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Old Sep 28, 2009, 10:20 PM
More Pile-it than Pilot
mdennis's Avatar
Shawnee, Kansas
Joined Nov 2002
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Build Log
$250 Winch Line Retriever with Automatic Pickup

If you own a winch, somewhere in the back of your mind is the desire to ditch your parachute and own a retriever.

At least that's what I wanted, and I'm not really that picky. All I wanted one that was;
  • Small, so I could transport it easily
  • Light, so I could carry it
  • Fast, so I could spend more time flying than chasing down my chute
  • Simple to operate by one person along with the winch, so I could fly by myself when I have chased away all my friends
  • Easy to fix and maintain, because I am hard on stuff
  • And of course, cheap, cause I wanted it to fit my personality
I couldn't find one like that, so I decided to build my own. (I may be cheap and too lazy to go get my own parachute, but I like building stuff.)


Several guys in the club I fly with have retrievers that look like large spinning reels. They were made by Jim Harger and are no longer available. Many people don't seem to like them for contests, but they have worked well for our guys. They are small, light and automatic, but they do require a little finesse to operate.

There are others out there like the Rham retrievers and the ones with the bicycle wheel. These babies are brute force fast, require another person to operate it and they better know what they are doing or someone will be missing fingers.

Lastly there are retrievers out there that do have automatic pickup of some sort. They work, but are usually expensive



I purchased a small retriever to experiment with. It was a Harger retriever that had been modified by removing the bail and had a stronger motor installed. I mounted the roller bearing on a movable pickup arm and had almost exactly what I wanted. It is light, strong enough to make a quick return, simple enough that anyone can safely operate it and it can be operated by the same person operating the winch.

The club guys liked it and since anything can be improved, I decided to build a better one. It needs to have ball bearings at the moving parts, should be made of parts that anyone can get, should be able to be made by anyone with a reasonably equipped modelers shop and of course it needs to be a little faster.

The pickup arm idea should be able to be installed on just about any existing retriever. I have one of the retrievers with a bicycle wheel that I plan on modifying after I finish this one.

I have posted some videos of a Jim Harger retriever, my prototype retriever and my finished $250 retriever in action down in the Sailplane Video forum at this link.

http://www.rcgroups.com/forums/showt...6#post13225105
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Old Sep 28, 2009, 10:36 PM
More Pile-it than Pilot
mdennis's Avatar
Shawnee, Kansas
Joined Nov 2002
1,118 Posts
A few pictures of the prototype retriever before I start building.

This prototype retriever does not have ball bearings on the drum, it just has brass bushings.

The pickup arm has two bearings mounted back to back. The new one will have the same two bearings, but there will be a V shaped bushing over them to center the line and load on the bearings. This will also be larger in diameter, which should be easier on the line.

In case you are wondering, there are magnets in the rim of the drum to hold the pickup arm up. When the drum turns, the arm drops and picks up the line, guiding it onto the ball bearings.
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Old Sep 29, 2009, 12:30 AM
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Thomasville, GA 31792
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Where did you get that green part? It looks like pieces cut from a small tank of some sort. How big is it?
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Old Sep 29, 2009, 07:11 AM
More Pile-it than Pilot
mdennis's Avatar
Shawnee, Kansas
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Rogerflies - I did not make this part, but you are correct, Jim Harger made his retrievers out of propane bottles like you use for your Bar-B-Que grill. The newer bottles do not typically have this shape and/or parts attached the same way. It is about 9 1/2" in diameter at the widest part.

Mark
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Old Sep 29, 2009, 11:17 AM
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Thomasville, GA 31792
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I have access to dozens of empty freon bottles. I'll take a look at them to see if they are the right size/shape.

What are you planning to use for the drum, and how do you plan to put it together?

Roger
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Old Sep 29, 2009, 11:39 AM
More Pile-it than Pilot
mdennis's Avatar
Shawnee, Kansas
Joined Nov 2002
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I am going to use an idea that I first saw proposed by Mark Drela in a drawing for a retriever a few years ago. Use a frying pan.

I purchased a 10" pan with the thickest aluminum I could find. Cast Iron would be stronger, but a lot heavier. I had several to chose from, so I chose one that had a circular pattern on the bottom that would allow me to easily find the exact center. While I was at the store I also purchased a couple of plastic cutting boards. They are about 19" x 14" and about 3/8" thick.

