Thread: Mars Lathe DC motor conversion.

Originally Posted by Ueee

I was a bit confused to start with though, they have 72 and 73 back to front in the list, but it is right in the description.

Hadn't noticed that one yet! lol

Motor is on and running.

My first impressions where that the fan is noisy, and it doesn't stop quickly enough....Not much i can do for the fan but the stopping.....The lowest i can get the ramp down time is 3sec without getting an over voltage fault in the higher gears. I tried setting the DC braking but it seems to be useless for this application. If set to say cut in at 20hz, it does work.....like a dead stop, even with the voltage set to .1%. But the worst bit is you loose everything under 20hz, inc jog and run. I added a resister for braking but there doesn't seem to be a PD for telling the VFD its there, and it is making no difference. I will have to play some more and see what i can do.

As for the jog ramp up and down speeds, they were set to 80 sec......I have noticed you can set things differently than the range that the book says

Originally Posted by Ueee

I have noticed you can set things differently than the range that the book says

oops yeah forgot to let you know about that
Makes setting them up all the more interesting.
What numbers are you using for
pd028
pd030
pd031

I have a brake resistor but am yet to try it out. I have seen in another thread that some of these VFDs have the terminals for a resistor but there isnt anything there really.(though that doesnt seem to be a problem for you)

Stuart

Sorry to be the bearer of bad news Ueee: I read this in one of the threads here or on another forum - and then checked all my (3) VFDs: the external resistor braking electronics are NOT installed at all..... Seems that the eBay low-cost Huanyang VFDs don't have them. The function is described in the manual as you found, but none of the resistor braking stuff works.....
You will have to work around the triopping current with downslopes and DC braking instead. I found on one occasion I set it 'wrong' and the motor stopped so suddenly it nearly jumped off my workbench! and I nearly crapped myself.... So it is possible to get a fair bit of braking force, just with the settings that are there.

Hi Joe,
I "believe" its there on my VSDs though am yet to prove it

Here are some pictures Ewan

https://www.woodworkforums.com/f170/t...tml#post973533

Stuart

Hi Stuart,
I will check the settings tomorrow, i should really be writing what i change down......

Hi Joe,
That is bad new but i guess its what we get with these cheap versions. I know what you mean about the DC braking though, its like someone dropping a bar into the motor fan, even at 10hz everything goes clunk.....
My biggest concern is that i have a screwed spindle nose, i don't want the chuck coming off!

Hi Ueee,

When I was playing with the ramp down times, I set it so low at one stage that the motor nearly came to a sudden stop. This was without any DC braking. I have never played with the DC braking as I have found the ramp down times can be set quite aggressively if I really wanted to.

Cheers,

Simon

I wonder if it has something to do with Ewans 2800rpm motor?

Hi Joe,
The plot thickens, I was just out in the shed and though "I'll just check to be sure I recalled correctly", took the cover off and only 3 wires! "What? I'm sure there were 4". Took the cover off the next VSD...... 4 wires. So I've not lost my marbles completely. I'll check the other two tomorrow. These 4 VSDs came from one supplier in one shipment.


Hi Ewan,
Did you see the link in my post at 8:58

Stuart

Yes thanks Stu, i'll check tomorrow.

It could be the 2 pole motor, but i think my lathe also has a lot less friction in the bearings than most roller's, being plain it will sail around for a long time if left to freespin. At 2 sec ramp down it is good at 5-1 and 10-1 drivetrain reductions, but at 2-1 i get the over voltage, and this was just with a collet in the spindle, no 8" chuck to add to the momentum.

Originally Posted by Stustoys

oops yeah forgot to let you know about that
Makes setting them up all the more interesting.
What numbers are you using for
pd028 5.00
pd030 2.00
pd031 0.1 Doesn't seem to change the stopping power at all, it just stops dead at any setting

I have a brake resistor but am yet to try it out. I have seen in another thread that some of these VFDs have the terminals for a resistor but there isnt anything there really.(though that doesnt seem to be a problem for you)

Stuart

Some other interesting things. I have PD042 (jog Freq) set to 5.00, but the VFD reads 8.00 when i am jogging.
The lowest i can set PD015 is 4.3 without getting a fault on ramp down when in fast gearing with an 8" chuck.
I don't seem to be able to set PD028 to more than 5.00 without loosing my jog, if i set it any higher i get a buzz from the VFD when i hit jog.
What i did find was on page 40-41 of the book is setting 30(as per those pages, it is different on page 21), "Braking resistor act", but my VFD doesn't have Y1, Y2 or KA, KB, and in the wiring "diagram" it says FA, FB and FC are multi out, 240vac and 30vdc ???

I have worked out how to switch between ramp 1 and 2 through the multi inputs, so i can use my coolant switch to change from 4.3sec ramp down for the higher speed to 1.5sec (still playing with that time) for the lower gears.

On the upside my VFD has the relay missing in post#67 that Stuart linked above, but i have no link wire at P+ like in post #70.

You can change your ramp down speeds externally at will?

I never knew that! I'm going to have a look at what mine has/ doesn't have!

Simon

Hi Simon,
You can set one of pd044 thru pd049 to 18 and use a switch to change from ramp time 1 (switch open)to ramp time 2 (closed) or 3 (i think it is 3)

Well I seem to have two of each VSD, assuming the ones with the extra wire do in fact work with a brake resistor. Of course the two that have the wire are all mounted up, on the hoist and the camelback drill, neither of which need a braking resistor changing the one on the hoist will be a right pita.

Hi Ewan,
I've been playing with my dc braking this afternoon. Haven't come up with much useful as yet.


"FA, FB and FC are multi out, 240vac and 30vdc ???"
That one had be scratching my head for ages. In some places they are called inputs, other places outputs.
They aren't either! its a switch(a reply in fact), one is com, one is NC and one is NO, they are switched depending on the option you select on pd052.
Haven't worked out the others yet.


The vsd on my drill is set to
pd015=0.1
pd028=50(another mistake in the manual)
pd030=3
pd031=20
So braking comes on almost straight away at max. If I make pd031 lower is slows down slower....I guess maybe as your brake is only coming on at 5Hz it seems to stop straight away?
I tried to use jog at 25Hz and got the same sound as you.

As yours is currently setup I think I would switch to coasting stop(at least for the minute). 4.3 seconds is going to be a long time!(incase you don't know, while it is ramping down it will still have what ever power it would normally have).
Maybe using multi speed spindle instead of jog would be better? then you might be able to bring the brake Hz above the min speed?


Stuart

Hi Ueee,

WRT your coolant switch, Why would you link the use of coolant to the ramp down times? and,

I like the idea of a 3 way coolant switch, on, off and on with motor. I have been thinking of doing the same. What triggering do you use to link the motor on/off to the coolant motor? Normally a fairly trivial thing to do but since the motor is driven from the VFD, I not sure how you go about it.

TOT: Just picked up another 3 phase motor for $20 with a B3 mount. It's a Fuji and made in Japan, but It's 415V but with only 3 wires so hopefully it's Y wired. Doesn't say on the plate. I'll have a closer look when I finish my mill. hoping it will be perfect for the lathe!

Cheers,

Simon