New Lathe Motor

[2_many_hobbies]

I found a PMDC motor and would like to ask you guys if I should buy it so I don't waste $150 on it.

Dimensions in inches: 6.5 (w\shaft) x 3.5 round
Weight: 4.85 Lbs

Motor Type: 2 Pole PMDC
Rated Volts: 42 VDC
Rated RPM: 4000
Rated Power: 250 Watts
Rated Current: 8.4 A

I already have a 3/8 XL timing belt at 3:1 that I can throw it onto but I previously bought a 12V 15A 70% efficient motor which is 250W and it is VERY week and cant handle a tool or even spinning a large mass on the lathe.

Should I buy it?? It looks twice the quality of the 12V one I have, thanks!

[LeeWay]

That is a bit of cash for such a small motor.
Unless you want a perm mag motor for some reason.
My small DC motor on my lathe cost about $25 IIRC. The controller for it and heat sink was around $100. That and a DC06 board from Homann designs all works great with Mach 3.
Less than $200 all in.
80/20 benchtop lathe build

[Al_The_Man]

I agree that is a bit steep to pay for that small a motor, even MotionTek Canada who advertise on this site have new motors much cheaper than that.
They come in 90vdc version, so if you want to use as a spindle you can use one of the KB or Baldor SCR drives off ebay etc direct on 120v mains.
Al.

[2_many_hobbies]

The only other motors Ive been able to find are ones like this 1.5HP 48v 4,600RPM but its only 4" round and 4" long so I question its capabilities.

The main problem with ebay for me is $50 for shipping kills me, anybody know of a place in the lower mainland (vancouver, british columbia area) that I can get used/new dc motors for <$100?

As for controllers I build my own, Ive got a stock of 400V/50A fets I make H-Bridges out of that can handle almost anything and their only $2/each

[Al_The_Man]

What size/torque are you looking for? I have a fairly large DC servo with tach on Kijiji right now, I could let it go for $75.00 shipping included to BC.
ElectroCraft 4" dia x 7" length 5/8" dia shaft.
Al.

[2_many_hobbies]

The motor I have on right now is a 1/4HP AC and I defiantly wont go lower than that, Im looking for the 1/3 - 3/4HP range.

Doing a HP = Torque (in-lbs) x RPM / 63025 and converting (16 oz-in = 1 in-lb)

I would like at least 500oz-in @ 500RPM (1/4HP @ 500RPM) but I do the majority of turning at 1000 to 1500RPM.

What are the spec of your DC servo? I currently have a 48V 7.7A and 24V 25A power supply. Thanks!

[Jeff-Birt]

Guys keep in mind that you need a continuous duty rated motor. The stock Taig motor will produce 1/4" continuously. Many cheap motors and servo motors are rated at peak torque, the continuous duty torque is much, much lower, maybe 1/4 the peak rating.

I've been looking at getting some custom PMDC motors made for the Taig and have to say that $150 is not a bad price for a good motor. You can of course get lucky on Ebay, or buy a cheap motor and expect to replace it often.

[2_many_hobbies]

One of my spindles is dedicated for engraving, it uses the stock Dremel collets and nut but on my own spindle with angle bearings and much higher precision.

I dont know what kind of Brushless DC motor to get to drive it though, Ive found:

http://cgi.ebay.ca/Aeolian-GT-Sensor...3%3A1|294%3A50

Would spin at 52,000km @ 12V and geared down 3:1 should make it plenty powerful for all my engraving needs (the odd milling pockets into 0.080-0.125 sheet aluminum) but it might sound like a router at that speed, theirs 800kV motors but I don't know if they would be powerful enough.

What one should I choose? My spindle is 4" long, 1.125" round and takes 1/32-1/8 bits

Also how would I interface those types of controlers into mach3? Would i need to make a pic that outputs the 16,000Hz PWM signal and takes in mach3's pwm?

[Schweinhund227]

Just bumping this post !

I too would like to know how to control a Servo Drive with Mach3 ??

Since I just aquired "Al_the_man" ElectroCraft DC Servo on Kijiji !

and would also need info on In Line Breaking circuits !


Thanks in advance !

Keep this thread going !


Norm

out