The handle comes off the frying pan with one screw. Carefully cut off the stud and sand the area smooth.

Using the pattern on the back of the pan, I marked the center and laid out 16 holes around the perimeter of the pan just inside the edge, on the flat area. I drilled a 1/2" hole in the exact center of the pan. and the 16 holes sized for for #10 screws. Mark one of the 16 holes as #1. Take your time and be sure to get the hole as centered as you can. Another tip - Lower the speed of your drill press as low as you can when working with metal. The slowest mine will go is 220 rpm. It gives the bit a chance to work and does not build up a lot of heat.

I cut an 11" circle out of one of the cutting boards and two 8" circles out of the other one. Lay out your circles on the boards allowing a little room around each. Drill a hole in the center and cut them out about 1/8" too large on the bandsaw, (a jigsaw will work). Then I used a router attached to a home made circle cutting jig to cut them down to size. This jig is nothing more than a board with a hole to pivot around the center of the circle on a screw and the router attached so the edge of the bit is the right distance away. You can buy nice commercial made jigs or make one out of a scrap of plywood.

Drill the center hole out to 1/2", if it is not already that size, and using a 1/2" bolt, fasten the pan and the three plastic discs together. Make sure the bolt is square, (perpendicular), to the disks. Drill out the 16 holes on the perimeter. Mark the front of the circles and identify which hole is #1 on each disk. This is important, because when you get ready to put this all together, the only way you can be sure everything will line up is with these identifying marks.

On the back of the 11" disk you will want to counter sink the screw heads to be flush or a little below the surface. On the front of this disk you want to lay out the holes for the magnets. These magnets will be used to hold the pickup arm in the cocked position. I purchased my magnets from the local hardware store for ~$3.50 for 6. They are made of neodymium and are 12mm in diameter and 3mm thick. Since it was convenient, (and since I wasn't thinking), I laid out for 8 of them. These holes are about 1/2" in to the center from the edge of the disk. I used a 1/2" paddle bit and drilled the hole just deep enough so that the front of the magnet is flush with the surface of the disk. Then I drilled a small, (1/8"), hole out the back of the disk in the middle of each of the 8 holes so that when I glue the magnets in there will be no air pocket behind them to push them out. (It also give the glue someplace else to hold onto the plastic.) Use Goop to glue the magnets in and wipe off the excess front and back. Use Toluene to clean up the surfaces.

Wipe off the disks, put your 1/2" bolt through the hole in the middle of the disks and pan, then line up your 16 holes using the #1 mark you made. Fasten the 11" disk to the two 8" disks and the frying pan using 16 - #10-32 flat head machine screws. I used stainless steel screws and nylon lock nuts, but any hardware will work. Use lock washer if you use regular nuts.

The drum will be driven by and 8" pulley mounted on the back. If you buy this pulley with a 1/2" hole in it it will be easy to line up the center of the pulley with the center of the disks and pan. Drill a 1/4" hole in the center of each of the pulley spokes about 1" in from the outer edge. You may have to flatten out a spot on the spoke to do this. Again, using a 1/2" bolt, attach the pulley onto the disks and pan, making sure that the bolt is perpendicular to the face of them. Using your drill press, drill through the spoke holes and through the disks and pan. (This can be done by hand, but be sure that you are as perpendicular as you can be.) Mark one of these holes as #1 on the disks, pan and pulley. I used some scrap plastic as a spacer between the pulley and the back of the 11" disk. This can be done with washers or 1/4" tubing as well. You will need the pulley to be spaced up off of the back of the disk so the belt won't rub on the back.
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Old Sep 29, 2009, 01:35 PM
More Pile-it than Pilot
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Shawnee, Kansas
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Now it's time for bearings. I plan on using a 1/2" bolt as the main support for the drum. After we have fit all the pieces together we will drill out the center of the drum pieces so they won't rub on the 1/2" bolt and ride only on the bearings.

