Important Update regarding Open-EZ Rev 5 Templates

[filiperosa]

Hello Jon,

I would like to talk you for all the work you made with the drawings.

[JTest]

G'day / Hello

It is good to see the Canard Zone back online.  I thought it was gone forever years ago.  Thanks for getting it back to life.  

I guess it is time for me to get back to work on the Open EZ, that I started all those years ago.  Funny, I almost have it done too.  Maybe this year it will be...

Good to be back,

Cheers

Jeff

[Sammac91]

Hi Jon,

         Is revision 6 available yet? Looking to start cutting bulkheads soon and would like to have the updated plans if possible. Thank you so much for your work on these.

Cheers,

Sam

[Jon Matcho]

Hi Sam, thanks for the reminder.

If you have the drawings and plans, you can continue by updating with the corrections noted in the first post of this thread. If you do not have the drawings let me know.

I am not yet finished with the updates but remain committed to getting them done and available to put an end to this confusion.

Thanks,

Jon

[Sammac91]

Hi Jon,

I haven't printed the plans yet but was going to scale them as per the dimensions noted in the first post. I have to print them on A1 as the original arch size isn't available here in Australia so I will have to scale them regardless.

Cheers,

Sam

[Jon Matcho]

On 4/19/2017 at 1:16 AM, Sammac91 said:

I haven't printed the plans yet but was going to scale them as per the dimensions noted in the first post. I have to print them on A1 as the original arch size isn't available here in Australia so I will have to scale them regardless.

That sounds perfect, although I recommend printing one page without any scaling adjustments. You may likely find that everything measures out just fine. Paper sizes A1, B2, or C2 are fine (B2 and C2 leave less unused area, but you could just cut that away when done).

Thanks for the reminder... I just spent a few moments with the Open-EZ Rev 6 updates. I too cannot wait to announce and make this confusion NO MORE.

[Shane Crawford]

Is there an Open-EZ Rev 6 available?

[Shane Crawford]

9 hours ago, Shane Crawford said:

Is there an Open-EZ Rev 6 available?

Or I should ask what is the most up to date version and where would I find it? As I have only come across rev 5...

[Voidhawk9]

There is nothing later that I am aware of, and this site is where you would find it.

[Shane Crawford]

2 hours ago, Voidhawk9 said:

There is nothing later that I am aware of, and this site is where you would find it.

Thanks

[Shane Crawford]

So far I've been able to find:

• Long EZ plans pdf
• Open EZ drawings rev 5   (Will check against warning at the top of this thread)
• Long EZ plans updater
• Roncz Canard Template
• Rollover plans
• CP's

Do I still need the TERF CD, is there any extra information on there?

[Voidhawk9]

The Long-EZ documents in the TERF CD are:

• High-performance rudder (full-length)
• Special Performance Canard (Roncz)
• Lycoming Engine Installation
• Operating Manual
• Plans

As well as a few low-quality photos and a cutaway.

So I'd say you do not need the TERF CD.

In case you haven't seen yet, I recommend watching this if you are planning to build (do it!):

 

[Voidhawk9]

Mike Arnold's videos are also a great resource:

 

[Shane Crawford]

Great, thanks.

[zolotiyeruki]

@Jon Matcho As a birthday gift to myself, I got prints of the Open-EZ Rev 5 templates, and found/corrected the markings.  But I do have a question:  How much inaccuracy in the print is allowable? In my prints, there are a few where the shorter dimension is off by 1/16", and several where it's off by less than that.  Is that close enough?  The plans, on page 3-13, state that any dips or bumps >1/16" in a 12" span of a critical surface must be repaired, which makes me think that there's a fair amount of tolerance built into the design.

[Kent Ashton]

17 hours ago, zolotiyeruki said:

there are a few where the shorter dimension is off by 1/16", and several where it's off by less than that.  Is that close enough?  The plans, on page 3-13, state that any dips or bumps >1/16" in a 12" span of a critical surface must be repaired, which makes me think that there's a fair amount of tolerance built into the design.

