This file is one of the Wolfstone archives of the Halloween mailing lists. You can find out more, and reach the entire collection here: http://www.pobox.com/~wolfstone/_r/HalloweenArchive.html This particular archive deals with "motors/pumps/fans" topics. This includes: o fans o motors o pumps for liquids (for air pumps, see pneumatics) - - - - - From: "Fields, Karl" Subject: HALL: stepper motors Date: Wed, 18 Nov 1998 20:45:31 -0500 Been a long time since I played with these. If I remember there are 5 and 6 wire ones, controlled in single phase, dual phase or half step. Anybody have any words of wisdom on the route to take for controlling an anamatronic *thing*? I've got some circuit boards, somewhere :-), that allow 4 motor controls per printer port using a ULN2803. Anythere better and/or easier out there? - - - - - From: MONKEE1291 at aol.com Date: Wed, 18 Nov 1998 21:09:12 EST Subject: Re: HALL: stepper motors I've used these from time to time,mostly for robotic arms and such.The chip that I've found to be best over the years is the 1027 stepper control chip by signetics(or phillips since they got bought out)this chip will drive almost an amp load directly on each phase if i remember right and needs no further parts(other than a clock pulse 555 etc.) You can use them with rc servo electronics to control this chip and make a "stepper servo" or you can use the direction pin with a yack circuit and have the stepper control a mouth move VERY easy! - - - - - Date: Wed, 18 Nov 1998 22:25:04 -0800 From: Chuck Rice Subject: Re: HALL: stepper motors At 08:45 PM -0500 1998/11/18, Fields, Karl wrote: > Been a long time since I played with these. If I remember there are 5 and 6 > wire ones, controlled in single phase, dual phase or half step. Anybody have > any words of wisdom on the route to take for controlling an anamatronic > *thing*? > > I've got some circuit boards, somewhere :-), that allow 4 motor controls per > printer port using a ULN2803. Anythere better and/or easier out there? > Karl Karl, my company also makes a stepper controller chip, but be careful. Steppers do not provide very much torque, unless you get up into the big bucks range. Steppers are better when you need exact positioning. You can gear them down, but then you are talking slow movement. Winch servos ($50 to $100 each) would probably be better. -Chuck- - - - - - From: Ekker at aol.com Date: Thu, 19 Nov 1998 09:21:23 EST Subject: Re: HALL: stepper motors If you go to ythe links page on my web site, I have some links to plans for I/O boards that can be used to control stepper motors. http://members.aol.com/ekker/ekker.htm - - - - - From: Ekker at aol.com Date: Thu, 19 Nov 1998 13:58:51 EST Subject: Re: Re: HALL: Re: Caged Dragon Idea. Here is what I know about steppers, for what it is worth. <> << A few questions: 1) Are stepper motors available that will be able to lift say 5 or 6 pounds each? >> I believe there are indusrial steppers that can do this, but cost(Too High) and speed(Too Slow) would probably be a factor. <<2) Do stepper motors, by definition, lock in place after positioning? One of my main questions about motors is which ones to use (AC or DC? Stepper or with IR encoder wheel?). I know from previous experience with hobby DC motors that once you remove power from them they will free-spin. That isnt what I want. Once I position the head I want it to stay there until I re-position it.>> Yes and No, If you remove power from a stepper, it will be free to rotate (there is a small resistance to movement in some but it is not much). You can lock a stepper at a particular step ( or between steps depending on the driver circuit) if you keep the current flowing. This Information is accurate as far as I know, there may be exceptions that I am not aware of. - - - - - Date: Thu, 19 Nov 1998 13:15:19 -0600 From: "Edwin Wise" Subject: Re: HALL: Re: Caged Dragon Idea. On 11/19/98, at 12:54 PM, sealslst@brylane.com wrote: >drives to position the heads. A few questions: 1) Are stepper motors >available that will be able to lift say 5 or 6 pounds each? Don't know... > 2) Do stepper >motors, by definition, lock in place after positioning? Yes and no... if you keep power attached, they will hold. They are made to *move* by changing which internal coils you apply power to, in sequence. When you stop sequencing, they stop moving. If you could find a gearhead motor (that is, a motor with gears already built onto it), you can get lots of power, and there would be *some* resistance to motion... depending on the gears. If you had a system with a worm gear, it would hold pretty good; or something like the satellite-dish actuators. If you move away from the concept of servos, you can get good position control if you add some type of position feedback -- potentiometers at the joints, or encoder wheels on the motors,that type of stuff -- but most of this requires a decent computer setup to control it. - - - - - Date: Thu, 19 Nov 1998 12:56:45 -0800 From: Chuck Rice Subject: HALL: Servo Motors At 03:24 PM -0500 1998/11/19, sealslst@brylane.com wrote: > > Winch servos ($50 to $100 each) would probably be better. -Chuck- > << > > Do you have sources and/or web resources for winch servos? We do not sell any motors, and I am not sure where you can get the best price, but any Hobby Shop that sells sail boats will have them. There are links to Tower Hobbies and Sheldons at: <http://www.busprod.com/ferrettronics/links.html> If anyone else knows of other better sources, I would like to add them. Someone posted a link to <http://www.emsjomar.com/> today and they appear to carry them, but I know nothing about the company. Looks interesting. -Chuck- - - - - - From: milwiron at btprod.com Date: Thu, 03 Dec 1998 16:01:48 -0600 Subject: Re: HALL: Servo questions At 04:16 PM 12/3/98 -0500, you wrote: >> At 03:36 PM 12/3/98 -0500, you