Centroid Community CNC Support Forum

ScotY wrote: ↑Sat Jan 20, 2018 1:25 pm Hi Milton,
...and she said regulated 48v input was too high. She recommended I continue to use the 36v switching PS.

Yeah, it sorta pi$$es me off that they say 50V in writing and don't really mean it. But then again, since they're so cheap we got what we paid for...I think.

I've certainly learned a lot fooling around with it & learned what I'll be looking for next time.

I know...I thought the same thing after receiving that answer. Cheap Chinese carp.

There is no good reason NOT to use a switching power supply with steppers, and they cost almost nothing these days.

Regards,
Ray L.

RayL wrote: ↑Sat Jan 20, 2018 5:37 pm There is no good reason NOT to use a switching power supply with steppers, and they cost almost nothing these days.

Regards,
Ray L.

Not exactly correct.? If they have Voltage protection built into them which often they do. Then back EMF from steppers can cause them to trip. This is very common in routers and why Unregulated PSU is much preferred.

RayL wrote: ↑Sat Jan 20, 2018 5:37 pm There is no good reason NOT to use a switching power supply with steppers, and they cost almost nothing these days.

Regards,
Ray L.

I'm not fond of switchers for bigger machines...I like the toroidal power supplies from Antek. http://www.antekinc.com/

Dickeybird....bite the bullet and either lower your supply voltage and see how your machine performs or replace the drives where you aren't pushing them I suppose....

martyscncgarage wrote: ↑Sun Jan 21, 2018 5:38 pmDickeybird....bite the bullet and either lower your supply voltage and see how your machine performs or replace the drives where you aren't pushing them I suppose....

I hear you Marty. I'm trying to finish up a good paying job for my bud down the street as I type. I'm going to unwind & clip 5 turns off the secondary, retest, wash, rinse, repeat until I get it down to 42V at the drives & call it good. Should be safe as mentioned in an earlier post. Not cutting edge fast for sure but that can come later if needed with the purchase of ANS (All New Shite). I'm not one of those ubiquitous internet CNC speed freaks.

Sounds good Milton.
Let us know how it goes...

jazzcnc wrote: ↑Sat Jan 20, 2018 6:43 amI can tell you with 100% certainty that if you run at 50V you will Kill the drives. Over the years I've used many these drives and even at 45V you can run the risk of damage in an unregulated system due to power line fluctuations and back EMF.
If all the stars align wrong then they are very touchy when it comes to Voltage and even thou they say have overvoltage protection it doesn't work very well and will damage them.
In my experience, 42V is safer voltage and never had any fail at this level but I have at 45V.

My other machine has the same DM542A drivers with a 36V switching power supply. If I were to change it to a 48V switching "server" PS and turn down the onboard voltage adj. pot, would that be reasonably safe as far as driver reliability? I'd like a bit more speed with the high-inductance motors it uses. The average server PS's are powerful & fairly well built so they should be able to handle back EMF surges easily. Besides all that, they're cheap as chips on ebay.

DICKEYBIRD wrote: ↑Tue Jan 23, 2018 12:11 pm My other machine has the same DM542A drivers with a 36V switching power supply. If I were to change it to a 48V switching "server" PS and turn down the onboard voltage adj. pot, would that be reasonably safe as far as driver reliability? I'd like a bit more speed with the high-inductance motors it uses. The average server PS's are powerful & fairly well built so they should be able to handle back EMF surges easily. Besides all that, they're cheap as chips on ebay.

Problem with these type of PSU's isn't cannot handle back emf they do that fine but it's more how they do it that causes the problems. They tend to clamp or shut down to protect their circuits which ain't good.
Voltage for the drives is the same advice really wouldn't go much above 44v to stay on safe side. That said lot of this does depend on machine type and how it's used. IE routers travel much faster than mill so generate more B-emf so more safety is required.

Personally I only ever use toroidal transformers because simply suit cnc best.

OK, thanks a bunch for your input.