Humps

[themayor]

What would cause me to get humps while machining ? I am using a rotary table vertically and while cutting from one pass to the next i am getting humps like the sides are cutting deeper than the tops ? Dont really know how to explain it. I am using a 1in alpha mill cutting aluminum

 

[gadget_lover]

A picture would really help. :)

If there is a raised spot from one pass the the next it usually indicates that the mill is not trammed properly. When in tram, the cutter is perpendicular to the table in all directions.

Daniel

 

[Th232]

Got a picture? What spindle speed, feed rate and depth of cut? Not exactly sure what you're describing either.

 

[precisionworks]

You may want to look through the Korloy specs & make sure the feed & sfpm are in the recommended range.

Setup should have the spindle as close to fully retracted as possible. Lot of spindle overhang exaggerates every little issue. Use the spindle lock to assure maximum rigidity.

RT locks should be set to drag as much as possible while still allowing the table to rotate without undue force. Both X & Y table locks need to be engaged.

Cutting with some kind of lubricant-coolant? A spray bottle filled with water soluble oil can be a great help.

Index the inserts if they seem to be at all dull.

http://www.korloy.com/korloy_en/contents/file/k22.pdf

 

[themayor]

after taking the pic i can clearly see it not trammed right but that makes no sense since i did re trammed when i noticed it

 

[themayor]

got the part done still never found out what was wrong trammed off the table n that didn't work so i tried tramming off the part n that didn't work. Put the vise back on the was getting double circles so it was trammed right

 

[gadget_lover]

That is an interesting piece you are working on. I could not quite figure out what it is.

Daniel

 

[themayor]

 

[themayor]

it is going to be for my knife grinder i am making it will be for the over center cam so the arm can come down n i can change belts. Looks bad in first pic cause i was jumping from spot to spot

 

[gadget_lover]

That came out looking really nice. Congrats. Tramming again did the trick?


Daniel

 

[themayor]

thanks and no never got to cut right so i just went in small steps on the rotary table n used the y in and out

 

[Gtamazing]

when you were cutting was the center of your cutter on the center of the rotating axis? If it was that can leave "humps" as the inserts will cut full depth perpendicular to the axis be rotated. However in line will the axis being rotated some of the material will go under the cutter without being cut off if you using an indexable cutter. When roughing stay off center slightly to cut with the side off the tool and not with the bottom. When finishing it's ok to be on center if your using a center cutting endmill. I have this issue a while back while doing a rope drum sort of part.

 

[themayor]

Ya i did have the cutter centered that must have been the problem how much should i move over next time

 

[Gtamazing]

Half the cutter diameter away from the direction of the cut will get you cutting with the edge and not the bottom, but then you might get a concave(dip) profile instead of convex (hump). You can also try a tool with a different insert. A square insert will work better than something like a triangle.