No problem, I’m loving these extrusions, I feel like they really stiffen things up.
That is the same one i used though I had them from the days of the Shapeoko 2. They work great! I suggest tapping the holes on the end to M5 (with a GOOD CNC tap like this: http://www.ebay.com/itm/M5-x-8-D4-3-Flute-Spiral-Point-Plug-HSS-EX-TiCn-ANSI-CNC-Combo-Tap-YG-1-T3284C-/151083162393?hash=item232d421b19:g:~c4AAOxyHE5RpjTv and not some cheap hand tap.) Then either mill or 3d print a plate to lock it in fro the tapped holes and the extrusion span on the front and back of the mill. You will also need a few M5 8mm screws and some M5 drop in T nuts. Works like a charm and no drilling of your nice mill bed to mount it.
C’mon, live on the edge!
I’ve already bought a 10-32 version of the above and have cut threads with success. Still a bit nervous about cutting real threads on real parts. Might save me a load of time though if I can nail down the tool paths. 
I have been looking into the same thing as I have had to ramp up production to the point where even with a tap head, the tapping is taking too much time to keep with with demand. I think in the next week or so I will switch over to thread milling on everything I do also. Trying to tap 200+ holes a week in 3 sizes is not fun at all. Will also be very helpful in the custom RC parts I am starting to make. Talk about lots of threaded holes! What did you use for CAM? HSMxpress does it so will stick with that so far as it is dead easy to so. But never fun to watch an expensive end mill go in for the first cut as you hope you programmed everything right.
Good old fusion 360 for me. It also does everything. Just add your thread size, select the hole, set the pitch and tell it how many passes to make (i usually do 3, but 2 the is “recommended” number).
Fusion 360 does threads just like that? Hmmm…
Its not hard. You can just drill the hole to be the minor diameter, then bore with a thread mill to the major diameter at a given pitch. For example, a 10-32 thread would have a 1/32 pitch (.0313) and you can set a number of passes at a given width of cut.
I think theres also an actual thread milling setting somewhere, but its not really necessary.
Nice to hear we have options on software that will cut threads. Where do you get your thread mills and which sizes do you find most useful?
The link a few posts back is where I got mine. I didn’t buy the M5 one in that link, rather the #10 version, since I have to tap american threads.
HI Travelphotog what is the part that you are making?
It is a hot end mount for a delta 3D printer. You can see more info about it at my site http://713maker.com/
Holy Hell! 