wrote: >> >Here are a coupla questions for the servo gurus on the list >> >1) how much force does an average R/C servo exert (range)? >> Hey Pete, >> Typical hobby servos run 40 to 160 inch ounces. >Thanks for the help. The first foray into this stuff is always >a jungle of unknowns. >inch-ounces....hmm nothing like another odd unit. Odd? It's easier than those metric Newton Schmootons (meters). ;-) I tend to think in units of Grunts and Bloody Knuckles. As in- The compensating sprocket nut on a Hog is tightened to 8 1/2 Grunts and 2 Bloody Knuckles. Rear axle nuts are tightened to 4 Grunts, 0 Bloody Knuckles. >So, if I understand correctly, there are 192 inch-ounces in a >foot-pound, >and a 40 inch-ounce servo can to what - lift a 40 oz weight one inch? A lever at one inch distance from the fulcrum, or the centerline of the servo's drive shaft in this case, will lift 40 ounces. I've found over the years it's best to design with a load factor of 25% with hobby servos for better life expectancy. A small fish scale from a sports shop is very helpful. >So, this $12-50 is for new hobby servos? Yes. You can find them a bit cheaper and a bunch more expensive. Also, look at single board computers like Stamps for storing your servo programming, they aren't expensive and fit in to spaces a little easier than a 486. ;-) - - - - - Date: Thu, 3 Dec 1998 14:38:26 -0800 From: Chuck Rice Subject: Re: HALL: Servo questions At 04:01 PM -0600 1998/12/03, milwiron at btprod.com wrote: >>So, if I understand correctly, there are 192 inch-ounces in a >>foot-pound, >>and a 40 inch-ounce servo can to what - lift a 40 oz weight one inch? > > A lever at one inch distance from the fulcrum, or the centerline of the > servo's drive shaft in this case, will lift 40 ounces. I've found over the > years it's best to design with a load factor of 25% with hobby servos for > better life expectancy. A small fish scale from a sports shop is very > helpful. Just to expand on this a bit, the rating is a ratio, so 40 ounces at 1 inch radius would be 20 ounces at 2 inches 10 ounces at 4 inches 5 ounces at 8 inches 1 ounce at 40 inches Of course, the last line is not really practical since the weight of the arm would use up all of the lift weight. Another problem you run into is that it is difficult to adjust the speed of the servo. When you tell it to seek a position, it will use all of its force and speed to get to that position. To slow it down, you either have to PWM the power to the servo, or you have to tell it to seek intermediate positions. This may or may not be a problem depending on what you want to do. -Chuck- - - - - - Date: Thu, 03 Dec 1998 17:47:34 -0500 From: Diana Keeton Subject: Re: HALL: Servo questions I am not into math but I did used to run a hobby store of r/c related items. The reason most servos are different prices because they make them to handle different strengths, for about $140- dollars you can buy a large serve, ball bearing that can hold an extremely large load, so generally speaking the more you spend, the higher the load. Your $15.00 servos don't last long and have little more strength than to turn the wheels of an r/c car. The range is determined by your transmitter. - - - - - Date: Fri, 4 Dec 1998 08:38:53 -0800 From: Chuck Rice Subject: Re: HALL: Servo questions At 08:54 AM -0500 1998/12/04, Pete Hardie wrote: > PWM? Whassat? Pulse Width Modulation. Think of a fan connected to a light switch. You like the fan, but it turns too fast and thus blows too hard. To slow it down, you could stand next to the light switch and turn the fan on for 1 second, then turn it off for 2 seconds, then back on for 1 second and so forth. By switching it on and off, and adjusting the time it is on and the time it is off, you can control how fast the blade will turn. Roboticists do the same type of thing to control the speed of motors, except that they have a computer flip the switch on and off. By adjust the ratio of on time to off time (aka Pulse Width) they control the speed of the motor. Of course they use millisecond on and off times instead of seconds, but the principal is the same. They call it Pulse Width Modulation or PWM. -Chuck- - - - - - Date: Fri, 4 Dec 1998 20:48:34 -0800 From: Chuck Rice Subject: HALL: Servo questions (very technical) At 07:25 PM -0600 1998/12/04, John Dolan wrote: > On Fri, 4 Dec 1998, Chuck Rice wrote: >> By adjust the ratio of on time to off time (aka Pulse Width) they >> control the speed of the motor. Of course they use millisecond on >> and off times instead of seconds, but the principal is the same. >> They call it Pulse Width Modulation or PWM. -Chuck- > > Hey Chuck (or anyone), > If you don't mind I'd like to pick your brains a little more to > see if I finally somewhat understand this... The interval of the > "pulse" determines the length of travel and the interval btw > pulses (or the frequency of pulses?) determines how fast the > servo moves? Is that close??? Not quite. I am afraid that this may be more than everyone wants to know, but since you asked... I was speaking of two separate control signals. Servos have three wires: First is the ground. All grounds MUST always be connected together, even if they will be used with separate voltages or control signals. ~~~ Next you have the control signal. This wire (and the ground wire) connects to some device (computer, RC remote control, etc) that will send it a special pulse sequence. This line must get a 1 to 2 millisecond (ms) pulse every 20 ms. The pulse would look like this: 0 Degrees: _____ _____ | | | | 20ms | 1ms | 20ms | 1ms | 20ms --------------- ------------------- ------------ 180 Degrees: __________ __________ | | | | 20ms | 2ms | 20ms | 2ms | 20ms ---------- ------------------- --------- The width of this pulse determines the position of the servo. If the pulse is 1 ms long, the servo motor