Author Topic: Tickmarks  (Read 374 times)

Dr PR

  • Hero Member
  • *****
  • Posts: 5398
Tickmarks
« on: October 22, 2016, 09:57:07 AM »
V26.1x64 10-Oct-16
Win 7 Pro 64

I needed to place 112 tickmarks (Draw/Tickmark) along a line and got the message that the "Sections" number has to be between 1 and 100!

But if I set a small "Mark Distance" number I can get a lot more than 100 tickmarks - at least 500.

The "Sections" limit of 100 if far too small.

****

Now I am going to try to figure out how to place 112 equally spaced tickmarks along a complex CURVE where I can't find the midpoint!

Phil
DesignCAD user since 1987

Lar

  • Hero Member
  • *****
  • Posts: 2484
Re: Tickmarks
« Reply #1 on: October 22, 2016, 01:49:31 PM »
Here's a wild approach, since you want 112 tickmarks but the tickmark command asks for sections, and is limited to 100 (ie, 112 tickmarks means you would have to put 111 in the 'Section:' box)...

1] Extend your curve by its length divided by 111 (this is so you can put 56 (ie, 112/2) in the 'section' box, put 2 in the 'divisions' box and when done remove the last tickmark):

... select the curve and get its length from the info box, divide this by 111, then draw a circle with its center at the end of the curve with a radius of the result above, then intersect the end of the curve with the circle...

2] Do the Tickmark command (56 sections, 2 divisions, make 'small tickmark' the same as 'large tickmark'). This will result in 113 tickmarks, with #112 right on the center of the circle.

3] Ctrl+E (Delete Last) to get rid of tick #113, move the end of the curve back to the circle's center (ie, back to its original location) and delete the circle.

Result: 112 tickmarks.

Of course, if you really want 112 sections just ignore the extending of the curve part (steps 1 and 3).

Lar
« Last Edit: October 22, 2016, 02:09:17 PM by Lar »

Dr PR

  • Hero Member
  • *****
  • Posts: 5398
Re: Tickmarks
« Reply #2 on: October 22, 2016, 07:51:22 PM »
Lar,

Thanks.

In that example I needed 113 tickmarks after all. But I accomplished it in a different way.

I was creating a riveting design that called for N x rivet diameter spacing between rivets, where N was the maximum allowable spacing.

I drew a line (actually a surface intersection) along which the rivets were to be placed - actually multiple parallel lines. I used the Info Box to get the length of the lines and divided this by the maximum spacing. This usually gave a fractional number. I rounded up to the next whole number and used this to divide the line length. Then I used this number to define the spacing for tickmarks.

It is just odd that I can get many hundreds of tickmarks this way (over 500 in one test) but I am limited to only defining 100 spaces.

****

This is just one of the shortcomings of the Draw/Tickmark function. Many versions ago (V18?) I reported that occasionally the last tickmark is misplaced - not at the end of the line but at the position of the next to last mark, or the one before that.

And if a curve curves in three dimensions the ticmarks fall all around the curve but do not actually have endpoints on the curve.

Phil
DesignCAD user since 1987

Lar

  • Hero Member
  • *****
  • Posts: 2484
Re: Tickmarks
« Reply #3 on: October 23, 2016, 05:55:53 AM »
If you only need the tickmarks as markers and don't necessarily need them perpendicular to the curve then you can use 'surface connect' by drawing another line (of any shape) to connect between. You are limited to 198 divisions but you have the option of calculating along the full line or using the points of the line (when the 'curve' is a vectorized-arc, for example. Notes: this option seems to only work for vectors so for actual curve entities you will have to use 'curve to line', do the connect, then 'line to curve'; not limited to 198, will use the number of points in the first line you click on; to get perpendiculars create the 2nd line using a parallel command, but this does not work well for 3d lines).

Lar
« Last Edit: October 23, 2016, 06:01:17 AM by Lar »

Dr PR

  • Hero Member
  • *****
  • Posts: 5398
Re: Tickmarks
« Reply #4 on: October 23, 2016, 10:22:21 AM »
In this case I just needed to set points at equal spacing along a curve. The slight offset of the tickmarks from the curve weren't large enough to worry about.

The points along the curve were for locating the positions of rivets along a curved and twisting surface. I set three handles on the rivet head and used the tickmark end as the center, the next tickmark to set one direction and snapped to the edge of the surface to set the second direction. This places the rivet heads "flat" on the surface. I posted a picture here to show the results:

http://forum.designcadcommunity.com/index.php?topic=6725.0

Phil
DesignCAD user since 1987

DrollTroll

  • Kindly Curmudgeon
  • Administrator
  • *****
  • Posts: 4121
Re: Tickmarks
« Reply #5 on: November 07, 2016, 01:52:09 PM »
Find the length of the curve in the Info Box. Click on that 'change' button at the bottom of the Tickmarks dialog. In the Distance field, enter the length of the curve divided by the number of divisions you need (ex. 111 in this case). Rounding error may cause it to skip the very last tickmark, but that can easily be added manually if necessary.

But the limit of 100 sections seems bizarre and arbitrary -- I'm sure we can increase that limit.
« Last Edit: November 07, 2016, 01:54:10 PM by DrollTroll »
2016 marks my 24th year in DesignCAD-Land!