Rotating tabs - inconsistencies

Here I am, faced with a bunch of entities to cut out of a metal plate by either of two techniques: water jet cutting or laser cutting. In either situation the plate is held by the edges. If the process cuts all the way around any one object, it will fall out of the hole and down into what amounts to oblivion, that is, it will likely get lost.

Therefore, I have to leave an uncut tab on the periphery of every object so that it will remain attached to the plate.

So far, I have managed to create a series of blocks, each one depicting a tab pointing in a useful direction. This effort is not without its problems. The main one is that when I attempt to open and modify a tab and then create another named tab from it, thereby being given the opportunity to name the new tab, I find that after I have closed what I think is the new tab, I find that I have modified both tabs and now have two identical tabs with different names.

How to I turn the original tab back the way it was originally pointing ? I find that both "Move and Rotate" and "Mirror" produce unpredictable outcomes. Sometimes "Mirror" rotates my tab by an uneven multiple of ninety degrees. I don't know what is the meaning of "angle" in this context - on an absolute polar-coordinate system or just relative, applied to the object's desired motion.

What's worse, now I've discovered that four out of six versions of this tab have gone blank. They will have to be re-created ... but I have lost all confidence in how to accomplish that. I need six more positions on my compass, 45 degrees apart.

On top of that, I find that editing a tab (from the list of tabs) changes all instances of that tab that have been put in my drawing, so I have to create and finalize all the desired tabs before ever starting to use them in my drawing.

Best regards,
georgesbasement

CONTENTS DELETED

Neither of the previous two sets of suggestions works for my drawing, which consists of almost seventy discrete objects; plus another drawing also in the works, and three candidate vendors waiting for updated files ...

I appears that what I will have to do is create Tab-A, save it in my Blocks folder; close it; close LibreCAD; reopen LibreCAD, create another tab, rotate that new another position, save that under a new name, etc, etc. until I have eight such tabs. Then I should be able to import each tab, apply it as many times as needed, save the main drawing under a new name, proceed to Tab-B, etc., etc. with as many overlooked positions as remain to fill in until every object has a tab and they all stay put.

If "Rotate" were a separate menu item, this might be easier, but that is for a later version. The developers probably had an entirely different application in mind when they wrote this code, and I cannot fault them for that.

Best regards,
georgesbasement

Getting past all the various inconsistencies, I have managed to create eight differently oriented tabs, angularly spaced around the compass, but I've put them into their own "Blocks" folder within my "Drawings" folder.

I can import one such block into my main drawing, but when I try that from the next block in my list, LibreCAD puts it in with the first one along with several opaquely named copies, some of which are blank, and renames most of what's there. When I ascertain which ones I want to keep and delete the rest, I find that all but one of the remainder are now blank. If I were to leave well enough alone, I would end up with umpteen copies, blank files, etc. from which I would have to again ascertain which ones are useful and make up my own scorecard in order reliably to pick them out for later insertion at the appropriate places in my drawing.

Is there a less tedious way of doing this "tabulation" of my drawing ?

Best regards,
georgesbasement

Plunging ahead, I imported each of eight tabs into my drawing, edited each appropriately so I could be sure that each possesses a reference point, I find that only one of the blocks can be pasted into the drawing. All the rest both fail to indicate their reference point or basic shape, but also fail the import procedure, with blank result - my drawing has no newly imported tab.

Dead in the water,
Best regards,
georgesbasement

Correction: There is indeed a "Rotate" menu item, and it is faster & easier to use than "Rotate, Move."

My apology to the developers.
Best regards,
georgesbasement

If the the overall drawing isn't too complex, it might be easier to dispense with using blocks and doing the rotation and editing / adapting of the single tabs simply in that main drawing. Later then you can isolate  / copy these single tabs into extra drawings (files) for each one to send to the cutting service.

By the way, as you where talking of that sleepy eye icon with eyelashes, it seems you are not using the latest stable version, which is 2.1.3. Some bugs annoying you may have been fixed.

If you provide a drawing file of what you already have achieved and a sketch of what you want in the end (a scan or photo) I could help you with the drawing.

Thanks to dellus for mentioning that there is a later stable version of LC than mine. I have been checking Trisquel's software update & upgrade functions, but that branch of Linux, which is based on Ubuntu, but from which every shred of proprietary (non-free, per the Free Software Foundation) software has been removed, hasn't yet caught up. In the meantime, I'm not aware of any troublesome bugs ... just slow learning on my part.

In the morning today, having recovered a little from my case of sleepy eye, I went back a little and studied one of my earlier posts and re-learned the procedure for creating blocks. What has been successful for my most recent drawing (various brackets and links) for the same project is that I opened each of my (not-yet-block) blocks (those of the eight compass orientations) for edit, selected the "Create Block" icon from the left-side toolbar, then used "Select All" from the upper-edge toolbar, picked a reference point, and then saved the newly created _real_ block with a (slightly) new block name.  Once I did all eight blocks, I could then select them one-at-a-time and use the "Import Block" item from the "Block" menu to poke the selected block into appropriate places on the drawing. I could then adjust the positions of the resulting tabs to be closer to the outlines of the selected objects. Putting the block/tabs onto all of the objects in the drawing took less than ten minutes. Adjusting them will take a little longer. These are destined for laser cutting from a sheet of quarter-inch-thick steel flat stock.

Thanks again,
Best regards,
georgesbasement

Continuing to a successful conclusion, I became more familiar with the "Snap" functions, "Rotate", "Rotate & Move", etc. and the importance of "Save." Even "Copy" and "Paste." The latter became necessary when LC quietly (off my expanded view of the drawing !) deleted major portions of the end curves on a couple of my objects. "Undo" was past "do" so I found I could draw an arc with three points on top of another example of the same curve and then select it (right on top of the original curve !) and move it with copy and past to repair the damage without affecting the original curve.

Rotating, moving, and patching in the tabs was fraught with inconsistencies because the transitions could never be perfect, and so I had to connect the fillets at each side of the tab with straight lines between points placed on the fillets and on the curve or straight side of the object.  All eight of the different orientations behaved OK, but I found one object which flat out refused to let me delete the unwanted curve between the two fillet curves & their extra patch-in lines, so I just deleted it from the object and put another tab at a different position.

Sometimes, "Divide" worked great: I'd select the command, click on the unwanted portion between the two fillets, etc., and then select the two intersections at the ends of the unwanted portions, whereupon the unwanted portion would disappear ... or at least turn blue, waiting for me to use "Select Entity" and "Delete" to get rid of it.

Sometimes, this procedure would cause part of the main object to become unselected, and in those instances I found that I could sometimes use "Trim" on the not-unselected portion of the object with one of those added-in straight lines as the cutting entity. Then, clicking on the not-unselected portion of the object would cause the unwanted section between the fillets to become deletable. Sometimes this attempt would crash LC, and I not-quickly-enough learned to save after each successful step, or I'd be faced with the tabular guessing game again.

"Trim 2" was most likely of all to cause crashes, and I don't remember getting any positive result with it. Plenty of other tools did work, however.

I now have a completed .DXF drawing with 32 objects and their quite shapely tabs sticking out in all directions; there are a half-dozen tiny gaps remaining in some of the transitions between arcs and straight lines, but those are easily fixable in the morning after a good night's sleep.

Thanks for all your very useful help & advice.
Best regards,
gergesbasement