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Old Oct 16, 2014, 05:30 PM
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George Franklin's Avatar
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Build Log
Drill powered Winch for RC Gliders

As I said in the previous post, here is the build log for the Drill powered Winch.

Couple of goals
Precision pedal throttle control.
Dependably launch Gliders as large as 4 meters.
Must not tear the wings off of any glider either by controlling input torque and/or by a safety link (like full scale).
Launch to at least 400 feet AGL.
Keep total cost under 100 bucks including the drill.
Man portable, weight under 40 lbs.
Easily obtained materials and standard fasteners.
Build using standard hand tools, no machine shop work or welding. No special skills.

I started with the spool build. I selected PVC pipe fittings as the easiest way to do this. Wider spools are better for several reason. You get a more even torque input and the line should lay flatter even without a level wind.

This first shot here is the spool parts just set together. There is a extra long union in the middle with a piece of 2 inch PVC pipe on either side. The 2 regular unions. On either end is the 2"to 3/4" union and then a 1/2" plug (3/4" OD) in either end.
The shaft is 5/16 steel and the bushing will go into the winch frame to support the outside end of the spool.



The inside end of the spool will be supported in the chuck of the drill. This is a little different configuration than some winches.
I tried to drill the 1/2" end caps by marking and drilling by hand. The first attempt was pretty close. Second one was about .050 off. That is more eccentricity than I wanted. Thought I would just "pull" the hole and fill it with epoxy but that didn't feel right. Went back to the hardware store got 2 more 1/2" encaps (they are cheap) and a brass busing with a nylon sleeve. The ID in the back side of the 1/2" cap is .800 diameter. The brass busing was .75 OD, so I shimmed with with 3 layers of electrical tape. That made brass busing a slip fit in the back side of the 1/2" end cap. The ID of the nylon bushing is .25.




Nylon is not real sturdy and you can see that drilling just 2 holes it is already showing some wear here. Drilled the end cap .25" through the bushing and then drilled the hole out to .3125 in each.
Glued the end caps in the 2"X 3/4" unions with UFO glue.



Scuffed the shaft pretty heavy with a file and scuffed the inside of the 1/2" end cap with sandpaper.



Placed the end cap with the 2" X 3/4" union on the shaft in the correct location on the shaft and then filled it with Gorilla glue.



The center main part of the spool is also assembled with UFO here. Sanded the text off the edges of the unions so that they would fit closely. Note that the 2" PVC is not visible. The unions are pressed firmly together.
Temporarily installed the rest of the spool parts to hold it in alignment while the glues dries in the end cap.



Once this is done I will test to make sure torque can be transferred from the shaft to the PVC spool parts.
When gluing PVC together I put the glue on the inside part and then plug the other part in. This prevents glue from squeezing out. With this spool the inside can be messy without hurting anything. It is the outside that needs to be smooth.

The drill is the 18 volt Black and Decker with 2 batteries purchased at Walmart.
So far I have about 20 bucks in this spool.
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Last edited by George Franklin; Oct 17, 2014 at 04:12 PM.
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Old Oct 16, 2014, 07:10 PM
Noob making progress
Australia, NSW, Mt Colah
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I've got an added advantage, a woodworking workshop, complete with lathe

regards
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Old Oct 17, 2014, 01:06 AM
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Oh yeah!

I'm hanging on every moment here...

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Old Oct 17, 2014, 06:20 AM
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United States, MA, Waltham
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When you're done flying for the day, you might want to pull out all the line and wind it back in gently. 250 feet of line at 10 lbs tension, on a 2.5" dia spool, is something like 7,600 lbs of compression, and may make the PVC creep, especially if it gets warm. I know you'll have more than 250 feet of line to wind up, but I figure 250 feet is probably how much you'll pull in under significant tension.

If you're trying to keep the winch frame light, consider making it out of wood. I have a wood frame winch which seems lighter than most other winches with the same motor, even though it's very crude, the drum is a bit heavy, and those others are made from welded metal tubing. (Ok, if you make it from cut up old bicycle frame pieces, a metal one could be quite light. At least if you're willing to braze and weld.)

It will be interesting to see how this project goes. Certainly that adjustable torque gadget the drills have is a nice feature.
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Old Oct 17, 2014, 09:24 AM
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The Gorilla glue seemed to take extra long to dry. So I left it overnight. This morning I tested the strength of the joint. It held fine on the lowest torque setting of the drill. But up around 10 or so it failed. I think this because the Gorilla glue was too old. So I got out the dremel and scuffed the shaft and the inside of the 2"X 3/4" union. Mixed some US Composites 3:1 epoxy and poured that into the 2" X 3/4" union and filled it to the brim. (This epoxy is left over from my last kayak build.) Normal cure time is 4 hours but it is a little cool out there right now so it may take a little longer.
So I am pretty sure that the torque limiter on the drill is going to work at limiting line tension to prevent wings from being destroyed. Will probably still use a weak link appropriate to each glider.
Looks the like ridge might be working this morning. Kinda of a rare occurrence here.

Ridge wasn't working.

Came back to the local hobby shop and picked up a Sport Club S, just in. My first power plane besides quadcopers.

