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Author Topic: Winders, winding stooge, torque meters, winding methods  (Read 39159 times)
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Art356A
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« Reply #125 on: August 20, 2010, 12:29:24 PM »

Nice to hear that, Alan. I've been spending time, treasure, sweat and a little blood refining these things. I'm learning a little more with each one about what factors of sloppy manufacture make them feel notchy and how to correct them. They're still cheap to make, but I'm trying to transfer the tuneup work into the initial layout so that they'll have minimum parts (like idlers, which are essentially there to correct layout mistakes) and run smooth right off the bench. It's good to know that it's not all for naught.

Oh, I forgot to mention that you've laid hands on one of my models, too, and it flew much better for it.

Art.
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PeeTee
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« Reply #126 on: August 20, 2010, 01:31:30 PM »

Art

I've only just read your post about cheapo pocket calculators & immediately put "pocket keyring calculator" into the search engine and came up with this:

http://www.sourcingmap.com/pocket-digit-key-chain-red-calculator-p-14902.html?currency=GBP&utm_source=google&utm_medium=froogle&utm_campaign=ukfroogle

As it quotes prices in GBPounds I suspect that it's an offshore supplier, but at less than £2 it should work out the same in dollars, or no more than $3. I also spotted a site selling Radioshack calculators which were cheaper, but it stated "out of stock". I'm sure you could find something cheaper quite easily Wink

On the outdoor torque meter front, I spotted a torque sensing stooge (no not me Grin) at Poitou which looked quite neat. It was for winding motors external to the model, and when i find the photo I took I'll post it here.

Keep up the good work as what you are doing is brilliant.

TTFN

Peter
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Alan Cohen
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« Reply #127 on: August 20, 2010, 03:43:41 PM »

A suggestion on the winder. Make the wire handle as beefy as possible. You do not want any flex there. Makes for better feel of the rubber.
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Olbill
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« Reply #128 on: August 20, 2010, 04:52:00 PM »

One thing I know for sure is that nobody is in much agreement how to do anything in indoor duration. One of my flying buddies told me recently that two of the top USA fliers always do their back off by counting turns - not by going to a torque number. I do the opposite. I always back off to a torque value that I think will get me to the ceiling without getting hung in the process.

As far as centering the turns used in the max turns in the motor I agree that's a good point to aim for but when I look at my flight data I don't see that happening. I nearly always have from 2 to 4 times the number of turns remaining as the number I back off. Shortening motors to change this relationship is a slippery slope. A shorter motor wound to the same torque puts a lot more stress on the motorstick. Some models will handle this okay but mine like to dive in at launch if I overdo the motorstick bend a little. This is at least partially due to my trim method that I've talked about before.
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Art356A
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« Reply #129 on: August 20, 2010, 04:54:54 PM »

One of the earlier ones was made of .047 wire because it was a nice fit in the Tefzel bushings that were available in the stash. I could feel a little flex in the crank as I pushed 2K turns on an H-Rat motor (which is the heaviest motor anyone uses indoors, right?). There was also a fabrication problem in keeping the .047 wire centered in a tube that was .063 square inside. The current ones have .063 wire running in bushings sliced from Gold-n-rod or Nyrod which are ±.070 ID. Nice and beefy.

Art.
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Alan Cohen
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« Reply #130 on: August 20, 2010, 05:16:28 PM »

Perfect.
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Tapio Linkosalo
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« Reply #131 on: August 21, 2010, 12:14:40 AM »

Talking about winders: In Belgrade my yellow K&P felt a little "rough", as if it needed some lubrication. What kind of maintenance do these units require?
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applehoney
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« Reply #132 on: August 21, 2010, 12:51:52 AM »

None .. may just be overstrained?  Does it rattle? There are five tiny ball bearings .. I had one winder go belly-up years ago and I found that their retaining ring had worn and allowed one to escape. If you take it apart do so with care for the balls will drop out and I know that one can vanish forever into the pile of the carpet..... Roll Eyes If anyone needs replacement bearings I have four ......
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Hepcat
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« Reply #133 on: August 21, 2010, 12:29:59 PM »

I have just finished reading Mike Burrows’s book ‘Bicycle Design’. Mike is the chap who designed those aerodynamically efficient, monocoque machines (sometimes known as the Lotus bikes) that helped Chris Boardman to gold at the 1992 Olympics. He also did design work for Giant, the largest cycle maker in the world. Very interesting you say (yawn) but what has it to do with aeromodelling?

