Max MRR in plastic?


(martin redeby) #1

So I’m still having chatter issues… after changing spindle and getting fancier tools… so Im doing something wrong (pushing it to hard) or the machine is still messed up…

So could some of you who work in hdpe or delrin/acetal/pom post your max mrr cut data with 6mm 1/4 tools (prefably with single flute endmills) so I can compare.

Or just your max MRR with any tool in those materials… I need to remove lots of material in some of my future projects…


(William Adams) #2

We do have Delrin and HDPE for 1/4" tooling listed at:

and I used them successfully on some cutting boards from the local restaurant store.

We do have some notes linked to from: https://wiki.shapeoko.com/index.php/Materials#Usage_notes_.28Carbide_3D_HDPE.29

There are some recommendations for endmills for plastics at: https://wiki.shapeoko.com/index.php/Endmills#Plastics


(martin redeby) #3

yhea seen some of that, but all of it is for the SO3 and I was looking for some Nomad specific experience…


(William Adams) #4

My apologies, didn’t see that this was posted in the Nomad section.

Start with the chipload data from: https://wiki.shapeoko.com/index.php/Materials#Nomad_883 and translate it to the endmill you’re using?

There are two schools of thoughts on 1/4" endmills in the Nomad:

  • they require more torque than the motor can put out when used in harder materials — only use in easily cut materials such as foam or Renshape
  • the added mass allows the endmill to maintain its speed when cutting, so is an advantage

The official Carbide 3D answer is the former I’m afraid.


(martin redeby) #5

torque doesn’t seem to be the issue, rigidity though…

well I guess I’ll try the same surface speed as those in that chart… though at 3000rpm ish torque might be an issue


(Phil Gorsuch) #6

I’ll second that on the torque - I have a 3? 4? flute 0.25 mill that doesnt seem to drop RPM when engaging HDPE whilst still delivering good chips. Away from the PC so I dont have feeds and speeds. Will note conventional vs climb milling made a large difference in chatter for me with the larger end mill. As I recall climb was the ticket.


(mikep) #7

Here’s the power chart for the spindle motor (the spindle has a 2:1 ratio):


(Phil Gorsuch) #8

Uh-oh… rainy Sunday pondering - so really… if one changed the motor to spindle pulley ratio (existing must be 1:3 or so) one could get more power delivered at lower spindle RPMs… hmmm…


(martin redeby) #9

well, running low speeds (3500rpm) didnt help, guess I’ll scrap the single flute 6mm for now and move on to the 3flute.

I wonder if changing the spindle bearings to something that require the shaft to be press fitted would help. Or some high precision angular contact bearings, though paying 200$ for a pair of bearings, that experiment is not super enticing.


(martin redeby) #10

so common anyone who wants to brag about their highest mrr?