cmorlier
05-19-2006, 06:00 PM
This is the latest installment in our example project series.
Britt and I hacked this little project together while doing final testing of the most recent software release. I had suggested a plane when Britt did his train, so this time around we decided to give it a go. I have a degree in Aerospace Engineering, so the best thing about this project was taking it home and telling my wife, "I finally got paid to design an airplane!". Unfortunately, like the original Spruce Goose this plane won't be doing much flying...unless you put it in your luggage.
This project combines cutouts with some creative use of surfaces.
For the fusalage, Britt found an image of the side view of a WWI biplane, which he traced using the spline tool. At points where he desired a sharper angle, he changed the Intersect type from "Spline" to "Normal" by right clicking on the vertex. To get straight lines, he changed the Form of the segment to "Line" also by going through the right-click menu. And at the bottom of the landing gear, he changed the Form of the segment into an "Arc".
The outline was adjusted to be more pleasing, and then we modified the outline to provide support for the upper wing and an indentation to accept the lower wing. We did not really try too hard to match the curvature of the lower wing, and if you look closely at where the bottom wing meets the body you will see it. In the attached project file for the body, I attempt to match the curvature a little better, but we have not attempted to recut body so it may need a little more work.
The shaping of body was achieved by using rectangular carved regions on both the front and back of the board. The rectangles were positioned to just touch one another. For the vertical tail, upper fuselage, and landing gear strut we just left the regions flat, with no surface applied. For the curved part of the fuselage, we applied a vertical dome.
We cut the body out 3/4" thick material, but it might be interesting to try something thicker and deepen the surfaces. Just remember that if you want the machine to cut it out, then you can't make it thicker than 1".
The wings were my task, and I took a slightly different approach from Britt. I browsed a few pictures of biplanes to get an idea of the shape and proportions of the wings. Then set about drawing the outline of the wings. I tend to be more comfortable using lines and arcs, so that I can ensure tangency between the curves and lines. Sometimes, the constraint system can be a little difficult when you have a bunch of lines and arcs with tangent constraints, and won't let you do something that should work. The trick to avoid this is that once you are happy with a section, attach it to both vertical and horizontal edges or centerlines (I later removed these attachments to position the pieces for carving).
Once I was happy with the outlines of the wings and horizontal tail pieces, I added the curved surfaces. Oh, I forgot to mention on the fuselage, when we applied the curved surfaces to the regions on both the wings and fuselage, we increased the height to ensure that the surface would range from max depth to the original board surface.
The wings and wheels were carved on 4"x1/4" material. 1/4" thick boards are supported by the machine, but they are so thin that their flexibility can cause problems. Also, the 4" wide material was not wide enough to handle the project as I had laid it out. So we opted to jig the project by using double sided tape to attach the two of the 4"x1/4" boards side by side on a more stable (and wider) 1/2" thick board. When doing this, it is important to ensure that all of the areas to be cut out are taped to the jig board, because the tabs will be left in the jig board and not in the pieces you intend to keep.
<Side note>
We actually cheated a little bit, by using a small piece of 1/2" thick material to fool the machine into thinking the board was only 1/4" thick, but this does have some possible complications so I don't recommend it. However, I mention it because in the next few releases of the firmware, we will begin to provide support for using jigs. Those of you out there who have tried to use a jig have probably had to go through a few contortions to make it do what you want. I would love to hear any tricks that you have found helpful or specific problems encountered when using jigs, so that we can provide a well thought out set of functions to make jigging easier.
</Side note>
Once all of the pieces were cut out, we did a fair bit of sanding to round the corners and taper the wing tips; cut two pieces of 1/4" dowel for the wing supports and a shorter piece for the wheel axel; and glued it all together.
Design time: ~1 hour
Carving time: ~2 hours
Enjoy!
Britt and I hacked this little project together while doing final testing of the most recent software release. I had suggested a plane when Britt did his train, so this time around we decided to give it a go. I have a degree in Aerospace Engineering, so the best thing about this project was taking it home and telling my wife, "I finally got paid to design an airplane!". Unfortunately, like the original Spruce Goose this plane won't be doing much flying...unless you put it in your luggage.
This project combines cutouts with some creative use of surfaces.
For the fusalage, Britt found an image of the side view of a WWI biplane, which he traced using the spline tool. At points where he desired a sharper angle, he changed the Intersect type from "Spline" to "Normal" by right clicking on the vertex. To get straight lines, he changed the Form of the segment to "Line" also by going through the right-click menu. And at the bottom of the landing gear, he changed the Form of the segment into an "Arc".
The outline was adjusted to be more pleasing, and then we modified the outline to provide support for the upper wing and an indentation to accept the lower wing. We did not really try too hard to match the curvature of the lower wing, and if you look closely at where the bottom wing meets the body you will see it. In the attached project file for the body, I attempt to match the curvature a little better, but we have not attempted to recut body so it may need a little more work.
The shaping of body was achieved by using rectangular carved regions on both the front and back of the board. The rectangles were positioned to just touch one another. For the vertical tail, upper fuselage, and landing gear strut we just left the regions flat, with no surface applied. For the curved part of the fuselage, we applied a vertical dome.
We cut the body out 3/4" thick material, but it might be interesting to try something thicker and deepen the surfaces. Just remember that if you want the machine to cut it out, then you can't make it thicker than 1".
The wings were my task, and I took a slightly different approach from Britt. I browsed a few pictures of biplanes to get an idea of the shape and proportions of the wings. Then set about drawing the outline of the wings. I tend to be more comfortable using lines and arcs, so that I can ensure tangency between the curves and lines. Sometimes, the constraint system can be a little difficult when you have a bunch of lines and arcs with tangent constraints, and won't let you do something that should work. The trick to avoid this is that once you are happy with a section, attach it to both vertical and horizontal edges or centerlines (I later removed these attachments to position the pieces for carving).
Once I was happy with the outlines of the wings and horizontal tail pieces, I added the curved surfaces. Oh, I forgot to mention on the fuselage, when we applied the curved surfaces to the regions on both the wings and fuselage, we increased the height to ensure that the surface would range from max depth to the original board surface.
The wings and wheels were carved on 4"x1/4" material. 1/4" thick boards are supported by the machine, but they are so thin that their flexibility can cause problems. Also, the 4" wide material was not wide enough to handle the project as I had laid it out. So we opted to jig the project by using double sided tape to attach the two of the 4"x1/4" boards side by side on a more stable (and wider) 1/2" thick board. When doing this, it is important to ensure that all of the areas to be cut out are taped to the jig board, because the tabs will be left in the jig board and not in the pieces you intend to keep.
<Side note>
We actually cheated a little bit, by using a small piece of 1/2" thick material to fool the machine into thinking the board was only 1/4" thick, but this does have some possible complications so I don't recommend it. However, I mention it because in the next few releases of the firmware, we will begin to provide support for using jigs. Those of you out there who have tried to use a jig have probably had to go through a few contortions to make it do what you want. I would love to hear any tricks that you have found helpful or specific problems encountered when using jigs, so that we can provide a well thought out set of functions to make jigging easier.
</Side note>
Once all of the pieces were cut out, we did a fair bit of sanding to round the corners and taper the wing tips; cut two pieces of 1/4" dowel for the wing supports and a shorter piece for the wheel axel; and glued it all together.
Design time: ~1 hour
Carving time: ~2 hours
Enjoy!