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Author Topic: Winders, winding stooge, torque meters, winding methods  (Read 39329 times)
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Olbill
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« Reply #25 on: April 19, 2010, 03:07:38 PM »

Motor with Sleeves

Here's my method of making up a motor with sleeves. Sleeves are a good idea on long motors for LPP, PP, A6 and maybe others. They will help prevent knots from bunching up at the rear hook - causing a CG shift - or at the front hook - causing the prop to stop.

My sleeves are made form heat shrink tubing. The tubing I had on hand was a little larger than I wanted so I shrunk it in short sections on a piece of 1/8" aluminum tubing and then cut it up into approximately 1/4" lengths.

I like to use the rear knot to hold the rear sleeve tight against the rear hook. It's difficult to do any manipulation of the rear sleeve after the wound motor is attached to the model, so a way to automatically position the rear sleeve is helpful.

Step 1 - For both ends of the motor, thread the end through the sleeve, through the o-ring, and back through the sleeve. (first picture)
Step 2 - Tie the loose ends of the motor. (second picture) (see earlier post for knot)
Step 3 - Pull the knot against the rear sleeve and o-ring and pull the front sleeve against the front o-ring. (third picture)
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julio
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« Reply #26 on: April 19, 2010, 08:29:08 PM »

Olbill

Thanks a lot for this topic. Plenty of useful information and pics. Great work! Very kind from you!

Julio
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Art356A
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« Reply #27 on: April 19, 2010, 09:50:24 PM »

Very good advice on this thread. I took Olebill's knot in reply 2 to Sarasota last weekend and showed it to a couple of the guys. We had been trying to teach ourselves to tie that mountain climber's knot on the Indoor Duration site without losing 2 inches of rubber every time and Olebill's knot was welcomed. Not as tiny and elegant, but it ties quick and easy, loses no length, and it's plenty strong enough.

I made this contraption up this afternoon after one "proof-of-concept" model this morning. I took seriously what Hepcat wrote (I always take Hepcat seriously) in #15 about being able to quote actual numbers, and I had been mulling this around in my head for a couple of weeks. I just wound a Hangar Rat motor on it to its normal 1600 turns, and the machine registered .8200 oz/in when I locked the winder in. Then I just sat there mesmerized, watching it count down to about .7400 in less than a minute. There's a lesson there, but I'm not sure what it is. There's gotta be a way to do that on purpose and then take advantage of it.

My initial problem was transferring the motor from the device to the Parlor Mite without wrecking it. A couple more readings of Olebill #14 and I'll have a better shot at it.

A.
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Tmat
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« Reply #28 on: April 19, 2010, 11:34:12 PM »

Wow!

Art, that's brilliant! Can you give us some more details?

I can see that the bracket is metal (steel?) and the wire shaft is mounted in some type of bearing (both sides I presume) and I also assume that the distance from the center of the shaft to the end of the outrigger is exactly 1 inch in order to give a reading in in/oz?
Is there a thrust bearing on the back side?

It doesn't look like you are using an O-ring. If not, then an O-ring should help you get the motor off of the hook with less problems.

Very clever imo!

What's the scale read in. 0.001 oz?

Tony
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Art356A
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« Reply #29 on: April 20, 2010, 12:36:05 AM »

Details... This is how I did it... you don't have to. The brackets are .062 aluminum, shaped so they clear the scale and the pivot holes are one inch to the left of the center of the tray and about 1/8" higher. The wire is all .031. The arm is one inch, as is the counterweight arm. From front to back, there's the hook, fwd bracket, a cheap ball thrust bearing, and a rubber tube spacer to make the thrust load go onto the bearing face rather than its hub. The wire arm is wrapped twice around a short piece of 1/16 brass tube and the whole thing is soldered on (that's the first operation... the spacers go on after). Behind that is a loose fit piece of gold-n-rod to prevent the whole ass'y from being pushed back as you remove the rubber from the hook. The holes in the brackets are 1/16.

The pic is of the first test motor; from now on everything will have 2 o-rings.

This pic is of the first one, showing the winder holder, which is probably wrong. Somebody will have to tell me how to do it right. Maybe lock the winder handle rather than the hook, so that end of the motor is more easily handled. Those big bearing blocks had a slight bind in them... the current ones don't. The arm was 2.835" long, and I was reading off the gram scale and dividing by 10 to get oz/ins. Stupid. The reason for the dog leg in the new brackets is so the shorter 1" arm hits the tray right in the middle. The ounce scale reads to 4 decimals.

Other scales may present other, or fewer, problems.