You could drill the hole in the drum out and install a bearing in each end that is 1/2" inside diameter, (ID), and 1 1/8" outside diameter, (OD). (These bearings are ~$10 each) I decided to use bearings already mounted on a 4 hole flange. These are more expensive, but if I need any adjustment I can get it. I purchased these from Grainger, which is a national supply company like McMaster Carr. The Grainger Part number is 1F552 and they are about $20 each. Centering them up is easy, because they have a 1/2" hole. Just put your 1/2" bolt down the middle of it and the drum. The bearings have 3/8" holes already drilled in them, so just drill through them and the drum. You will have a bearing on each side of the drum. If your holes are straight, the holes will line up on each side. Before you mount the bearings, drill out the center of the drum pieces to any size over 1/2".
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Old Sep 29, 2009, 02:31 PM
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Shawnee, Kansas
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The drum will be supported on a wooden box. I chose wood because it's easy to work with and the storage area inside of it is nice to have for the foot switch, stakes and other accessories.

You can make this out of steel tube or whatever you want. You are only using 50 lb test string, so that is far and away the weakest link. Overkill strength is nice, but you usually pay for it in added weight.

I used 1/2" Birch plywood that I had laying around, but it's not really the best choice of wood for this project. Plain old plywood is fine. Be sure you give the box several coats of polyurethane before final assembly.

I broke down and bought another plastic cutting board to use as a bottom. Here in the midwest there is dew on the grass in the mornings and I just hate putting my nice wood box into the water.

The bottom is 13 7/8" wide x 12" front to back

The sides are 8 1/2" wide at the bottom and 4 1/2" wide at the top

The front is 13 7/8" wide and 11 1/4" tall. The beveled angle is 20 degrees on the top and bottom edge.

The top is 13 7/8" wide and 5" from front to back where it attaches to the front and about 4 3/4" at the very top edge because of the 20 degree bevel of the front of the retriever.

The back is 12 7/8" wide by 10 1/2" tall. It is held on by a couple of brass hinges on the bottom and a small brass hasp at the top.

I decided to change the angle of the front face so the string guide could be placed farther out in front of the retriever, This will center the string onto the bearings better coming off of the guide ring. Down in post #53 I have the new box dimensions.

The stud support block is 4" x 4"

The drum support stud is centered top to bottom and is 6" over from the right edge of the retriever. (Right side if you are looking at it from the back)

The starter motor is from a 16 hp motor. I purchased mine from a local starter shop I deal with for $85, but they are available online for $70 plus shipping. It's not as strong as a Ford Long Shaft starter, but it doesn't have to be. It turns counter clock wise if you look at the motor from the shaft side.

I mounted the motor on a hinge and will keep tension on the belt with a spring.

The solenoid is just a standard Cole-Hearse 12 volt unit.
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Old Sep 29, 2009, 02:42 PM
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The drum stud is a 6" long x 1/2" bolt that I cut the head off of.

The pivot point of the hinge is perpendicular to the front face of the box and is located just high enough that the positive stud on the starter does not hit the bottom of the box with the hinge all the way collapsed. The curve cut into the front of the box is determined by the pivot of the hinge. Just drill a series of holes and cut out the excess with a jig saw to smooth the edges. The motor shaft sticks through the front so the geared part of the shaft does not protrude past the plywood.

You will need a 28" long 4L belt.

Put the belt over the pulley on the drum and slide the drum onto the stud on the box. The back of the bearing flange on the drum goes right up against the nut holding the stud in to the box.

The drum will be held on the shaft by a 1/2" locking collar. Grainger Part #2X568. There are set screws on the bearing flange pieces, but I don't use them.

The pulley mounted on the motor is 1 1/2" diameter with a 3/8" hole in it. you will have to drill the hole out a little bit bigger to make it fit onto the shaft. If your local hardware store doesn't have it you can buy this pulley from Grainger as well. (Part #3X891) Put the belt over the pulley and align the drum and motor pulleys. I filed a flat spot on the shaft so the set screw would have a better place to bite.

The brass handle is located a little off center towards the motor because that is the balance point with the drum installed.
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Old Sep 29, 2009, 04:37 PM
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Thomasville, GA 31792
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Well, the cans are the right size, but the bottom is rounded with three protrusions to give it feet to stand on. The tops have a blow-out plug that would have to be dealt with.

You could put two bottoms together by welding the feet, but you'd have to put some sort of ring between them.

Probably too much trouble.

Roger
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Old Sep 30, 2009, 02:10 AM
RIP MC
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United States, CA, Midway City
Joined Dec 2003
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Way kool. Looking forward to seeing it completed. Thanks for sharing!
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Old Sep 30, 2009, 05:51 AM
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mdennis's Avatar
Shawnee, Kansas
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Quote:
Originally Posted by rogerflies
Well, the cans are the right size, but the bottom is rounded with three protrusions to give it feet to stand on. The tops have a blow-out plug that would have to be dealt with.

