basis I setup the clamp meter (over the power input into the VFD - I will check the motor side tomorrow) and the trusty Fluke 87 and used the Min/Max hold function to see what was going on. The results were pretty astounding..

RUNNING	AMP RUSH	STABLE RUNNING
FWD
LOW	5.11a	2.15a
HIGH	9.66a	3.44a
REV
LOW	26.4a	7a
HIGH	32.33a	Trips VFD

As you can see the results are quite astounding. What's more from time to time I was able to get it to reverse at high speed. This only happened 2 times out of about 30 test runs. When it was successful I recorded via the clamp meter an astounding 50.22 to 52 amps at the rush. No idea why the VFD did not trip out. I changed a lot of settings but could not get a repeatable solution in terms of it performing high-speed reverse. It would do it once then the next time (with the same settings) trip the VFD and record a much lower max-amps.

I am starting to wonder if the amp-rush is half due to the spindle slipping (see my other Boley 5LZ thread for details). It makes me wonder if that slippage is somehow causing the ramp-up to take longer than the VFD is willing to accept. Maybe the times it successfully ran it had enough stiction to ramp in time.

Incidentally when it was supposedly pulling 50 amps (albeit very briefly) nothing got hot. The power and motor cords were not even warm. It also doesn't trip the 20 amp breaker in my circuit board (it is on a 15 amp line).

When I reverse in low speed then change the speed setting to high it never fails. Spins up without issue. It it spins scarily fast!

IMG_0370.jpg IMG_0371.jpg

Originally Posted by cba_melbourne

Just as a try. Have a play with PD032 and PD033.

I tried these today. I got some decent amp pull numbers but nothing stable. PD032 set at 10 got me a successful 52 amp run. Tried to repeat by stopping and starting again. Unfortunately it tripped out the VFD

Originally Posted by eskimo

could it be PD119, PD120 thru to PD125 or others in that vicinity of the manual?

Yep. This is the main section I have been focusing on. I tried a ton of different numbers for all of them. Funnily enough reducing 121 down to 0.1 (lowest setting) got me a successful run at high speed pulling 50.26 amps. It was a fleeting victory however as my next run with the same settings resulted in tripping out the VFD with low-ish amp rush numbers. It makes me wonder if there is mechanical slippage that is possibly the root cause of this issue.

Good snooping !

Originally Posted by variant22

As you can see the results are quite astounding.

No really - the rotating mass has considerable inertia and you are asking it to reverse and go 4 times faster, its about what I would expect.

What's more from time to time I was able to get it to reverse at high speed. This only happened 2 times out of about 30 test runs. When it was successful I recorded via the clamp meter an astounding 50.22 to 52 amps at the rush. No idea why the VFD did not trip out. I changed a lot of settings but could not get a repeatable solution in terms of it performing high-speed reverse. It would do it once then the next time (with the same settings) trip the VFD and record a much lower max-amps.

Like breakers the VFD trip current will be determined by integrating the current over a certain amount of time ( Current x Time) if the product of the two is within spec it probably won't trip.

I am starting to wonder if the amp-rush is half due to the spindle slipping (see my other Boley 5LZ thread for details). It makes me wonder if that slippage is somehow causing the ramp-up to take longer than the VFD is willing to accept. Maybe the times it successfully ran it had enough stiction to ramp in time.

I'd say the opposite, the 2 times it worked the clutch slipped long enough for the VFD to catch up with the system. The other times were shorter but had much higher currents - which you couldn't see and that's why it tripped.

Incidentally when it was supposedly pulling 50 amps (albeit very briefly) nothing got hot. The power and motor cords were not even warm. It also doesn't trip the 20 amp breaker in my circuit board (it is on a 15 amp line)

That's not surprising either,
The breakers are designed to cope with short bursts of high current.
On my 3HP dust collector I typically see and inrush current of 60A and the 20A breaker on that dedicated 15A GPO circuit has never tripped.
In terms of heat the copper has a thermal inertia and it takes some time for it to heat up.
If you can feel it through the insulation in that short period of time then it has really got hot.

Is there anything in the manual about increasing brake and clutch times?
They're not simply on/off are they? Looks more complicated than that in the wiring diagram.
What do you have on the spindle now? I'm guessing adding a chuck and workpiece will make things worse still.

My only other thought(and hopefully its a little to soon for this sort of thing). Would adding inertia help?
Stuart

Originally Posted by BobL

That's not surprising either,
The breakers are designed to cope with short bursts of high current.
On my 3HP dust collector I typically see and inrush current of 60A and the 20A breaker on that dedicated 15A GPO circuit has never tripped.
In terms of heat the copper has a thermal inertia and it takes some time for it to heat up.
If you can feel it through the insulation in that short period of time then it has really got hot.

