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Posted: Sun Sep 26, 2010 11:59 am
by JPG
I took Dutsy's speed control 'question' as meaning 'use the speed control to adjust the quill speed'. That would work IF the motor shaft was driven by the external motor.
An alternative is to connect the external motor(by belt) to the idler shaft pto. This would also provide a 1.66:1 further reduction in quill shaft speed.
Any attachment of external power(mechanical) except directly to the motor shaft should only be done with the speed control set to 'fast' as described and explained above(to minimize internal operating speed[motor ...])
Since the object is slower range, all the internals would be operating at below 'normal' speeds.
Since the 'normal' torque limiter(poly-v belt or Gilmer clutch) would still be operative, too much torque disappears as a concern.
A disadvantage is the resulting driving of the motor(still below normal speeds).
I would not worry re motor acting as a generator - just make sure power switch is 'OFF' and the power cord unplugged!
IMHO the idler shaft is a better choice(all else being 'equal' and more 'practical' than the motor shaft).
Connecting the external motor to the quill(pto) shaft would be the least preferred(unless the pulley needed is too large for either of the other two shafts.
Posted: Sun Sep 26, 2010 1:59 pm
by robinson46176
I have not done so yet but I decided long ago to set up one of my "extra" Mark V's with external changeable pulley drive. Rather than try to mount a set of cone pulleys on the stub shafts I later decided that it could best be done with single steel pulleys in several size combinations (both for extra high speed and extra slow speed) and a spring loaded idler for belt tension. All you would need to change on the SS headstock is remove the upper drive belt (either Gilmer or poly-vee). Under some applications the upper external pulley may be in the way but my thoughts were that I would only want the extra speeds for such things as drilling, turning or routing/shaping and that it would not matter if it stuck up too high for flat table uses. Of course I would also not be using it with SPT's but that could also be done by adding drive hubs to the pulleys. The idler and the fact that I would use a twist lock belt should take care of any different belt lengths needed.
This would eliminate the need for an external motor and any worries about turning the SS motor while not under power. If the motor were turning very slowly it might not be fast enough to flip the centrifugal start switch (kind of an unknown) and cause it to wear (it does not touch when up to speed).
The tension on the external belt from the idler would provide the "slip clutch" effect needed. Of course a simple guard would be needed, probably on a hinge. It would be the most handy if the pulleys used the same Allen wrench size as the SS.
Remember that this is an "extra" SS in a shop with a good number still in "normal" mode.
Posted: Sun Sep 26, 2010 3:31 pm
by dusty
Some of these ideas about changing speed ratios utilizing pulleys are intriguing but they sorta seem like a giant step backwards technologically.
Now, having said that, I must tell you that this all has me thinking also. For years now, my belt sander has been on a power stand with its own motor and I am now thinking I may need to change the pulley arrangement to get slower speeds.
I have also been thinking about how I might change the Crafters Station by incorporating some additional power arrangements.
But I need to take control of myself and get to work. I have holiday demands closing in on me fast. I must get wood this week and let it start acclimating before I start cutting.
Posted: Sun Sep 26, 2010 3:51 pm
by robinson46176
Posted: Sun Sep 26, 2010 6:51 pm
by JPG
Are they still available?????
A half century!
Posted: Sun Sep 26, 2010 11:09 pm
by backhertz
Posted: Mon Sep 27, 2010 2:12 pm
by peterm
from Pop Mechanics Apr.1982, another maker:
[ATTACH]10518[/ATTACH]
Very expensive back then, more now if still made?
Speed control
Posted: Fri Oct 01, 2010 2:19 pm
by hcbph
Why not consider either a DC motor and controller or a 3 phase with a VFD? Both should be able to run the entire machine and have the ability to control the motor speed as desired, extending the speed control within the unit.
Just a thought.
Posted: Fri Oct 01, 2010 4:16 pm
by peterm
Post #8 notes intent to use a variable speed DC aux. motor. I have a small treadmill motor I want to try.
Posted: Sun Oct 03, 2010 2:04 pm
by peterm
Well, I set up that aux. motor drive; thanks for the discussion so far:
[ATTACH]10544[/ATTACH]
I used a McMillan Electric Model 2716 dc treadmill motor, 120v, 6 amp, fed by a rectifier (EDIT:see post #42 for rectifier details) hooked to a router speed control. The router speed control is good for up to 2hp routers so handles this load ok. I run it at near slowest setting and am not hearing any strange noises from the SS (yet?). The treadmill motor runs very smoothly. SS is left on slow and unplugged. Here is a closeup of the motor and rectifier:
[ATTACH]10546[/ATTACH]
The motor base plate has a slot where the two thumb knobs are, to allow belt tensioning. There seems to be plenty of power with these pulleys. I am using a 3" and 10" pulley but want to get one smaller than the 3"when I can (or maybe bigger than the 10") to get even lower speed. I had to bore the 3" out on my metal lathe to suit the odd shaft diameter on the treadmill motor. At slowest speed it seems to be turning the SS at under 200rpm, a guess since I have not measured it yet.
[ATTACH]10545[/ATTACH]
The big pulley had to go on the upper shaft. I used the base I made for the 7" grinder and drill sharpener and can easily reuse it for those again (see this post
https://forum.shopsmith.com/viewtopic.php?t=5672 )
Here it is running.
[ATTACH]10547[/ATTACH]
I want to use it first to polish the tubes off that old greenie I am slowly refurbing. Safety would suggest I should make some guards next.
A half century!