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Milling with the Hobbymat

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Roger B:
It is many years (decades) since I used a ‘normal’ milling machine. All my work has been carried out with a vertical slide or a combination lathe and milling head.

I needed to mill a piece of 6mm wide EN8 as part of my current project. I used a 16mm end mill running at 365 rpm (lowest available) with a 0.5mm depth of cut and a feed rate (by hand) that felt comfortable.

http://www.youtube.com/watch?v=weLhTMHnhhw

Does this look and sound reasonable compared to a proper milling machine? There is visible movement of the compound slide. The finish is OK for the purpose and can be cleaned up a little with a file if required.

Zephyrin:
I would say that it's not very fast...on the flimsy equipment that I have, I would prefer faster rotation and slow advance.
On a slightly weak mount, I'm afraid that the large cutter, especially with few teeth (2, 3, or 4), will engage with the workpiece and ruin it if the rotation is slow compared to the feed rate...
But why use a 16 mm cutter for a 6 mm workpiece? Simply because the cutter is already mounted?

Charles Lamont:
The cutting speed of 60 ft /min sounds about right to me for EN8.

I agree the cutter length means things are not as rigid as with a shorter one.

It sounds to me as though the end mill may not be all that sharp.

I would not machine steel with an HSS cutter without using some cutting fluid. 

john mills:
the years when i was using milling machines all the time i often run that size end mill at about that speed
it was usually tool steels but that speed will give reasonably good tool life  for light machines why run faster and have a short tool life with a relative feed looks good to me
john

Jasonb:
Sharpness of the cutter would be the first thing I would look at. If you have been using it previously with the vertical slide taking the same shallow 0.5mm cuts then the end is likely to be worn.

As mentioned above a smaller dia cutter so that you always have at least one flute engaged, preferably 2 will also help with the bonus of keeping the gearbox noise down.

Smaller cutter for the smaller width cut also works out more economical as an 8mm is likely to wear at the same rate as a 16mm but the 8 is a lot less expensive. It is also quicker as for the same chip load you can feed faster due to the higher spindle speed that can be used with the smaller cutter while still keeping the cutting speed the same.

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