Review Update: Delta 16" VS Lathe - PM/Jet VFD Info (long)

As an update, couldn't find the old DIY interface card, so I drug out the old IC data books and cobbled up a new one. Far fewer parts this time around, due to the more modern ASIC's available. Gotta love that misc. semiconductor junkbox that the ex-SWMBO wanted me to toss.

It took far longer to find the almost forgotten prototype stuff than to build the RS232/RS485 interface. Granted, it's not destined for retail distribution, but it satisfied my curiosity as to what's going on in the controller. At least I now have a dump of the internal register settings - few of which differ from the factory defaults. Suddenly, a CNC lathe for turning segmented vessels is sounding like an interesting (and complex) project. One hand turned original, and a limited production run of signed, machine turned copies. That CNC hollowing rig is sure to be a bear to design.

These damned evil computers are now invading the woodshop... Is there no escape?!

FWIW

Almost indispensable for digital work. Problem then becomes keeping up with the constant need to upgrade to ever increasing sample rates.

Everything has become so intricate and specialized, it seems there is little room for generalists these days - particularly those with low thresholds for boredom, a desire for breadth, and an inherent mistrust of all blustering authority.

FWIW

The original post discusses problems with runaway motor speed and failure to remove motor drive when the stop button is pressed. Additional info as follows.

These findings are applicable to all AC motor/VFD setups. Additionally, I am now able to reproduce the fault at will.

The process of exploration reveals that the motor rotor is a rich source of EMF which is induced by the harmonic rich pulses from the VFD Drive. It seems to be aggravated by the 10kHz carrier rate chosen. Imagine my surprise when I discovered that there is up to 45 volts of crap present on the rotor, and current up to .5 amps. The unpowered-state resistance of the rotor to ground varies from 0 to 125 ohms. I would hazard a guess that bearing erosion or fluting is a potential problem since the only path to ground for this potential lies in the bearings themselves. A prudent consideration on any VFD setup that does not use a specialty motor would be some sort of rotor grounding mechanism. A graphite tipped grounding strap which rides on the end of the rotor shaft, for instance; similar to almost every VCR head drum motor ever built.

But this is not the only source of my immediate problem, however. Apparently, the controller is working as advertised, but excessive regeneration is causing the controller to hang in an infinite state of overvolt protection while waiting for the DC Bus voltage to subside before decelerating the motor. The feedback from the freewheeling motor never subsides, so the controller just sits and waits. How do you reduce regeneration? Well, one way is to apply a load - and sure enough, placing heavy pressure on the handwheel causes the controller to respond and continue on to decelerate the motor.

So, what is the cure? That's a tougher question, since any meaningful changes would probably require rewriting register settings in the controller and/or the addition of a zero phase reactor and/or shielded motor feed wiring - which would most likely nullify their picky-ass warranty. But since any number of replacement controllers are probably going to respond in the same way, the fix is probably not as straightforward as replacing a defective part. So we end up in a Catch-22 situation that has probably resulted in loads of these lathes being shipped back as terminally defective. And I'll be darned if I'm waiting until January of next year for a part that probably won't fix anything, or paying for the modifications out of pocket. I've got at least two hours in the project already - not counting the interface and VFD familiarization.

The thing that gets me, however, is that I bought a lathe to turn wood, not to troubleshoot in lieu of the seemingly dysfunctional R&D team at Block and Wrecker, or to sit for 3 months+ waiting on a fix. This could get ugly... ;-)

Could that (feedback) be the real problem I had with my controller?

I had to extend the deceleration time so it would work properly. Otherwise it would trip off and the lathe would coast to a stop rather than elecytrically brake. The error signal I got was somthing like "line voltage problem" and when I asked at delta they said I have a main power problem. Somewhere, I think the book, gave me the idea to adjust the de-acceleration pot. It never happens with slightly less electric braking. It is extended maybe 3 or 4 seconds.

John

Your controller sounds like the old Baldor unit. And from what I understand, many had problems with it going into FAULT mode a lot.

The Delta.tw unit is totally digital and contains no potentiometers. The accel/decel rates are set by writing to EEPROM registers through an RS485 port. There are two groups of registers for fast and slow, selectable by switch. However, mine is already set to slow.

