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Joining Beziers
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July 13, 2016, 10:06:05 AM
I have notices that when I join Bezier curves, in TCv19, I need to convert to Polylines first.  Then, after joining, I need to convert back to a curve to reduce the number of small Polylines.  However the convert to curve does not, of course, choose the same points I had previously.  All of this conversion leads to inaccuracies. 

Has there been a revision since v19 that allows joining Beziers directly?

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* July 13, 2016, 10:35:42 AM
#1
It is usually not necessary to join Beziers or Splines or Polylines when these entities are used as profiles for 3D objects. Simply enable "Use compound profile" after activating the 3D tool but before selecting the profile(s).

Henry H

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July 13, 2016, 10:40:41 AM
#2
Mr. Karlmann.

I just used TC2016 Deluxe to draw 3 Bezier Splines and join them without any conversion necessary. I'd suggest downloading a trial of 2016 and seeing how it works for you.

Henry,

Keep in mind that compound profiles are a Pro Platinum feature.


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* July 13, 2016, 10:43:40 AM
#3
Mr. Karlmann.

I just used TC2016 Deluxe to draw 3 Bezier Splines and join them without any conversion necessary. I'd suggest downloading a trial of 2016 and seeing how it works for you.

Henry,

Keep in mind that compound profiles are a Pro Platinum feature.

Yup. I wasn't aware that Mr. Karlmann is using Deluxe.

Henry H

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July 13, 2016, 11:31:51 AM
#4
I'm not aware of whether he is or isn't so either of our input may have been helpful.

As always your assistance is greatly appreciated Henry.

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* July 13, 2016, 11:36:16 AM
#5
Yup. I wasn't aware that Mr. Karlmann is using Deluxe.

He isn't (or wasn't), he was using v19 pro plat last year, so your spot on as usual  :D.

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July 13, 2016, 01:50:48 PM
#6
I have v19 Platinum.  Also I was just on the phone with Travis on another matter.

As to your solutions, I'm not sure they are helping, so I'll describe what I'm doing.  I have Plans that allow me to print a 2D version of gears with the intent on cutting them from wood.  To get the 2D drawing into TC, I input the gear profile as a picture, and then I traced out one tooth with Beziers.  Then I do a Radial Copy.  Then I need to join all those teeth, 42-teeth to be precise.  I found that Exploding the beziers into polylines is not precise enough to allow the start of one tooth to match the next.  So I had to edit the first segment and snap it to the last tooth, delete all the other teeth, then radial copy the corrected tooth, and then join all the teeth, then convert back to curves.  (Whew!)

Then (!) I began thinking: Why not use the TC Trace Command?  Upon discussing this with Travis, I was informed that my 64-bit version does not have the Trace Command, so I need to get the 32-bit version of TCv19 installed.

Does anyone know if the Trace command has the required precision for my Gears?

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July 13, 2016, 02:30:52 PM
#7
Mr. Karlmann,

The Trace tool probably won't create a closed profile that you can join together without node editing like you are already having to do using radial copy.

I'm still kind of surprised that the gear contour tool can't do what you need to do here much more simply. If you know the number of teeth, the diametral pitch and so on you should be able to simply engage the gear contour tool, click a point for the center of the gear and then hit tab to put in the various parameters for the gear in the inspector bar. It sounds like if you can get this to work it will save you a ton of time.

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* July 13, 2016, 02:45:47 PM
#8
Just gave it a try by saving  a gear contour as png file then using the trace tool in v18,  results, tried adjusting the settings but - erm, probably would get better results cutting out the gear with a chainsaw.

I'm slightly confused though, would the cnc machine (I'm assuming you are using one) not accept lines and arc's, these would be much easier to use, more accurate and should radial copy without further editing, and can be join-polylined with ease (which one shouldn't use on curves).

That said Travis's idea would save you a lot of work assuming the teeth shape from the tool is correct. 

