New CNC Engraver Spindle

[whydontu]

In the process of replacing the existing 24VDC brushed DC spindle on my cheap engraver.

Bought an Amazon <500 Watt> brushless Dc spindle motor, with 48 volt DC power supply and driver board.

https://www.amazon.ca/RATTMMOTOR-Brushless-12000RPM-Controller-Switching/dp/B0B11R2Q7T/ref=sr_1_5?crid=TT9NLPF8NC1F&keywords=rattmmotor+spindle&qid=1700965578&s=industrial&sprefix=rattmotor+spindle%2Cindustrial%2C136&sr=1-5&ufe=app_do%3Aamzn1.fos.71722c10-739d-471b-befb-3e4b9bf7d0d6

The good - decent runout, seems to be reasonably made. Nameplate says 12,000 RPM, at no load at full speed my mechanical tach read 11,200 RPM, my optical tach read about the same.

The bad:

If this is 500 watt, I'm next in line to be Secretary General of the UN. No load @ 48VDC the controller pulls 1.55 Amp, so roughly 85 watt. Just because I'm a fussbudget, grabbed the Fluke meter and stuck it on the AC line to confirm. @ 120VAC, pulls 0.51 Amp. 61 watt. DC ammeter isn't filtered, so the reading bounced around a lot.

Meh. Probably more than adequate for use.

Maybe it would get to 500 watt under severe load, but it's intended to spin 1/8" mills or engraving bits at 12,000 RPM. Any cut aggressive enough to pull 500 watt is likely going to turn a 1/8" carbide end mill into dust. I'm using the cutters in the last photo.

Next step is re-do all of the controls, install new stepper motors, make up a nice cabinet for all of the little boxes and cables, and replace the effing horrible factory wiring with real cables and plugs.

So far, my $200 3018 CNC toy engraver has cost me about $1k. Should have just bought the bigger better one from the get go, but what's the fun in that?

 

[Susquatch]

In the process of replacing the existing 24VDC brushed DC spindle on my cheap engraver.

Bought an Amazon <500 Watt> brushless Dc spindle motor, with 48 volt DC power supply and driver board.

This is EXACTLY my experience so far using the same motors on my toolpost grinder. Just like you, my measurements indicated totally underwhelming power.

But my optimism ended up being my Achilles heel. I first wrongfully assumed that the problem was measuring unloaded motor current. So I loaded the motor to the stalling point. Still no joy. So then I figured maybe it was a power supply limitation. I bought a bigger 700W unit and put the 700W supply on the 500W motor. Still no joy.

They all lie. All skumbags.

I think we have to spend the big bucks on bigger motors that actually have a hope of meeting half the claims. I also fear that only a VFD type speed control has any hope of being able to run such a motor at Variable speeds without crumbling when the torque requirements are high.

 

[PeterT]

I've never understood their power ratings, but I am not electrically savvy either. Apparently they multiply power supply max voltage by max amperage where windings melt & call that rated watts. But what real life combination of operating mode does that equate to? I was looking at pretty much the same brushless unit for a completely different application but another CNC builder did comparable measurements & I backed off. The other thing to consider is bearings. If they don't mention them them, you should be suspicious & dig deeper. Some of the <cough> 500w brushed motors I saw had rubber rings between the bearings & end bell & quoted 0.001" runout. Hmmm.... Now what would happen with even the slightest side load? I accept there is a quality & price range with the offshores, but they often play loose with sticker specs to the point of being nonsense.

 

[whydontu]

Almost there. New engraver controller based on Arduino and CNC shield, new 24VDC power supply for larger stepper motors, built-in tach, ability to control spindle speed by PC or manually, Reset/Run/Pause buttons on front panel so I don't have to find the mouse cursor when something goes badly. Need to clean up all the wiring and make prettier board mount plates, but as proof-of-design it works well.

Cabinet used to be a Fisher CD changer, $8 at the thrift store!

 

[whydontu]

Engraver CNC Controller 2.0. Thrift store cabinet ($12 for this one!) with 36v stepper and 48v spindle power supplies, three DM542 stepper drivers, a supposedly 500 watt brushless dc spindle motor controller, Arduino GRBL interpreter, second Arduino as a tachometer. Panel markings done in my manual engraver and filled with wax. I’m quite pleased with the results.

No magic smoke or weird noises on initial power-up!

 

[Johnwa]

I

So far, my $200 3018 CNC toy engraver has cost me about $1k. Should have just bought the bigger better one from the get go, but what's the fun in that?

WOW! You really fell down that rabbithole! If it’s any consolation it makes me feel better about my 3018. I swore I wasn’t going to upgrade it, but……

 

[whydontu]

The thought process was that while doing all these upgrades, they would be suitable for larger stepper motors. If I decide to go to a more robust CNC setup the controller would be capable of handling much higher amperage than the original 3018 controller. I’ve fried two 3018 controllers already, so going to separate stepper drivers and spindle controller means less chance of frying everything if I make a mistake.