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Wreathed handrail
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September 05, 2015, 12:00:12 PM
 I do the sort of custom handrailing shown in the attached photos using 2-D CAD and templating, some purpose-built milling equipment, and the traditional design method called "tangent handrailing".    I'd like to hear from someone who has used Turbocad Pro solid modeling to design this type of railing. ------ Or at least has a sense of how to approach this.  Before responding please ask yourself if you are familiar with the issues in accomplishing this with solid modeling.  This is not simple spiral railing.  There are changes in pitch as well as in plan radius.  I've already been lectured by one CAD sales guy on the nature of my craft and its complexity; I don't need more of that. I'm aware that programs like Solidworks or Inventor may work very well for this, but I know regular A-cad does work and I'd like to stay with a conventional 3-D cad program if possible.  Also any suggestions on resources re. the issues of CAD export to CAM would be appreciated.
Ultimately, I want to produce models/designs which can be exported to CAM for use in 5 axis CNC. Admittedly I have work to do in learning the program, but am confident in my ability to do so.

The rail in the photo was completely laid out, machined and joined in the shop.  There were no on-site modifications for installation. 

Dan Bloomer
Waterville, ME

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* September 05, 2015, 12:40:27 PM
#1
I do the sort of custom handrailing shown in the attached photos using 2-D CAD and templating, some purpose-built milling equipment, and the traditional design method called "tangent handrailing".    I'd like to hear from someone who has used Turbocad Pro solid modeling to design this type of railing. ------ Or at least has a sense of how to approach this.  Before responding please ask yourself if you are familiar with the issues in accomplishing this with solid modeling.  This is not simple spiral railing.  There are changes in pitch as well as in plan radius.  I've already been lectured by one CAD sales guy on the nature of my craft and its complexity; I don't need more of that. I'm aware that programs like Solidworks or Inventor may work very well for this, but I know regular A-cad does work and I'd like to stay with a conventional 3-D cad program if possible.  Also any suggestions on resources re. the issues of CAD export to CAM would be appreciated.
Ultimately, I want to produce models/designs which can be exported to CAM for use in 5 axis CNC. Admittedly I have work to do in learning the program, but am confident in my ability to do so.

The rail in the photo was completely laid out, machined and joined in the shop.  There were no on-site modifications for installation. 

Dan Bloomer
Waterville, ME

I can't help with this, but just have a comment....beautiful workmanship!!

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DonCW
2017 Pro with Light Works Plug in
2018 Platinum

Windows 10
There's so much to learn and not much time left to learn it.


September 05, 2015, 03:52:56 PM
#2
Thanks, Don.  That's always good to hear.  There's more than a bit of blood and sweat in the doing and learning.  In mentioning how it was done I meant to communicate that the design is worked out (essentially by a 19th century system based on cylindric sections) before the rail is actually made.  Although I have a couple production methods I'd love to incorporate to further improve my efficiency, it's getting to look like 'John Henry and the Steam Drill' business-wise.  I recently found out the cost that that particular rail was quoted on by a shop with 5-axis CNC.  As attached as am to the antique technology I've had my head in for so long, I've got to move forward.  More free time away from the shop is not an entirely bad idea.

I've been spending time going over the 2-D environment of Platinum, and it seems close enough to the ancient version of 2D A-cad that I've been using that I'm satisfied and encouraged.  All of the above may be too much information, but it would be lovely if it inspires a Turbocad ace to engage.

Anyway, I've been looking over the 3-D tools.  What I've run into with 3-D programs (I'm quite proficient with SketchUp) is that when a profile is extruded along a spiral, or inclined circular path (wreathed in "stairbuilder-ese") it twists.  I believe there is a setting or parameter which is set in A-cad which controls that twisting even as it maintains the face of the extruded(swept, drawn, etc.) profile essentially square to that path.  If this is so, I'm hoping that same control is available in Turbocad Platinum.   

Another thought ------ If I were to define a proper path for such a rail via NURBS, and then place 2-D objects correctly oriented at necessary locations along that path, could the rail be developed using a version of the loft tool?  If this were to work would it be accurate enough for export to CAM or only a rough or distorted approximation?

Dan Bloomer
Waterville, ME


 
« Last Edit: September 05, 2015, 04:18:50 PM by volute »

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* September 05, 2015, 04:36:40 PM
#3
"I believe there is a setting or parameter which is set in A-cad which controls that twisting even as it maintains the face of the extruded(swept, drawn, etc.) profile essentially square to that path.  If this is so, I'm hoping that same control is available in Turbocad Platinum."

That can be done if the path has a constant helix angle; otherwise the twist cannot be removed completely. I'll have to amend that statement: Somtimes it can be done even if the helix angle is not constant. See attached screenshot.

"Another thought ------ If I were to define a proper path for such a rail via NURBS, and then place 2-D objects correctly oriented at necessary locations along that path, could the rail be developed using a version of the loft tool?  If this were to work would it be accurate enough for export to CAM or a rough approximation?"

That's doable, too, and it'll probably be accurate enough if the 2D profiles are rather closely spaced. TCad offers two different tools that will place copies of a 2D profile along a designated path, but both of them require that the orientation of each profile be adjusted manually. (The plane of the profile will be normal to the path; it's the orientation with respect to the normal that has to be adjusted.) The path can be almost any 2D or 3D line or curve.

Henry H
« Last Edit: September 05, 2015, 05:24:34 PM by Henry Hubich »

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* September 05, 2015, 08:44:04 PM
#4
Here's a quick sample of a handrail modeled in TCad. Curved sections were made by Rail-Sweeping a profile along a half-helix and adjusting the Twist. Straight sections are Sweeps along straight-line paths.

Henry H
« Last Edit: September 05, 2015, 08:47:13 PM by Henry Hubich »

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September 06, 2015, 08:41:05 AM
#5
Thanks Henry,  Your response exactly the sort of thing hoped for. 

I'm guessing that creating a twist parameter for a wreathed rail with dramatic changes in pitch might be more of a pain than working out a process for leveling the horizontal center lines of each of the placed profile objects (which would also be centered on the line defining the path) and then doing the loft thing.
To be honest, I have to plow some more time into learning the Tcad program right now,  but your response confirms that this program should do what I need.   

You can be sure I'll be back here soon with more questions.


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* September 06, 2015, 09:56:40 AM
#6
Thanks Henry,  Your response exactly the sort of thing hoped for. 

I'm guessing that creating a twist parameter for a wreathed rail with dramatic changes in pitch might be more of a pain than working out a process for leveling the horizontal center lines of each of the placed profile objects (which would also be centered on the line defining the path) and then doing the loft thing.
To be honest, I have to plow some more time into learning the Tcad program right now,  but your response confirms that this program should do what I need.   

You can be sure I'll be back here soon with more questions.

Glad to help.

...BTW, what's a "wreathed" handrail?

Henry H

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September 07, 2015, 01:05:26 PM
#7
Yeah,   It's old time stair builder trade terminology for any handrail section or fitting which is curved and inclined at the same time.  Spiral rail is a type of wreathed rail, but not all wreathed rail is spiral. 

FYI -  In stair speak, a "spiral stair" usually connotes a smaller manufactured unit which is purchased pre-fabbed to a particular set of sizes and installed.  A "circular stair" is usually fully custom, mostly larger in scale, and may or may not be pre-fabbed in a stair shop.   

I checked out some of your old posts, and there are several operations mentioned which I'm curious about.  I'll be back on those later.  I'll wait until I'm more grounded in this program.   

Thanks again,
Dan

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