This dog won't stay petted!!! I have an application that unspools wire with a dancer operated switch controlling a @35 RPM 1/15 HP ac gearmotor belt driving a roller that a wooden spool fits on. I know I have to use "Shaded Pole" or "Permanent Split Capacitor" motors as a cap start motor will burn-up in a day due to the constant on/off switching. I have three of these de-spoolers and need to make six more. These gearmotors are about $250 ea and I have to replace at least two a year now. Any suggestions an a better solution? Anybody got any gearmotors they want to sell? I keep an eye on ebay and surplusscenter.
Consider using a DC motor. If you want to use a switch then the brute force method is to use supply with some overhead and a great big resistor to limit current to the motor. If you want to get fancy then use a potentiometer on the dancer along with a PLC or other motion controller (and get ready to learn about control theory, PID tuning, and a bunch of other stuff, oh boy).
I just got a nice 24v DC gear motor off a "stair climber" at the dump. You might check the places that repair them.
Or, along the same lines: a 3 ph motor and VFD with feedback control. Can you salvage the gearboxes from the ones that have failed and just replace the notors? With DC or 3 ph.
Hmm.. feeding wire.. How about a plain ol' mig wirefeeder with a rheostat hooked to the dancer? Feeders can be had pretty cheap, used, or at least that's my experience, and they sure last a long time.
Is something pulling off the wire, or are you feeding it into something? If you're pulling it off, I've used pretty simple dancer rolls activating a brake to provide constant tension. On the takeup side, I've used the dancer - pot idea.
I developed one design needing a very constant takeup tension with varying takeup roll size. I routed the web over a roller at 120 deg with the roller mounted on load cells. This read web tension directly. I used this to control a magnetic particle slip clutch driving pinch rollers, which gave very repeatable linear torque response to the signal voltage.
If a drip of resin fell on the web and jammed at the pinch rollers, the sensing roller would immediately see the lower tension, and the slip clutch controller would smoothly increase the torque on the spring loaded pinch rollers until they swallowed the lump. The torque would rapidly return to setpoint. I was using a PC based process controller. This is where you get into tuning PID loops, or in this case PI loops (if you need derivative, buy a fuzzy logic autotuning controller). The web control worked great.
Maybe there's an idea somewhere in the above you can use.
Thanks! The wire just needs to be "available" for the slide feed that feeds the machine. The slide feed is one-way clutch rollers on an air slide, it needs wire with little or no tension. The slide just has to yank the dancer.
Maybe short term. It sounds like your motors are constantly stopping and starting. Most AC motors are not designed for this, but DC servomotors do it routinely.
And, if I finally understand your original approach, with your drive unspooling just enough wire to reduce the load on your linear feeder, the dancer arm with a pot and the appropriate control would regulate the speed of the dc motor to avoid stopping or starting at all. The speed would gradually increase as the diameter of the feed reel decreased.
It doesn't even need to be an expensive servo motor. A cheap Dayton gearmotor with the lowest price drive which would take an analog signal for speed regulation would work. Or you could look for a drive with a PI controller built in.
Your application seems to be best suited for the AC gearmotors you're using.
I think the best components for your application would be the small fractional HP PSC motors made by Oriental Motor (sizes range up to 1/8 HP). AFIK, other manufacturers don't offer the adaptability that the OM models do.
There are several series of these motors that give you all sorts of options.
Variable speed, if you need it, and the small models use small octal socket sized controllers. Speed control will make fine tuning easy, especially if you want to change the production machine's speed in the future.
Separate/modular-design gearheads that allow you to select a specific output speed (or a range of speeds when it's variable), with ratio ranges from about 3 to 90:1, and also an inline 10X multiplier gearbox . The output shafts of the motors are geared, so the accessories mate to the motor face.
High quality ball bearing gearheads, and ball bearing enclosed/non-vented motors. Dependability from simplicity, there's not much point in adding a lot of microprocessor technology to such a simple task.
Some models include motor brakes for fast stopping (and reversing), and other models with brake/clutch packs.
