Thread: External Panel Option for HuanYang VFD

Originally Posted by jhovel

This is the machine I'd like to also experiment on with a radius dependent spindle speed - eventually.

I've been thinking about that a bit more, and there is a twist, in that different materials (even tips) call for different surface speeds. Having a pot connected to the slide (whether rotary or linear) could be set up for one speed but would not work straight out of the box for others.
As far as I have gotten in the thought process (and bearing in mind that electronics are something I've never been able to get my head around), I think what you would need to do is use a pot of some sort to give you a proportional signal as a voltage divider and then massage that in a black box with desired surface speed as an input so that it emerges as a signal (voltage) that can then control the speed in the VFD between the correct limits. As you wouldn't turn this thing off just because you were not facing, there would need to be another control so that speed could be adjusted from say 30% to 110% to allow for chatter avoidance etc.

Michael

Michael, sounds complicated. I imagined you would have your main speed pot connected somehow (series?) with the cross one. So you would set your starting speed at the OD to suit material and tooling and the cross pot would then adjust speed in simple proportion to slide position. The main pot could still be used for tuning out chatter etc.

I guess I don't really understand your post.

Originally Posted by Bryan

I guess I don't really understand your post.

That could well make 2 of us.
The point I was trying to make (and at the same time suggest a solution) was simply along the lines of material A has a particular recommended surface speed. Material B has a different one - therefore, one pot will not do both as everywhere along the radius the speed for material A will be the same ratio to material B.
In addition, while strictly speaking surfacing should be done as per the surface speed requirements, on a long slender workpiece, the speed may generate too much chatter to be useful, so some sort of reduction dial is required. This suggests to me that a simple arrangement with 1 pot won't do it and some thought will be required to make something that will give you a constant surface speed while facing, if not surfacing.

Michael

I agree. I think using the input from a crossfeed screw or a linear pot moved by the cross slide might need to be used just as the input to a processor in a black box. That data could then be used to set the spindle speed with the additional input of a surface speed required - maybe by a dial - and an indication of the radius where the tool is actually engaging, as well as some allowance for tool tip geometry and chatter aoidance. I all that could be aried during actual cutting, this might be a pretty good group project.
But I think we should moe this discussion to a new thread.
I'll try and do this.

You guys are talking about a CNC lathe. I looked at writing the software to do this many years ago but the hardware wasn't fast enough at the time. Not sure if it is, yet - I wanted closed feedback systems for positioning not the open loop type systems.

Basically I lost interest. Probably a good thing.

PDW

In relation to the above post, see here:
http://www.woodworkforums.com/showthread.php?t=185437

Ok as most of you know by now I have a thing about using the same method to stop the machine in an emergency as I use to stop the machine normally.
I choose a switch and real brake pedal on my lathe. That gives me the option of anything I like between coasting stop and full braking.

Enough waffle. to my point.
Lets say you put two switches on a "brake" pedal, adjusted so one opens first(in fact one would open first unless you adjusted them not to I would have thought). So the one that opens first you connect to your normal stop. The one that opens second you connect to your E/stop.
Then you just (I would assume*) need a short delay on the normal stop circuit, just long enough that if you push the pedal fast the E/stop circuit opens first.

Easy?
Stupid idea?
Thinking to much? lol

Stuart

*I assume you cant change the ramp time once the VSD is in a ramp.

You still have two PD002 Joe

Blast! I'll fix it later. One of them should be Pd001 of course....
I might try changing ramp while it's already ramping down. Sounds like a good idea Stuart. By setting the normal ramp a bit longer it would be obvious pretty easily.
I like the idea of a foot switch 'brake' actually.

Here is the corrected diagram - Pd001 = 1 amended:
VFD Remote Control Circuit final.jpg
Cheers,
Joe

Yes you can change the ramp on the fly. On the Mars i had a switch for 2 different ramp times, one for smaller chucks etc, one for bigger ones. If i had left it on the slow ramp down when i had a small chuck on, i was able to flick the switch as the machine was ramping down and it would change it to the fast ramp down and slow down much faster.

Ew

Hi Ewan,

Thank you. Thats the second time assuming things about these drives has surprised me.

So that means no delay needed, just need the switches "further apart".

Can you switch back to the longer ramp?(I assume so lol)

Stuart

p.s. thinking about it a little more we should have seen this coming Joe. That was the worry about changing the ramp time and switching the VSD off at the same time that I thought might be an issue in the first place.

Well, since opening the line to DCM is not 'switching off' the VFD, it simply goes to decelerate at the deceleration time 1 value - inmy case the emergency stop setting. Makes sense to me..
I can't test this reight now, since I've just disassembled my entire mill for reconditioning, starting this weekend.
In the process I discovered why my mill has so much back/generation power when forced to slow down bythe VFD: contrary to what I remebered, the motor is NOT a 4 pole but an 8 POLE motor! Never seen one before (and surprised I didn't remember something like that (I would have read the label when I got it 25 years ago...). It's also by far the biggest 2Hp motor I've seen so far.... that may explain why it takes about 10 seconds to stop from flat out....

IMAG1246.jpg

Hi Joe,

Think I've got a Crompton Parkinson 2hp in the shed. But I think its 1440rpm and its heavy enough thank you very much! They are smooth on the outside with the cooling air in ducts?

By switching off I meant the output
I'm pretty sure I've tried this with the TECO and once its in a ramp you cant change it.......... I think. It was awhile ago... Maybe I should write these things down.

Stuart

Yes, Stuart, I understood what you meant. We are NOT switching the output off though - that's my point. We are feeding it rapidly decreasing Hz and finally DC. Its only once the motor has actually stopped that we are switching the output off.

Originally Posted by Stustoys

I'm pretty sure I've tried this with the TECO and once its in a ramp you cant change it.......... I think. It was awhile ago... Maybe I should write these things down.

Stuart

Hi Stuart, I do that all the time with the pump control systems, I use modbus to change acceleration ramps and start modes on the fly. But for this application, I think just a D/A with either 4-20 or 0-10V would be easier to implement and more portable across a range of drives, modbus is nice but every brand of drive has a different register map..

Ray

I have nothing to add electronically, but practically...

The 10EE has it's spindle forward/reverse lever up on the headstock near the chuck... I have been doing some tapping of brass rod with a tap in the tailstock.. Due to the length of the rod being tapped I have to run the tap right up to the drill chuck that is holding it... I can get it virtually just kissing, then reverse immediately... The machine has dynamic braking, so at slow speeds the forward reverse is pretty much instant....

I will try to get a vid of it...