topic Queue Item Placement Issue with Rotated Horizontal Cylinders in FlexSim Forum

Queue Item Placement Issue with Rotated Horizontal Cylinders

borja_lorenzo — Thu, 07 May 2026 08:00:19 GMT

[FlexSim 25.2.0]

I am working on a simplified model to visualize steel tubes stored in Queues.

The items are created by a Source using an Arrival Sequence. In the Source On Creation trigger, I read a label that contains the tube length. Depending on this value, I assign the item a commercial tube length of 3000, 6000 or 12000 mm, change its color, set the cylinder size, and rotate it to represent the tube in a horizontal position.

To implement the dynamic change of the flowitem visual/size according to the label value, I used as reference the following forum post, which works correctly for the size assignment itself:

“Change one flow item to another different flow item (in process flow or processor flow)”

However, after applying the horizontal rotation, I found a problem with the Queue item placement.

In the simplified model I have two Queues for comparison:

In one Queue, the cylinders remain in their default vertical orientation.
In the other Queue, the cylinders are rotated horizontally using the On Creation trigger.

When the cylinders are vertical, the Queue item placement works as expected: the tubes are grouped together without relevant visual overlap.

However, when the cylinders are rotated horizontally, the Queue placement no longer behaves as expected. The tubes appear overlapped or visually misaligned, even though the size, color and rotation are being applied correctly.

My question is:

What is the recommended way to make the Queue placement work correctly for long cylindrical flowitems that are rotated horizontally?

I would like to obtain the same kind of clean visual arrangement that I get with the vertical cylinders, but with the tubes lying horizontally.

Thanks.

Re: Queue Item Placement Issue with Rotated Horizontal Cylinders

FelixMoehlmann — Thu, 07 May 2026 10:19:16 GMT

The placement logic of the queue doesn't take item rotation into account. It only looks at the size. Hence why the item centers are placed in the same locations in both queues.

For better placement you can:

- Define a flow item where the length of the pipe is the x-axis (change Shape Factors in the "More Visuals" window). But the placement logic of the Queue also frequently leads to weird arrangements when items of different sizes are stored.

- Write your own placement logic in the On Entry trigger.

- Use a Floor Storage instead.

Re: Queue Item Placement Issue with Rotated Horizontal Cylinders

borja_lorenzo — Thu, 07 May 2026 12:20:42 GMT

Thanks for the clarification.

I tested the `FloorStorage` approach and it works much better for this use case. The horizontal tubes are stored correctly and the visual arrangement looks as expected without overlap issues.

However, I found another related issue:

When the items leave the `FloorStorage` and enter a Conveyor, the visualization becomes vertical again, even though I already applied the horizontal rotation to the flowitems.

I tried reapplying the rotation in the Conveyor `On Entry` trigger, and the trigger is executed correctly, but visually the items still appear vertical once they are on the conveyor.

So it seems the Conveyor is overriding or reapplying the item orientation internally after the entry event.

Thanks again for the help.

Re: Queue Item Placement Issue with Rotated Horizontal Cylinders

FelixMoehlmann — Thu, 07 May 2026 12:38:08 GMT

The Entry Transfer sets the item rotation when adding it to the conveyor. See "Entry Orientation" in its properties. If you later want to change the rotation of an item on a conveyor, use the "Movement -> Rotate Item" option in DP/PE/Station triggers.

Re: Queue Item Placement Issue with Rotated Horizontal Cylinders

joerg_vogel_HsH — Thu, 07 May 2026 16:39:17 GMT

I am not sure if this answer is related to this question. It deals with center of rotations.

Re: Queue Item Placement Issue with Rotated Horizontal Cylinders

borja_lorenzo — Mon, 11 May 2026 11:23:57 GMT

Thanks, your suggestion works partially.

I added a Decision Point at the conveyor entry and applied rotation + translation triggers there. Visually, the tubes are now correctly positioned horizontally on the conveyor.

However, a new issue appears: the conveyor entry spacing still seems to be calculated using the original cylinder diameter instead of the effective tube length after rotation. As a result, the tubes overlap once rotated horizontally, as can be seen in the attached image.

This becomes more challenging because the model contains multiple tube lengths.

One possible workaround I am considering is temporarily blocking the conveyor entry and only releasing the next tube once enough space is available according to its length.

Each item already has an "L_MP" label with values such as 3000, 6000, and 12000, which identifies the commercial tube length. My current doubt is how to evaluate the length of the next incoming item without relying on a Process Flow list and use that information to trigger the downstream Decision Point logic.

Before implementing that logic, I wanted to confirm whether the conveyor is still using the original bounding box/orientation of the flowitem for spacing calculations even after the visual rotation, or if you know of a more standard alternative to dynamically avoid this visual overlap with different tube lengths.

Thanks in advance

Re: Queue Item Placement Issue with Rotated Horizontal Cylinders

borja_lorenzo — Mon, 11 May 2026 11:27:47 GMT

Thanks Joerg.

I understand that this could also be related to the center of rotation and the spatial reference behaviour.

I think this may also be connected to the new issue that appeared after visually rotating the tubes on the conveyor. I described the overlap behaviour in more detail in my reply to @FelixMoehlmann, (Moehlmann reply ), since the items start overlapping as if the conveyor were still calculating spacing using the original bounding box before rotation.

However, I still have doubts about how exactly to apply the example from the linked post to this case, since there the focus seems to be more on modifying the container object itself, while here the spatial behaviour changes dynamically on rotated flowitems moving along conveyors.

I would appreciate any guidance to better handle this visual simulation of the items.

Thanks in advance.

Re: Queue Item Placement Issue with Rotated Horizontal Cylinders

FelixMoehlmann — Mon, 11 May 2026 11:48:53 GMT

The side defined as being the forward axis in the Entry Transfer will be used to calculate when an item can enter the conveyor. Changing that instead of using a Decision Point trigger will solve the problem.

Re: Queue Item Placement Issue with Rotated Horizontal Cylinders

borja_lorenzo — Mon, 11 May 2026 12:12:22 GMT

That works much better and solves the main issue, thank you.

I would still like to fine tune it a bit more by adding a small configurable gap between the tubes so they are not completely touching each other visually.

Is there a standard way to configure that directly from the Entry Transfer/conveyor settings, or would I need to rely on some supporting logic such as temporarily blocking the entry port for a short time before allowing the next item to enter?

Re: Queue Item Placement Issue with Rotated Horizontal Cylinders

FelixMoehlmann — Mon, 11 May 2026 12:54:43 GMT

The spacing options in conveyor properties allow you to set fixed gaps between items.

Re: Queue Item Placement Issue with Rotated Horizontal Cylinders

borja_lorenzo — Mon, 11 May 2026 13:21:41 GMT

That works perfectly, thanks!