A.
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Olbill
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« Reply #30 on: April 20, 2010, 02:17:43 AM »

That is extremely clever! One meter does it all and to an accuracy level we never dreamed of.

A normal torque meter doesn't have to have a fancy bearing because the torque wire takes all the thrust. I would guess on this rig you have to have a pretty good thrust bearing to keep the scale reading from lagging behind the actual torque. How well does your ball thrust bearing work for this?

As far as the reading falling while the motor is wound this can be a problem on a VP equipped model but not so much on a model with a fixed pitch prop in low ceilings. When you back off a bunch of turns to keep your model off the ceiling the motor will hold the lower torque for a long time.
« Last Edit: April 20, 2010, 02:28:14 AM by Olbill » Logged
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« Reply #31 on: April 20, 2010, 02:30:09 AM »

For a way to lock your winder go to the home page of indoornews.com and look at the lock that Dennis and Parker Tyson are selling for the yellow winders.
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« Reply #32 on: April 20, 2010, 07:20:24 AM »

Thanks for the info Art. I'll have to ponder this for sure.

I've attached a picture of Dennis' winder brake and his method of attaching it to the base. If you look on Alan Cohen's mini-stick thread you will see a slightly different solution. You need a way to adjust the length of the torque meter hook to winder hook length so that it matches your model's propellor hook to rear hook length. You might have several different models with different rubber lengths.

The shaft arrangement with a thrust bearing is similar to a P-30 front end. I've bought several small ball thrust races and have not been satisfied that they are less friction than a couple of good teflon washers.

I bought one of Dennis's winder brakes and it's a good investment imo and supports a good cause.

Here is the link: http://www.indoornews.com/

Tony
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« Reply #33 on: April 20, 2010, 07:37:10 AM »

Can someone post a link or photo of the setup for winding outside the model? For ex, the portion of the motor that hooks to the peg?

Thanks
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Art356A
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« Reply #34 on: April 20, 2010, 08:45:14 AM »

The shaft arrangement with a thrust bearing is similar to a P-30 front end. I've bought several small ball thrust races and have not been satisfied that they are less friction than a couple of good teflon washers.

I think that even the ball thrust bearing is overkill, considering that there's zero rotary motion of the shaft. All it does is transfer pressure. No bearings, bushings or gimbals required. The vibrating needle Bill likes to see as he winds is is displayed on this rig as the scale reading bouncing up and down thru a pretty good range.

I have some ideas about a sliding mount for the winder...I'll see what's floating around the shop to make something out of.

Thanks for the encouragement.

a.
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Tmat
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« Reply #35 on: April 20, 2010, 08:53:49 AM »

Can someone post a link or photo of the setup for winding outside the model? For ex, the portion of the motor that hooks to the peg?
Thanks

Indoor or outdoor Mooney?

Tony
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Art356A
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« Reply #36 on: April 20, 2010, 10:57:17 AM »

Fixed it. Drilled a line of 5/64 holes 1/2" apart from the winder hook 6" back towards the scale hook. A 2" length of pushrod wire flattened a little at the bottom so it stays in the hole, and dressed smooth at the top so it doesn't cut the rubber, holds the winder end nicely and simplifies removal and transfer to the aircraft. I tried it on a Phantom Flash because they're more damage resistant than Parlor Mites, although hanging the wound motor on the front hook is more of a challenge. I've been practicing with the Parlor Mites and the Minislick, too, and I think I'm beginning to master the technique.

I had the foresight last week to salvage the hose from a Waterpik that was tossed. .09 ID, .15 OD, 3 feet long. That's almost 300 o-rings! And bright white, too, so you can see them in dimly lit gyms.

Now I have to make an adapter to wind the Polly, the Pussycats, and other models with fuselages and rear pegs. No big deal, I don't think.

a.
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« Reply #37 on: April 20, 2010, 01:14:03 PM »

Art

For years I used salvaged tubing from pump sprayers and any other unsuspecting source I ran across. This is fine as long as your o-rings meet one major criteria - they can't twist under maximum torque. The nylon pressure tubing that I've been using for several years now holds up well as long as you don't make the rings too thin. For my F1L motors wound to around .5 in-oz a too thin ring from 1/8" tubing will wind up with the motor and it stays that way permanently. Once this happens it's very difficult to make the motor hookup on the model.

On my F1M motors that go to about .8 in-oz I've started using the 3/16" tubing just to avoid this problem. At Lakehurst last year my last flight was just before dark. It was my last good motor with a wind that got to the target torque without breaking and the last possible flight due to the disappearing daylight. The combination of low light, fatigue and bad eyes was enough of a challenge without having to deal with a collapsed o-ring.
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« Reply #38 on: April 20, 2010, 04:10:17 PM »

Art

Brilliant. I suspect that you have changed the style of indoor torque meters for many years to come.

