Machining Outside Round Corner - Manual Mill

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Phil3

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How can you machine an outside rounded corner on a manual mill? How else might I create the corners? See pic attached, and you can see the four rounded corners. I need to do the same on a similar project. The material will be 6061 aluminum. My mill is smallish with table travel of 12" (X) and 5-1/2" (Y)

Thanks,

Phil
 

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Some ideas I like:
Personally I would use rotary table or file the radius - either by eye or using filing buttons if it should look really nice

Wysłane z mojego SM-N950F przy użyciu Tapatalka
 
There is a way if you have a hole at the center of the arc. You put a close fitting dowel rod in the hole and use it as an axle. The common way is to straddle the vise jaws and clamp the work. You face the edge appropriately and then rotate the work slightly and cut again. Depending in how finished you wish the cut surface, you make your adustments coarser or finer. Some hand blending to finish.

Another way is to use a RT with the center of the arc on the axis of the RT.

A third way, with some DRO's is an arc cutting routine. It xcuts the arc in steps so the more steps, the better the arc. Tedious and it usually requires some hand finishing. In theory, you could do the same without a DRO but it would require a lot of calculations of coordinates and be highly opertor error prone.
 
It's possible to do this. A corner rounding endmill is the common way of doing it. I normally use a corner rounding router bit. Harbor Freight has a 5 or 6 piece kit for cheap. I use those sometimes, I also have some 1/2'' shank corner rounders from better vendors.

Another way is to use a rotary table and fixture the part to the table.

If it just an appearance feature a belt or disc sander works great too.
 
By the time you have read all these replies you could have hand filed the four corners. As Nike likes to say, Just do it.
 
Winegrower said:
Stand the part vertically in your mill vise and move the cutter perpendicular to the flat plane of your part. Four passes, or more with lighter cuts...presto!
Click to expand...

Wow, do I feel dumb. That definitely should work...and should have seen it myself. My only concern is that my vise is small and standing the workpiece vertically, will leave quite a bit of material unsupported. But, the person who wants this is liking Delrin which is easier to cut (but also somewhat weaker). I will find a way to hold it solidly. Thanks! - Phil
 
Phil3 said:
Wow, do I feel dumb. That definitely should work...and should have seen it myself. My only concern is that my vise is small and standing the workpiece vertically, will leave quite a bit of material unsupported. But, the person who wants this is liking Delrin which is easier to cut (but also somewhat weaker). I will find a way to hold it solidly. Thanks! - Phil
Click to expand...

Make a quick set of vice jaws that support most ot the material, or maybe just put a piece of metal on either side of the part and use a couple of small C-clamps. to hold everything together.
 
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