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July 13, 2016, 03:37:18 PM
#9
Travis:  with v19 P, I cannot seem to alter the shape of the gear teeth.  The Diametral Pitch seems to size the gear, but the gear tooth profile stays the same.  The version that I have in print form has shallower teeth for the same number of teeth and diameter.  I tried like crazy to use diametral pitch, but the value, of course, changes with the number of teeth.  So I just used the standard "2" for DP, and then measured the distance across one tooth of the gear generated, and scaled it to the desired result.

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July 13, 2016, 03:45:51 PM
#10
Just gave it a try by saving  a gear contour as png file then using the trace tool in v18,  results, tried adjusting the settings but - erm, probably would get better results cutting out the gear with a chainsaw.

I'm slightly confused though, would the cnc machine (I'm assuming you are using one) not accept lines and arc's, these would be much easier to use, more accurate and should radial copy without further editing, and can be join-polylined with ease (which one shouldn't use on curves).

That said Travis's idea would save you a lot of work assuming the teeth shape from the tool is correct.

Maybe it's me, but I tried using Polyline and selected Arc-segments, but then I had no control over the arc's radius!  I could use straight line segments, but arcs of the correct diameter would be best.  I could draw the circle, snip the ends and join to the lines for one tooth, yes, that I could do.

As stated earlier, TC's v19 gear generator cannot seem to allow a different gear tooth profile for a given # of teeth and overall diameter -- at least I can't do it.

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July 13, 2016, 05:01:33 PM
#11
Sounds to me like the tooth profile in your referred to drawing is a stub gear tooth profile. As far as I know the gear contour tool is only for standard tooth profiles hence the difference.

HTH

Regards
Bob

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TC 14 Deluxe, TC 19 Pro
Windows 7, 64bit 8GB Ram


* July 13, 2016, 06:10:25 PM
#12
I have v19 Platinum.  Also I was just on the phone with Travis on another matter.

As to your solutions, I'm not sure they are helping, so I'll describe what I'm doing.  I have Plans that allow me to print a 2D version of gears with the intent on cutting them from wood.  To get the 2D drawing into TC, I input the gear profile as a picture, and then I traced out one tooth with Beziers.  Then I do a Radial Copy.  Then I need to join all those teeth, 42-teeth to be precise.  I found that Exploding the beziers into polylines is not precise enough to allow the start of one tooth to match the next.  So I had to edit the first segment and snap it to the last tooth, delete all the other teeth, then radial copy the corrected tooth, and then join all the teeth, then convert back to curves.  (Whew!)


I'd do the job in much the same way, with a couple of modifications. After tracing one tooth and radial-copying the result, I'd modify the original tracing so that the final point on the curve coincides with the intial point on its immediate neighbor. Then I'd delete all the copies, leaving only the modified original, and then radial-copy that remaining object. After selecting everything and applying "Place on Workplane," I'd extrude the whole set with "Use compound profile" enabled. I would not explode the curves and I would not try to join them.

Henry H

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July 13, 2016, 11:03:39 PM
#13
Sounds to me like the tooth profile in your referred to drawing is a stub gear tooth profile. As far as I know the gear contour tool is only for standard tooth profiles hence the difference.

HTH

Regards
Bob

The author of my purchased printable gears has successfully implemented his gear profile, so it's hard to argue with success, but I could try both.  It just seems odd that TC's Gears all have the same tooth shape.  Also, this same author has his own rather inexpensive Gear Generator program for sale, and it is far more flexible in tooth shape than TC's.  His program is $26, it animates, and affords many parameter changes.

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July 13, 2016, 11:07:16 PM
#14
Mr. Karlmann.

I just used TC2016 Deluxe to draw 3 Bezier Splines and join them without any conversion necessary. I'd suggest downloading a trial of 2016 and seeing how it works for you.


Travis:  (OT):  I re-checked the TCv20 new features video, and it sure looks like those gears are animating -- and without much fuss:
https://www.youtube.com/watch?v=rXkW8pt-Qlo
Timecode 1:18.  Let me know if this alters your thinking on v20 animating gears.
« Last Edit: July 13, 2016, 11:09:31 PM by T. Karlmann »

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July 13, 2016, 11:17:26 PM
#15
I have v19 Platinum.  Also I was just on the phone with Travis on another matter.

