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This is the instructor's thread for the fourth project of 2016, Rocking Prop. Frog Prince of Stinkerbell n Frog Princeis the instructor and he will be posting the materials list and start date soon.. Please note this thread is for the instructor's use only. Please post all questions and comments in the student's thread found here.
 
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I'm going to post the materials list shortly, but first I wanted to give a little bit more of a description. What we are going to be building is mechanism for back and fourth, or side to side movement. When I was taught to build this it was called the rocking Grandma prop, but it is so much more versatile than just for rocking Grandma. I have used this build to make a skelly rock side to side in a pot, and to make a two man, or in this case two skelly saw move back and fourth. I have also used modified versions of this build to make a dragon wing move up and down, also to make an ape arm move up and down. So it can be used in a lot of applications. I'll take some video of the completed build, to give y'all a better idea.

FP
 
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Wiper Motor Prop parts list.

#1. Wiper Motor.
#2. Power supply.
#3. Wiper Motor Crank.
#4. Wiper motor electrical connector.
Below the parts list is information on where to source a wiper motor and power supply.
#5. 2X6 board that is 16” long.
#6. 2X4 board that is 9” long.
#7. Board 1/2”X4 ½” - 6” wide and 10” long (plywood will work for this).
#8. 1X2 or 2X4 board that is as long as the width of the #7 board.
#9. One door hinge, like a standard door hinge you might find on your bathroom or front door.
#10. 1" to 1 1/2" long decking screws 13 of them.
#11. Metal bar 1 foot long 1/8” thick 1 Inch wide.
#12. One 1” long 1/4” lag bolt.
#13. One 3/16” bolt 1” long, preferably with a small head.
#14. 2 nuts that fit your 3/16” bolt.
One of the things that is really great about the prop is its flexibility. Not only can it make a lot of different stuff move, but also it can be built a lot of different ways. I don't build it exactly like I was taught, and often I don't build it the same way twice. Mainly this happens because I like to use what I have on hand. So sometimes I end up using slightly different bolts, or wood sizes. What I have on the above list is the ideal things to have for this build. I'd highly recommend for the first time that you follow the parts list as closely as possible especially with the wood.


Options sourcing a wiper motor and power supply:
There are lots of ways you can go about getting a wiper motor and power supply. The cheapest thing is to buy a used wiper motor and power supply, but because this is presumably your first time building a wiper motor prop, I'm going to recommend that purchase your power supply and wiper motor from Monster Guts. I recommend that you purchase this kit http://www.monsterguts.com/store/product.php?productid=17760&cat=3&page=1 It will come all ready to go out of the box and will really simplify the build for you. And you will have parts #1 though #4. Plus mounting bolts for the wiper motor will be included. The down side is the Monster Guts kit is $47.00, so if that's a problem I'll give you some advice on used sources. But just to put it into perspective the wiper motor that is included in the kit costs $72.00 at my local parts store, and there is no mounting bolt or power source so actually it's a pretty good deal.

Getting a used wiper motor / other sources.
I have gotten many of my wiper motors at the local U-pull it wrecking yard for about $10 - $12. I usually like to go for older Dodge truck wiper motors, from the later 80's though the mid 90's mostly because I find that they have a good mount for prop use, but they are different from the monster guts unit. Many Saturn's have wiper motors with the same mount as the Monster Guts unit, but they will have a different electrical connector and saturn units are much harder to remove than the Dodge units. You need to remember to cut the electrical connector off the vehicles wiring harness so you can hook the power supply to the motor. If you get a used unit try to get one of the ones I mentioned above if possible, because I'll be better able to help you figure out how to mount it since I'm familiar with those ones.

Used Power Supply:
A laptop power cord or similar works, but they can be hard to come by. My usual source is the local thrift store. I've tried used computer stores, but they cost quite a bit more, at least in this area. What you'll need is a power supply that will ideally produce 12 volts and as close to 5 amps as possible. When your selecting a used power supply remember this, to a point high voltage will make the motor turn faster, lower voltage will make it turn slower. High amperage will will allow the motor to handle larger loads, lower amperage will cause the motor to stall more easily. Now I've used power supplies with only 2 – 3 amps, and they are fine for moving something like a light weight wing, but it won't work for an over sized ape arm. Once I bought a power supply that had 18 volts and only 3 amps because I was in a pinch. 18 volts is way to high, I had to string a series of heater blower resisters together to slow it down to something reasonable. I'd say 12 – 14 volts is usable and 3 – 5 amps is best but the closer to 5amps and 12 volts you can get the better it will work, but it will difficult if not impossible to find the ideal 12 volt 5 amp unit.

One last thing. I'm posting all of this early so anyone interested has a little bit of time to get supplies together before we start the build in early June.

