topic Help with Schematic Thread with partial thread in Dynamic Blocks Forum

Help with Schematic Thread with partial thread

JBerns — Mon, 27 Oct 2025 17:19:34 GMT

Community,

I am trying to develop a schematic thread that can be stretched in 1/8" increments.
As the block is stretched, the root and crest lines should appear.

In other words, begin stretch and a crest line appears.
Continue stretch and then a root line appears.
Continue stretch and another crest line appears.
An alternating pattern.

I can get the root and crest to alternate, but they do not appear as soon as they should.
They "lag" one thread behind the current length.
The block is using chained actions.

I have seen other thread examples on this forum, but all show an array of a full thread in the pattern. My goal is to allow partial thread patterns (root / crest).

<< This thread >> shows an "alternating" pattern, but I have not been able to get the process to work in my block.

I tried using a hatch pattern to fill the area, but that gets messy having to move the hatch origin.

I have seen videos on this forum that move the linear parameter start/end points by 0.001", but that does not help correct the "lag" issue.

The block contains three linear parameters, one move action, and stretch action, and two array actions.

I have attached a drawing for review. Block name is SCHM_THRD.

I hope this is possible. I look forward to your replies.

Regards,
Jerry

Re: Help with Schematic Thread with partial thread

Libbya — Mon, 27 Oct 2025 18:12:27 GMT

The first new arrayed object appears when the associated linear parameter length is equal to 2X the column offset, 2nd new object appears at 3X, etc... You can use a chained linear parameter associated with the array in order for each object to appear precisely where you want it by changing the as-drawn length. Use the info in the first sentence of this comment to determine what that length should be. You had those chained parameters in there, but their lengths were incorrect. I also needed to do RESETBLOCK for each of the existing insertions in model space. See attached.

Re: Help with Schematic Thread with partial thread

j.palmeL29YX — Mon, 27 Oct 2025 18:26:11 GMT

Something like the attached suggestion?

(If you whish you may adapt the value set of OAL to your needs).

[EDIT]: Additional explanation: I used two PATHARRAY (not array action).

Re: Help with Schematic Thread with partial thread

JBerns — Mon, 27 Oct 2025 18:47:53 GMT

@Libbya,

Thanks for the quick reply and solution.

I kept trying increments of 1/8" because that was the thread pitch. Thanks for finding the mistake.

Regards,

Jerry

Re: Help with Schematic Thread with partial thread

JBerns — Mon, 27 Oct 2025 19:15:41 GMT

@j.palmeL29YX,

That works too! I have never tried a PATHARRAY in a dynamic block.

How did you make the paths disappear? A "path" appears to be a LINE on layer 0, with normal (default) properties.

When I try to recreate your block, my paths are visible. What's the trick?

Regards,

Jerry

Re: Help with Schematic Thread with partial thread

j.palmeL29YX — Mon, 27 Oct 2025 19:28:05 GMT

@JBerns wrote:

How did you make the paths disappear?

Convert the lines to ConstructionLines (command bconstruction). They are invisible in block references.

Re: Help with Schematic Thread with partial thread

JBerns — Mon, 27 Oct 2025 19:43:44 GMT

@j.palmeL29YX,

Wow - learned something new today!

Was not aware that AutoCAD had construction geometry in blocks. Must explore this.

There is no distinction between a normal line and a construction line when using LIST, PROPERTIES, or ActiveX DumpAllProperties.

Only AutoLISP showed the XDATA info that it was a BConstruction object.

Thanks again for the info.

Regards,

Jerry