You could put two bottoms together by welding the feet, but you'd have to put some sort of ring between them.

Probably too much trouble.

Roger
Looking at the drum on my prototype, I think that the part that is the drum used to be the top of the tank. The ring that is welded on was the top where the handle is. That part was cut off just below the handle hole. Where the shaft goes through was where the valve was. The bottom of some of these tanks used to have a ring welded on that served as the feet instead of the three bumps that are there now. That part would work and you could bolt the flange bearings on just like I did above.

I am still looking around for something with the right shape that is steel and readily available. The frying pan and the plastic works; the plastic is pretty heavy, but the frying pan is cheap. Cheap is a relative term I guess. I think I paid $10 for that pan, but the average guy would have to buy a propane tank for $20 and still have to cut it off. If a person has access to a company that sells plastic, (Here in Kansas City there is a company called Regal Plastics), there is a product out there called Komatex. It is a foamed PVC sheet product that is quite a bit lighter and less expensive than the plastic cutting boards, but a big part of this project, to me, was to make the retriever out of materials that the average guy could get and use tools and methods that are within his means.
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Old Sep 30, 2009, 01:41 PM
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mdennis's Avatar
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Joined Nov 2002
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The string pickup arm assembly has two sides separated by a bearing assembly and a spacer.

I made these pieces out of 1 1/4" wide flat metal that is 1/8" thick. The pivot arm is the piece that will attach to the box and pivot up and down, it is 6 1/2" long. The pickup arm piece will have the arm attached to it to pick up the retriever string, it is 2 1/4" long.

The holes for the bearing support screw and the spacer screw are drilled through both pieces at the same time to be sure they are exactly centered. Just lay one piece on top of the other so the sides and end line up. The spacer screw hole is located 5/16" in from both sides in the lower front corner and the bearing support screw is 1 1/8" from the front edge and centered 5/8" from both the top and bottom edges. We are going to thread the holes in the pivot arm for 1/4"x28 screws, so use a 7/32" bit. The back hole in the pivot arm piece is 7/16" in from the back edge and centered 5/8" in from the top and bottom edges. This hole will be drilled out to 1/2", but the 7/32" bit is a good pilot hole.

You need to be sure that the holes that are threaded in the pivot arm are threaded perpendicular to the surface. I did this by chucking the tap into the drill press then hand turning the tap into the metal. (Do not turn on the drill press motor!) This is a tap for a 1/4" screw with 28 threads per inch. Fine thread screws and nuts are harder to find, but most good hardware stores will have them. I am using fine thread screws just to get more threads in the 1/8" thick metal than you would get with a coarse thread.

I am using a washer to keep the string from getting behind the bearing. By using 1 1/4" wide flat steel the washer can lay flat and there is no way for the string to get behind the washer. You will need 2 washers, one for each side of the bearing.

These washers started out as 1/2" flat washers, (for a 1/2" bolt), and are about 1 1/8" in diameter and pretty thick. I clamped then in the vise and drilled the hole out to 13/16". I didn't have a drill bit this big, but you you can buy one at Harbor Freight, (a national cheap tool chain). I bought a set of 2 sizes on sale for $15, but you can buy one for about $6. After I drilled the hole out I beveled the edge of the washer all the way around to guide the string to the bearing assembly. The bevel angle isn't critical, just make sure the surface is smooth so it does not snag or nick the string. I went overboard here and used silver solder to attach the washer on the pivot piece, but you could just as easily attach it with a couple of screws and use JB weld to build up a fillet around the edge to make the bevel.
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Old Sep 30, 2009, 01:58 PM
<>< AKA W4BPS
USA, TN, Tullahoma
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Thanks

I agree with the Wizard.. Great interesting thread.. Brian
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Old Sep 30, 2009, 02:34 PM
Dragons, Windmills. All Same.
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United States, IN, Indianapolis
Joined May 2002
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Ya, great thread and subscribed.

One major aspect I really like so far is I cannot see any required machining work, as a few of us do not have nor able/willing to spend.

When all the prototyping is done and the final design in determined, at least I hope to have the availability the purchase a legal copy of building plans/docs and such.

Also wondering on making naturally efficient but especially as light as possible for us more physically challenged. Would a small motor running off 12VDC and a pulley be possible?

Jared
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