Looked around the house for something to use as a end piece on the spool. Came up with ZipLock screw on lid. Centered the 2 of them up and cut the holes so that the 2" X 3/4" union fit snugly. Put on the 2" X 3/4" union that is bonded to the shaft. Snugged down the main body of the spool against the Ziplock cap with the hole in it. Ran a bead of UFO around the edge.
Mixed 2 oz of 3:1 epoxy and poured it in to the main body. Placed the other ZipLock cap on the other 2" X 3/4" union and then snugged it down into the spool main body. Tapped it down tight. Ran a bead of instant CA around the shaft, where it dome out of the 1/2" end cap. Sprinkled sawdust on the instant CA to make it cure fast.
Turned the whole thing end for end so that those 2 oz of epoxy run down to the other end against the seal I just created with the instant CA. Hung it that way from the work table vise.

Obviously there is alway residual torque in the drill so to get the line out just loosen the chuck and let the spool rotate in the chuck with out turning gears or motor.
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Last edited by George Franklin; Oct 17, 2014 at 05:48 PM.
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Old Oct 17, 2014, 05:44 PM
skumgummi dave
Gresham, OR.
Joined Mar 2004
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Lurking...
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Old Oct 17, 2014, 09:49 PM
Jim C Patrick
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Quote:
Originally Posted by George Franklin View Post
The Gorilla glue seemed to take extra long to dry. So I left it overnight. This morning I tested the strength of the joint. It held fine on the lowest torque setting of the drill. But up around 10 or so it failed. I think this because the Gorilla glue was too old. So I got out the dremel and scuffed the shaft and the inside of the 2"X 3/4" union. Mixed some US Composites 3:1 epoxy and poured that into the 2" X 3/4" union and filled it to the brim. . . . .
If you're gluing PVC pipe, THE fastest and strongest joint is PVC primer and PVC glue. Normally the pipe will shatter before a glue joint fails; the 'glue' actually is a form of PVC and you are chemically welding the parts together. It's available at any hardware store, from small Mom-n-Pop to big box stores. Since it's not for plumbing you can use clear primer instead of the purple stuff. A 'plus' it can take full pressure within an hour. Same with CPVC, and also ABS which has its own glue.
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Old Oct 17, 2014, 10:42 PM
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Minnetonka, Minnesota, USA
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Quote:
Originally Posted by George Franklin View Post
The Gorilla glue seemed to take extra long to dry. So I left it overnight. This morning I tested the strength of the joint. It held fine on the lowest torque setting of the drill. But up around 10 or so it failed. I think this because the Gorilla glue was too old. So I got out the dremel and scuffed the shaft and the inside of the 2"X 3/4" union. Mixed some US Composites 3:1 epoxy and poured that into the 2" X 3/4" union and filled it to the brim.
Gorilla Glue (urethane) requires moisture to cure. Wood/ leather/ skin contain moisture, which is one reason why Gorilla Glue works so well with them. Metal and plastic don't contain moisture, so it's critical to add some with a spray mist of water. If that's not practical, then you're better off using a different glue.

PVC is difficult to bond with any "stick to it" type of glue. I don't know how well Gorilla Glue or epoxy will work the way you're using them, but the PVC-specific cements all contain a solvent called Tetrahydrofuran (THF)... read the label of the PVC plumbing cement. It works more like welding (melt the material, mush it together, re-solidify), not by "sticking" to it. You may have better results with such a solvent cement.
http://en.wikipedia.org/wiki/Tetrahydrofuran

Regards,
Tim
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Last edited by Esprit2; Oct 17, 2014 at 10:52 PM.
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Old Oct 18, 2014, 09:29 AM
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Thanks for the advice guys.
I have used Gorilla glue with good success on lots of things. This bottle is old and pretty sure that is what caused the problem. It never did cure right.
Trying to minimize costs so that is why I didn't buy PVC specific adhesive. Epoxies have worked well enough for me in the past with PVC. The critical bond is PVC to metal.
The spool is assembled. Need to clean up the stray adhesives and cut the shaft to length. The scrap end of the shaft will be used for the "turn around" stake.



This morning I tested the spool all the way to 18 on the drill. No problem.

Still trying to come up with a good "turn around" pulley. Need something with a diameter of around 2" I think. And I want to be able to pull the parachute through it. Might just need to build it.
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Old Oct 18, 2014, 09:51 AM
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People used to use hubs off bike wheel, fitted to a ply base with piano wire guides for the line. Always worked well although todayys thicker lines might be a problem.
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Old Oct 18, 2014, 10:10 AM
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USA, NY, Bellmore
Joined Aug 2006
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Picked up a very nice medium height bike hub at a fleamarket for a buck!
Heard some bike store throw away wrecked rims which yielded a nice hub for free for a friend.
Kilwein, where are you? Got a nice wide TA from him but not as cheap as the afore mentioned hubs.
Rudi
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Old Oct 18, 2014, 12:58 PM
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After some fumbling around came up with a passable way to build a turn around pulley, using a fishing line spool. Center hole is a 1/2". Have the bolt washers and nut. Just need to make the clevis.
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Old Oct 18, 2014, 03:02 PM
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This turnaround has been turning around for decades , never a line wear issue or failure . Cost to build , - basically free
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Old Oct 19, 2014, 03:15 AM
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I think a roller skate wheel would make an excellent turnaround pulley once you cut off the "tire". Just be careful how you cut the "tire" off! Bike hubs are fine too. Suggest getting one that's fat in the middle so the rpm's won't be as high, though perhaps with your drill it won't matter.
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Old Oct 19, 2014, 03:20 AM
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P.S. you may want to back up those end caps with plywood or something. If the line builds up on the end of the spool there will be a lot of pressure on the end caps.

Ever consider a rolling pin for the winch drum? Might be less work if you're going to build another one sometime.
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