moves all the way to the left (0 degrees), if it is 2 ms long, it moves all the way to the right (180 degrees). If it is 1.5 ms long, the servo moves to the center (90 degrees). So by controlling the length of this pulse, you can cause the servo to move to any position from 0 to 180 degrees. The problem with this is that it is fairly complex to generate these pulses. And you have to keep sending another one every 20 milliseconds This can use up a lot of computer time. So our company created a small computer chip to do this automatically. The Big computer sends our chip a number between 0 and 255 and we convert that to the proper pulses, and we keep sending the pulses till told to do something different. ~~~ The third wire connects to a +6 volt source (along with the ground). This wire powers the motor inside the servo. Normally, this wire provides a solid +6 volts, so when the pulse on the signal wire (above) changes, the motor will use its full power to move to its new location. This is normally enough. If you want to slow the servo down, you apply a PWM signal to this third wire. You still must be sending the control signal to the second wire, but at the same time, you start turning the third wire on and off. If it is on 90% of the time, then the servo moves to its new location at nearly full speed. If it is on only 10% of the time, then it will move at a slow speed. We do not (currently) offer a chip that does this. So to control the _position_ of the servo you use the second wire (the signal wire), and to control the _speed_ you use the third wire (the power wire). - - - - - From: "Ron Tye" Subject: HALL: servo 333oz/in $45 - Here's the source Date: Fri, 14 May 1999 08:17:38 PDT Hi Kids Here is the address for the biggest servo I've ever herd of, it's only $45 and you can order it over the net. Hobby shack also has lots of other good stuff(inc a 40oz/in servo for $10) http://www.hobbyshack.com/gallery/444281.htm 2.48 x 2.22 x 1.27 5.22oz (148g) 0.22 sec/60 deg 333 oz/in (24 Kg/cm) Ball Bearings CS-600 FET Jumbo Servo for older Airtronics/Sanwa This is the big one! The CS-600 is the strongest servo you will find. And, thanks to the special FET motor drivers, you do not have to sacrifice speed to achieve high torque. This servo boasts an incredible 333 oz./in. of torque (6v supply), yet it is the fastest servo in the Cirrus line! We recommend the use of a high capacity 6.0v battery pack when using this servo. One Year Limited Warranty! Ron (no affiliatioin with Hobby shack except as a happy customer) - - - - - Date: Fri, 14 May 1999 21:36:38 -0500 From: Chuck Rice Subject: RE: HALL: Re: Skel How-To Page - Bucky's not too heavy At 12:16 PM -0400 1999/05/13, Fields, Karl wrote: >Hate to ask Ron, but what was the cost on that "monster" servo? Where did >you find it and how big can they go? >Karl How big can they go? I got the following from Fred Marks at FMA Direct which I posted to the robotics mailing list a few months ago. -Chuck- At 11:38 PM -0800 1999/03/19, Chuck Rice wrote: >I think that FMADirect <http://fmadirect.com/frames.htm> also offers these, >though I have not seen them on the site. I was talking with Fred at FMA >and he send me the following info. There are several things that might be >of interest to robot builders there. Check out the metal servo. -Chuck- > > >At 1:33 PM -0500 1999/03/13, Fred Marks wrote: >> >>At 09:59 AM 3/13/99 -0800, you wrote: >>>At 12:06 PM -0500 1999/03/13, Fred Marks wrote: >>>>ÊÊÊ By nature of the design, our servos are torque-limited by the >>>>amplifier so >>>> that the gear train will not strip under the static stall load.Ê The gear >>>> train has at least a 50% margin above the stall torque.Ê Dynamic loading ( >>>> Instant, repetitive reversal, impact, or control surface flutters) can >>>> strip the gears.Ê We have a wide range of servos.Ê Those for use in higher >>>> impact loads such as cars and large airplanes have metal gear trains.Ê We >>>> still use thick nylon gears for the output because it is naturally >>>> lubricated, can cold flow and come back under impact, and is considerably >>>> lighter than metal.Ê The S500 series has an output gear that is >>>>almost 3/8" >> >> thick and has a 3/8" output shaft. >> >>ÊÊ Depending on what the end use is, we have designed and can >>make available >>>> a servo we designed for educational robots thatÊ uses a cast >>>>metal chassis, >>>> steel gear train with a 1/2" thick output gear and a 1/2" steel output >>>> shaft.Ê I never measured the torque on it except qualitatively >>>>when I put a >>>> 10" Vise Grip plier on the output shaft and could not hold it against the >>>> torque.Ê The idea is to have a servo so powerful that when a child grabs >>>> the arm on the robot, it does not strip the servo.Ê Actually, it could arm >> >> wrestle a gorillo! >> >>ÊÊ Our servos and equipment see a lot of use in the entertainment and >>>> advertising business.Ê Each Budweiser frog has 28 of our >>>>smallest servos in >>>> it.Ê I'm not exactly sure how they use them, but the X-Files production >> >> uses quite a bit of our equipment. >> >>ÊÊ IÊ am interested in adapting your interface from the computer >>to the servo >>>> driver for test of our servos.Ê I am turning over in my mind >>>>that one could >>>> use a pc to set up a more accurate cycling test instead of the steady >>>> cycling we use.Ê We could set up an automated check of resolution and >>>> centering to relieve the operator of the task of judging performance.Ê It >>>> is a boring, repetitive task.Ê I think we might be able to set up a demo >>>> test for trade shows thatÊ shows people for sure that our servos, though >>>> half the price of the competition, are still better than they are. >> >> Best regards, Fred Marks >>> >> >Is it ok if I forward some of this info? -Chuck- >> >__________________________________________________________________________ >> >Chuck RiceÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊ <mailto:Chuck at WildRice.com> >>ÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊ >>> >>>Yes it is OK to forward.