John
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« Reply #39 on: April 20, 2010, 05:28:28 PM »

Hi Gang: I used to use "O" rings from bic lighters that a friend collected for me. I had another source from a hobby shop that specialized in electric R/C cars. Haven't flown indoor for a while, but still have a bunch that I'm saving for future use.

Ron (Old Dog)
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« Reply #40 on: April 20, 2010, 06:40:54 PM »

John... this evolved from your reply #15, which got me thinking about how I could calibrate a couple of my homemade tube/musicwire/disc type meters using the gram scale as a reference. Once I got this far I realized that I could wind right to the calibration apparatus and discard the old-fashioned meters.

Ron... Dave Andreski had suggested that there was a treasure trove of discarded Bic lighters in the gutters. Just pick 'em up and strip the parts out. But he lives in the Conch Republic, where smoking is just one of the more benign of what we might call "negative behaviors". I rarely see lighters in the streets around here.

Art.
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« Reply #41 on: April 21, 2010, 08:45:16 PM »

Art,
How are you finding your gram scale as pictured? With some gram scales I have tried for other applications, they stop after a slight pause in the weighing and show the weight at that point. This wouldn't work for the torque meter application.

Tony
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Art356A
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« Reply #42 on: April 22, 2010, 09:45:08 AM »

It's a Digi-weigh, a $10 (+$6 s&h, even though the postage was only $2.54)) e-bay "buy it now" job. No damping at all... just blow on it and the numbers change. It's possible that the seller can tell you if it's undamped if you ask them.

a.
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« Reply #43 on: April 22, 2010, 10:53:23 AM »

Here's a link to over a hundred different pocket scales:

http://www.scales-n-tools.com/index.php?main_page=index&cPath=5&zenid=v38q7gghobmucj58qmksnts1c3

Art, why the counterbalance on your rig? Wouldn't zeroing the scale take out the effect of the arm weight?

I'm working on a design that does away with the rear bearing and also puts a little bit of pre-load on the scale. After I get back from Kent I'll try to cobble one up and see if it works.
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« Reply #44 on: April 22, 2010, 11:23:32 AM »

Bill, why would you need a pre-load?

Tony
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Art356A
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« Reply #45 on: April 22, 2010, 11:47:15 AM »

Why the counterbalance on your rig?

Why not?

EDIT: Sorry, that was a kinda snotty rejoinder. Actually, as I'm not an engineer and not totally familiar with the forces involved, I just figured it couldn't hurt. a.
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« Reply #46 on: April 22, 2010, 12:22:17 PM »

Hi All,

I am very impressed with this pocket scale torque meter idea! very clever!!

So how do you read the scale readout as you wind though? Or do you just wait till you get all the way back to the stooge? I ask because it might be fun to try this on an outdoor stooge but I need a way to see the readout easily.

B
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« Reply #47 on: April 22, 2010, 01:48:29 PM »

Tony

Pre-load just to keep everything from flopping around and to set a reliable zero point. Understand I haven't tried this yet.

Bernard, this bothered me for awhile but actually when I'm winding I don't really use the torque meter until I'm almost all the way back to the table. This is another thing that needs to be explored. I looked at hundreds of different scales to see what was available with LARGE readouts. Not much.
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« Reply #48 on: April 22, 2010, 02:26:57 PM »

Bernard...

I thought of that at the beginning and figured that I'd just place the scale vertical. This scale wouldn't work vertical (others might, though).

So I just ran some measurements, which are valid for my setup. The scale tray is about 38" above the floor, and my eyes are 24" above that. I can see the readings clearly from about 30-36" away from the hook. I think that for indoor work, where we have either 30" high bridge tables, or similar picnic tables, you're covered.

Outdoor, wind-'em-til-they-bleed genre isn't my field... I'll defer to Bill on that.

a.
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« Reply #49 on: April 22, 2010, 04:57:50 PM »

You might also be able to use a simple mirror to let you see the scale for the indoor winder. Outdoor has some other issues.

To get accurate torque readings on an outdoor meter, you need to wind the motor outside of the model using a 1/2 tube (or similar) type of arrangement like we do in F1B. If you want to try it while winding a motor in an airplane, you have to remove the wings (wind gusts act like a torque arm and change the reading). Even a large stab might cause an issue. Winding the motor itself solves that problem.

Tony
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