Interesting BobL. Makes me more comfortable with the current spikes.

Originally Posted by Stustoys

Is there anything in the manual about increasing brake and clutch times?
They're not simply on/off are they? Looks more complicated than that in the wiring diagram.
What do you have on the spindle now? I'm guessing adding a chuck and workpiece will make things worse still.

My only other thought(and hopefully its a little to soon for this sort of thing). Would adding inertia help?
Stuart

Stuart, I have not found anything in the manual about increasing the brake and clutch times. I would really like to tweak the clutch, but the manual sheds no light on that from what I have read. The manual is available here: http://passion-usinages.forumgratuit...607-boley-5-lz

I don't have anything on the spindle. It's a bit of a long story. But basically the lathe came with a threaded spindle without the locking nut. I had to make one. It is not fully finished (need to mill flats to tighten it properly). This stops the chuck unwinding during braking/reverse. Apologies in advance for the out of focus image.

IMG_0112.jpg IMG_0106.jpg

Before I start down the road of adding inertia, I may well whip out a Parallax Propeller I have handy and interface with the clutch to tell the motor to slow down (mid-speed on the VFD) and then sending the signal (after waiting 1 sec) for the high speed command. I want to avoid that path as it is a lot of stuffing around. I was hoping some VFD wizardry might get this running.

Aside from the reverse it's perfect. I can switch it fast from stop to high-speed and it does not blink. Just the darned reverse...

Next WAG. How did you tension the flat belt?.............. maybe, if that wasn't so tight it would slip a little on reversing......no idea if its meant to or not.
Having said that(and I think I asked this before, and I can't see anything from a quick flip through the manual)...... was it ever intended to auto thread at high speed? what is high speed? I'm guessing over 1000rpm........that makes reverse over 4000rpm. I think I'd be ducking before the VSD tripped anyway ..... or am I missing something?

Stuart

Originally Posted by Stustoys

Having said that(and I think I asked this before, and I can't see anything from a quick flip through the manual)...... was it ever intended to auto thread at high speed? what is high speed? I'm guessing over 1000rpm........that makes reverse over 4000rpm. I think I'd be ducking before the VSD tripped anyway ..... or am I missing something?

Stuart

Good point. I know there's no way I'd even think of plug-reversing my Chipmaster if it was spinning at 3000 rpm..... of course that'd be reversing the motor as well as the entire drive train, but still.....

I too am not surprised about the short period current draw figures. I also think a big chuck & workpiece are going to make this worse, and *eventually* there's a good chance something in the drive train is going to let go.

If it's intended for fast reverse threading, I'd only use it at slow speeds. Be interesting to hear what the other Boley owner has to say here.

Makes me appreciate the single tooth dog clutch setup for threading on my Monarch. OK I don't get fast reverse but I could fix that with a VFD if I wanted to.

Must come by & take another look at it all including the backplates for the chucks.

PDW

You said previously:

“The reason for the VFD, is that I purchased a 5hp RotaryPhase Converter (Phase Changer brand) but it was bogging (running at max load)when I switched to high speed.”

This should not happen, I run mine happily on a 5hp RPC.It possibly suggests that you have mechanical problems. High speed (3500 rpm)needs special oil in the plain bearings and even then it’s possible they get toowarm and start to bind if things are not adjusted just right. You should give more information about thepulley bearing housing rotating 180 degrees as I mention in the other thread.This suggest some sort of binding which could result in high amps.

There is no instant, plug reversing, when you operate switch C.The clutch disconnects the motor and the brake stops the spindle, then the twoclutches together engage the 4 speed reverse after the brake has released. The motor never stops or reverse direction and the clutchesprovide a soft start which is less abrupt than starting the motor in eitherdirection from scratch.

Do the high amps continue when in reverse at high speed oris it just during spin up. The 4 speed reverse is for threading only so youshould not be doing this at high rpm. Forward threading should maybe be limitedto 200 rpm or so, which means reverse should not be more than about 800 rpm. Ithink you will wear out the clutches and the brake very quickly if you areperforming this operation at 2000 or 3000 rpm.

For some reason the text editor on this forum doesn’talways register my key strokes and if I paste from a word processor I frequentlylose the space between two adjacent words. Anybody know how to fix this?

Phil

You can also mechanically reverse the spindle direction with lever B, so if you use your ammeter you can maybe determine if the issue is mechanical and not electrical.

Phil

Originally Posted by philbur

For some reason the text editor on this forum doesn’t always register my key strokes and if I paste from a word processor I frequently lose the space between two adjacent words. Anybody know how to fix this?

If you are using IE there may be issues as there have been before.
(try toggling the compatibility or better yet, use something else)

Michael