Ê We have many things that the animatronics >>community can use.Ê You mention a switch; we have two switchs capable of >>handling 18 and 20 amps that work off the standard 1.0 to 2.0 ms pulse. >>When 1.0 ms is set, the switch is off.Ê As the pulse width goes through 1.5 >>ms to 2.0 ms, the switch comes on.Ê Although we do not stock the big steel >>servo, I can have them made.Ê I will give you a price quote.Ê By the way >>they work off 12 V.Ê Current drain at stall would be pretty formidable, in >>the neighborhood of 10 amps.Ê At stall, they should lift a pickup rear! >Frd Marks - - - - - Subject: Re: Hall: Solenoids & Color Organs? From: "Tim D" Date: Wed, 25 Aug 1999 00:01:04 -0700 There are some potential problems with using solenoids with color organs. This is assuming that the color organ is one of the small cheap types that uses an unfiltered SCR (type B106 or similar.) The solenoid should not = care much about the 'varying' voltage (actually switching at varying times in each cycle of the power wave) except that the voltage from the color organ is rectified by the SCR and thus will only reach about half power. That = may not be enough to activate the solenoid. The bigger concern is damaging = the SCR in the color organ. When the solenoid turns off there may be a significant voltage spike that can exceed the limits of the SCR. A surge suppressor can help that problem. THe SCR may also not turn off properly unless there is a resistive load (like a light bulb) in parallel with the solenoid coil. The resistive load can also help dissipate the voltage spikes. More expensive professional color organs may have fewer potential problems. I would try it and hope for the best. The replacement parts = are pretty cheap. - - - - - Subject: Re: Hall: cheap skeletons From: Crow979797 at aol.com Date: Tue, 14 Sep 1999 12:37:49 EDT In a message dated 09/14/1999 12:35:23 PM Eastern Daylight Time, Crow979797 at aol.com writes: << i checked at the hardware store and discovered an inline induction fan for the vent pipes it runs off of 120v and it pushes = about 80cfm which just blows away the muffin fans. cant wait to get everything together to let everyone know how it works. >> Whoops forgot to mention the induction fan was only $17 - - - - - Subject: Re: Hall: Remote Control Spider From: "Davros76" Date: Wed, 20 Oct 1999 19:33:12 -0400 A few days ago I purchased an automotive windshield sprayer pump (I know very little about cars but I figure this thing should be good at squirting, especially if you restrict the opening a bit). Haven't had time to try it yet. This is not a good retrofit for small model R/C car but great for a larger homemade vehicle or static monster prop using a heavier duty power supply! For the monster prop you can have an oscillating fan or stepper motor to rotate the head back and forth while you spray. One warning: these sprayers are not rated for continuous duty, the parts salesman emphasized this, so only squirt it at intervals with sufficient cooling time in between. --Davros76 -----Original Message----- From: Anthony Pontiac To: Halloween List Date: Wednesday, October 20, 1999 6:03 PM Subject: Re: Hall: Remote Control Spider >I want to rig mine up to squirt silly string! - - - - - Subject: small air compressor From: "bridget nuth" Date: Thu, 9 Nov 2000 10:56:06 -0500 It's been rambling thru my mind that an air compressor would be useful for next years props. I started late this year and only used oscillating fans = to animate 2 monsters[ and burnt 1 fan motor in the process]I hadn't thought about fish tank air compressors-[bubblers] or a nebulizer that my youngest daughter used a few years ago for asthma meds-but was getting dusty in the pantry. Anyone out there with creative ideas to use these?They are not terribly powerful like the ones to lift a corpse, but maybe they could = pull off some special effect?? - - - - - Subject: RE: Hall: A few questions From: "WebMistress" Date: Thu, 16 Nov 2000 22:53:06 -0500 I was informed by hubbie that Bendix makes one also. :) They are used = more in really old semi-trucks. WebMistress ---------- Original Message ---------------------------------- From: "WebMistress " Reply-To: "Halloween List" Date: Thu, 16 Nov 2000 22:43:34 -0500 >Sorry but a Bosch 1500 does go back and forth. Very common in Honda's = 1972 - 1989. They have pretty good torque per f/lb too. > >WebMistress >---------- Original Message ---------------------------------- >From: Carl Chetta >Reply-To: "Halloween List" >Date: Thu, 16 Nov 2000 21:36:48 -0600 > >>At 06:57 PM 11/16/2000 -0700, you wrote: >>>Q 1) Use a windshield wiper motor that goes back and forth ... hook a = rod on >>>it that pushes on the floor, >>> >>> >>>WebMistress >> >> Hi, Just a note, A windshield wiper motor >>does not go back and forth. IT just rotates in one direction only. The >>mechanical arms in the cowl do the back and forth thing. - - - - - Subject: Re: Hall: A few questions From: "Rus Hardy" Date: Fri, 17 Nov 2000 09:19:39 -0600 Carl Chetta wrote: > At 06:57 PM 11/16/2000 -0700, you wrote: > >Q 1) Use a windshield wiper motor that goes back and forth ... hook a = rod on > >it that pushes on the floor, > > > > > >WebMistress > > Hi, Just a note, A windshield wiper motor > does not go back and forth. IT just rotates in one direction only. The > mechanical arms in the cowl do the back and forth thing., And once you = take > it apart it don't go back and forth any more. I tried it my self. > Carl Chetta Carl, We've had this discussion a number of times over the last year.... = Thought you'd want to know that there are actually self contained automobile wiper = motors