FP
 
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I've gotten a little behind on this so I do apologize. In this video I will talk about what we will be building, I'll give some examples of what it can be used for and then I'll show you one. Also you'll get to see the finished project. Later this week I'll get the instrucational how to video up. After you have watched this video if you have any questions about what it might be used for or anything else feel free to ask.

FP
 
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So here is the instructional how to video on building the rocking prop. And I'm warning you ahead of time it's 30 minutes long. So you don't have to take the video out to your shop and keep pausing it and replaying it I will be posting a step by step tutorial with pictures in the coming days that should help too. But y'all welcome to start whenever your ready too.

FP

 
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Step #1 if you haven't already, cut your 2X6 board to 16 inches long. Then attach 1/2" thick board (#8 in the parts list) to your 2X6 board with three screws, this is your base brace. Reference the photo below for attachment location.
#1 Base Brace.jpg


Below Photo of the base brace after it is attached to the 2X6
#2 Base Brace Attached.jpg
 
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Step #2 for this step we'll be working with board #7 in the parts list. I want to start by saying this is going to be by far the hardest part of the build. I'm going to try to elaborate on what I said in the video here. If something I have said doesn't make sense to you please feel free ask about it.

To complicate matters in the video I give some drill sizes that maybe incorrect. In the photo below I give the correct sizes. I have found that the outside diameter of the mounts can vary a little bit and I would rather that everyone drill holes that are a little on the small side and end up having to make them a little bit bigger than have everyone drill larger holes and potentially end up ruining a board. So go with the figures that are in the picture.

We are going to start with making the hole for the shaft on the motor first. But before we begin we need to keep a few things in mind. When you drill this first hole all the other holes and cuts will follow, so please keep in mind that the bolt holes need to stay at least one inch from the edges to be sure that there is enough strength. And that the bottom of the motor (the black part) is high enough to not hit the brace board. It is also best that the black part of the motor is as close to centered side to side as possible, however if you look at the pictures, mine is not centered because I used a board that is 4 1/2" wide, that's about the narrowest board you can get away with and you'll end up with the motor a little off center with that, but it's no big deal. You don't need to measure any of that out if you don't want to, mostly it's just for a guide.

After you have figured out the best spot for the shaft of the motor drill the hole, next drill the holes for the mounts and follow that by recessing the holes. When you go to drill the recesses the best thing to use is a depth stop. I don't have a depth stop so I just eye balled it. If your not comfortable eye balling it and you don't own a depth stop you can also put a small piece of tape on your drill bit at the desired stop point. Watch the tape when your drilling, when it lines up with the wood your done. If your using a 1/2" thick board as recommended you'll want to recess your mount holes by 1/4". If your using a thicker board you'll need to recess the holes a bit more. Last you will make the cut out for the black part of the motor to fit into. I gave some suggestions in the video on how to mark the location of the holes and the cut out if you need them.

Once you have the mount made attach it to your base brace, using 4 screws, two on each side of your cut out.

Hopefully that all made sense. If you have questions or are unsure of something please feel free to ask.

#3 Mount Base.jpg

#4 mounting the base plate.jpg

#5 Base plate Mounted.jpg
 
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Step #3. Now that we have the mount attached to the brace, we need to install and bolt the wiper motor in place. This is the point at which we find out if we have made any mistakes when we were building the mount. If the wiper motor won't mount up correctly take the time to make any needed corrections to the mount before moving on to the next step.

#6 mounting wiper motor.jpg

#7 Mounting wiper motor.jpg

The word that is cut off in the photo is WOOD.
 
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Step #4. Assuming you have bought the kit from monster guts, there will be two cranks in the box for the wiper motor one with two holes and one with one hole and a ball joint. The crank we want to use is the one with two holes. You'll put the 3/16" bolt though one hole in the crank and then mount it to the shaft of the wiper motor using the nut that came with your wiper motor. Use the photos below for reference. In particular you need to make sure that the shaft of the nut will be facing outward after the crank is bolted to the motor. Once you have the bolt in crank, you can mount the crank on the motor with the nut that is included in the kit.

If your using a wiper motor that came from a wrecking yard you'll only have one crank, and it will have a ball joint on one end. In this case you will need to remove the ball joint. It's a bit of pain but I have done it many times myself so if you need help removing the ball joint, post a picture of your crank in the student tread and I'll give you some suggestions on removal.

#8 Bolt crank.jpg

#9 Install Wiper motor crank.jpg
 
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Step #5. Take your 2X4 board. If you haven't already cut it to 9" long. This is going to become the flapper board. You will want to screw the hinge to one end and then screw the other end of the hinge to the 2X6. Reference pictures below for measurements.

