Defining a thread mill

[BillGEGHV]

So I have a #4 40-64 TPI thread mill I need to set up. I am threading an M3 .5 thread about .2 deep.  

• 1st is there a library of common sizes, there are only a few and all lg di. 
• How to define flute length? Seams strange its called flue length seams more like the thickness of the cutting edge?? 
• The thread pitch is .5 correct? 
• Using SFM from Manufacure (Online Carbide) of 800 this maxes out my spindle, my max is 7500 so do I just change the spindle speed to 7500 and the sfm will just adjust? This part of SFM confuses me any extra input would be nice. The other part that Im always unsure of is when changing SFM it does not change the cutting feed rate and in this tool im at 40 in min and that just seems CRAZY to me with such a small tool. the shaft is no bigger than a toothpick. 
• I changed the plunge feed rate to .00022 as per manufacturer but again why does this not change th cutting feed rate? OR does the cutting feed rate just not apply since its a thread mill and the cutting in reality is only being done by the vertical feed rate? 

   

[leo.castellon]

We use Scientific Cutting Tool thread mills, they work great, and they have a huge variety of sizes and lengths to choose from, Harvey Tools also has a large selection. The advantage with the Harvey Tools is that there is a library available to download from them into your Fusion 360. What I usually do is look for a Harvey Tool that is close to what I have and use that for the tool model. Regarding feeds and speeds, remember that interior hole work, the feeds need to be adjusted. I use this as a guide, tm_sptmun.pdf (sct-usa.com) 

When I choose a thread milling operation, I get an option to set cutting feed rate separately from plunge feed rate, these are not tied together. If I type in the surface speed in the box and type in the suggested chip load per tooth, and then override the spindle speed, it does change the feed rate in my Fusion.

7000 RPM for a thread mill operation seems awfully fast, but I have no idea what material you are machining. I would suggest doing a test on a scrap piece of metal to dial in your settings for the thread mill. Always sucks to spend so much time on a part and the last thing you do is put threads in it, by hand tapping or thread milling and then have the project go sideways. I guess that is why Helicoils and thread inserts were invented, 😃.

LeoC

LeoC

[BillGEGHV]

Ya these molds are a big investment in time, 5 hrs of machine time. trying to get them to reliably run unattended RN.  Im running 6061 T6