Novamill - Sprint motor control presets confusion!

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WestonMetalwork
Posts: 2
Joined: Wed 02 Nov , 2022 11:24 am
Hardware/Software: Novamill
Mach 3
Fusion 360

Novamill - Sprint motor control presets confusion!

Post by WestonMetalwork » Thu 03 Nov , 2022 3:28 am

Hi All :D

I have a Novamill that has been converted to run on Mach3 by a previous owner. I would start by saying I am relatively new to CNC machining and my electronics knowledge is limited.

The short of it is the rated speed printed on the machine specification label is 3000rpm, my understanding is that Novamills are normally 5000rpm, so perhaps mine was limited on manufacture for safety reasons on request by a customer.

The photo isn't clear but it states:
3000 RPM
0.25 HP
.18 KW


I can near enough stop the spindle by hand at most speeds, particularly in the lower range. Presumably this is not normal.

I opened the rear of the machine and checked the motor tag with a mirror and it appears to be a standard Novamill Baldor.
74-AH-0
180 DC
1/2 HP
5000 RPM


The previous owner has wired a 10K Pot into the Sprint Board on pins 1 2 &3 to manually control the spindle speed. I would prefer this to be through Mach 3 but ill address this down the road when my understanding is better.

My question is, can I adjust the settings on the Sprint board to allow the full 5000rpm from the Motor?

I understand the motor will slow down somewhat under load but at present griping it slows to near standstill. . My understanding of the relationship between torque and speed and DC motors is vague at best but id like to get the maximum performance from the motor possible. The sprint manual indicates there are torque settings, could adjustment of this give me a bit more power to the motor?

I have read the sprint manual but being new to CNC and electronics in general I'm really quite confused.

I'm in no rush so any pointers on the learning curve and advice to put me in the correct direction would be massively appreciated.
I don't want to start poking around without really knowing what I'm doing.

Thanks,

Paul.
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WestonMetalwork
Posts: 2
Joined: Wed 02 Nov , 2022 11:24 am
Hardware/Software: Novamill
Mach 3
Fusion 360

Re: Novamill - Sprint motor control presets confusion!

Post by WestonMetalwork » Fri 04 Nov , 2022 1:53 am

A friend came over to my workshop who knows more about cnc electronics than I and we went ahead and adjusted the Max Speed Preset on the Sprint Drive. Bit by bit and testing with a handheld tachometer we got the speed up to just shy of 5000.
The power is still a bit lacking, but a marked improvement.

Could anyone shed any light on the Torque Control and overspeed limiting?

With a pot on T64 and S3 switched on what would this translate to in a real world milling operation or is this of more use in other motor applications. Does it work in reverse as well, if the speed reduces due to load would it adjust up to keep a constant rpm? Im unclear how it knows whats happening in real time, does it need a tachometer signal or is this measured an alternative way?

Learning as I go here! Apologies if this seems obvious or stupid to some, to me its all a big mystery!

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