Hot Motors

[Cartierusm]

I've done searches but can't find anything. I could have sworn that I read something a while back about it, but here it goes.

I just made my very first cut on my CNC router that I built. 48" x 30" table using 425 oz. Keling Motors wired parallel bi polar. How hot should the motors be to the touch. Mine were pretty hot after the cut and when just sitting there and messing around they get pretty hot. Not hot enough to burn but hot enough to not beable to hold them.

[fireballcnc]

Motors will get hot. In general, they can run up to around 170 F before
you need to be concerned. I used a cheap Infrared thermometer from
Harbor Freight to check/watch the temp on mine....

http://www.harborfreight.com/cpi/cta...emnumber=93983

Nice thing to have around and works well.

The "Hot motors" question comes up all the time on different lists. I don't
like my motors running close to the edge..heat wise...so I got the
HF thermometer, and I adjust the current down until mine are around
140-150F. That only cuts the power down by a small amount and at
least here on my machines, any power loss is unnoticeable.

That's with the newer square bodied motors...I don't know about the
round bodied ones.

Just my $0.02

John

[Cartierusm]

I've got the square body motors. I don't know what you mean by cut the current. I'm running a24V system, do you mean try a lower voltage or less amps, because my motors can handle up to 50V and I was thinking of trying 48V. I want to try higher voltage to see if my motors run faster and or stronger. Nothing wrong with them now but my settings in Mach3 are 40 velocity /20 acceleration for the motor tuning and that seems slow compared to other people settings.

[fireballcnc]

Use less amps. If you can hold your hand on the motors for say,
20 seconds then they're fine...heat wise...

The voltage really is dependent on what your controller will handle.
If it says it'll go up to 50V...don't go that high. The voltage in the
AC line to your transformer will vary and could cause the DC output
to go over 50v. If your controllers are rated to 50V...I'd stay safe
at about 42V as an example.

John

[ger21]

Increasing the voltage will increase the heat as well. What is the current rating and what current are you running them at? The motors rated current should never be exceeded. And what is the motors rated voltage as well?

[Cartierusm]

The power supply was part of kit by Keling so I'm sure it's fine. Anyhow, I'll be getting the temperature gauge mentioned earlier today and test it out.

[Cartierusm]

I just got done cutting a few 3" circular pockets and the temp never got above 132 degrees Fahrenheit. Most of the time it stayed between 115-120 degrees.

My circles are not coming out perfect. I noticed a little chatter from the bit. I was using a 1/4" router bit, I may also be the router I've had it for 20 years or so. I had some defelction in the Z axis which I took care of and I can see the bit moving and not the cnc router.

[fireballcnc]

They'll got the hottest when just sitting still. Like if you forget to
turn of the controller. Your temps are good. That little thermomoter
can really give you some peace of mind...I know mine does!
And it allows you to get a good balance between the voltage and
amperage. Volts x Amps = Watts, Watts is how much heat the motors
have to dissipate.

Like Gerry says, raising the voltage will create more heat. In which case
you'd be going for speed. Lowering the amps to get to the wattage that
makes the motor temp "comfortable-to-live-with" is easy now

John

[Cartierusm]

I've got a ton of aluminum heat sink material I was thinking of bolting some to the motors and mouting a 80mm computer fan to each one. I would mount them with the motor in the center like a sandwich. Does that sound good? I could then do another test on one of them and see if brings down the temp.

P.S. I would also use some thick heat sink compound to bridge the gap.

[fireballcnc]

It likely would bring down the temp. I've seen it done nicely
before and it'd make for a cool project. I don't worry too much
about the reduction in amperage. My thinking is that if 1/2 A
made any real difference then I'd be be pushing my system too
hard.

I use Geckos on a 36" x 36" homebuilt router table. I run them at
55V and 2.5A and cut MDF at 90IPM. It'll go faster, but there's no
need to. Everything stays comfortably warm and stable. I tried
many configs over the years and began to work towards what
the machine actually needed to do the work, as opposed to squeezing
every once of power from it.

Others will tell you different and for their machines and applications,
they're right.

I DO like your idea though...cool projects are, well, COOL!

John