Endmills Breaking

anyone having issues breaking endmills? So far I’ve broken 3 of them. I’m generating my toolpaths on Fusion360. Most recent one was Using endmill #51862 (1/16 Diameter x 5/16 single flute 2inch in length). I set Feed per tooth to 0.0008in, optimal load 0.02in, maximum roughing 0.02 in, which I believe is far lower than recommended for this endmill, and it broke very quickly. using aluminum stock. any suggestions? these endmills are expensive!

Let me know what model Pocket NC you are using, your spindle rpm, and the amount of stick out on your tool. I have attached a pdf that describes the feeds and speeds necessary for a Pocket NC V2-50 in case that is the model that you are using. I did not include the spreadsheet mentioned in the document since you are using different a different tool.

I would reduce your optimal load down to 0.003 in (roughly 5% of the 1/16" diameter of your tool).
V2-50 Speeds and Feeds for Aluminum and Brass.pdf (185.9 KB)

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the pdf mentions a xlsx file - where can we find this?

I have attached the spreadsheet mentioned in the pdf. The values are specific to the tools indicated on the sheets but are good starting values when trying to determine speeds and feeds for different tools.

V2-50 - Aluminum.xlsx (51.4 KB)

Thank you for the file!

Hi Chuck, thank you for your reply. I am using the v2-10, are those values you listed above ok for this machine as well or specific to the v2-50

Unfortunately, those are values specific to the V2-50. Our V2-10 standard feeds and speeds can be found here.

My limited experience has shown me not all carbide end mills are handling aluminum the same way.
For instance I had a 3mm 2 flutes (Black coated) carbide endmill that quickly accumulated aluminum and became obsolete, making a very bad noise.
On the other hand, I have a 6mm carbide 4 flutes specifically for Aluminum, and never have such problem.
For sure the 3mm would not evacuate the heat as well as a 6mm. For having worked with aluminum for a while, I know it is a problem, and that coating on the 6mm really works. Unfortunately, the maker (DBLi -Here in Taiwan) has not identified the coating precisely, other than designating it for Al…

Also ran a 1mm carbide made by Speed Tiger to cut in stainless steel, no problem…

I’ve used ZRN-coated end mills with good results on my Tormach mill, but always use a FogBuster with that. So far as I know, the Pocket NC mills do not tolerate coolant well, though might be able to slide by with dinimal drops of TapMagic Aluminum or WD40 bottle liike one of these:

You’d probably want one of the smaller needle sizes (larger gauge size) and the smallest bottle should fine.

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