DC Motor Upgrade? Yay or Nay?

[Lumber Yard®]

I didn't take it that way. My post isn't really a ding on you if you are enjoying the process. In the past I've done a lot of what you are doing in your shop now. I've refurbed lots of vintage machinery over the years, made shop made tools and made DIY CNC routers, etc. The experience of working on machinery is worth something as you will gain a better understanding of what to do when you run into issues and hopefully you save some money along the way. I would feel comfortable tearing into any of the machinery in my shop if they had issues. In the end, at least for me, I've learned that I just want something that works and does the job when I need it to. If I am going to spend some time making a piece of machinery functional then it can't take months and get in the way of the actual work that needs to be done. With that, everyone's situation is different and I can see where you are coming from.

[®smpr_fi_mac®]

It's alive! Bearings came in today. Got them installed and the motor reassembled. Fires up and runs almost silently.

I hooked an amp meter around the power cable and started it on the bench. Didn't even register any draw. Mounted on the blower with the impeller attached and it read about .2A. Yes, 1/5A. I'm assuming that will go up once I place the inlet cover back over the impeller and then hook it up to the ducting again, right?

Oh, and the air speed coming out of the exhaust felt like sticking your hand out the car window while running down the highway. It was impressive.

[TDKPE]

I hooked an amp meter around the power cable and started it on the bench.  Didn't even register any draw.  Mounted on the blower with the impeller attached and it read about .2A.  Yes, 1/5A. 

Doesn't sound right.  Off by a factor of 10 at least.  A 3 hp capacitor-start, induction-run motor at 240V will draw something like 5-6A with no load, unless it's also capacitor-run in which case it will be a bit less with no load.  Less at full load, too, due to improved power factor, all other things being equal.  

The 3 hp Marathon motor in my Unisaw draws around 3A or so unloaded, with 12.4 FLA, but it has a run capacitor.  Most motors in that output range draw something approaching 1/2 of the FLA rating with no load on them.  

Check your meter.

[®smpr_fi_mac®]

It's probably operator error. I just opened the box and it's the first time I've used the clamp style. I'll figure it out.

[TDKPE]

I just opened the box and it's the first time I've used the clamp style.

Make sure the jaws are fully closed, metal-to-metal at the ends, with the conductor flopping around loose inside.  Otherwise, you don't have an inductive loop around the conductor.

[®smpr_fi_mac®]

I realized my mistake: I was measuring across both lines in the main bundle. Opened the switch box and measured one line. No load but connected to my ducting (6" main, 4" hose) showed 14.5A.

I'll hook up a blast gate later and test it.

[TDKPE]

I realized my mistake:  I was measuring across both lines in the main bundle.  Opened the switch box and measured one line.  No load but connected to my ducting (6" main, 4" hose) showed 14.5A.  

I'll hook up a blast gate later and test it.

That’s more like it.

What does the motor nameplate say for FLA?  That’s the number you don’t want to exceed, at least for continuous operation, and that value is at or getting close to it for a 3 hp.