that have the mechanics built in. The key to finding them is asking the = "Junkyard guy" for rear window wipers. Most of the rear window wipers are self contained and are a "through hole" design. Meaning that the shaft bushing is threaded so that it can be = pushed through a hole then held with a nut. - - - - - Subject: RE: Hall: Washing Machine motors From: "Michael Baumann" Date: Sun, 7 Jan 2001 13:16:13 -0800 > On 1/6/01, at 11:40 AM, JonS999 at aol.com wrote: > > >These motors run off alternating current and if you lower the voltage = you > will burn them out. > > Nah, you should be able to lower the voltage on any motor... raising > voltage is more of a problem. > > Dimmers work on a special principle, though -- they take the smooth AC > waveform coming in from the power line and they truncate it at specific > points in the cycle... the less of the cycle they let through, the = dimmer > the light. > > Now, what happens when you suddenly turn off the voltage to an inductive > (eg: anything with coils of wire in it, such as a motor) device? The > inductor resists this transition -- the suddently collapsing > magnetic field > passes through the coil of wire and generates it's own opposing spike of > electricity! This shoots back up to the dimmer control and, unless it = was > designed to manage this spike, fries it. Or at least, makes it very > unhappy. Close, but you've got it a bit backwards. Most home dimmers use a triac control circuit, where the turn on of power is delayed. Solid state switches (triac, SCR) don't turn off once turned on, until no power is passing through them (0-volt crossing) The problem with the inductive loads is more the way they shift the voltage/current waveforms. It is possible to have maximum current with minimum voltage.. and that can really annoy some solid state stuff. (I'm using some solid state relays to control some stuff around the house, and they are rated for up to a power factor of 0.5) - - - - - Subject: Re: Hall: Use of a RC Servo in a prop question From: "Tim D" Date: Sat, 21 Apr 2001 22:56:49 -0700 A 275 oz-in torque can provide a force of 275 oz at a tangent radius of 1 = in or 1 oz of force at a tangent radius of 275 in.Ê It is a leverage thing. With a short enough servo horn you could lift a great weight, but only for = a very short distance.Ê The closer you get to the torque rating of the = servo, the harder it will have to work, probably effecting speed and accuracy unless it is a very high quality device.Ê Also, there is a very high risk = of damaging the servo gears if it is operated fully loaded at high cycle = rates. The accelerations quickly increase the transient forces. Do not let all of this scare you. My rules of animation: 1. Make the moving part as light possible (to reduce inertia) 2. Balance the moving part at the pivot point (or as close as possible, = use counterweight) 3. Add springs to counter any unbalanced conditions if possible (think MacPherson strut) 4. Apply sufficient power to move the animated part under good control without overstressing the actuator (Servo). This all goes to creating a system where the motor is only concerned with moving the least amount of mass without fighting inertia and gravity. The head is probably not much trouble unless it is heavy and accelerating quickly.Ê The arm may be trickier.Ê Do the following withany props or costume loads attached. Find the point at which you want to attach the actuator rod and measure = the force (in oz) required to move it with a spring scale.Ê Divide that force into 275 (oz-in) and that will give you the maximum radius of the servo = horn on that motor.Ê Multiply that radius by about 1.4 to get the approximate stroke of the actuator.Ê Does that distance give you the action that you need?Ê If so then you're probably OK.Ê If you need more distance then you need a more powerful motor, a lighter figure, or a less radical action. - - - - - Subject: Re: Hall: Use of a RC Servo in a prop question From: "Chuck Rice" Date: Sat, 21 Apr 2001 23:25:45 -0700 At 12:07 AM -0500 4/22/01, David E. Basile wrote: >I'm going to try to use a basic stamp for a halloween prop this year.Ê = It's >a very simple plan but I want to make a head turn to the left or right = and >then have the arm raise.Ê I'm just starting with my basic stamp so it's a >learning process but I was hoping some one could explain the servos = Torque >in Oz-In in simplified terms. > >If I have a servo rated at 275 oz-in torque what does that mean exactly? >How much weight can it lift?Ê The reason I want to know is I plan on = having >a servo raise an arm made of PVC but I believe this will to much for the >servo.Ê Are there some calculations I can use to figure what type of = servo >or motor I may need to do this? Torque is a measurement of force. It gives the amount of mass that can be moved by a lever of a given radius from an axle. So when you say that your servo is rated at 275 ounce-inches, that means that a one inch lever attached to the axle can lift 275 ounces. This is a ratio (275 to 1) that is easily converted to other lever sizes. If, instead of a one inch lever (your animatronic arm in this case), you used a 5 inch lever, then at the 5 inch distance, you could lift 275 ounces divided by 5 inches, or 55 ounces. At 10 inches, you could lift 27.5 ounces, and so forth. As to your project, I have done something like this. Visit <http://www.wildrice.com/Halloween/Construction/> and take a look at my skeleton animatronic. There is a bit more to the story though. First, the ratios only calculate "perfect world" torque. There are a number of other factors involved. Most are insignificant and can be ignored. But one problem you will run into is the extra torque required to start and stop the movement of the arm. Servos are often quite fast. When you move the arm an inch or two, the torque