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Author Topic: Winders, winding stooge, torque meters, winding methods  (Read 25056 times)
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FLYACE1946
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« Reply #75 on: May 26, 2010, 03:20:16 PM »

Good idea for transporting model boxes. What size boxes do you use and where do you locate them?

Are the boxes new or used?
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Olbill
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« Reply #76 on: May 27, 2010, 07:55:51 AM »

Since I rarely fly to contests I use any large boxes that I find. I put one or two completely assembled models in one box. I'm leaving for USIC in a few minutes and this is what I hope will go in the car. (see photo)
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FLYACE1946
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« Reply #77 on: May 27, 2010, 11:01:25 AM »

Thanks for the tip on recycling those big old boxes. I use 2 old vacuum cleaner boxes for storing and also traveling to fly.
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Art356A
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« Reply #78 on: May 27, 2010, 02:09:42 PM »

This one is in addition to the unit in the earlier photos. It's made for winding the motor on the model. The rocker is made to hold a 1/8"diameter hub, which most of my indoor planes have. The main feature is the brass piece that loosely holds the hub. I've eliminated the long board with the winder holder, so the model can hang loose. It has a diagonal cut thru into the hole in the fwd hanger (like in a prop hanger) so the rocker ass'y can be loaded.

The second is a simple adapter for models with fuselages which must be wound from the nose. The third shows it in use.

To change the subject, the last shot is my current box, an American Racing mag wheel box, 20 x 20 x11. Two cleats were glued in to stop the flaps, and diagonal dividers were added. Right now it carries two Pussycats, two Phantom Flashes and a Hangar Rat and there's room for more. The side compartments hold props, rags, motors, lube, whatever.
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My arms are so weak, it's like that pushup I did last year was a total waste.
Olbill
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« Reply #79 on: June 13, 2010, 07:10:48 PM »

Here's my first working electronic torque meter. It's actually my second try with mostly the same parts but the first one had too much friction in the bearings.

This one has an .020" wire inside a 3/32" brass tube. The wire has a 90 degree bend at the back bearing and is secured to the rear vertical plywood. When the wire is secured at the rear bearing it's located to give a small preload to the 1" arm as it rests on the load cell. The wire is doubled at the front to make a hook strong enough for PP size motors. The 3/32" tube has a very loose fit into larger brass tubes at both bearings.

After I've done some real world testing with the meter I plan to do a small production run. The next ones will have all the wiring concealed, the battery box on the inside of the rear support and the triangular openings on the sides will be filled with plywood pieces. All the plywood parts will be laser cut.

The friction problem on the first version showed up in backing off turns from a very light EZB sized motor. I found that a good, easy way to check for this problem is to turn the meter on, twist the hook to a low reading and then let it go. The LCD reading should go back to zero. In fact it should go back to zero from any amount of torque but low torques are what caused the problem in the first version.
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Olbill
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« Reply #80 on: June 21, 2010, 05:34:18 PM »

Here's the URL for a 20g x .001g scale for $15.23 including shipping. I ordered one today in hopes it will be good enough to take to contests instead of my plug-in Acculab. I'll post a report when I get it in my hands.

http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=280392289572

The digital torque meter had some problems this weekend. The simple one was that the solder joint on the torque arm failed. The more major one is that I discovered that the centerline of the torque meter tube has to be the same distance above the table as the hook on your winder when the winder is docked. If the rubber motor is pulled out of line with the meter the torque readings will change. This is probably true to some extent with normal torque meters but seems to be more critical with the digital one. For the same reason the centerline of the meter hook - the point where the rubber motor or o-ring sits - needs to be really close to the centerline of the torque tube to minimize the effects of the motor being off-axis.

At this point I'm still buying and disassembling scales to find one that makes a neater and simpler installation.
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Tapio Linkosalo
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« Reply #81 on: June 22, 2010, 02:18:24 AM »

Bill,

have you found a scale with a LARGE display? My T-meter, from a cheap DealExtreme scale has quite a small display, and I think (have not tried yet) it will be hard to read that 2 to 3 meters away, that you need to stretch a F1M motor...

The force sensor seems to be a common circuitry of 2 strain gauges in a square bridge (thus temperature compensated). I tried to connect that to an op-amp circuitry that I have (for reading thermocouples), but for some reason I did not manage to get a proper signal out of it. Increasing amplification just drifted the base level higher, but gave no stronger signal, hence I did not get sufficient resolution of the reading. I do not know what went wrong, have to take a closer look in the autumn. Anyway, if that would have worked, then I could have used a micro-controller to output the readings in a serial format, and use any computer (hand held or whatever) as display, and getting a larger display to read.

I wonder about your binding problems, as the measurement should not be any different from conventional meters. What kind of bearings do you have on the meter? Can it be, that the sidearm is sticking to the sensor element?
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Olbill
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« Reply #82 on: June 22, 2010, 10:54:08 PM »

Tapio

One of the scales I've got has a 1.5 x 4 cm display which is larger than any others I've looked at. It's the switchblade type scale. It also has a smaller weighing surface than the others and a mounting system for the load cell that would make it very easy to use. The drawbacks are that it's a little more expensive than the others at $15 and the part containing the display is 4" wide. This would add considerably to the bulk of the finished meter. (pictures below)

I think I can overcome any binding problems by using loose fitting bearings. The torque tube is suspended at the rear bearing by a full length .020 wire so there is no friction problem there caused by motor tension.

