Author Topic: Fraction equivalent chart  (Read 8874 times)

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ELOQUINTET

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Fraction equivalent chart
« on: January 29, 2008, 02:32:52 PM »
Hey guys,

I am looking for a fraction equivalent chart but let me explain this in detail. Our Dimension style Precision and Roundoff are set to 1/32 but our unit Precision is set to 1/256.

I am having to take drawings sent to us from our vendors and make them buildable. which means that none of the dimensions should read less than a 1/16".

I was plugging along and came across a situation where The overall was 9" and all of the interior dimensions were adding up except one which was 1/32 off. I went in and measured the model and discovered that the model was all screwed up and this was causing the descepency.

What I have done now is created a dimension style with it's precision set to 1/256 and roundoff set to zero which I will use to check the model's correctness.

The problem I am having is that sometimes the dimension will read in /256ths and other times in /64ths and sometimes in /128ths and so on.

So I guess what I would need is some sort of routine or chart which would show me 1/16ths on one side and ranges of the equivalents in the other fractions on the other side so I know how far I need to stretch the model to fix it.

Does this make sense?

M-dub

  • Guest
Re: Fraction equivalent chart
« Reply #1 on: January 29, 2008, 02:41:31 PM »
For what it's worth... Here's a little chart I made in Excel years ago...

ELOQUINTET

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Re: Fraction equivalent chart
« Reply #2 on: January 29, 2008, 03:09:38 PM »
Thanks MDub but that's not exactly what I'm after. What I am looking for is all fractions. In other words, I need a range of say 113-?/256 = 7/16. Does that make sense?

daron

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Re: Fraction equivalent chart
« Reply #3 on: January 29, 2008, 03:29:48 PM »
Perfect world meet imperfect world.



Sorry, couldn't be much more help. I absolutely hate fractions and that people expect perfection when it isn't feasible.

M-dub

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Re: Fraction equivalent chart
« Reply #4 on: January 29, 2008, 03:38:00 PM »
I can't tell exactly what it is you're after Dan, but if it is what I think it is, Excel is likely your best bet for creating something like this.

Again, don't know exactly what you're looking for.

ELOQUINTET

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Re: Fraction equivalent chart
« Reply #5 on: January 29, 2008, 04:34:14 PM »
Mike,

I created a sample drawing to illustrate what I'm trying to say but how do I get to the pond again to upload it?

David Hall

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Re: Fraction equivalent chart
« Reply #6 on: January 29, 2008, 04:56:05 PM »
what about using the decimal equivalent and doing ranges = ?/16  like 0.000001 -> 0.625=1/16
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David Hall

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Re: Fraction equivalent chart
« Reply #7 on: January 29, 2008, 04:58:10 PM »
I snaged this from Cadalyst tips to do roundoff, maybe it will help
Code: [Select]
(defun tepRNDoff (x y)
  (* (fix (/ (+ x (/ y 2.0)) y)) y)
)
X is the number, and Y is the part you want to round off to.  It always rounds down from what I can see
Everyone has a photographic memory, Some just don't have film.
They say money can't buy happiness, but it can buy Bacon and that's a close second.
Sometimes the question is more important than the answer. (Thanks Kerry for reminding me)

Josh Nieman

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Re: Fraction equivalent chart
« Reply #8 on: January 29, 2008, 04:58:22 PM »
Mike,

I created a sample drawing to illustrate what I'm trying to say but how do I get to the pond again to upload it?

You can attach it to your post.

Just below-and-to-the-left of the text box where you type your reply is a blue text toggle that says "Additional Options"

Expand that and wah-lah.