As to your solutions, I'm not sure they are helping, so I'll describe what I'm doing.  I have Plans that allow me to print a 2D version of gears with the intent on cutting them from wood.  To get the 2D drawing into TC, I input the gear profile as a picture, and then I traced out one tooth with Beziers.  Then I do a Radial Copy.  Then I need to join all those teeth, 42-teeth to be precise.  I found that Exploding the beziers into polylines is not precise enough to allow the start of one tooth to match the next.  So I had to edit the first segment and snap it to the last tooth, delete all the other teeth, then radial copy the corrected tooth, and then join all the teeth, then convert back to curves.  (Whew!)


I'd do the job in much the same way, with a couple of modifications. After tracing one tooth and radial-copying the result, I'd modify the original tracing so that the final point on the curve coincides with the intial point on its immediate neighbor. Then I'd delete all the copies, leaving only the modified original, and then radial-copy that remaining object. After selecting everything and applying "Place on Workplane," I'd extrude the whole set with "Use compound profile" enabled. I would not explode the curves and I would not try to join them.

Henry H

Other than the last part about Extruding, that's what I did.  I did find that I needed a real number for both rotation angles (for the 42-tooth gear), and I copied the result right into TC from the Windows Calculator.  The matchup was nearly perfect.  Hmm, I thought Extrude requires a closed polyline to work?

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* July 14, 2016, 04:03:24 AM
#16
Extruding an open profile builds a sheet surface that doesn't have physical properties aside from surface area and doesn't do volume Booleans.   It used to be that closed profiles had to be closed polylines to create solids with physical properties, but that isn't needed because compound profile recognises closed profiles automatically.  Don't have to be joined, so not exploded.  Been that way since V9 or V10.  It's an open question in my mind whether 2016's ability to join curves into polylines without deprecation makes TC more useful.   

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* July 14, 2016, 07:03:47 AM
#17
Sounds to me like the tooth profile in your referred to drawing is a stub gear tooth profile. As far as I know the gear contour tool is only for standard tooth profiles hence the difference.

HTH

Regards
Bob

The author of my purchased printable gears has successfully implemented his gear profile, so it's hard to argue with success, but I could try both.  It just seems odd that TC's Gears all have the same tooth shape.  Also, this same author has his own rather inexpensive Gear Generator program for sale, and it is far more flexible in tooth shape than TC's.  His program is $26, it animates, and affords many parameter changes.

TCad gear teeth are a close approximation to the involute shape, which is by far the most widely used tooth form. But it is not the only shape that will work.

TCad Pro version 2016 offers the "Curve from Law" tool, which makes it feasible to draw gear teeth with true involute form.

Henry H

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July 14, 2016, 07:21:11 AM
#18
Sounds to me like the tooth profile in your referred to drawing is a stub gear tooth profile. As far as I know the gear contour tool is only for standard tooth profiles hence the difference.

HTH

Regards
Bob

The author of my purchased printable gears has successfully implemented his gear profile, so it's hard to argue with success, but I could try both.  It just seems odd that TC's Gears all have the same tooth shape.  Also, this same author has his own rather inexpensive Gear Generator program for sale, and it is far more flexible in tooth shape than TC's.  His program is $26, it animates, and affords many parameter changes.

TCad gear teeth are a close approximation to the involute shape, which is by far the most widely used tooth form. But it is not the only shape that will work.

TCad Pro version 2016 offers the "Curve from Law" tool, which makes it feasible to draw gear teeth with true involute form.

Henry H

If I needed to use that Law feature, it seems to me I would need to do an nth-order Polynomial Regression to fit a curve I drew or created, (actually an 8th-order would probably nail it.).  That may not be worth the effort.  Additionally, it gets even more complicated as I need the gears to mesh at 90° -- which changes the angle the gears are cut at, which may also drive the gear profile.  The aforementioned author now includes this feature in his $26 program.  I am also thinking about true Bevel Gears for this application.  AFAIK, that is not in either program.  I think Involute gears are designed to work with their axes on the same plane.

