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Woodturning CAD

Do’s and Don’t’s reproduced with kind permission from a lofting master.

And an inspiration to us all,  Mr. Henry O Hubich

1. Don't try to loft a Group.

2. Don't bother drawing symmetrical profiles to make a symmetrical object. Model half the object, then  mirror-copy it.

3. Do draw a single profile, then place a copy where you want the next profile to be and then edit it as necessary. Repeat for each successive profile.

4. Do make the profiles as simple and clean as possible.

5. Do be aware of the Format|Create solid|From surface option, new in v10. In many cases, you can use open profiles and then invoke that option to fill in the resulting hollow shell. (Doesn't always work well.) Also be aware that a hollow shell is acceptable in some cases.

6. Do consider alternative approaches to profile arrangement -- e.g., terrain can be lofted from contour lines or from cross sections.

7. Do anticipate adjusting your profiles to repair imperfections in the finished loft.                   Lotsa luck.

Lofting with TurboCad

Do you need to loft,  - Can a form be better achieved using extrude with a twist, extrude along path, or boolean,  these are  lofts that may be better extruded -------- I lofted them just for fun

Profile -Think of yourself as a navigator, and Genie (the heart of TC) as the driver, your job is to guide her using the best and smoothest route, if Genie thinks your navigation (profiles) are crap she will cut corners, come to a stop and complain, (throw up self intersecting error),  or put in a few dents and scratches and blame it on you,,,,, hmm  - does that scenario sound familiar

Quantity and positions of profiles is trial, error, and experience, I use guidelines to roughly tell the positioning, quantity is guesswork, but try not to overdo’ it, too many can actually cause problems

What can be lofted - ‘all Open’ or ‘all Closed’  2D profiles, be they polylines, arcs, circles, spline, bezier, and 3D spline’s v10.2 pro on, (not sure about v10.1) But not if they are a Group, Region, Block or Symbol, these must either be exploded down, or groups and block can be lofted in their own edit mode,   You cannot loft between an open and closed profile

Drawing guidelines - My  personal approach is to draw  spline guidelines for the  profiles to follow, this helps to simplify alignment,  as in Fig 1.2, most often it is just one or twp spline guides, be they hand drawn or offset. I usually eyeball most things

One note on the Offset tool, if you use the offset to get different sized profiles, and your shape has tight corners, the offset tool may round these over, as in the cloud in Fig 1.3, this is not a bug but the way TC calculates the offset centre,  Its better to draw the inner first and offset and node edit the outer, or scale the image and node edit,  

Genie makes nice clouds - shame to let offset mess them up

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