[dlaery]

I am cutting a 3d cavity in a 2 part mold, aluminum. it is 12 inches long by 1 inch wide, rounded, tapering long ways down to 1/8 inch
I use a 1/4BM, then a 1/8BN to finish, my mill has lead screws, so a little play not much but some, which cut will give me the smoothest finish?
the first 4 molds halves I have used climb, the finish is probably ok but looking for an opinion if i switch to conventional will it be worse or better?

Thanks

[peteeng]

Hi David - Climbing is the best strategy. Conventional cutting the chip is zero thickness at the start and thick at the end. This means the tool skids slightly before it starts. Tools have to be sharp and machine very stiff to get best results. Climbing cuts thick to thin so the starting cut is more consistent, Ensure your chipload (chip thickness or chip thickness per tooth or feed per tooth) is correct for your tool. If Fz is correct you will get a nice finish... Peter

why use 1/8 to finish? Use the biggest rad you can. Talk to the tool supplier to determine the best depth of cut for the finish pass and the best feed per tooth for the tool you are using. Or get a tool designed for finishing. I'm using "diamond like carbon or DLC" tools at the moment and they are brilliant...

[dlaery]

thank you! i will keep climbing.
what is "Fz"?

[peteeng]

Hi David - Fz is feed per tooth. Its the size of the bite of material the tool takes as it moves forward. Tool suppliers have Fz guides for their tools. Guhring have one thats specs Fz and various cutting info. If the bite is too small and the machine is not rigid the tool slides and you get a poor surface and high tool wear. If the bite is too big the surface is rough. If its just right its smooth... Peter


Katalog_Fraeswerkzeuge_EN_2017.pdf (guhring.com.au)

Hi david - good site - but you may need to fix this! Peter

[dlaery]

Hi David - Fz is feed per tooth. Its the size of the bite of material the tool takes as it moves forward. Tool suppliers have Fz guides for their tools. Guhring have one thats specs Fz and various cutting info. If the bite is too small and the machine is not rigid the tool slides and you get a poor surface and high tool wear. If the bite is too big the surface is rough. If its just right its smooth... Peter


Thanks! i will look into that.


Katalog_Fraeswerkzeuge_EN_2017.pdf (guhring.com.au)

Hi david - good site - but you may need to fix this! Peter

It's a test to see if anyone is paying attention. You are the first one that has commented. :cheers:

[peteeng]

Hi David- Here's an Amana tool data sheet maybe easier to start with vs Guhring. Its a big catalogue...They will have a similar sheet for their round tools. Peter

[dlaery]

Thanks, i will have to study that a while.

[joeavaerage]

Hi,
climb milling is generally prefered but only if you have no backlash. With conventional machine like an old Bridgeport with a swag of backlash
you cannot climb mill, you risk 'pulling' the job in. Don't worry if you don't understand, it will happen to you just once and be a real 'f-up' and you'll then
know the difference between climb and conventional.

Craig