Oh, I'm learning more about Gears!  I think the parameter that can change the shape of the tooth is Addendum, and the other gear is Dedendum -- this still keeps all the gears as Involute.
« Last Edit: July 14, 2016, 08:40:19 AM by T. Karlmann »

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July 14, 2016, 07:40:28 AM
#19
Extruding an open profile builds a sheet surface that doesn't have physical properties aside from surface area and doesn't do volume Booleans.   It used to be that closed profiles had to be closed polylines to create solids with physical properties, but that isn't needed because compound profile recognises closed profiles automatically.  Don't have to be joined, so not exploded.  Been that way since V9 or V10.  It's an open question in my mind whether 2016's ability to join curves into polylines without deprecation makes TC more useful.   
Great point!  As soon as I find a Surface in any of my drawings, I need to make it into a solid.  I recall that Henry does use surfaces.  I think that TC-2016 joins Beziers to lines, etc. directly, without conversion to Polylines -- that IS useful -- but I need the Upgrade Price from v19 to get that feature.

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* July 14, 2016, 07:44:52 PM
#20
Oh, I'm learning more about Gears!  I think the parameter that can change the shape of the tooth is Addendum, and the other gear is Dedendum -- this still keeps all the gears as Involute.

Another is pressure angle.  Used to be that 29 degrees was usual, stub gears often used 20.  I visited Australia's National Museum a couple of days ago, one of the displays was an example of the 1948 Holden, a GM brand that was the first Australian-built car in volume production.  The car on display was accompanied a hobbing machine and a cluster from that model's gearbox. 

Many decades ago, I built a hobbing machine from a model engineering magazine series, designed to be built from stock steel and alloy sections.  I was into slot cars and early R/C cars, it let me do any gearing I wanted.   It was a brilliant design, people are still building designs derived from it.  http://www.lathes.co.uk/jacobs/ has some nice shots of the original design, mine was very messy and ad hoc because I had access to a power drill and occasional use of a lathe at a garage (what we called gas stations and car repair joints) with advice from a mechanic.  The designer also wrote a number of articles about gearing that were the first education I had on the subject.  When he wrote the series, a well-known engineering professor did the drawings, the author wasn't confident of his drafting.  I knew nothing about interpreting shop drawings, so I taught myself to sketch isometrics of the parts to envisage them and understand how they fit together.  This thing is the actual root of my interest in computer modelling. 

I lost the original articles in the late 1970s when I emigrated, but I found them again in bound volumes of the magazine on ebay early in the new century.  What a nostalgia trip.

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July 14, 2016, 09:38:28 PM
#21
Oh, I'm learning more about Gears!  I think the parameter that can change the shape of the tooth is Addendum, and the other gear is Dedendum -- this still keeps all the gears as Involute.

Another is pressure angle.  Used to be that 29 degrees was usual, stub gears often used 20.  I visited Australia's National Museum a couple of days ago, one of the displays was an example of the 1948 Holden, a GM brand that was the first Australian-built car in volume production.  The car on display was accompanied a hobbing machine and a cluster from that model's gearbox. 

Many decades ago, I built a hobbing machine from a model engineering magazine series, designed to be built from stock steel and alloy sections.  I was into slot cars and early R/C cars, it let me do any gearing I wanted.   It was a brilliant design, people are still building designs derived from it.  http://www.lathes.co.uk/jacobs/ has some nice shots of the original design, mine was very messy and ad hoc because I had access to a power drill and occasional use of a lathe at a garage (what we called gas stations and car repair joints) with advice from a mechanic.  The designer also wrote a number of articles about gearing that were the first education I had on the subject.  When he wrote the series, a well-known engineering professor did the drawings, the author wasn't confident of his drafting.  I knew nothing about interpreting shop drawings, so I taught myself to sketch isometrics of the parts to envisage them and understand how they fit together.  This thing is the actual root of my interest in computer modelling. 

I lost the original articles in the late 1970s when I emigrated, but I found them again in bound volumes of the magazine on ebay early in the new century.  What a nostalgia trip.