But the problem is that it WON'T shut off the motor. I'd prefer a coast down condition over a won't stop running situation any day.

nonsensical ramblings... I do note that they have the Braking Resistor Threshold set at 380v but the Over Volt Stall Threshold set to 370v. Normally the OVST would be set a little higher than the BRT. The AVR is turned off during decel as well. All three of these are potential suspects.

I'm guessing that if the BRT were set to 370 and the OVST were set to

380, all would be good in the universe as concerns the failure to shutdown motor drive.

FWIW

I don't know about that- we've all been getting a line of bs about the "service industry" and "information economy" for a while now. Sure, it might be cheaper for now- but if we keep sending everything away to be made by cheap foreign labor for too long, there isn't going to be enough equipment and know-how left in the US to make things we need should it become necessary. Sure, there may still be plenty of engineers- but they're not going to be out on a shop floor running parts, and it takes time to train new operators. Especially if the labor pool is made up of cooks, salesmen and office assistants. It's getting bad enough that a lot of people can't even read a measuring tape or rule- much less a caliper or a mic.

It's going to pinch us in the long run. No doubt we can rebuild the factories, but that does take time. It's worthwhile to pay the extra to preserve US manufacturing capability- and it's still true that you get what you pay for. Every factory I've been in here has tolerances and standards far tighter than the stuff I see on the shelves at the WalMart.

Sure would be nice to see another *real* American tool company- they're still around in the industrial market, but I'd love to have the choice for my tools at home.

I hear ya there. Gotta have a real big toolbox to be a floater in today's world.

Heh. Reading through this thread has made me truly appreciate my second-hand reeve's drive Delta (even has a Made in USA tag). Had a loose bolt on it once, but that was the extent of the trouble, and the sucker is over twenty years old. No special tools or computers required- a welcome change from the *ahem* real world.

Hey, leave my toolbox outta this... ;-)

Greg G.

Spent months a couple of years ago looking for an older Unisaw. Week after week I read gloats from guys who found 4-8 year old Unisaws, complete with accessories, for $1200 - and less. Pennsylvania in particular seems to have been lucrative for some.

Never came up with anything used here, however, and the local "used" dealer wanted WAY too much for my tastes. So I bought new stuff. Can't explain why, but people around here don't seem to have much interest in anything done with their own two hands. Mostly corporate fuel-screw types. Most of the "old-hands" either moved away or died after I moved to Florida. And they apparently took their old US made equipment with them.

I'm going to be buried with my collection of Chinese pot metal, a testament to the changing times. Ahem, indeed.

Greg G.

DGG wrote in news:f6kfi2pf83lgrf4qsd6k47fvblk5q2ls2v@

4ax.com:

So who makes the VFD for Delta/Jet et. al.?

Yep, no luck with the saws around here either- I spot one every so often hidden under a pile of boxes in someone's garage, but the story is always that it was Grandpa's and has sentimental value. I always suspected they just didn't want to bother with moving the boxes, myself.

The lathe was a one-of-a-kind find, as a friend of mine had bought it in the early eighties, used it in his shop for 20-odd years, and then decided to move up to a Oneway. I happened to have just finished helping him build his turnery, and got the right of first refusal from him. Pretty good price, and it had been taken care of- ready to go the day I got it, even had brand-new link belts.

I think one of these days, I'm just going to get fed up and start making my own tools. A little engine lathe, a decent welder and some negotiation for a little personal time on the equipment at work might add up to a winning combination. Still have to buy the motors and switches, but that seems like a minor problem at best- I'm continually surprised that no one (that I know of) has started a little tool factory in their garage to cater to discerning woodworkers yet. Seems like an untapped market that gets a little bigger every year as overall tool quality declines- though that may be just wishful thinking.

As mentioned WAAYY up this thread, it is Delta Electronics of Taiwan. No relation to Delta WW. I thought perhaps they were labeling their own until the need revealed that it was an independant Asian company.

An industrial user relates his experience:

--------- I have a lot of experience with Delta drives.

