G540 - 4 motor connection problem

**John S** · 30-01-2017

Originally Posted by m_c

I'm well aware of the benefits, but how often do the motors run fast enough and long enough to have the full voltage applied?
The only time you'd see problems is during prolonged time at high speed, which even on a router, I'd doubt you'd sustain for long enough. But it's worth bearing in mind, that you could easily destroy a stepper motor very quickly by pushing too far.

It's not about maximum speed but percentages of the same.
If your 40v system is running at 1/2 speed on acceleration it probably used 20 volts.
If an 80 volt system is running at half speed it gets 40v and so even in the short distance it can reach the designed acceleration faster.

What we also have to take into account this that the home hobby CNC market has bee around for quite a while now.
Anyone remember the fledgling CAD_CAM_DRO group on Yahoo. I quick look at a stored database tells me it started in December 2003 [ edit 1999 ]

In that time a lot has changed but the same information gets repeated, that's the way of the internet.
Marris was very popular on there and he stated a lot of things that have now moved on.
I remember him being very vocal about Leadshine pinching his designs, this for a basically one man band accusing a large corporation with over 300 just employed in R&D alone ?

Leadshine now have closed loop digital drives and have had they for years whereas Gecko never produced a digital drive, they are all analogue.

The Gecko's might go down well in America as it's a large market and there are a lot of loyal rednecks but by the time you get a Gecko drive over here with the £ to $ shuffle, the 19% import duty and the 20 % VAT you are paying thru the nose for outdated technology.

The outdated 542 drive from Leadshine is a far better drive and for more reliable but as i say even that is now outdated.

Another thing that has slowly impinged on the scene are the switched mode supplies.
It was stated in the early days that they were not as good as a decently designed and made torroid but because they have become more affordable and popular early advise is being ignored.

Fact is a switched mode power supply cannot handle back EMF from motors and the faster they run the more you need that facility.

But they are now being bundled with a set of drives and motors that may well match someones purse but it doesn't mean to say they are a good match machine wise.

Switched mode is fine for logic power supplies that supply 5v / 12v / 24v end of story.

Whilst drives and motors have improved no end with advanced R&D and materials the basics behind them hasn't

Always over spec everything if a drive is running at 50 % it will never get hot, it will never be placed in an overload position and so it will last.
Buy well designed drives that have large heat finned cases for just the previous reasons.

Steer clear of micro based units that for some reason the designed has deemed it will look better if it's the size of a postage stamp.

There are physical limitation in running four 7A rated tracks side by side to a motor, 10 thou spacing whilst looking neat does not meet that criteria.

Above all seer clear of the integral motor and drive units.
It's a fact of life that stepper motors want to run hot and drive want to run cool, so why would some twonk want to bolt them together. Or cram 4 drives onto the smallest possible heat sink that will hold them without one falling off the edge ??