Take a look at this:  https://www.youtube.com/watch?v=9Dl5J9b8GBw
I thought I'd seen large machines, but this was new for me.  Check out these huge arms that come out at about 23:00 -- these are in addition to his lathe and his dividing head!  This guy makes it sound like everyone has a machine like this monster!  This is all about making gears in a Real Machine Shop, I guess -- it fascinated me.

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* July 14, 2016, 10:29:14 PM
#22
The idea of cutting gears in a single action without indexing is what does it for me.  Indexed modular cutters don't produce involute flanks, so gears have a limited range of size relationships, whereas hobbed involutes will mesh with anything from seven tooth pinions to racks.   
« Last Edit: July 14, 2016, 11:04:44 PM by murray dickinson »

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* July 15, 2016, 06:07:39 AM
#23
Hi Everyone,
I didn't read through this thread until just now.

I am new to TC & find myself thinking still in terms of machining & what I would do to get the job done in a machine shop, in this case with a shaper or slotting machine.
So it's very easy to produce any gear tooth profile you require with TC as long as you can calculate the Involute curves for the required pressure angle, the root dia, base dia, pitch dia etc.

Just draw a TOOL profile & extrude it, set it in place on a cylinder, radial copy & then 3D subtract & you have your gears of any tooth profile you wish.

I have attached a very quick example, not to scale etc, just as an example only, you will see what needs to be subtracted & job done.
I subtracted the profile & then radiused the base of the gear teeth but this radius & or anything else could easily be added to the profile first.

Cheers
David


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* July 15, 2016, 06:59:56 AM
#24
Hi Everyone,
I didn't read through this thread until just now.

I am new to TC & find myself thinking still in terms of machining & what I would do to get the job done in a machine shop, in this case with a shaper or slotting machine.
So it's very easy to produce any gear tooth profile you require with TC as long as you can calculate the Involute curves for the required pressure angle, the root dia, base dia, pitch dia etc.

Just draw a TOOL profile & extrude it, set it in place on a cylinder, radial copy & then 3D subtract & you have your gears of any tooth profile you wish.


David

To draw the involute curve, one only needs to know the base circle radius. Type the parametric equations into TCad's "Curve from Law" Laws Editor, click in the drawing, and the TCad Genie will draw the curve. Pressure angle, root diameter, addendum diameter, and pitch diameter are all determined by which portion of the curve you use to build the tooth itself.

Go to https://en.wikipedia.org/wiki/Involute and scroll down to "Involute of a circle."

Henry H

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* July 15, 2016, 03:58:21 PM
#25
Hi Henry,

Yes, your correct for True Involute Curves that's for sure!

However we should not forget non circular gears & also at times it's possible to move from the base circle radius to quickly create differing right to left flank profiles for certain applications.

I did say, "any tooth profile" :)

Anyway what matters I guess is the fact that TC can do it without problems which is very good.

I haven't had a look at the Curve from Law tool as yet but it looks very interesting, still learning the basics & will move on when I can.

Cheers
David

« Last Edit: July 15, 2016, 04:36:53 PM by willeng »

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July 16, 2016, 12:52:07 AM
#26
Laws:  Aren't they only in TC-2016?  I have TC-v19 only.

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* July 16, 2016, 04:48:26 AM
#27
Every TC version since V19 has been able to save back to V18, so if you ask someone to produce an involute in 2016 and save it as V19, you can hack it about, scale, use and abuse for any tooth profile you need. 

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* July 16, 2016, 05:55:28 AM
#28
Laws:  Aren't they only in TC-2016?  I have TC-v19 only.

Afraid so.

Henry H

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* July 18, 2016, 10:38:18 PM
#29
Hi Everyone,

I thought this may be useful for people with earlier versions of TC pro without the Curve from Law tool to get good Involute profiles or geometric spirals or anything really into the drawing area easily without having to manually draw each one, it's a time saver.