required to start and stop the arm is not too great. But if you want to move the arm a foot or two, by the time it reaches the new position, it will be moving quite fast and the servo will try to use all its force to stop it at once. For me this caused problems with stripping the gears in the servo. I was able to overcome this with programming by using slow starts and stops, but it is a consideration. To understand this better, take a stick about the length and weight of your arm. Hold it in your hand and wiggle it an inch or two as fast as you can. The wiggle it a foot or two just as fast. Note how much more power your hand must use to move it just as fast. -Chuck- - - - - - Subject: Fountain pump alert!!! From: "Ron Tye" Date: Thu, 07 Jun 2001 03:07:49 -0000 Hi Kids, Harbor Freight tools retail stores (not web site) are haveing a fathers = day sale including a submersible mimi pump for $11.97 (lot #41287). I got one of these a few weeks ago $15 and for the money it's one hell of = a pump (local craft store sells them for $40). Perfict for Halloween = fountains (but probibly not up to thick liquid). - - - - - Subject: RE: Hall: Built me one of them MFL's From: "KkrazyKkaren" Date: Tue, 3 Jul 2001 01:39:52 -0400 Glad you like the plans. You can "float" many other objects just use your imagination. Your pictures look great. For those of you that have not seen the plans here is the link again. < http://wardellhauntedhayride.digelements.com/floatlantern.html > Also here is the link to the mirror ball motor I believe the regular duty one will work fine for you. < www.cheaplights.com > or the direct page http://www.cheaplights.com/cat.f/cat.p17/page17.html model # MBM-2 $10.95 Plus S&H - - - - - Subject: RE: MFL Mirror ball motor (was: Ordering from Cheaplights.com) From: "KkrazyKkaren" Date: Tue, 3 Jul 2001 18:51:01 -0400 This KkrazyKkaren's Kkeeper Brian Here are a couple of links for mirror ball motors for the MFL sorry about the confusion with cheaplights' minimum order. Hope this helps. < http://www.onstagevisuals.com/chauvet/chauvet5.htm > Scroll down . . MOT-2 (2rpm) or MOT-5 (5rpm) $7.95 each < http://www.djtronix.com/mirbalmot.html > $12.99, but has free shipping < http://wardellhauntedhayride.digelements.com/floatlantern.html > Bob Poniatowski wrote: > So now I'm in need of a mirrorball motor. > > Cheaplights.com has 'em for $11. - - - - - Subject: Re: 3 Phase stuff From: "Dave Bell" Date: Tue, 7 Aug 2001 21:49:35 -0700 (PDT) I came in on this thread a bit late, but it is following a familiar trend. This comes up in various techie groups from time to time. Karl, one way to get 3-phase power at a decent price is to use an extra 3-phase motor as a rotary converter. As someone posted today, it will indeed generate the missing phase(s). Just needs to get spun up, with single phase power applied to one of it's phases. You can either spin the big 3-phase motor (it has no load on it) with a small motor, or a pull cord, as described. However, there's apparently an easier way, that I haven't had a chance to build up. If you apply single phase power to one phase of the motor (between two terminals, say X and Y), and connect a big = motor run capacitor (see Granger's) from one of those terminals to the third (Z), it will spin right up. Won't have full torque, so you won't want to run your compressor directly this way, but once it's up to speed, you can disconnect the capacitor, and it will continue running! Now, throw = the switch conecting all three terminals (X, Y, Z) to your equipment motor, and the rig will continue to output 3 proper phases. Rule of thumb is the "spare" motor should be at least as high horsepower rating as your load motor. Fortunately, 3-phase motors are pretty cheap on the surplus market! I'll *try* this in ASCII!! / +------/ ^-------------> Start Sw. | Cap / | / *------------+---||--/ ^--+---+------/ ^-------------> \ / Run Switch 220 VAC line \ / (3 pole) To Load (X) (Z) "208 V 3-ph" Spare motor (Y) | / *-------------------+----------------/ ^-------------> - - - - - Subject: Re: Hall: Re: air compressor From: "Tim D" Date: Tue, 7 Aug 2001 22:28:06 -0700 Most large portable generators are three-phase so you should have no problem. I do not know if your compressor came with a motor starter, but you should have one. A motor starter is a high-current switch, usually = with thermal overload protection. These can be manually actuated or use a solenoid. Be sure that you have someone who really knows what they are doing to handle your power distribution and hookups, preferably a professional electrician. The safety issues, particularly with portable power, are many. -The Enchanter (There are some who call me ...'Tim'?) Visit www.hauntinggrounds.org "Nostri Spectaculum Fabricatum Stercois" ----- Original Message ----- From: "Pirates of Emerson" To: "Halloween List" Sent: Tuesday, August 07, 2001 5:30 PM Subject: RE: Hall: Re: air compressor > Sorry for the confusion. The only reason I mentioned household current = is > that is all I'm familiar with. This will not be at a house but in the middle > of a big old field, > > I will be driving a 3 phase motor that runs a compressor. It will be powered > from a 50KW (or KVA - I forget) diesel generator about the size of a VW. > > This same generator will be powering a 200 service panel that is not > attached to public power. - - - - - Subject: 3 Phase Stuff was: air compressor (little long) From: "ThirstinHowl IV" Date: 7 Aug 2001 09:10:02 -0700 Karl, To address your generator/compressor/120Volt load connections, some = additional information is required. 