We have a lab set-up where we did the Pepsi challenge with Delta versus other drives. (The tester is a NEMA 4 cabinet with heaters and a variac to raise the line voltage to over 500 vac to simulate NA utility conditions. Externally it has a bonitron unit for braking, marathon blackmax motors, and opposing drives which have torque limiting to provide loads. It's a really interesting set-up needless to say.)

We ran these drives at ~150*F at 520 vac for over a month. We ran them loaded with an 5 sec accel and decel time. All the other drives failed, these ones, we couldn't get to trip or fail.

It was a test to see how well they were made. The research that I found, was that Delta is one of the biggest power supply mfg. in Asia. We felt that if they make great power supplies then their drives would be made just as well.

Inexpensive yes, Cheap no.

The problem with most Asian drives is that they are voltage intolerant on the high end. In Japan for instance, the micro-drives are designed for a 400 volt system. When they go to get UL listed, they have to drop there high end to 460 instead of 480 to meet the requirements. They can still be used with great success if the proper line reactor or bucking transformer is used to stay under 460 +/- 10%.

The Delta's don't have this problem.

I'm not a salesman or rep...I have no real brand loyalty per say. Are there drives out there that can do a better job with more bells and whistles, sure. But I happen to agree with dpc. If they work for you, then use them.

IMHO, Carl

---------

FWIW

Sounds like the classic American dream, but current market conditions would appear to make that problematic at best. Never worked up a prospectus on such a thing, as I have neither the engineering talent nor the funds for such an undertaking, but it would be an interesting adventure. In today's mass produced, imported 50 cent an hour, blister-packed culture, it would be difficult to compete in an already competitive (and limited) market without some real innovation, quality control, and marketing. But hey, some of those fancy planes they're selling today are pretty high dollar.

Casting or forging steel and iron would be especially difficult in the garage. But hey, they did it in Israel and Palestine in 1300 BC... And that's probably the quality we're getting in our tools now. ;-)

And yes, I too wish for the space and bucks for some metalworking equipment. Perhaps with winnings from the lottery I don't play. But guess where a lot of that machinery comes from these days...

Greg G.

sticking my neck out a bit, as I recall a bit earlier in the thread the problem lied with interference in the logic. could a Marconi shield be easily manufactured to solve the problem?

Troy

Greg G. wrote:

Casting Iron, yes- that's a problem. But maybe not too bad if you buy thick sheets and grind them yourself. As far as forging steel goes, I think I'd pass. What I've seen in some big industrial equipment is more my speed- they cut several pieces from thick sheet goods, then weld them together to make thicker parts. That's possible with a cheap plasma cutter, and bound to be better than cast pot-metal.

Far as innovation goes, I think I'd pass- seems like there's a crying need for some simple, well-built tools. I'd pay more for a simple saw with good parts than I would for one with lasers and a plastic base.

But sadly, I believe you're right- it'd be awfully hard to make it pay as a business venture. I was thinking more along the lines of a guy making one at a time as orders came in, and selling them to interested parties in his (or her) spare time. You don't get rich that way, you just get the satisfaction of making good stuff.

I've got the space in the garage, but not a lot of discretionary income. I'll build a metal shop someday, but it'll be slow going like the wood shop was.

Innovation doesn't necessarily translate into cheap gimmickry. It can be a simpler or better way of accomplishing a goal.

Same here - for the moment.

Greg G.

Prometheus wrote: I'm continually

Steve Knight comes to mind.

Well, kudos to Delta/B&D for getting a replacement part shipped well ahead of the computer projected date. Received it yesterday, and I am now finishing up a large 13" Ash and Black Mesquite bowl.

I've been using a small 6" straight rest for bowl interiors on the Jet Mini, and with a certain amount of adjustment, it works fine. But now that I've progressed to larger diameters, it turns out that a straight rest doesn't deal well with deeper bowl bottoms. Bought a Delta

46-404 "French Curl" tool rest, and consider it a bargain at $23. Made in Taiwan, reasonably well finished, although the curves are not quite what I expected. The acutely curved side works OK on interiors, but the other side was probably designed to be used on bowl exteriors, and due to the bulk and design of the rest, the angles are wrong for interior work. And if the bowl were much deeper, it would be less useful. I would have preferred two interior curls, one large, one small, as I still use a straight rest on the exterior, but that's my preference.

FWIW