Incorrect Thread Pitch posted

[Anonymous]

Houston, we have a problem!

I drew a threaded nipple that has 1.375-12 left handed thread.  When I moved into the manufacturing workspace and set up my machining operations.  I saved everything and then posted to the post processor.  After installing on our Haas ST20Y, we ran 1000 parts.  We thought everything was good until the customer said the threads were not good.  Upon inspecting the parts, using an imperial thread gauge, the threads didn't fit correctly.  I checked the threads using a metric thread gauge, and they matched for a 2.0mm thread pitch.  I then checked to post on the machine and the posted feed was 0.0787(2mm thread pitch) not 0.0833(12 threads per inch thread pitch).  I check Fusion 360 this morning and it posted the same but incorrect thread pitch this morning.

I feel that somewhere that the thread pitch was messed up in Fusion.  I think I have found a solution to salvage the 1000 part run, but The Team needs to do some checking.

Andy

[HughesTooling]

The CAM does not read any info on the thread apart from the diameter. You have to set the pitch when you set the OP up.

Mark

[HughesTooling]

Just noticed the thread OP should read the info from the tip. I usually use AG partial form tips so hadn't noticed that before.

Mark

[Anonymous]

I set the thread up in the design workspace as a 12 threads per inch. All
of my dimension in preferences are in imperial dimensions.

[Anonymous]

I specified the thread pitch in the design workspace not in the manufacturing workspace.  In my preferences, I have all my dimensions set as inch(imperial).

[HughesTooling]

Like I said the Manufacture workspace does not read any info on the thread apart from the diameter. No parameters are passed between the different workspaces at the moment, the tool and tip you select in the library set the pitch.

Mark

[Anonymous]

If Fusion does not pass information between work spaces, how does it know that it is running the correct thread pitch.  The diameter I was threading is 1 3/8" which is extremely close to 35mm.  Evidently Fusion took it upon itself to use a 2mm thread pitch instead of the 12tpi thread pitch that was used on the design page.  Both of these thread pitches are close, but at 1/2" in length, the 2mm will not thread any further.

What setting should I set to ensure this does not happen again?  This almost cost a 1000 part run!

[HughesTooling]

Fusion only reads what's set in your tool library. You need to set the tool tip to the pitch you want.

Mark

[wmhazzard]

I can't help you on the CAM problem but why wouldn't you inspect the first part off the machine to make sure it is correct instead of letting your customer point out that you screwed up?

[Anonymous]

because in 1/2" length, the thread pitch difference is about 0.020.  The item the customer gave us to check the threads with was loose enough, the threads worked.  They have some with a little tighter diameter that the parts didn't thread into which is how we discovered there was an issue.  The thread pitch for a 2mm thread is 0.0787, 12tpi is 0.0833, the 0.0046 difference is so **** close, you don't see it.

[Jools-Taylor]

I've come across this before and just had it today too. I modelled a 1.25mm pitch and the field for thread pitch in the CAM was populated at 2mm. 

Surely if they can't import the info from the design then they should leave that field as 'zero'. At least that way if you didn't add something it would failsafe and not generate a tool path rather than generating an incorrect one.