[tremx]

Hi, I´m learning about CNC machines and now I am with a school project, I need to build a toy from a solid block of acrylic. I already did the design in a CAD software and I'm almost done getting the code for the machine, but I can't find the best feeds and speeds to get a good finish in the less time posible (the time is important).

The solid block is 2 x 3 X 5 inches.

I also have another restrictions, I can't use more than 4000 rpm in the spindle, and I only have this small tool diameters 3,4,5,6,8 millimeters, and I can't do a lot of tests in the machine, every time I use the machine my "efficiency grade" goes down. The tools are some of 2 flutes but most of them are 4 flutes.

I already try some speed and feed that I calculate, probably bad, becaue I almost break the tool.

Where can I find this speeds?
Reading in this forum I found someone with a similar problem, he said that he will try a Feed rate of 600 with 1500 rpm in the spindle, but then he don't post how it went. His speeds are reasonable?

Edit: first time I use cut dephts of 4 mm, now I think I should use 1.5 or 1 mm

[tremx]

also any suggestion in the operations to decrease time is welcome, I use cavity mill and then contour area. I am using NX.

[rustybotak]

also any suggestion in the operations to decrease time is welcome, I use cavity mill and then contour area. I am using NX.

feed rate=2400mmpm
rmp=8000
stepover=40% of cutter dia
stepdown=2mm

this is what i use for dia 6 hss cutter...

[tremx]

I can't use 8000 rpm, Do you think I can get a proportional equivalece?

For example, 4000 rpm with 2200 mmpm?

Thanks!

[rustybotak]

I can't use 8000 rpm, Do you think I can get a proportional equivalece?

For example, 4000 rpm with 2200 mmpm?

Thanks!

u mean 1200 mmpm right? if that the case it should fine...btw it for 4 flutes cutter

[tremx]

u mean 1200 mmpm right? if that the case it should fine...btw it for 4 flutes cutter

sorry, yes I mean 1200 mmpm, I also have 4 flute cutter so I hope it works.

THanks rustybotak!

[neilw20]

After getting a reasonable finish, a flash of heat with a flame works wonders.
It is a bit tough trying to do this - can't do much testing.' efficiency grade goes down!'
Some of this needs a bit of practice - it only seems to come with experience.
Different cutters and different material (specs) give vastly different results.
Cut depths are a function of the cutter diameter and strength.
Look at specs supplied by tooling suppliers. Email, ask..

Rusty? Nice. :wee::wave::cheers:

[rustybotak]

After getting a reasonable finish, a flash of heat with a flame works wonders.
It is a bit tough trying to do this - can't do much testing.' efficiency grade goes down!'
Some of this needs a bit of practice - it only seems to come with experience.
Different cutters and different material (specs) give vastly different results.
Cut depths are a function of the cutter diameter and strength.
Look at specs supplied by tooling suppliers. Email, ask..

lol...give u a 'like' :cheers: