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Woodturning CAD

Simple Open Profiles, -  This next one is done as an sheet object

In some cases it is not necessary to have a closed ‘solid’ object, a mirrored open ‘sheet’ will do.

The Profile was drawn as a 2D open spline, Fig 4.1The ref point is then relocated to the vertex and then ‘N’ snapped to the guideline (red)  once they are all in position, they are re-orientated and re-scaled so the loft will follow the curve,  the loft is done in two pieces (Orange and Green in Fig 4.2 , Self intersection is avoided by the ‘join’ point being above the X,

The beauty of this method is speed and ease of editing, having a vertex makes relocating ref point a snip, and lofting can sometimes be more accurate than using a solid, by that I mean less kinks or twists.

These  can look just as good and sometimes loft better than a solid, one can still do boolean add if its necessary to join two bits together, and if a solid is found to be needed later it might - (and that’s a big might) be able to convert it to solid, - often but not always,  If one lofted a garden and wanted to dig a pond, this on its own is no good as you would fall through as soon as you cut the surface away,  but if no digging was required this would produce a quick and pretty accurate top surface,

Problem, - Back of loft not flat, and boolean add shows a gap

Cause - snapping to guideline accuracy (a bummer in 10.2)

Solution, - there are times in TC where the snaps ‘miss’ their target, in 10.2, the ‘N’ SEKE is notorious for this on my system, it is often necessary to zoom in  to ensure the SEKE goes when one wants it, Zooming in side view will show if this has happened, if not corrected there may be a gap when mirrored, simply find the offending profile and re snap it the guide, and re-loft, or if the loft looks ok, - cheat and slice off the extra bit

Simple Profiles 2 Editing, -  This one simply shows the ease of altering simple profiles, once in position, i.e. for a design change.(or you messed up when designing the first attempt)

The object was done using an open spline Fig 4.4, and the method described previously, it actually lofted fine, but I decided to a change the shape, one method would be to redraw the profile and replace the existing ones, but as it  lofted pretty well, I decided not to disturb their position, Ok I’m being lazy, so,

The first thing was to select all the profiles which needed altering, then make a copy, group it, and put the copy on  its own layer, Select the copy and move its ref point to a back vertex, the whole copy was then scaled in height by 50%  Fig 4.6, in one direction only, (Y = 0.5 in this case), Next each profile needed altering, in node edit mode, (with grid and ortho snap on), move the two centre nodes of the original profile back to touch the copy, as  Fig 4.7, Its not necessary to use a snap or  SEKE just place by eye, I use the grid purely as a visual indication, Next select the group of copies, check ref point is ok, an re-scale height (same box as previous) , type in 3,  Lastly move two intermediate nodes up to meet the copy, again using eyeball is sufficient (fig 4.8)

Simple Profiles 2 Editing continued, -

The result is shown in Fig 5.1 .

Whilst this method may seen cumbersome, there are no problems with alignment, and actually only takes a few  minutes, to alter the whole lot

The problem of self intersecting with the ‘green’ profiles is overcome  by lofting in two pieces, either overlap or single start profile for both sides Fig 5.2,.