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Old Jul 30, 2012, 04:31 PM
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Question using the calculater

I downloaded and extracted the program and it looks very nice. My question is: I cannot change the value of "700" for the wire type? Does this mean it will only give specs. for 700 resistivity? Or am I missing something? Any teaching moments will be appreciated. Thanks.
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Old Jul 30, 2012, 10:17 PM
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Hmm, sorry, that shouldn't be locked, You should be able to change that value. I'll re-upload a corrected version tomorrow.
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Old Jul 31, 2012, 01:55 AM
If I build it, it will fly
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I thought that was odd, thought I had commented on it also.

For proper value, how do we check resistivity?

~psguardian
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Old Jul 31, 2012, 02:05 PM
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Okay, I've updated the resistivity section to allow user input. I've attached the latest version to the first post in this thread, and will now just maintain that one so people don't have to hunt through the thread for it. It will always be the latest version.

psguardian, the resistivity is relative value actually calculated from user reports of actual cutting settings that they use. Thus it reflects real world values rather than artificial values. The more people who report their cutting settings with different wire types, the better this calculator will get. Up to you guys.

There are suggested values to plug in for several wire types listed in the calculator -- but obviously we could use more if people want to report their settings. Or verify the ones we already have.
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Old Jul 31, 2012, 02:53 PM
If I build it, it will fly
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I am happy to provide my results for improved accuracy.

what setting do I use? My ohm meter has: 20 / 200 / 2k / 20k / 200k / 2m / 20m / 200m / 2000m ohms. What is your reference length? What is your reference temp?

~psguardian
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Old Jul 31, 2012, 03:14 PM
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psguardian an ohmeter won't work, because we want the resistance at cutting temperature.

It's a calculated value from readings of your actual cutting amperage and voltage. These must be measured values, not nameplate values.

I also need the actual cutting wire length (measured between alligator clip points), wire diameter and type of wire.

See a lot of the early posts in this thread for what was provided by users to get the calculator and values we have now.

Ideally we could use values for wire types we don't already have, or the ones we don't have many measurements for. Stainless is pretty well covered. But the rest are pretty sparse.
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Old Jul 31, 2012, 05:36 PM
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I have tried the newest download and found, when inputting the "Watt per inch" the field goes to either the next rounded up/down number. None of any decimal numbers work. Also it could use a calculate button so when you make a change in any of the inputs you don't have to keep clicking another field to get the output to change. Also the resistivity box does not show any change (stays 700) when a different type of wire is clicked.
Please understand I do appreciate the work you've put into this and hope you do not take this as criticism of your work. I'm only pointing out my experience with it so far.
Keep up the great work.
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Old Jul 31, 2012, 09:28 PM
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I
Quote:
have tried the newest download and found, when inputting the "Watt per inch" the field goes to either the next rounded up/down number. None of any decimal numbers work.
Sorry, that doesn't happen for me. What platform and spreadsheet software are you using?

Quote:
Also it could use a calculate button so when you make a change in any of the inputs you don't have to keep clicking another field to get the output to change.
You mean you'd like to "keep" clicking a calculate button" instead of clicking anywhere on the sheet, as an improvement?

Sorry, keeping this as universal, simple, and straightforward as possible for use with alternative spreadsheet programs, and that means no macros or other doodads.

Quote:
Also the resistivity box does not show any change (stays 700) when a different type of wire is clicked.
Sorry, but you will have to manually type in 3, possibly 4 digits with your fingers in that location. Clicking on something doesn't automatically enter it anywhere else on this sheet. As I said it a simple straightforward spreadsheet.

Quote:
Please understand I do appreciate the work you've put into this and hope you do not take this as criticism of your work. I'm only pointing out my experience with it so far.

Keep up the great work.
Thanks. I think with a little practice you will find it reasonably easy to use, even without those features.

I am concerned that you can't enter decimals in the watts per inch section, but it should be fairly simple to track down the cause.
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Old Jul 31, 2012, 10:01 PM
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I've downloaded the spreadsheet unzipped and opened it again and tried using decimals in the watts per inch section. And it still works for me.

So I examined the number formatting for that cell and it shows zero decimal places -- apparently a default setting. So that means a bug in the office spreadsheet software used to write it (Libre Office Calc), since it shows decimals for me despite the no decimal place default.

I've changed it to one decimal place and will upload it again shortly as version 1.4 beta.

I'll also add some explanatory notes to the effect that the wire resistivity figures are suggestions.

And a note to click anywhere in the spreadsheet to re-calculate for any change. Thanks for your feedback.

EDIT: Okay, ver 1.4b is up on the first post in this thread.
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Old Aug 01, 2012, 12:36 PM
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vtdiy,Thanks for the fast and helpful replies. The latest version works just I had hoped it would. One question, when trying to use it to create a small handheld tool it keeps showing the wire size is too small IE. .oo4. how do I work it to make a handheld tool using 12 ga. copper household wire of about 8-12" long?
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Old Aug 01, 2012, 01:46 PM
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Jerry, you'll have to reduce the voltage.

Or change the wire material.

Incidentally, copper isn't shown so far in our data.

You would want to maximize resistance in a short thick conductor so that the voltage is at some practical level.

This is a good learning tool to understand what happens!
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Old Aug 01, 2012, 01:57 PM
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I've often thought of using D cell batteries in parallel to get low voltage for formed cutters.

Or Nicads/NimH batteries -- if you have old spares.
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Old Aug 02, 2012, 05:07 AM
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I realize this is not a build forum but an associated question.
could one use the LED dimmer (mentioned earlier http://www.ebay.co.uk/itm/1x-DC-12V-...item2a1dc13e589) just connected onto a 3 cell lipo without using the brushed ESC, with a volt meter/amp meter inline to the bow?...or is this a stupid question?
Thanks
B1
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Old Aug 02, 2012, 07:58 AM
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I haven't tried it, but I don't see why not. As long as the LED DC lamp dimmer is rated for the job. I believe it is rated 12-24V and up to 8 amps. Not sure if the 3 cell lipo might drop below that -- or how critical that "12V rating" is.

If it was me, I'd put an automotive fuse inline so as not to exceed the dimmer's amperage rating. Also, a pilot light so you don't leave it on.

With the voltmeter you can monitor your cell's remaining capacity so you don't go too low.
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Old Aug 02, 2012, 11:53 AM
If I build it, it will fly
United States, NY, East Rochester
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My goal is to get one of THESE, I have attempted & destroyed 3 wings thus far on my current set up. Not sure if its the supply or the wire lol.

~psguardian
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