I used Excel to give me the X, Y & Z coordinates of what curves or spirals I wanted, Z being "0" for 2D obviously, I copied the coordinates into notepad & saved with the .XYZ extension.
In TC, open up Ruby & select Import XYZ Lines, select your saved file & it loads it on the screen for you to work with, it's interesting to see big files being layed out on the screen..

I just Scale to get the base circle radius I want.

I have been playing around with it & it appears to be very useful for many things even though TC will do some things already.
I have attached a couple of pictures, obviously you only need a portion of the Involute curve but I've been playing around like a kid with a new toy with it?.

I have to check the accuracy of my shoddy calculations in Excel but it will work when done correctly!

Cheers
David







« Last Edit: July 18, 2016, 11:12:56 PM by willeng »

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* July 19, 2016, 07:18:13 AM
#30
Hi Everyone,

I thought this may be useful for people with earlier versions of TC pro without the Curve from Law tool to get good Involute profiles or geometric spirals or anything really into the drawing area easily without having to manually draw each one, it's a time saver.

I used Excel to give me the X, Y & Z coordinates of what curves or spirals I wanted, Z being "0" for 2D obviously, I copied the coordinates into notepad & saved with the .XYZ extension.
In TC, open up Ruby & select Import XYZ Lines, select your saved file & it loads it on the screen for you to work with, it's interesting to see big files being layed out on the screen..

I just Scale to get the base circle radius I want.

I have been playing around with it & it appears to be very useful for many things even though TC will do some things already.
I have attached a couple of pictures, obviously you only need a portion of the Involute curve but I've been playing around like a kid with a new toy with it?.

I have to check the accuracy of my shoddy calculations in Excel but it will work when done correctly!

Cheers
David


That's really slick, David. I haven't used Ruby; can you tell us a little more about "Import XYZ Lines"? It sounds as if the result is a Polyline drawn through the coordinates calculated in Excel. Is that anywhere near correct?

Henry H

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* July 19, 2016, 02:03:00 PM
#31
Hi Henry,

Yes, it seems that if you import 2D X Y data with "Z as all zero's " you do get a Polyline on screen, I found that when extruded you need to change the simple extrude to a solid with one explode or the computer takes forever to do anything.

If you import X Y & Z data you seem to get a 3D Polyline on screen.

You have to enter something in the Z data field or Ruby will not accept the file, as mentioned all zero's for 2D, you can only have the X Y & Z coordinates, no comma's or text or anything else.

It's all new to me as well at this stage but it is very interesting & the possibilities are endless depending on how one thinks.
You will know more about how TC accepts this than I do & your input is more than welcome as I would like to understand this better myself to be honest.

Cheers
David





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* July 19, 2016, 02:53:51 PM
#32
Hi Henry,

Yes, it seems that if you import 2D X Y data with "Z as all zero's " you do get a Polyline on screen, I found that when extruded you need to change the simple extrude to a solid with one explode or the computer takes forever to do anything.

If you import X Y & Z data you seem to get a 3D Polyline on screen.

You have to enter something in the Z data field or Ruby will not accept the file, as mentioned all zero's for 2D, you can only have the X Y & Z coordinates, no comma's or text or anything else.

It's all new to me as well at this stage but it is very interesting & the possibilities are endless depending on how one thinks.
You will know more about how TC accepts this than I do & your input is more than welcome as I would like to understand this better myself to be honest.

Cheers
David

I'm afraid that I don't, David.

Henry H

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* July 19, 2016, 05:25:20 PM
#33
Hi Henry,
That's not what I wanted to hear :)

For those who may be interested in designing or modelling airfoils or Turbine blades etc this technique is very good & is why I started looking into it in the first place.
For Airfoils, there are some huge data bases giving the X Y coordinates of many airfoil profiles, one can be found here:
http://m-selig.ae.illinois.edu/ads/coord_database.html

Just click & open the .DAT files & you have the X Y Coordinates, for Ruby to understand this you will have to add a Z axis with all Zero's, this is easy to do in Excel.

The picture attached is from one of the .DAT Files available from the site mentioned.

Just thought I would mention this as it is a very quick way to get profiles & or to modify existing profiles.

Cheers
David




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