I built an EZ from those plans.  That dimensional difference will not matter.  A 1/16"-deep wave in a wing _would_ matter but the act of cutting wing foam with a hotwire that is hotter than normal or using wire that is bigger than needed will melt away a bit more foam than otherwise giving a similar result.  Also, make yourself some extra copies you can cut up and glue to templates.  I like Formica.  Can usually find some scraps at the Habitat stores.

[zolotiyeruki]

To assuage my curiosity, I opened up the .TIF files in GIMP and started comparing the dimensions in the image to the dimensions as printed.  What I've found is some slight scaling inaccuracies in the scanned drawings.  For example, the "16.5" dimension in drawing A-1 is 16.55", while the 23" dimension is within 10 mil. 

As you say, Kent, it doesn't matter, but if/when I start building my own, I'll make sure to re-scale the images, if for no other reason than to make myself feel more confident that I'm building it as accurate as possible.  And I'll probably purchase the wing and canard cores from eurekacnc

[zolotiyeruki]

I went through all the templates, and rescaled to get the marks as precise as possible.  I've attached those files.

However, it appears that the inaccuracies aren't just in scaling.  For example, A-1 and A2 contain the template for the instrument panel, but where the two sheets join, the outlines of the panel don't match.  I measured the drawings both as printed and in the images, and there's some keystoning--on A-1, the instrument panel is 22.26" wide at the bottom and 22.33" wide at the top, and on A-2, where the panel joins the template from A-1, it is 22.26" again.

 

Edited June 12, 2023 by Jon Matcho
Removed this post's modified file (see the following 2 posts)

[Eric87]

Hi! Very new to the site as well as the Open EZ plans. Does the rescaled revision include the update mentioned at the beginning of the page? 

[Jon Matcho]

1 hour ago, Eric87 said:

Does the rescaled revision include the update mentioned at the beginning of the page?

No. Go to the first post. Download the files, and just make the simple edits called out in the first post in this thread.

I just checked the files provided by @zolotiyeruki above (not sure how I missed that post until now!) and as soon as I saw the same dimension markings on drawing A2, I realize these files are going to further confuse the matter. I removed the file from the post 2 above this one. 

Before I consider incorporating into the update I need to know what specifically was done:

On 3/17/2022 at 7:53 AM, zolotiyeruki said:

I went through all the templates, and rescaled to get the marks as precise as possible.  I've attached those files.

How did you exactly do this? What reference did you accept as "true"? The paper size? The markings on the paper. I ask because no scaling (at least how I define it) should have been done at all.

On 3/17/2022 at 7:53 AM, zolotiyeruki said:

However, it appears that the inaccuracies aren't just in scaling.

I repeat, there were no inaccuracies in scaling the images during the scanning process. The errors were only what was printed, ex. change "17" to "16". No changes in aspect, length, width, etc. of the actual image should be done.

On 3/17/2022 at 7:53 AM, zolotiyeruki said:

I measured the drawings both as printed and in the images, and there's some keystoning--on A-1, the instrument panel is 22.26" wide at the bottom and 22.33" wide at the top, and on A-2, where the panel joins the template from A-1, it is 22.26" again.

What, specifically, are you measuring to get "22.26 wide at the bottom and 22.33 wide at the top"? You are comparing the images to what you printed from them, or a different set of prints, or what? I'm just trying to understand.

[zolotiyeruki]

It's been long enough that I don't recall the exact numbers, but I'll explain what I did.  I opened the TIFF files in GIMP, and measured the distance (in pixels) between the tick marks on the page, comparing them to an expected value.  For example, if the distance on the page was marked as 16.5", and the resolution is 150dpi, I would expect the tick marks to be separated by 2475 pixels.  Instead, I found that the tick marks were 2483 pixels apart.

14 hours ago, Jon Matcho said:

What, specifically, are you measuring to get "22.26 wide at the bottom and 22.33 wide at the top"? You are comparing the images to what you printed from them, or a different set of prints, or what? I'm just trying to understand.

