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4+1 vs fully 5 axis, what can I not do?


Apr 17, 2015
Taipei Taiwan
I am concidering purchasing a 5 axis mill for making low volume/high end motorcycle parts and Electronics enclosures. Note all the parts that will be machined will be designed in house.

One option that I had not intially concidered is to get the machine with a 4+1 controller that can so simultanius machining using any of the 4 axis at a time. From what I can tell I will miss out on full 5 axis deburr passes. I don't exspect to NEED 5 axis swarf passes on my parts. Is there any other machine issues I should exspect from this choice of control vs the full 5 axis?
Really depends on the shape of your parts. 5 axis simultaneous does enable better control of cutting conditions at the tool tip. It really becomes a need on complex 3d surfaces that are deep and difficult to reach with tiny details as in mould making. If money isn't a problem 5 axis simultaneous is the way to go as you will definitely be more efficient and you will have the extra capability even if you don't initially use it.
For complex 3D surfacing applications, the tool would need to approach the workpiece from any direction (to avoid interference), which would continuously change. This would be possible only with a 5-axis simultaneous control. However, in majority of cases, even 4+1 also will do, if any 4 out of the 5 axes can be simultaneously controlled.
in my experience, 3+2 is a hell of a lot more than 5%. sure, a lot of it can be done in 3 axis, but way faster as 3+2
I agree.

If this is not the case likely a better CAM software may be in order to help utilize strategies that improve machining that can be done in 3 axis but with 3+2 can allow for shorter tools, more efficient surface finishing and more. I cannot recall the last time I only used XYZ for machining a component.
When I worked at DN/Doosan, the 4+1 machine was limited only in that it couldn't move all 5 axis simultaneously. One could cut with any 4 out of the 5, with the 5th one stationary.
SME tell us that 80% of all milling is 3 axis and the rest is divided up, so if money is a concern, a 4+1 can save you quite a bit and still accomplish a lot.
In my experience, the breakdown is something like this, exact numbers may vary:
80% 3 axis.
10% 3+1
5% 3+2
3% full 4
1% 4+1
1% full 5

I think the total of 4% for Full 4 and Full 4 + 1 is... highly optimistic.

Just look at the CAM toolsets for doing that kind of work - they all suck. There are a couple of 4th axis wrap type paths available across most CAM packages... and then you get a whole slew of full 5 axis tools for everything from a basic swarf cut to hardcore turbo machinery, port, and airfoil processing. Very few 4 axis machines have the hardware, processing chops, or control features (TCPC) necessary to do quality simultaneous 4 axis work... and when you DO get into those kind of parts, everyone has just moved up to a real 5 axis machine and skipped this 4 axis middle ground business.
My parts are generally prismatic or blended prismatic. The most challenging part I am likely to do is brake caliper or motorcycle brake lever. I do not plan to do anything such as a impeller.