Others may disagree but I don't really use the torque meter until I'm pretty close in so readability isn't a big problem.
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Olbill
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« Reply #83 on: July 06, 2010, 05:43:20 PM »

Here's the URL for a 20g x .001g scale for $15.23 including shipping. I ordered one today in hopes it will be good enough to take to contests instead of my plug-in Acculab. I'll post a report when I get it in my hands.

http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=280392289572


The scale described above came in the mail today. I tested it with an inexpensive set of calibration weights and found it weighed everything from 10mg up to its 20g capacity withing a milligram or two of the stamped weight. This is about the same accuracy as my Acculab Vic-123 that cost about $240. The disadvantage of this scale is the tiny weighing pan. This will call for some adapters to be made for it to be useful in the field.
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Olbill
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« Reply #84 on: July 06, 2010, 11:07:26 PM »

have you found a scale with a LARGE display? My T-meter, from a cheap DealExtreme scale has quite a small display, and I think (have not tried yet) it will be hard to read that 2 to 3 meters away, that you need to stretch a F1M motor...

Tapio

After destroying a number of scales I've settled on the one in the foreground of this picture. The one in the background has numerals that are .6cm high. On the foreground one the numerals are .9cm high. It has a backlight which goes off after about 25 seconds of no use. The scale turns itself off in 1 minute in spite of the instructions saying 3 minutes. Ordering this scale from China (from the USA) costs about $6. Here's the URL:

http://cgi.ebay.com/500g-x-0-1-Gram-Jewelry-Digital-Scale-Balance-Pocket-/250636775037?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item3a5b1dae7d
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frash
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« Reply #85 on: July 08, 2010, 05:07:48 PM »

The disadvantage of this scale is the tiny weighing pan. This will call for some adapters to be made for it to be useful in the field.

Bill, when you get the adapters acceptable for your use, please post what you have done. Others of us find the price right and the scale acceptable but hard to load onto the tiny thimble. I use a balsa platform on the thimble, but the thimble still shifts, and a larger platform obscures the readout. Nevertheless I use mine a lot.

Fred Rash
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Tmat
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« Reply #86 on: July 08, 2010, 05:16:45 PM »

Hmmm, turns out I have the same scale too.

I just make a balsa base (square) that sits on top of the aluminum tray supplied (slightly bigger to not obscure the read-out). I glue a piece of small diameter wire to the base to create a hanger that I use to hand wings or tail surfaces from.

Seems to work fine.

Tony
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Olbill
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« Reply #87 on: July 29, 2010, 12:20:55 AM »

Here's my solution to the small weighing pan:

I used a blob of 5 minute epoxy to glue a short length of 5/32 tubing to the center of the weighing platform. I tried to keep this tube as perpendicular to the pan as possible. Then I glued a 1 1/2" square of 1/16" plywood to a length of 1/8" carbon tubing - also with 5 minute epoxy. You could stop there but I thought it would be neat to not have to lift the plastic lid so I drilled a 1/4" hole thru the lid. Here are pictures of the 2 pieces separated and in action with a 2 gram weight on the extended pan.

I tried moving the weight around on the platform to see how much variation the scale would show. The answer was not much. The numbers would sometimes change a couple of milligrams. I think 1/10% is accurate enough for my purposes.

I also re-checked several of my (cheap) standard weights on this scale and on my Acculab Vic-123. The Acculab is very unstable for a good while after you fire it up so the pocket scale was clearly the winner if you're in a hurry. After the Acculab had settled down the weights shown on the two scales were within a couple of milligrams on all the test weights. And again, the Acculab was $240 and the pocket scale was $15.
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Art356A
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« Reply #88 on: July 29, 2010, 05:08:39 AM »

Here are a couple of chain drive, smooth as silk, 1-20 winders. No.2 is the test mule, which is a viable winder on its own, only it's a little ugly. They cost under $20 to make, and future ones will have GizmoGeezer's magnetic counter, or else provision for it will be made. There's one on the mule, but it wouldn't quite fit into No.4, which will have to be made about 1/8" thicker at most (No. 4 is 3.1 x 1.8 x 1.1).
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Tmat
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« Reply #89 on: July 29, 2010, 08:52:57 AM »

Nice idea Bill.

Just out of curiosity, why did you make the carbon rod so long? Wouldn't it be better if the platform was just above the cover?

Nice winders Art. Reminds me of my old Mechano set!

Tony
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Olbill
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« Reply #90 on: July 29, 2010, 11:09:12 AM »

Tony

Weighing whole models often requires some vertical space to get everything off of the surrounding obstacles. With the Acculab I have to put a model stand on it to hold the model high enough and keep it stable. I haven't actually tried weighing complete models on the little scale yet but may do so today. More adapters will probably be in order.

