[porter]

We've started using thread mills to machine threads for ports (ex: SAE J1926/1). The problem we're having is that we're getting a fine hairline strand of metal at the start of the threads. We've been using a razor knife to remove this. Has anyone else had similar problems and/or ideas to eliminate this?

Let me know if I need to provide more info.

Any help is greatly appreciated.

[sambo67]

I just completed a thread milling job with the same problem . I ran the end chamfer to the maximum of my tolerance and was able to fix the burr issue.Also are you starting at top and going down or bottom and going up?

[porter]

We start at the top and go down.

I ran the end chamfer to the maximum of my tolerance and was able to fix the burr issue.

Are you referring to the "L1" dimension (Spotface to angle break depth)?
Thanks.

[sambo67]

IT IS BETER TO START AT THE BOTTOM AND COME UP, ALSO ARE YOU USING CAM SYSTEM OR CONVERSATIONAL PROGRAMMING

[porter]

CAM system but I believe we used Vardex software to generate thread milling code.
(Fadal Mill)

[sambo67]

I believe you are referring to your tool using L1.I am talking about the actual thread lead chamfer on your part

[porter]

The L1 I was referring to is part of our port specifications. See: http://www.goodyearrubberproducts.co...n1.Page477.pdf

[sambo67]

we are talking same.you have +.015 on your tolerance as you know.that may not be enough to do away with burr.try running from bottom up conventional milling with a couple of light finish cuts

[extanker59]

The L1 I was referring to is part of our port specifications. See: http://www.goodyearrubberproducts.co...n1.Page477.pdf

Ah yes. I remember doing some aluminum manifolds with multiple ports similar to those. Also threadmilling. You're right about those very fine hairs at the top where there is an incomplete thread.
It's been a while but I think we put our porting form tool in twice and threadmilled twice in an attempt to get it burr free. (also threadmilled from bottom to top to climb mill). It was better but still had something there to deburr no matter what.
If you get some method that works, post it here so we all can learn.