Mike and I were Young Modelling Buddies back in the fifties and sixties and he was probably the best English glider flyer of the time. His designs had skinny wing sections, he kept pushing aspect ratio higher than anyone else and, probably most important, he introduced the world to tubular tail booms in the form of glass fibre fishing rods. OK, you say, so he was an aeromodeller but where does that fit in with winders and suchlike?

I was coming to that. In the transmission chapter of the book he reminded me of something I had forgotten although Art (being the consummate engineer that he is) obviously had not. Chain drive is the most efficient way of transmitting power – better than gears and far better than rubber toothed belts. No wonder his winders are impressive.

Art, have you thought of adding a derailleur mechanism so that you can provide gear ratios of, say, 5:1, 10:1 and 20:1 in the same unit? Smiley
John
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Art356A
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« Reply #134 on: August 21, 2010, 03:45:02 PM »

John, did the F-N reference provoke that idea?

I'd like to think that Archie is up there somewhere, smiling down on the effort. MacReady used chains, too, but I never saw any credit to the heritage, only the corporate sponsors.

Art.
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Art356A
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« Reply #135 on: August 21, 2010, 06:16:14 PM »

K & P have 1:5 and 1:10, and they're inexpensive. An inexpensive 1:20 machine doesn't exist, and a 1:20 machine with an accurate, easy to read counter doesn't exist at any price. That dearth is what I'm trying to address. The intermediate shafts on mine run at 1:5, but they just float within the frames and aren't hooked up to anything.

One machine with multiple outputs is beyond my intellectual and fabrication capacity. I'd think that 3 machines would take up less room in the toolbox than one with multiple outputs (and cost a lot less money).

The unit in the background in the previous post is all set up with the sensor and reed switch, and the $18 counter should be here in the middle of the week. It will need to be modified to make it resettable, but that won't be a big deal. It will count by tens.

I have some thoughts on an outdoor torque meter for Peter. Maybe I'll try to make one up in a Peanut/Bostonian size to see if it comes together. If it looks good somebody can make a big one. I think a big one would have to read gm/cm's so we could work with a 4 inch arm rather than a 1 inch. I know that inexpensive scales are available in the right weight range.

Art.
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gvwezel
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« Reply #136 on: August 28, 2010, 02:10:47 PM »

Hello people

Here the new builder from the Netherlands how want to build a digital torque meter.

Okay here is a summary as I think you build a digital torque meter and if wrong then correct me.

Because with this information, I would build one.
- the wire that's in the analog torque meter torquedraad was (pianowire) should not twist the digital one, so no twist at all.
- So this is the best one to use a brass tube .
- all should be well trapped between two points so that no friction.
- I would torqeudraad between the measuring element by let. The measuring element is vertical put down.
- Between the element I make a reticle rotation so that he will press on the element.  He pressed the two component parts will separate.

okay this is what I think to do. I hear what you think.

And yes sorry for my bad English but I hope it is clear

Greetings Gert-Jan from the Netherlands
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Olbill
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« Reply #137 on: August 28, 2010, 09:14:21 PM »

Hello people

Here the new builder from the Netherlands how want to build a digital torque meter.

Okay here is a summary as I think you build a digital torque meter and if wrong then correct me.

Because with this information, I would build one.
- the wire that's in the analog torque meter torquedraad was (pianowire) should not twist the digital one, so no twist at all.
- So this is the best one to use a brass tube .
- all should be well trapped between two points so that no friction.
- I would torqeudraad between the measuring element by let. The measuring element is vertical put down.
- Between the element I make a reticle rotation so that he will press on the element. He pressed the two component parts will separate.

okay this is what I think to do. I hear what you think.

