Warning and Issue with Two Co-linear Opposing Tapped Holes

Zane_Morris

Hi there,

I have a cylindrical solid bar. In each end, there is to be a counterbore/cylindrical cutout for the shoulder of a shouldered socket head cap screw, plus a tapped hole. The direction of the threads in the taps will oppose each other.

I modeled the bar as an extrude. I modeled the shoulder cutout features as extruded cuts. I then created a tapped hole with the hole feature on one end as shown in image 1. It is an M4x0.7mm tap 10mm deep, with the pilot hole being 14mm deep, to allow room for a plug tap. Call this tap1.

I then move on to create the second tapped hole feature. It is to have the same drill and tap depth as the previous tapped hole. Call this tap2. To do this, the drilled regions of tap1 and tap2 will intersect, but the threads won't. However, when I try to create tap2, what I get is an error saying "the hole does not intersect the part". I do not get this error when I reduce the drill depth of tap2 to be such that the drilled regions from tap1 and tap2 don't intersect (as seen in the image below).

Therefore, the issue is independent of the thread depth. The error message is incorrect. The drilled hole for tap2 does intersect the part, and would remove material, up until it reaches the drilled region from tap1. It seems that the hole feature doesn't allow intersection with another hole feature.

From a manufacturing perspective, it may be bad practice to drill and tap tap1, then drill and tap tap2 (as the order is described above). In actuality, you'd likely drill the pilot hole thru the part (in onshape, use an extruded cut), then tap from either end (in onshape, two separate tapped holes). However, I cannot replicate this last workflow in onshape, as the "tapped hole feature" will have a warning saying that it doesn't interest the part (no geometric change), and the hole won't generate.

Therefore, I'd like two things:

1. Perhaps an explanation from someone who works for onshape explaining why this is the behavior of the feature. I see this as a valid limitation to current modelling capabilities. This part can definitely be manufactured, but can't yet be modeled in onshape. If I am incorrect, please do let me know!
2. A possible workaround, so that I can portray the threads from the two threaded holes in a drawing with the correct depth of tap2, and be able to send a drawing for this part to our manufacturer on time.

Thank you for any information you're able to provide!

Zane

Oliver_Couch

I have reproduced your problem.

Without knowing for sure I suspect it is failing when creating the conical surface at the bottom of the hole.

Changing from a blind hole to a through or up to hole appears to resolve the issue for me.

Scratch that. It seems it doesn't work. I'm not sure what I did that I thought it worked.

IIt also fails when the hole bottom is set to flat.

Seems to me there's no native way to counter tap a hole as the hole feature is the only way to add internal threads unless I'm mistaken.

I played with depth. It works until there's less than or equal to 0.1mm overlap.

Here's an example: https://cad.onshape.com/documents/824b0a930dd2127b66ddf496/w/c8a01aaf230fce8e3085086f/e/2ba86451a70f4e52a2c978e0

GregBrown

Did you try it with a counterbore holes instead of separate features for the shoulder cutouts?

If you're seeing an error you should submit a support ticket.