After I did the minor rescaling, I printed them and laid them out on a work bench, and that's where I noticed the templates not lining up.  So I measured them as printed, and then (as I recall) went back to the scans and measured them in GIMP.  The prints were consistent with the image, and both had the same inaccuracy.

[Jon Matcho]

On 6/13/2023 at 9:48 AM, zolotiyeruki said:

I opened the TIFF files in GIMP, and measured the distance (in pixels) between the tick marks on the page, comparing them to an expected value.  For example, if the distance on the page was marked as 16.5", and the resolution is 150dpi, I would expect the tick marks to be separated by 2475 pixels.  Instead, I found that the tick marks were 2483 pixels apart.

I understand your intent, but this approach is not valid. Modifying the image files in any way will change the dimensions in a way that was never meant to be.

The original prints were measured and hand-marked on original plans paper templates. In other words, 16.5" was meant to mean exactly 16.5". The purpose of the measurements is solely for validation of the printed output (given that all printers are slightly different with regard to how they handle dpi, and whether those dots are perfectly square or not).

For example, if after printing you measure 16" instead of 16.5", you would then need to adjust the print for your specific printer so that the reprinted measurement could be verified at 16.5".

This is why I took the "fixed" files you posted down.

[zolotiyeruki]

I think we may be talking past each other.  I measured the distances digitally (i.e. counting pixels) in the scans *before* printing, and that's where I found the slight discrepancies.  Once I scaled the images so that the tick marks were separated by the correct number of pixels, I printed them and measured the physical (paper) prints.  The physical prints matched the (scaled by me) images, indicating that the print was accurate to my source file.  The hand-marked measurements on the paper (e.g. the 16.5") were spot-on.  By the associative property (which I somehow remember from the first few days of Algebra), since the prints are correct (in those measurements), and the prints are true to their digital source files, the digital source files are also correct with regard to those reference distances.

FWIW, I did this on a per-page basis, since there are slight differences in the scanning errors from page to page.

[Jon Matcho]

54 minutes ago, zolotiyeruki said:

I think we may be talking past each other.

I understand exactly what you did.

54 minutes ago, zolotiyeruki said:

I measured the distances digitally (i.e. counting pixels) in the scans *before* printing, and that's where I found the slight discrepancies.

This method of measurement is not accurate. TIFF files are not guaranteed to reproduce original length based on pixels or DPI calculations. For example, if you were to open the same TIFF file in another graphics package you would likely get a different result. It's possible you sized and printed perfectly for yourself, but that's not guaranteed to translate perfectly to anyone else's graphics tool or printer (PDFs are much better for this purpose). If you're also saying the original scans are flawed, then you are mistaken as they were done on a high-end architectural Oce scanner. 

On 3/17/2022 at 7:53 AM, zolotiyeruki said:

I measured the drawings both as printed and in the images, and there's some keystoning--on A-1, the instrument panel is 22.26" wide at the bottom and 22.33" wide at the top, and on A-2, where the panel joins the template from A-1, it is 22.26" again.

Here you mention "keystoning" which is technically not possible with the scanner hardware being used (scanning slices of the same width top-to-bottom). Accepting your measurements for purposes of discussion only, you're calling out just 0.07" which is well within the expected error for how and when these templates were hand-drawn. The difference is nothing to worry about, at least in the context of 22" over half the instrument panel bulkhead. To compensate, line up as best you can, then cut on, inside, or outside the lines. This is the same procedure for dealing with other imperfect drawings such as the Cozy Mark IV drawings.

PDF files are better at preserving actual dimensions (as well as CAD files, although they're not very portable from one CAD system to another) and should be the files used for printing. The README file is not clear about these issues, but describes how to correct for specific behaviors with individual printers (as you experienced).

With all the confusion on this, as well as for other reasons I will rescan the drawings for all plans (Long-EZ, VariEze, Defiant, etc.) using a Contex high-end scanner (mainly to fix the dimension marks). and may generate only PDFs for distribution. I am also considering whether to provide a verified printing service for those who just want the paper templates.

[zolotiyeruki]

Fair enough.  If .070" is an acceptable error between the drawings, I won't make any more fuss about it.