3 Phase power seems a little = mystical, but it is a very good thing! If you have a 3 Phase generator, = this is also a very good thing. Some of the more common types of electrical services/systems are: 120 V Single Phase, 2 wire 240/120 V Single Phase, 3 wire 208/120 V 3 Phase, 4 wire (Wye) 240/120 V 3 Phase, 4 wire (Delta) 480/277 V 3 Phase, 4 wire (Wye) 480/240 V 3 Phase, 4 wire (Delta) 480/277 V 3 Phase, 3 wire ungrounded Most commonly, in 3 Phase generators of the =93medium output=94 such as = your 50 kva, will be a 208/120 V 4 wire (Wye), in which case, you will = still have 120 Volts to ground. Where it can get a little sticky is when = you want to run a 240 Volt load (like a single-phase motor). Most motors = of this variety don=92t like to run on 208 Volts, and will be short-lived. = If you have loads of this type that you need to run, you may need an = additional transformer, or, it is possible that your generator has one = built in (a small one). The most helpful information would be to take some pictures of the unit = and any nameplates, connection diagrams, etc. that may be found on it. If you would like my input on the matter I would be happy to assist. As = always, my contribution to the (hopeful) betterment of the IAHA, is to = offer my interpretation of the National Electric Code, electrical safety = issues and general electrical issues as a =93member benefit.=94 E-mail me offlist if you wish. ThirstinHowl_IV@Telesis-Entertainment.com Thirsty - - - - - Subject: RE: Hall: Re: air compressor From: "Rob Withoff" Date: Tue, 7 Aug 2001 16:09:58 -0500 > The idea is the generator (50KW) will be hardwired to a 200 amp service > panel for 120v AND to the 3 phase, 220v compressor motor. Any of you > electricians have some thoughts or guidelines here? I'm obviously > out of my > element because I don't really understand 3 phase. Eww-- I'm not a licensed electrician and I will defer to higher knowledge, but I think a three-phase generator has four wires (A, B, C, Neutral), = with the A, B, and C phases being 120 degrees from each other. A 200 amp = service panel is normally looking for a 3-wire (A,B,Neutral) where A and B are 180 degrees out of phase. I know there's a way of doing it. - - - - - Subject: RE: Hall: Re: air compressor From: "digger C" Date: Tue, 07 Aug 2001 18:02:15 -0400 im confused do you want to run a 3 phase compressor motor with the output from a generator driven by a 220 motor wired to household current. = household current is two pole single phase or two hots and a neutral each hot has = 110 to 120 volts togeather they are 220 nominal. ( electric clothes, dryers electric stoves) any one to neutral is 110 to 120.( a light bulb) three phase is three hots and a ground no neutral is involved and not found in = any home i know of. >From: "Rob Withoff" >Reply-To: "Halloween List" >To: "Halloween List" >Subject: RE: Hall: Re: air compressor >Date: Tue, 7 Aug 2001 16:09:58 -0500 > > > The idea is the generator (50KW) will be hardwired to a 200 amp = service > > panel for 120v AND to the 3 phase, 220v compressor motor. Any of you > > electricians have some thoughts or guidelines here? I'm obviously > > out of my > > element because I don't really understand 3 phase. > >Eww-- I'm not a licensed electrician and I will defer to higher = knowledge, >but I think a three-phase generator has four wires (A, B, C, Neutral), = with >the A, B, and C phases being 120 degrees from each other. A 200 amp = service >panel is normally looking for a 3-wire (A,B,Neutral) where A and B are = 180 >degrees out of phase. >I know there's a way of doing it. - - - - - Subject: Re: Hall: Re: air compressor From: "Rucker Posey" Date: Tue, 7 Aug 2001 18:38:05 -0400 Yea Karl - what he said , but you may want to go into a 3 phase panel = first and then break out your single phase . You need to check that your three legs are 120 volt each ( some are delta config and some are the "Y" )in = some cases there are high legs etc . Any way , the way to do this is to take three legs , a neutral , and a ground to a three phase panel , then from that panel you take two 120 = volt legs , a neutral and the ground into your 200 amp single phase panel - = thus creating panels for each service . But again - I'm not a licensed electrician . I have done a few of these for our generators at work though = .. Most places require you to drive two of the ground rods in for your generator . Ruck ----- Original Message ----- From: "Rob Withoff" To: "Halloween List" Sent: Tuesday, August 07, 2001 5:09 PM Subject: RE: Hall: Re: air compressor > > The idea is the generator (50KW) will be hardwired to a 200 amp = service > > panel for 120v AND to the 3 phase, 220v compressor motor. Any of you > > electricians have some thoughts or guidelines here? I'm obviously > > out of my > > element because I don't really understand 3 phase. > > Eww-- I'm not a licensed electrician and I will defer to higher = knowledge, > but I think a three-phase generator has four wires (A, B, C, Neutral), with > the A, B, and C phases being 120 degrees from each other. A 200 amp service > panel is normally looking for a 3-wire (A,B,Neutral) where A and B are = 180 > degrees out of phase. > I know there's a way of doing it. - - - - - Subject: Re: 3 Phase Stuff was: air compressor (little long) From: "Tim D" Date: Tue, 7 Aug 2001 16:28:11 -0700 Karl, Just to expand and clarify and agree with Thirstin, three-phase motors are inexpensive, efficient, and powerful for their size. If you have a three-phase motor on your compressor and only a single phase (domestic-type) power service, you will need to derive three-phase power = by one of the following means: 1. Generator, three-phase, matched to the voltage, current and frequency requirements of the motor. The generator can be powered by a single-phase motor to form a motor-generator (m/g) set. The generator could = alternatively be powered by an energy supply such as an internal-combustion engine or a turbine. 