#10 install hinge.jpg

#11 hinge orientation.jpg

#12 mounting flapper on 2X6.jpg
 
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Step #6. For some folks this step maybe a bit tricky for others it will be a breeze. Take your metal bar (# 11 in the parts list) if it isn't already 1 foot long, you'll need to cut it to that length. Then you will need to drill one 3/16" hole about a 1/2" from the end on both ends of the metal bar. If your not into drilling and cutting metal many hardware stores have metal available that already has holes drilled in it and it is likely they will cut it to your requested length, but this type of metal is more expensive and always weaker than a solid bar. But it's a valid option if you don't want to do your own cutting and drilling on the metal.

Next you will want to mount the metal bar to the wiper motor crank. This is the order of assembly you should have on the crank going from the inside (wiper motor side) to the outside. Bolt head, crank, nut, metal bar, nut, and then another nut. The nut that is next to the crank should be tightened securely. Then the metal bar placed on the bolt, the next nut should then be threaded on and left a little loose. The last nut should be threaded on and tightened securely to the other nut. I hope that made sense. In the end what you want to have is three nuts that area tight on the bolt and the crank should be tight on the bolt to, but the metal bar needs to be able to move freely. It's very important that the metal bar is able to move or it will bind up potentially causing something to break.

Once you have that end worked out it's time to bolt the other end to the flapper board with your lag bolt. You want your lag bolt to be at about the same height on the flapper board as the center of the crank on the wiper motor. It doesn't have to be exact but close. Feel free to eye ball it if you feel comfortable with that or measure from the bottom of the board to the center crank bolt on the motor. What you get for a measurement there is the same measurement you'll need for the flapper end.

#13 Installing metal bar.jpg
 
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Step #7 We need to wire up the electrics for the wiper motor. If you have the kit from Monster Guts that I recommended, a power supply came with it. Wiring for you will be very simple. On your power supply the end opposite the wall plug there will be two wires, Monster Guts has already put connectors on it the prongs on the wiper motor. On the power supply there are two wires. The solid red wire is the positive wire, the other wire (most are black with a red strip) is the negative. I think the easiest thing would be to have you look at the photo below to know where to plug the wires into the wiper motor. The photo is with the wiper motor unmounted because it was easier to get a shot of the terminals, but I normally do the wiring as the last step, with it mounted as you have yours right now.

If you have opted to source your power supply from somewhere else and / or your using a wrecking yard wiper motor let me know in the student thread if you need help wiring up your motor, because it will be substantially more complicated, but it is definately doable and I have done it myself many times. So here are the basic principals. You will need to cut the end off of the power supply, strip the wires back and determine which wire is positive and negative, the easiest way is usually with a multimeter. If you have more than two wires it gets a little trickier, though. On the wiper motor end it will be more a matter of guess work to figure out which terminal does what. If your using one off of an older car, say pre-1990 chances are the negitive side will be the body of the motor so you'll attach the negative wire of the power supply to the body and then it's just a matter of connecting the positive wire to each one of the terminals of the motor, turning the power on and seeing what happens.

#14 Wiring wiper motor.jpg
 
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Step #8. We are done. Everything is assembled and it is time to test it out. But before you plug the cord into the wall and watch it move you need to be aware of one thing. Wipers motors are very powerful, and if working properly properly it takes a lot to stall them out. Please be VERY careful around the moving parts as they will not stop if important things like your fingers. Depending on what your going to be making move you may want to consider building a simple enclosure with some small piece of plywood to cover the crank area of the wiper motor as this is where it is easiest for a bit of your prop, clothes or ouch your finger to get caught in.

Additionally the rocking prop can be used inside or outside, wiper motors are designed to handle getting wet, but not submerged. Also be aware that the power supply needs to be kept reasonably dry.

View attachment 279645

Done!
 

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Probably a dumb question, but how do you wire a used motor up to a laptop power supply/cord? Also, how slowly can you get the motor to turn with that kind of setup (I have a small rocker that will be 'haunted' (nothing sitting in it) and it won't take much power to move it. I'd like it to rock slowly. Thanks.
 
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Probably a dumb question, but how do you wire a used motor up to a laptop power supply/cord? Also, how slowly can you get the motor to turn with that kind of setup (I have a small rocker that will be 'haunted' (nothing sitting in it) and it won't take much power to move it. I'd like it to rock slowly. Thanks.
Do you know what the wiper motor is off of? If you do please post it so I can look up the part that would help. But basically on most wiper motors there are terminals for the following. Low speed, high speed, park, sometimes one for intermittent and sometimes one for ground, other motors use the housing for a ground.

For the power supply you'll need a laptop power supply. Cut the ends off of it that would normally plug into the computer. If your lucky there will be only two wires, if there are more than two wires you'll need to plug in the power supply and test the wires with a multi-meter, or a test light to figure out what is what.

