Need Help!- motor speed (RPM) control.

[Drools]

I just purchased a Wolfgang setup, spindle, mount motor etc.
The motor spec as listed is:
110VAC
20,000RPM
This should work great for isolation routing, I have seen videos of this setup which are very impressive.
I really do not want to change motors to drill PCBs but I do not want the spindle at full 20K when drilling. I think the motor is a "Universal motor" but I have yet to confirm that.
I'm trying to figure out what would be the best way to tackle this problem.
My options are:
1: change the motor to a DC motor and use PWM. I do have a 120VDC motor with roughly the same dimensions however I would need a 120VDC power supply.
2. Use the motor that came with the setup and slow it down.

Any suggestions?

[Al_The_Man]

If it is a universal motor, has brushes, then either an SCR or a TRIAC controller should work.
Al.

[Drools]

Will it work through Mach3?
What I'm after is to set Mach3 to route the PCB then stop for a tool change and once change is complete start drilling at the reduced speed.
I still have to make a 1/8 adaptor for the tiny drill bits but that should be fairly easy for someone with a lathe.

[jeffrey001]

I have bought the same spindle as you did.

The spring collet that came with tha spindle accept 1/8 shank.

Just asking, why would you like to reduce speed when drilling, 20 000 RPM is just OK fo such small drill.

What I did with mine is made a new larger pulley to increase speed as 30 000 RPM is better, as a matter of fact, with these tiny bits and drills, the higher RPM you can have, the better it will be.

But with this spindle, this was not a good thing to do as the use pretty cheap bearing so they are not made to accept higher than 20 000 RPM and they are dead.

So bought new ceramic bearing but did not try them yet so I can not tell if they are better.

Jeff


Ps, will work great with mach3 if this is the main spindle, if you include in your code a tool change, T01, M01, and spindle is connected with a relay or stop spindle with M5 and start with M3

[Drools]

hmm very interesting do you have a make and model for the ceramic bearings you purchased? How about a schematic for your wiring of the relays?

Thank you

[jeffrey001]

I'm 99.9% sure they are standart 3/8 X 5/8 X 5/32 bearing.

As for the schematic, will come back with it.

[wolfgang314]

My spindle is designed as an inexpensive alternative to the more expensive options that are currently out there, such as the Astro NSK-250E, which is a $2000 spindle,

http://www.omni-turn.com/Pages/Tooli...250%20Set.html


Please contact me if you would like the bearings replaced in your spindle, I'm sure we can work something out.

[Drools]

I found an interesting little chip, TDA1085C
Digikey stocks it in small numbers and is pretty reasonably priced @ 2.50CAD
I'm not an electrical engineer by any stretch so I'm wondering if the more enlightened people on here would comment on this chip.
http://search.digikey.com/scripts/Dk...TDA1085CGOS-ND

Thanks

[Drools]

Well Richard finally found my e-mails requesting the details on the motor. Here they are:
Johnson Motor #5053.
Motor is capable of running on AC or DC.
AC specs are 115 VAC, 70 mA , 12,000 RPM no load, 6000 RPM full load, approx 20 oz-in torque.
DC specs are 24 VDC reversible, 5 mA , 1500 RPM, 6 oz-in torque.

Shaft 5/32" dia. x 1/2" long. Front plate mounting with two tapped 4-40 holes. Two 0.110 spade terminals for connection with one 0.188 spade lug for grounding. Motor size, 1.5" x 1.25 x 2.5"L. New.

It can be run PWM but the DC torque & RPM is less than 1/2 the AC values.This is what the surplus website has on the specifications, I will have to do some digging.
http://www.herbach.com/Merchant2/mer...Code=DCPMFIELD