Automate turning of manual rotary switch?
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From: Spehro Pefhany on 31 Mar 2010 18:01 On Wed, 31 Mar 2010 17:37:14 -0400, Phil Hobbs <pcdhSpamMeSenseless(a)electrooptical.net> wrote: >> >For a one-off, I'd be looking at an RC airplane servo and a flexible >shaft coupling. You can get servos with nice titanium gears and brass >sleeve bearings for way under $100. The good ones have real genuine torque. > >Cheers > >Phil Hobbs Yup, here's one for $119 that has 250 oz-in of torque at 4.8V http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXTHR3&P=ML
From: markp on 31 Mar 2010 18:13 "Phil Hobbs" <pcdhSpamMeSenseless(a)electrooptical.net> wrote in message news:4BB3C08A.4050104(a)electrooptical.net... > On 3/31/2010 5:18 PM, markp wrote: >> "Tim Wescott"<tim(a)seemywebsite.now> wrote in message >> news:5qednQCgAZgvCC7WnZ2dnUVZ_rGdnZ2d(a)web-ster.com... >>> markp wrote: >>>> Got a little problem. I've been asked to come up with something that >>>> turns a manual 3 way rotary switch from one position to another and >>>> back >>>> again under software control. The switch is one of those bulky things >>>> with a pointer style knob. They basically want to control a piece of >>>> equipment without modifying it in any way. >>>> >>>> Does anyone know of a switch actuator manufacturer? I'm looking for >>>> something I can place over the switch with a motor or solenoid to turn >>>> the switch (about 45 degrees per switch position). >>> >>> I'll bet that you're doomed to rolling your own, but I'd sure do those >>> suggested web searches. >> >> Indeed, but this is a one-off so a ahnd crafted solution would be OK (as >> long as it's reliable!) >> >>> >>> Motor -> gear -> adapter on the mechanical side, position feedback -> >>> processor -> software -> drive -> motor on the electro-software side. >>> >>> Can you remove the knob and attach directly to the shaft, or do 'they' >>> want you to leave the knob on? >> >> Ideally leave the knob on, but could remove it and replace it. I'm not >> sure >> whether the knob is press-fitted or screwed. >> >>> Does it have to work under manual control when the software isn't >>> diddling >>> with it? >> >> No, there will be a little control box with a manual override so all done >> in >> software. >> >>> How much individual adjustment are you allowed? How can you anchor this >>> gizmo to the equipment? >> >> Good question. There are some existing fixings I could attach to, I'm >> sure >> they could accept a few holes drilled in the panel that has the switch. >> >>> >>> In principle this is a snap, but in reality there's some effort to make >>> it >>> all work. >>> >>> -- >>> Tim Wescott >>> Control system and signal processing consulting >>> www.wescottdesign.com >> >> This might be quite a tough mechanical challenge, as you say it sounds >> easy >> but the devil is in the details. The switch has click positions, I may >> need >> a way to sense it has seated properly in a particular position. Also I >> don't >> want this to ever sit just off centre of a position in case the switch >> contacts arc. >> >> Mark. >> >> > For a one-off, I'd be looking at an RC airplane servo and a flexible shaft > coupling. You can get servos with nice titanium gears and brass sleeve > bearings for way under $100. The good ones have real genuine torque. > > Cheers > > Phil Hobbs Thanks Phil. Wasn't aware that servos like this had good torque. I'll look into that. Mark.
From: markp on 31 Mar 2010 18:55 "Spehro Pefhany" <speffSNIP(a)interlogDOTyou.knowwhat> wrote in message news:hfh7r5tdggksl1tmq2ejrl0qvfcepr2q5d(a)4ax.com... > On Wed, 31 Mar 2010 17:37:14 -0400, Phil Hobbs > <pcdhSpamMeSenseless(a)electrooptical.net> wrote: > >>> >>For a one-off, I'd be looking at an RC airplane servo and a flexible >>shaft coupling. You can get servos with nice titanium gears and brass >>sleeve bearings for way under $100. The good ones have real genuine >>torque. >> >>Cheers >> >>Phil Hobbs > > Yup, here's one for $119 that has 250 oz-in of torque at 4.8V > > http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXTHR3&P=ML > > Nice. Thanks!
From: ehsjr on 1 Apr 2010 00:23 markp wrote: > Got a little problem. I've been asked to come up with something that turns a > manual 3 way rotary switch from one position to another and back again under > software control. The switch is one of those bulky things with a pointer > style knob. They basically want to control a piece of equipment without > modifying it in any way. > > Does anyone know of a switch actuator manufacturer? I'm looking for > something I can place over the switch with a motor or solenoid to turn the > switch (about 45 degrees per switch position). > > Thanks! > > Mark. > > Replace the knob with a gear. Drive that gear with a gear attached to a motor's shaft. A cam on the driven gear can activate a micro switch for the stop positions. You'll need a gear motor already reduced in speed to keep the driven gear relatively small - maybe something like cat # DCM-276 ($9.00) or DCM-245 ($13.75) or DCM-110 ($3.50) at Allelectronics. http://www.allelectronics.com/ The first two mentioned might provide enough torque to turn the switch with direct coupling and no additional gearing advantage. It's a kludge, but a kludge is what they're asking for, whether they are aware of it or not. The response will be slow at 5 or 6 rpm with the first two motors and 1:1 gearing or direct coupling, in the neighborhood of 1/2 second. With the DCM-110, it depends on the gearing you use. Without knowing the torque requirements it's a guess whether any of the motors will work for you. Ed
From: hamilton on 1 Apr 2010 01:31
On 3/31/2010 9:23 PM, ehsjr wrote: > markp wrote: >> Got a little problem. I've been asked to come up with something that >> turns a manual 3 way rotary switch from one position to another and >> back again under software control. The switch is one of those bulky >> things with a pointer style knob. They basically want to control a >> piece of equipment without modifying it in any way. >> >> Does anyone know of a switch actuator manufacturer? I'm looking for >> something I can place over the switch with a motor or solenoid to turn >> the switch (about 45 degrees per switch position). >> >> Thanks! >> >> Mark. >> > > Replace the knob with a gear. Drive that gear with a gear attached > to a motor's shaft. A cam on the driven gear can activate a micro > switch for the stop positions. You'll need a gear motor already > reduced in speed to keep the driven gear relatively small - maybe > something like cat # DCM-276 ($9.00) or DCM-245 ($13.75) or > DCM-110 ($3.50) at Allelectronics. http://www.allelectronics.com/ > The first two mentioned might provide enough torque to turn the > switch with direct coupling and no additional gearing advantage. > > It's a kludge, but a kludge is what they're asking for, whether > they are aware of it or not. The response will be slow at 5 or > 6 rpm with the first two motors and 1:1 gearing or direct coupling, > in the neighborhood of 1/2 second. With the DCM-110, it depends on > the gearing you use. Without knowing the torque requirements > it's a guess whether any of the motors will work for you. > > Ed If this is a one off project, you can get some old 8-track drives and remove the ratchet, paw and solenoid. Once you look it over, you'll understand how it works. hamilton |