[iGAK]

I added the optional Novakon Braking Resistor ($89 + shipping) to my Torus PRO mill. The results were amazing. The spindle use to take nineteen seconds to stop when spinning at 6000 RPM. The spindle now stops in less than one second.

The movies show the results before and after installing the Braking Resistor.

Novakon No Braking Resistor @6000 rpm - YouTube
No Braking resistor @6000 rpm


Novakon Braking Resistor @6000 rpm - YouTube
Braking resistor @6000 rpm

Novakon Braking Resistor @1500 rpm - YouTube
Braking resistor @1500 rpm

Installation of the Braking Resistor was a breeze. Connect two wires to the Braking resistor and the other ends to the Sunfar C300 VFD, terminals P+ and PB. Program the Sunfar C300 VFD parameter F0.11 to “0.5”. That’s it! The Braking resistor only works with the Sunfar model C300 – It will not work with the model C300A.

I strongly recommend the Braking Resistor as a big safety improvement to a CNC mill. Being able to stop the spindle in less than one second versus nineteen seconds is mandatory.

[Hirudin]

Thanks for posting this - I was getting tired of the slow slowdowns too so I ordered one last week. It's bad when the longest part of a tool-change is waiting for the spindle to stop. Thanks for showing how easy it is to install and how well it works!

[edit]Argh, I just saw that the braking resistor is/was backordered.[/edit]

Have you also "fixed" the spin-up time setting in the VFD? If not: I would highly recommend it. Here is some discussion on how to do it - starting with this post by SCzEngrgGroup.

[Hirudin]

Hmmm... I just looked in my cabinet and I have a "C300A" VFD. How certain are you that the braking resistor will not work with this VFD?

(later...)
I now see that same warning is in the Torus Pro beta manual. I also noticed they're using the same photos.

I wonder why I have a lesser VFD.

(a little later yet...)
I emailed John at Novakon and asked if having a C300A did, in fact, mean I could not use the braking resistor. In very short order (~15 minutes) he emailed me back and confirmed that the C300A will not work with a braking resistor. It sounds like they are going to swap out my C300A for a C300. I imagine I'll have to pay something for the upgrade. John said he'd put something together tonight. What service!

Of course, it would have been nice to know about this potential upgrade from the beginning. My order was pretty convoluted so I can understand how some things may have slipped by.

[Hirudin]

I finally got my braking resistor installed! I had some delay because I was waiting for my C300 VFD to be shipped to me (it was gratis except for shipping, thanks John!)... I am also a procrastinator. Anywho, as expected: it works!

I wanted to put it through its paces so I installed the heaviest tool I own: the Novakon "Mill Turn Chuck". The thing weighs over 2 kilograms! (Mine weighs precisely 2068.0 g. or approximately 4.5 lbs.) Below is a quick video I recorded of it spinning up to 6000 RPM and slowing down to a stop. This is with the C300 VFD parameters "F0.10" and "F0.11" set to 0.5.

For my own curiosity I weighed a couple of my other large tool holders. My 5/8" keyless drill chuck weighs ~1.2 kg. and my 2" boring head with a random boring bar installed is ~0.95 kg. I also weighed a random ER-20 collet chuck; it was ~0.28 kg.

I bought two braking resistors: one from Novakon and one that seemed to have "specs" that matched the C300 manual more closely. The one that is installed in this video is the non-Novakon resistor. I might switch over to the Novakon resistor though because it's larger - that makes me think it may dissipate heat more quickly. As a total novice and basing my opinion on appearance alone: I think the Novakon resistor is a better buy between these two. The Novakon resistor also has better mounts.

Link to the same model resistor that I currently have installed.
Link to Novakon's spindle braking resistor.

Novakon Torus Pro CNC mill with braking resistor installed - 4.5 lbs. tool stops in 2.25 seconds - YouTube

[CROSSHATCH]

Thanks for posting the links. I would be happy with your video resistor displayed. Nice job.

-Jason

[Hirudin]

Thanks and you're welcome!

Maybe I'm being dense, but I don't understand this sentence: "I would be happy with your video resistor displayed."

[zaebis]

I wouldn't be spinning heavy lathe chuck to 6K RPMs. Keep it below 2K. If you lathe parts below 3/4" in diam simply use collect as a chuck (then you can spool to 6K).

[Hirudin]

Thanks! I was planning to add something like "I don't know if it's safe or not, but I put in my lathe chuck and spun it up to 6000 RPM." but I guess I must have forgotten to. Not that I thought it would help very much, but when I did that test I wore my face shield.