2. There are electronic motor controllers available ($500-$2000) that can take single-phase power and create three-phase power. These devices have other useful features like speed and acceleration control. -The Enchanter (There are some who call me... Tim?) visit www.hauntinggrounds.org "Nostre Spectaculum Faeculentus" ----- Original Message ----- From: "ThirstinHowl IV" To: Sent: Tuesday, August 07, 2001 9:10 AM Subject: Hall: 3 Phase Stuff was: air compressor (little long) > Karl, > > To address your generator/compressor/120Volt load connections, some additional information is required. 3 Phase power seems a little = mystical, but it is a very good thing! If you have a 3 Phase generator, this is = also a very good thing. - - - - - Subject: RE: Hall: Re: air compressor From: "Pirates of Emerson" Date: Tue, 07 Aug 2001 17:30:29 -0700 Sorry for the confusion. The only reason I mentioned household current is that is all I'm familiar with. This will not be at a house but in the = middle of a big old field, I will be driving a 3 phase motor that runs a compressor. It will be = powered from a 50KW (or KVA - I forget) diesel generator about the size of a VW. This same generator will be powering a 200 service panel that is not attached to public power. Thanks to you guys I now have a clue. Thanks, Karl -----Original Message----- Behalf Of digger C Subject: RE: Hall: Re: air compressor im confused do you want to run a 3 phase compressor motor with the output from a generator driven by a 220 motor wired to household current. = household current is two pole single phase or two hots and a neutral each hot has = 110 to 120 volts togeather they are 220 nominal. ( electric clothes, dryers electric stoves) any one to neutral is 110 to 120.( a light bulb) three phase is three hots and a ground no neutral is involved and not found in = any home i know of. - - - - - Subject: RE: Hall: Re: 3 Phase Stuff was: air compressor (little long) From: "M. Little" Date: Tue, 7 Aug 2001 20:37:00 -0400 There are Add-a-phase and Roto-phase converters that generate 3 phase from single phase. They aren't as sophisticated as the electronic units, but they've been around for a long time. I have heard tales that a 3 phase motor will RUN on single phase power, but won't START on single phase... so some machine shops used to have 'starter ropes' (Yep, pull cords) on lathes to get them spinning... -Malcolm > Karl, > > Just to expand and clarify and agree with Thirstin, > three-phase motors are > inexpensive, efficient, and powerful for their size. > > If you have a three-phase motor on your compressor and only a > single phase > (domestic-type) power service, you will need to derive > three-phase power by > one of the following means: > 1. Generator, three-phase, matched to the voltage, current > and frequency > requirements of the motor. The generator can be powered by a > single-phase > motor to form a motor-generator (m/g) set. The generator > could alternatively > be powered by an energy supply such as an internal-combustion > engine or a > turbine. > > 2. There are electronic motor controllers available > ($500-$2000) that can > take single-phase power and create three-phase power. These > devices have > other useful features like speed and acceleration control. - - - - - Subject: RE: Hall: Re: 3 Phase Stuff was: air compressor (little long) From: "Jim Kadel" Date: Tue, 07 Aug 2001 21:28:36 -0400 Malcom, Kinda hard to "pull" start a motor that's belt or gear tied to a compressor :>) Jim (So maybe Karl's going to need a clutch between the two?) =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D REF = =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= At 08:37 PM 8/7/01 -0400, you wrote: >There are Add-a-phase and Roto-phase converters >that generate 3 phase from single phase. They >aren't as sophisticated as the electronic units, >but they've been around for a long time. > >I have heard tales that a 3 phase motor will >RUN on single phase power, but won't START on >single phase... so some machine shops used to >have 'starter ropes' (Yep, pull cords) on lathes >to get them spinning... - - - - - Subject: RE: Hall: Re: 3 Phase Stuff was: air compressor (little long) From: "M. Little" Date: Tue, 7 Aug 2001 21:56:39 -0400 Aw, there's bound to be some exposed shaft somewhere, right? Maybe rip that pesky guard off... Just run back there and pull the belts whenever the pressure got low? [PLEASE don't try this - I'm kidding] But... I seem to recall that some small shops had bought old lathes, which came with 3 phase units, and they would actually wind a pull cord around the headstock, flip the switch, and twist 'er off. I have no idea how efficient or powerful those motors were when running. I'm not sure I'd actually want to run one like that either. I do seem to recall that a three phase motor will actually GENERATE the missing phase voltages due to inducing voltages to be used as a motor/generator of sorts, but I think it required an auto-transformer and a cap or two. But you have to understand, this pulls from a section of my brain that I haven't had to access in over 20 years, so maybe a web search for info would be called for. -Malcolm > -----Original Message----- > From: Halloween-L at WildRice.com [mailto:Halloween-L at WildRice.com]On > Behalf Of Jim Kadel > Sent: Tuesday, August 07, 2001 9:29 PM > To: Halloween List > Subject: RE: Hall: Re: 3 Phase Stuff was: air compressor (little long) > > > Malcom, > > Kinda hard to "pull" start a motor > that's belt or gear tied to a compressor :>) > > Jim > (So maybe Karl's going to need a clutch between the two?) - - - - - Subject: Re: Hall: BBQ motors From: "Josh Coen" Date: Mon, 13 Aug 2001 08:42:38 -0700 You might try any thrift stores you have in your area. I picked one up for $2 last week and found another one for $3 that I didn't buy because it didn't work. But I think there are a lot of stray motors out there. Of course, you have to be patient sometimes and not need it immediately. - - - - -