As far as wiring it to the motor you can do trial and error, or again if you know what the wiper motor is off of I maybe able to get a schematic that would make it really easy for you.

The speed is determined by the voltage of the power supply, and the force is determined the amperage. Higher voltage = faster Lower voltage = slower. Higher amperage = more force lower amperage = less force. If your buying the power supply from monster guts they have a really neat speed controlled available http://www.monsterguts.com/store/product.php?productid=17741 With that you can slow it down to barely moving. Sorry I don't know the slowest RPM but very slow. If your getting your power supply used look for a lower voltage one. You can go down to 9 - 10 volts. It will move slow, but not as slow as with the monster guts controller. The problem with used power supplies is that it is really hard to find one that is much over 3amp (5 is ideal) and the slower you turn it the more likely you are to have stalling issues, with a low amp power supply. I would look for something is 9 or 10 volts and you indicated it's light so you could probably get away with 2 amps if you have to but again the closer to 5 amps the better, the less chance of stalling at low speed.

What your trying to do is totally doable with a used wiper motor and used power supply. I have used more used stuff than monster guts stuff because it's cheaper. It may take some experimentation to get the speed you want. Another thing you can do to slow down the setup is to wire in a resister from a heater blower motor out of a car. I have done that before and it's not hard to do but the resisters get hot so you have to be careful you don't burn yourself or create a fire hazard. I can make suggestion on the some good resistors for cheap online if you need it.

Thanks,
FP
 

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Do you know what the wiper motor is off of? If you do please post it so I can look up the part that would help. But basically on most wiper motors there are terminals for the following. Low speed, high speed, park, sometimes one for intermittent and sometimes one for ground, other motors use the housing for a ground.

For the power supply you'll need a laptop power supply. Cut the ends off of it that would normally plug into the computer. If your lucky there will be only two wires, if there are more than two wires you'll need to plug in the power supply and test the wires with a multi-meter, or a test light to figure out what is what.

As far as wiring it to the motor you can do trial and error, or again if you know what the wiper motor is off of I maybe able to get a schematic that would make it really easy for you.

The speed is determined by the voltage of the power supply, and the force is determined the amperage. Higher voltage = faster Lower voltage = slower. Higher amperage = more force lower amperage = less force. If your buying the power supply from monster guts they have a really neat speed controlled available http://www.monsterguts.com/store/product.php?productid=17741 With that you can slow it down to barely moving. Sorry I don't know the slowest RPM but very slow. If your getting your power supply used look for a lower voltage one. You can go down to 9 - 10 volts. It will move slow, but not as slow as with the monster guts controller. The problem with used power supplies is that it is really hard to find one that is much over 3amp (5 is ideal) and the slower you turn it the more likely you are to have stalling issues, with a low amp power supply. I would look for something is 9 or 10 volts and you indicated it's light so you could probably get away with 2 amps if you have to but again the closer to 5 amps the better, the less chance of stalling at low speed.

What your trying to do is totally doable with a used wiper motor and used power supply. I have used more used stuff than monster guts stuff because it's cheaper. It may take some experimentation to get the speed you want. Another thing you can do to slow down the setup is to wire in a resister from a heater blower motor out of a car. I have done that before and it's not hard to do but the resisters get hot so you have to be careful you don't burn yourself or create a fire hazard. I can make suggestion on the some good resistors for cheap online if you need it.

Thanks,
FP
Thanks, that helps a lot. I don't have the motor yet...was thinking of just get the Monster Guts stuff you suggested for my first try. I don't have much time for doing the auto salvage thing, though that sounds like a good idea. I have also noticed wiper motors being sold at Amazon (is there anything you can't buy on Amazon?) so I may try that at some point. Thanks again.
 
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Thanks, that helps a lot. I don't have the motor yet...was thinking of just get the Monster Guts stuff you suggested for my first try. I don't have much time for doing the auto salvage thing, though that sounds like a good idea. I have also noticed wiper motors being sold at Amazon (is there anything you can't buy on Amazon?) so I may try that at some point. Thanks again.
FYI If you decide to buy one new or rebuilt from either an auto parts store or Amazon the motor that will be closest to the monster guts unit is a Saturn. You might have to play around a little with year and model but most of the late 90's units are pretty close however keep in mind it won't come with the crank or the wiring pig tail. When I get them at the wrecking yard I try to go for dodge trucks from the 70's into the mid 90's as they are bolted to the firewall and I can have one off in less than 5 minutes. Cut the harness to the wiper motor (so you have the connector), three 1/2" bolts and the crank ball will pop out of the linkage. Where the saturn ones are buried in the cowling so it's not practical to get those used.
FP
 
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