Sorry about the subject. I couldn't resist.

I've had a Taig lathe since early 2000, and a 4-axis CNC Taig mill since late 2000. I was pretty active on the Yahoo Taigtools forum for a number of years, but a whole series of changes in my life and my shop pulled me off the forum over the past few years. Because of progressive failures in my mill controller hardware, my mill has mostly been idle for the last year and a half.

I'm in the process of converting my mill to using a Keling KL-G540-48 to drive its motors. I'm still waiting for parts for this, so the jury is still out. At the moment I'm using EMC2 to drive my mill. In the past I've used TurboCNC and SuperCAM. I've never tried any of the Mach software, though I probably will at some point.

Mostly I use my tools to make parts for my own projects or for projects that friends of mine are working on. This has included, but isn't limited to rocket bits, RC car parts, parts for toys for the kids in the neighborhood, model light sabers (for the same kids), scale model parts, parts for robots, parts for a guy who's building an autonomous quadracopter camera platform, and parts for my own hobby of kite aerial photography. I've also made parts for work, mostly bits and pieces for vacuum feedthroughs and parts for the internals of our cryo systems.

The jobs I really like to do are the ones that take me in a new direction. Unfortunately this has put me at odds with my mill at times, since this often means running up against a limitation in the hardware, the software, and most often myself. But the rewards can be a lot of fun, and make all the frustration worthwhile.

I hope I can get my mill running and happy again, so that I can get my hands back into home shop machining. And I hope to learn a lot from the folks here!

Thanks,

Tom

Tom,

There are some people in this group who are magicians and all are very helpful. All are good guys. Welcome to the group.

Rick

Hi Tom;
I've seen your name pop up many times in other places over the years. Glad you can join us here. Welcome!

Dean Williams

Shop Projects

Hi Tom, I just saw your message on CNCZone I'll copy my reply here too:

They are made by Linn Engineering part# 5718L-10D-01 they are marked as 1.00A. They are good quality motors but looking at the product page for this series: http://www.linengineering.com/LinE/contents/stepmotors/5718.aspx, it looks like they are likely custom made for Taig. Given that they are 200 oz-in 1A motors that indicates the inductance is really high. Check out the 5718L-01S for a similar motor which is rated at 15 mH per phase. In that configuration they are NOT well suited for a G540.

If you can rewire the motors in parallel it would be better but you will still have a pretty high inductance motor for the G540. I use/recommend some 2.8A 166 oz-in motors for Taigs, they work great with a G540. Take a look at: http://soigeneris.com/CNCParts.aspx.

Just curious what type of power supply came with your controller. I've seen quite a few folks hawking 12A power supplies for a G540. Given that the G540 has a fast blow 7A internal fuse a power supply that could really put out 12A seems like a waste.

Welcome Tom, I remember you from the Yahoo group way back when I got my 1st cnc mill in 04......If I remember correctly you helped get me going in the right direction

Hope this site can help with your needs, Alot of Great Folks here

Thanks for Joining

Hi Tom,

Welcome to the forum -

Dave

Thanks, everyone! It's good to be here.

In answer to your question, Jeff, I really can't say. It's still in the mail. But judging from what the Keling rep said on CNCZone, my guess is it's a 12A supply. I'm a little surprised the G540 has a 7A fast blow fuse, though. The schematics call for a 10A fuse. I know things can change between design and fab, so I hope the documentation that comes with the unit calls out the correct fuse. (I'd hate to inadvertently put in a 10A fuse, thinking it to be the right one, only to blow something that really needed the 7A fuse!)

On sizing, I can see two reasons why one might put a higher rated supply into a piece of equipment: The first is simply availability and pricing. It would make sense that a 12A supply would cost more than a 7A supply, but if there was some other high-volume application that meant hundreds of thousands, or even millions of these things were cranked out and were available at low cost, it might make sense to use the higher rated, but less expensive unit. There's a great example of this with bearings. If I'm building something with moderately sized bearings, I'll typically try to design it to use skateboard bearings. It's possible to pick up high grade skateboard bearings for a few dollars apiece, but change one spec and you can toss it into the $30 and up price range per bearing. It may be overkill for my application, but for the sake of bringing cost down, it makes sense.

The other reason I could see using a larger supply is from the standpoint of stressing the part. I spend an unfortunate amount of time working on instrumentation that lives and works at 14,000' of elevation. There's 40% less air there than at sea level, so cooling systems are typically a lot less efficient than they would be at sea level. As much as possible we try to overspec and overdesign to compensate for this. From an engineering standpoint it's wasteful, but it's saved us on countless occasions. If you take two power supplies and run one at its rated output and the other one at half its rated output, the one running at half its rated output will, on average, lead a longer life, even if it's not running at 14,000' of altitude.

As far as using an over-designed power supply as an advertising point goes, I do see what you're saying. It's misleading. And I'm glad you raised the point about the fuse in the G540. It gave me something to look for in the schematic, and brought to my attention the whole thing about potentially putting the wrong fuse in. (I'll update the copy of the schematic I stuck into my mill's binder with whatever value is installed in it when it arrives.)

In any case I'm planning to post my notes from the conversion in the thread I started in the Gecko forum here.

Tom

The G540 most definitely has a 7A fuse inside, here is the part#: 0251007.MXL, it is made by LittleFuse. I sell G540s and got the part# directly (and a few spare fuses) directly from Gecko. The schematic on the Gecko Yahoo group site is not from the production version. There are several areas that don't match what is being produced but it is close enough to give you an idea of how it is made.

The reason 'some places' are selling a 12A power supply with them is because people will buy it. Without knowing any better they run some calculation they find floating around on the web and come to the conclusion that they need a huge power supply. As I had mentioned earlier sizing a linear unregulated supply (what all the formulas floating around are fore) require up-sizing the current capacity to keep the supplies output voltage in a workable range. A good switch type supply will have almost no voltage droop at full load and will put out the rated current with a 100% duty cycle.

Now granted that a lot of the Chinese knock offs being sold now days have questionable ratings so a '12A' power supply may be closer to an 8A supply so I don't think you will actually wind up with a lot of 'extra' capacity.

I still get annoyed when it seems like good people get taken advantage of.

AHA!!! Hey, this is great information. I've got a Digikey order going out in the next week or so, so I'll tack on some of those fuses to the order.

So from what you're saying the hobby CNC world is kinda where the street tuner world is: "Buy our fabulous cat back exhaust system on your Honda, and you gain 12 horsepower!" Yeah, but if you're still choked off at your intake because it's stock, you're never going to see any gain at all, and your car will sound like a kazoo...

(Sorry if I insulted anyone with that last comment... I drive a Jeep, and it sounds like a cross between a rock crusher and some piece of yard equipment. I'm not one to point fingers and judge.)

Hey, as long as I can set up my mill so it never drops another step, I'm good to go.

Tom

Benedict,

That is what the name of the toy is, a Kazoo!!! Every time that I have heard one of the little cars with the ridiculous sounding pipes, I have tried to remember that word.

The main problem with electronic equipment is the fact that the power supplies are under engineered. The thought is that there is a big savings in those components, filter caps, transformers and rectifiers etc. The outcome is under performing systems.

I still have to set up my CNC system, but one of the factors that I will watch is the power capability to the motors.

Rick Kernell