[routalot]

\r\n \r\n With XPS foam you should have no problems at all.With 150mm long tools at 6mm diameter and either MDF or anything harder you are heading into challenging territory as they may be prone to chatter as well as increasing the loads on the spindle bearings.Anything with a length of more than about six times it\'s diameter needs to be treated carefully.Long end mills and a router for aluminium may work in theory but may equally well make a lot of noise and give a poor quality surface.You don\'t often encounter such extreme proportions even on machining centres built for exclusive use on metals and which have the advantage of very heavy construction to damp the vibrations.They tend to be used only for those operations where there is no realistic alternative and need to be run with very cautious cutting strategies.\r\n \r\n

[FiveO]

\r\n \r\n Ok, thanks. How to find correct speed for those extra long mills, and chip load, feedrate?\r\n \r\n

[routalot]

\r\n \r\n I think you will find that since so few people use such long mills on hobby machines,you will have to do some experimenting.Beware of the twin perils of flexing of the long tools and destroying the bearings at the nose of the spindle due to leverage.The typical recommendations for optimum speed will be based on industrial machines running conventional lengths of tool.\r\n \r\n

[FiveO]

Hi!

I am new to tooling/milling, just built my first machine. Spindle is 2.2kw 24k Rpm max, ER20 collet. What to consider(I don't want the bits to break) when milling:

MDF and XPS foam. I have 150mm long 6,8,10,12 diameter 2 flute HRC55 end mills and ball End mills.

Aluminium. I have 100mm long 6,8,10,12 diameter 2 flute HRC55 end mills and ball End mills.