3D Thread modeled

[yanouk73]

Hi,

After using STEP and 3D modeled thread, you can see there is a problem because the entry of the thread 3D helix is not concentric at all with the threaded hole, this can generate production errors if the CNC is made from the 3D thread center (that is miss align, not concentric).

The solution is to make a 3D champfer, using the ID of the thread as the origine, and the OD as the end output, this will fix several problems, because this way, on the drawing sheets, we will be sure to see the center of the threaded holes concentric, but also, if per exemple, the chamfer is made at same the diameter as the thread, you can dimension the thread using the OD of the chamfer and this is linked to the thread size, so it will follow the 3D modifications.

In the drawing, instead of diameter sign, we can add the M or US thread prefix, better, if when you generate the drawings, the thread appear automaticly using a check box option.

In the case that the entry of the thread is at angle, the OD limit of the thread can be extended as a cylindric shape up to the outside of the body, anyway, it's impossible to start a thread from a hole that is at angle entry from a surface, we need to make a flat surface entry first.

actual 3D threadIdea 3D threadActual Drawing of 3D ThreadIdea Drwaing of 3D Thread

[yanouk73]

Actual 3D ThreadIdea Of 3D Thread with Champfer

The Actual 3D thread is not concentric, it can make CAM mistake because you can actually find a different center if you select the center of the entry generated by the intersection of the helix and the entry surface.

With my idea of 3d modeled thread, this fix this in the 3D STEP file, in the drawing (because the champfer is made using ID of the drill size and OD of the thread size) per exemple, a M5 will have an chamfer larger diameter of 5mm and ID as the drill size. It's also concentric after my suggestion, so it good for using in CAM for selecting the screw center for drilling and threading.

Yan

[yanouk73]

Also when you send a 3D STEP file to a supplier that will mill the parts, he can find in 2 second the Thread size and the Thread drilling size, this way it's easier and safer to communicate, and no need for sending drawing, except for tolerancing (3D tolerancing is my next IDEA 😉

[yanouk73]

Here is a thread section view, I think an good option for using 3D step file to send a complete information for the machining of the parts is to use the thread as made on left side, with a additionnal body for the thread 3D volume, so this way, the file will stay lighter to work with, and all the data will be available, drilling size, thread outer diameter, thread depth, as we can see here, we can measure it in the 3D, we can find a M4x0.7 x 15mm depth thread.

The best of all, if we can make the additionnal solids that represent the thread volume without adding anything in the Tree, so the thread solid is linked to is body and unselectable, when we export in STEP, if it become separatly, it's not a problem. When we work in Fusion, we keep this as one master body with thread represantation attach to it.

The Thread on right is the modeled version, with a champfer entry that have the thread diameter at the largest point of the chamfer (4mmDia)

Yan