One thing I've been thinking about is a V shaped block of foam on the balsa platform that might work for weighing models with a variety of different MS configurations.
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Art356A
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« Reply #91 on: July 29, 2010, 12:43:29 PM »

I use a block of soft foam about 6" high. It doesn't need a "V" in it. Just put the plane on upside down.
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My arms are so weak, it's like that pushup I did last year was a total waste.
Hepcat
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« Reply #92 on: July 29, 2010, 04:34:55 PM »

The sketch below might suggest an alternative approach to dealing with the small scale pan on some digital scales. There is a beam with a pointer under one end to rest on the scale pan and a pivot near the other end. The pivot end of the beam can have a weight applied to give a near zero load to the scale pan before weighing begins.

There is a hook under the beam exactly half way between the scale pan and the pivot on which the thing to be weighed is hung. A hook is usually more convenient than a pan for the sorts of things that we weigh and in any case a pan can be hung on a hook!

A slight disadvantage of the arrangement shewn is that the weight registered on the scale must be doubled to get the actual weight. Other beam/pivot arrangements can do different things. We originally used 10:1 ratio beams to increase the accuracy of the early, cheap digital scales.

John
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Tapio Linkosalo
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« Reply #93 on: July 31, 2010, 12:47:20 AM »

Bill, that is really neat. I did the same modification to my milligram scale, with a few twists: made the tube on the platform shorter, so that it fits under the clear plastic lid, which I can close to protect the platform. And I rebuilt m plane stooge to take the same 3mm carbon tube as shaft, so I can insert it onto the scale to easily weight the models. The stooge has a 10cm plywood disk as base, with a tubing of the same diameter as on the scale, so the plane holder shaft can be also inserted to that base.
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Tapio Linkosalo
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« Reply #94 on: July 31, 2010, 03:14:37 AM »

... two pics...
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frash
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« Reply #95 on: July 31, 2010, 12:41:42 PM »

Bill,

I copied your modification of the small, inexpensive balance also as I had previously "threatened" to do. Thanks to you and to Tapio who first found these balances if I remember correctly.

Fred Rash
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Tapio Linkosalo
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« Reply #96 on: August 01, 2010, 02:21:42 AM »

Cannot recall for sure if it was me, or if I found the link to the scale on this forum... :-)

Anyway, preparing for the Belgrad contest, I made a stand for the digital torque meter to attach to my winding rod. Tested it on a couple of occasions, and it seems to work just fine. The torque readings are easily read, and seem correct (torque builds up while winding, and slowly fades away as the rubber gets tired). The current setup still holds the display and battery holder with rubber bands, as I will need to see later in the autumn, what position works for F1M. The current is ok for F1D, but "M"'s have so much longer motors, that the display maybe needs to be tilted to be seen from further away.

I'm using g*cm as torque readings, so the side arm is 1cm long. You can see the load cell, out of the scale, against which the side arm rests. The hook is of 1mm piano wire, and there is a sleeve of 2mm and 3mm brass tubing, acting also as the pressure bearing surface (some nylon sheet between the brass and the aluminium). A 3mm ID wheel collar works as a side arm, with a M3 bolt locking the collar to the hook wire. A washer between two nuts rest against the load cell, hence you can fine-tune the arm length by moving the washer between the nuts along the bolt.
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Olbill
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« Reply #97 on: August 01, 2010, 10:47:59 AM »

Tapio

In your torque meter are you taking the thrust load in the front bearing or the rear? It looks to me like it's the front but I wanted to ask to be sure.

I see you're using the same scale for your torque meter as mine. I'm glad it's working for you - I have 10 of them sitting here waiting for me to finalize the design for my meter.

On my milligram scale the hole in the top is not necessary for closing the top. I made the hole so that I could use the scale without opening it. I seem to always have a shortage of space when I'm flying so being able to operate the scale without opening the lid helps in that regard.

Art

The winders are very slick. One of the things that would make my torque meter setup easier is a winder with a hook closer to the bottom of the winder so the torque meter hook wouldn't need to be as high off the table. I guess this might be a future project.
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Tapio Linkosalo
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« Reply #98 on: August 01, 2010, 02:59:21 PM »

In your torque meter are you taking the thrust load in the front bearing or the rear? It looks to me like it's the front but I wanted to ask to be sure.

Front. The aluminum frame has 1mm holes to clear the hook, the 2mm OD (1mm ID) brass tubing is the length of the inside dimension between the two arms of aluminum frame, hence keeping the hook from moving to and fro, and also the front end of this tubing is the bearing surface to take the pull. Then there is a short length of 3/2mm tubing to sit on the thinner, and accommodate the wheel collars. The two tubings have some material removed so that the bolt in the collar meets the hook wire and locks it in place.
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« Reply #99 on: August 04, 2010, 11:51:41 AM »

Art356A,

I like your chain drive winder and would be interested in making one. Please post more information here on the components that you used or contact me off-line at "chris 'dot' stoddart 'at' gmail 'dot' com"

best wishes,
Chris Stoddart
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