I need free drawing software for 2D designs

[Nasor]

The patent APL got was only a design patent - basically on the shape of the case! but there was some importance to that as the RF energy it was weekly recharged with had to pass thru the case.

In that case an opponent could argue that the aspects of the shape that allowed RF to better pass through were functional, and so shouldn't be covered by the design patent...

Have you considered a patent on a method of making your tank?

 

[Billy T]

In that case an opponent could argue that the aspects of the shape that allowed RF to better pass through were functional, and so shouldn't be covered by the design patent...

Have you considered a patent on a method of making your tank?

Perhaps it was not actually a "design patent" - We, who worked with it were told not to say the patent was just on the case but commonly told each other it was the design of the case that was patented.

Case was made of a bio-compatable Nickel Chrome alloy to have high electrical resistance. That keep eddy currents in the case low (body could conduct away case heating) and let most of the RF recharge field reach the internal coil.

Almost all the doctors believed the patent was on the recharge system, and we did not tell them otherwise. RF recharge patents had expired long before we made system using them.

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Yes, I need to spend some effort deciding what type of patent to apply for, if do seek one. Perhaps, I will go head to head with thycole by making a big deal out of fact there are no abrupt directional changes in the stress field direction and the extruded fabrication.

 

[Billy T]

I removed sketchup8 and replaced it with downloaded DoubleCAD XT for reason told in post 12 quote of their website text and have drawn my first lines with input of terminal coordinate points. (I´m nearly sure can do same with arcs of circle.)

I will transform this thread into notes on how to use DoubleCAD XT for myself (& others) who also want to do only simple 2D drawings with coordinate points (not drag of cursor) inputs for exact shapes.

DoubleCAD XT currently downloads with "bonus" of 30 days trial use of the sold "pro" version. The Help Text is more than half concerned with it, but cleary marked so you can avoid using any of those features, if your needs are simple. (Not get trapped into buying later.)

After clicking on the desktop icon a box appears, which allows you to open file you have been working on and saved or make new work area. Either will make this box go away. Then in lower left corner of work area a note tells you to press F1 for help. That opens in new window, the 590 page .pdf file instruction manual at page 1. Change that 1 in box at top left to 8 to read index with page numbers of various subjects. Replace the 8 in box with page number of interest to you. (Much better than reading full manual looking for information needed.)

That is all for this post, later posts will tell details of how I drew lines and arcs with coordinates imputs, etc. instead of the default click and move curser but I am still learning. I know how to get grid displayed in work area (or hide it) but even when I have selected metric, the main grid lines correspond to inches. E.g. moving from one to next higher main line changes the Y coordinate by 25.4 mm - I hope I can gain better contol of the grid.