And yes sorry for my bad English but I hope it is clear

Greetings Gert-Jan from the Netherlands

I don't think I understood very much of that message but in general I think you're on the right track.

I'm going to Lakehurst next weekend and am currently testing motors using my prototype wood torque meter. It seems to be working fine and is much quicker to read than my old twisted wire meter. I modified my Geauga winder to put the output shaft at the same height above the work surface as the hook on my digital meter. This turned out to be a lot harder than I thought it would be but the end result works fine. I'm thinking now that I need to mount my winder and torque meter on the top of my model box so that I won't need to figure out a table top mounting system at Lakehurst.

So far all of the F1L motors that I made for Lakehurst are taking less winds than I need to have a shot at the Cat IV record. I may have to start over with longer and/or thinner motors.

Here's a picture of my model box that I hope to carry on to my flight to NJ. It has two F1L's and two LPP's inside.
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Tapio Linkosalo
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« Reply #138 on: August 29, 2010, 01:48:43 AM »

Quote
the wire that's in the analog torque meter torquedraad was (pianowire) should not twist the digital one, so no twist at all.
- So this is the best one to use a brass tube .

It does not make any difference, whether the torque rod twists or not. As a matter of fact, you could use thin piano wire as the rod and still measure the torque with electronic scale, if you set the back support so that it exerts the force onto the scale. After all, measuring the torque is based on: 2 pivot points, around which the torque rod rotates, ans the support point at a given distance from the rotation axis.

In my implementation I used brass tube (where the piano wire for the hook goes in) as it gives a simple way to make the bearing surface to take the axial load resulting from the pull of the rubber.

Quote
all should be well trapped between two points so that no friction.

Yup, you need the two pivot points so that the setup does not flop around, but the torque arm (length) is stable. All friction in the pivot points makes the torque reading less accurate, as if (of course) the case with also analog torque meter.

Quote
I would torqeudraad between the measuring element by let. The measuring element is vertical put down.

The arm that pushes to the scale should be perpendicular to the load cell of the scale. But actually, as the movement of the scale is minimal, it does not make that much error if it is not, the reading should just be corrected with the cosine of the movement angle. The placing of the load cell and side arm is irrelevant, the arm can push down, sideways or even up, as you are measuring torque, and the effect of gravity on the arm needs to be tared off anyway. Pushing the load down as in my implementation is most convenient, however, as that way you can use the gravity to hold the (unloaded) arm against the load cell.

Quote
Between the element I make a reticle rotation so that he will press on the element. He pressed the two component parts will separate.

Sorry, I do not understand the above. I gather that the sentence means that you install the side arm between the two pivot points, and it will press on the load cell of the scale. That is correct (while actually there is no need for the side arm to be between the pivot points, but that is probably the most compact design). In the second sentence, I do not know what two components you are referring to.
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gvwezel
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« Reply #139 on: August 29, 2010, 06:00:24 AM »

thanks for the info
okay it is difficult to explain.
but manage to guide you now to build one of the building will still try to send some pictures.
would also like to try calliberen as a standard analog torqeumeter.
nice box (sorry you know name)
is the standard case with a stake in it made?

greeting Gert-Jan
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Art356A
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« Reply #140 on: August 29, 2010, 09:33:58 AM »

Gert-Jan...

Just follow the pictures and build anything that looks like the simplest one here and you will have a meter that is 100 times more accurate and readable than the disc & wire type. Any sort of thrust bearing that works on a model plane will be more than good enough for the torque meter. On the other hand, you can spend 1000 Euros and a month of work to make a frictionless bearing, and your meter will be 101 times better than the common type.

 Just my opinion, but I'm a simple person.

Art.
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gvwezel
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« Reply #141 on: August 29, 2010, 01:14:45 PM »

oke Art

that's what i like yes i will build something like the photo's on this forum.

thanks
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Olbill
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« Reply #142 on: August 29, 2010, 10:53:57 PM »

is the standard case with a stake in it made?