ELOQUINTET

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Re: Fraction equivalent chart
« Reply #9 on: January 29, 2008, 05:11:38 PM »
wow that is sweet. is that new functionality in the swamp or am i just a retard, wait don't answer that. i'd always thought i had to upload it to the pond the paste the link then do cartwheels  :lmao: thanks for the tip

T.Willey

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Re: Fraction equivalent chart
« Reply #10 on: January 29, 2008, 06:13:25 PM »
Maybe this will work for you.
Code: [Select]
(defun c:Test (/ MinDist MaxDist tempDist)
   
    (if
        (and
            (setq MinDist (getdist "\n Enter starting distance: "))
            (setq MaxDist (getdist "\n Enter ending distance: "))
            (setq tempDist MinDist)
            (not
                (prompt
                    (strcat
                        "\n"
                        (rtos MinDist 4 16)
                        " [ "
                        (vl-string-trim "0" (rtos MinDist 2 16))
                        " ]"
                    )
                )
            )
        )
        (while (< tempDist MaxDist)
            (setq tempDist (+ (/ 1. 256) tempDist))
            (prompt
                (strcat
                    "\n"
                    (rtos tempDist 4 16)
                    " [ "
                    (vl-string-trim "0" (rtos tempDist 2 16))
                    " ]"
                )
            )
        )
    )
    (princ)
)
Returned
Quote
Command: test

 Enter starting distance: 3/8

 Enter ending distance: 7/16

3/8" [ .375 ]
97/256" [ .37890625 ]
49/128" [ .3828125 ]
99/256" [ .38671875 ]
25/64" [ .390625 ]
101/256" [ .39453125 ]
51/128" [ .3984375 ]
103/256" [ .40234375 ]
13/32" [ .40625 ]
105/256" [ .41015625 ]
53/128" [ .4140625 ]
107/256" [ .41796875 ]
27/64" [ .421875 ]
109/256" [ .42578125 ]
55/128" [ .4296875 ]
111/256" [ .43359375 ]
7/16" [ .4375 ]
Tim

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ELOQUINTET

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Re: Fraction equivalent chart
« Reply #11 on: January 29, 2008, 10:25:07 PM »
thanks tim i will give it a try tomorrow. what i'm ultimately looking for is a way to figure out which 1/16" dimensions the actual dimension falls between and give me the distance i would need to adjust it to correct it. Whether I round up or down will depend on which is a nice round number. For instance I would round it up to 1/4" even if it was closer to 3/16". If there was a way I could select the amount I wanted from a dialogue and it would issue the stretch command and plug that number in as the distance that would be the ultimate solution. If I have to copy and paste the results that would still be better than nothing. Thanks for your help everyone.

TimSpangler

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Re: Fraction equivalent chart
« Reply #12 on: January 30, 2008, 07:15:05 AM »
Here is what I use.  I type VF at the cmd and it shows the slide full screen.  It only goes down to /64 but I have also include the .dwg so if you feel the need you can add the rest to it.  I think it came from here (theswamp)  dont remeber exactly.  Pretty simple


[Edit] I did a search on the swamp and found this post, but I know it wasn't this one. (maybe adesk forums)  Anywho it looks like it may have come from the same author so in any case I'll give creadit to him http://www.theswamp.org/index.php?topic=1536.0
« Last Edit: January 30, 2008, 07:25:38 AM by TimSpangler »
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Rob...

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Re: Fraction equivalent chart
« Reply #13 on: January 30, 2008, 07:31:20 AM »
Eloquintet,

Just a little advice. To be truly accurate, try this approach. Instead of using the difference of the actual length and the target length, use the full length that you need. What you are describing will only lessen the problem that your are trying to fix. Your source measurements are still rounded off, albeit a very small number. Given enough continuous dimensions you will end up with the same problem you started with. The sum of the parts will be different than the whole.
CAD Tech

ELOQUINTET

  • Guest
Re: Fraction equivalent chart
« Reply #14 on: January 30, 2008, 09:49:16 AM »
Tim that's a cool chart but this is not really what i am looking for. I think I explained what I need in my last post pretty clearly. Also take a look at the drawing I attached. Rob I guess you're right that my dimensions are still being rounded off but this distance is so small and would not be distinguishable from either our distance command or dimensions so I don't see the descrepancy showing up in our drawings. This is the best I can do without redrawing the whole thing which I cannot do. Do you have any other ideas of how I can make it perfect without redrawing. I'm open to suggestions.