The new distributor prices are high, but there always seems to be a good supply of them on ebay. When buying separate components, some sellers aren't going to be able to help you with fit/compatability, so you might get some gearheads that don't have the same gear tooth to fit (there are some motors that have a straight geared shaft, and others that are helical). The OM website has most of the specs and application info available.
If you get a couple of motors with the application data sheets included, there will be charts to show which gearhead numbers will fit certain motor models. Some times the data sheets are in Japanese only, although many of them include English.
I just got one of these exact motors - 2.99 on eBay, small, Panasonic, with the data sheet in Japanese. Came with its capacitor. My only problem is that it has three wires (bl, wh, grey) and I don't know how to hook it up. Can anyone help?
> Don't be discouraged by all the high priced Hurst motors in the first few pages of AC gearhead motors. The surplus cheap motors start on page 5 or 6. I did not see any 35 rpm, but did see 40 rpm and 30 rpm.
Perhaps a hydraulic or pneumatic motor would cope better with the frequent start/stop cycle. Or switch an electric clutch instead of motor power.
If you have room for a slack loop you might be able to cut down the number of start/stop cycles by a factor of two or three. With a slack loop and an adaptive speed control the motor might be able to run continuously.
Yeah! Do it like the old reel-to-reel computer tape drives with a "compliance arm" that provides the minimum tension on the wire you require, then spools out, brakes, or retrieves with a direct-drive DC servo motor depending upon the position of the arm.
If the arm is pulled more "outward", the motor speeds up to provide slack until the compliance arm tension is correct again. If the arm is allowed to slack, it can either reverse and take up wire, or it can brake to a stop -- depending upon your needs. With enough sensitivity in the feedback element on the arm, you can keep the tension almost constant to a high degree of precision.
Such a mechanism could provide "available" wire all the time, regardless of the direction the end was moving.
One method would be to use an ohm meter to determine the stator winding connection order. If you don't have an ohm meter, you could possibly find the info on a Panasonic website.
A PSC motor's windings are two identical windings connected in series. (1)---------(2)---------(3)
The ohm meter check will show which leads go to the windings' connections, and also confirm that the two windings are identical (indicating that the motor is a PSC type). The resistance readings from 1 to 2 and 2 to 3 should be nearly identical, and equal to the reading from 1 to 3. If the readings are significantly different, the motor may be faulty. A resistance reading of infinity (over range, on some DMM meters) should typically be seen from all winding leads to the motor case.
The use of proper safe wiring techniques will prevent you from being injured. Use a grounded lead attached to a bare metal spot on the motor housing (standard 3-wire AC cord). Insulating the wiring connections properly will eliminate a safety hazard.
The capacitor is connected to terminals 1 + 3, and they are to remain connected to them. One AC line connection is connected to terminal 2, and is to remain connected to it. I prefer the AC neutral lead for 120V motors, so the motor isn't at line potential when the power is switched off. The second AC connection (line for 120V) is fed by a switch to either terminal 1 or 3.
Using a center-position-off double throw switch will allow the 120V motor to be started in forward or reverse without changing the lead connections (and also provide an off position - center).
For 240V motors, the safe method is to provide a double pole power switch to disconnect power from the motor when it's stopped/off. A separate switch can be used for changing fwd/rev.
There are other start/stop and fwd/rev switching methods that can be used for a variety of applications.
Attachment of power leads at random to a motor isn't a good practice. For a PSC motor, the motor will run properly if the power is applied in 2 different configurations (with the capacitor connected), where many other types of multi-lead AC motors won't. It's always best to find the motor manufacturer's recommended power connections.
Several things here need to be done. First off, the speed of the feed needs to be more matched to the usage rate so that the dancer doesn't move fast to either limit. This cuts down on the need for starting and stopping the motor. Second is that you want to use a universal motor rather than a shaded pole type. This will allow a speed control to be used so that the motor keeps running. A router speed control with it's speed knob being controlled by the dancer position will then keep the dancer more in one position and thus your feed rate will tend to stay constant. If your usage of the wire isn't constant, the dancer will eventually go to the stop position where the motor stops.
-- Why isn't there an Ozone Hole at the NORTH Pole?
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