Gert-Jan
If you are asking about my model box it's a 20" long plastic tool box sold at Fry's in the USA. My LPP and F1L wings are a little less than 18" span. The box is also a little less than 18" wide at the bottom. The wings barely fit in the box. An F1M wing made to the full 46cm span would not fit unless it was placed on the diagonal.

Here's a link to the box:

http://www.frys.com/product/3602025?site=sr:SEARCH:MAIN_RSLT_PG

 I used hot melt glue to hold the balsa sticks to the bottom of the box. I'm thinking of painting the box black to make it less threatening at the airline check-in!
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Wout Moerman
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« Reply #143 on: August 30, 2010, 04:29:44 AM »

Hello people

Here the new builder from the Netherlands how want to build a digital torque meter.

And yes sorry for my bad English but I hope it is clear

Greetings Gert-Jan from the Netherlands

Hoi Gert-Jan,

Mooi om je hier op HPA te zien, wanneer je hulp nodig hebt met het engels kan je altijd op mij een beroep doen: w.moerman(@)amd.ru.nl (en de haakjes weglaten). Ik begrijp dat je nu een torsiemeter gaat maken zoals hier al eerder beschreven staat? Dan kan het handig zijn om eerst te beslissen welke eenheid je wilt meten, ounce per inch of gram/cm. Dat bepaalt namelijk hoe lang de arm moet zijn die de weegschaal bedient.
Ik ben benieuwd naar je vorderingen!

Wout

Short translation
Hi Gert-Jan, nice to see you here at HPA, if you need help with your English you can always ask me for help. If you start building a torque meter decide which units to use: oz/inch or g/cm
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« Reply #144 on: September 01, 2010, 05:36:41 AM »

Update, Gert-Jan has contacted me via e-mail and we are discussing this topic in dutch. I've suggested him to use g.cm instead of oz.inch as unit, and I noticed I earlier made the mistake of mentioning oz/inch or g/cm as units. My fault.
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Art356A
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« Reply #145 on: September 01, 2010, 10:41:47 AM »

I think g.cm would be better. First, he's European. Second, with a longer arm he doesn't need to make a dog-leg on the supporting frames to get the end of the arm onto the middle of the tray. Would there also be an accuracy advantage with a centimeter long arm rather than the .394 cm arms that we use over here?

a.
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Olbill
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« Reply #146 on: September 01, 2010, 10:44:23 AM »

I'm using a 1" arm with the scale set to read in ounces to get a direct reading in in-ozs.

BTW - I've been testing motors for my Lakehurst trip using my digital meter. This has been going on for several days now and I've been happy with the performance of the meter and the ease of use. My only problem has been that the scale portion of this meter shuts off every time I have a pause in the action. The only way I can keep it on is to press down on the arm for a couple of seconds when I don't have a wound motor on it. I'm hoping that the new scale innards will not be as quick to shut down. So far I've never had it shut off while I was actually winding or unwinding for energy tests.
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craig h
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« Reply #147 on: September 01, 2010, 02:10:39 PM »

You guys built a really nice torque meter and winder combo.... but it's way out of my skill level ! I don't have the expertise or skills to build one .... but it's nice to read about it.
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Art356A
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« Reply #148 on: September 01, 2010, 02:31:47 PM »

Craig...

The winders are a female dog and a half to build. I've just finished the eighth one (including recycling earlier ones) and it's a gem, but I'm not yet entirely sure they're duplicatable. That's what's holding back the plans. It may be that unless you'e a CNC guy (I'm not) each one will need its own tuneup.

The torque meter, on the other hand, is simplicity itself. Just read reply #140 and do what it says. Anyone capable of building the simplest stick and tissue job ought to be able to knock one off in an hour or two.

Art.
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Art356A
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« Reply #149 on: September 01, 2010, 02:35:30 PM »

Ya gotta love that V-Chip, dontcha?

My best pal is a little black 'female dog'. Actually, she's an alliteration, but v-chips don't appreciate alliterations.

a.
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