End Mill as Finish Toolpath

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End Mill as Finish Toolpath

Postby ohiolyons » Fri Oct 06, 2017 4:34 pm

I'm asking this question for a person new to Aspire.

He is using an end mill in a Finishing Toolpath. I always use ball noses, but then I don't do flat 3d surfaces.
It is a flat surface.
The finishing toolpath does not prevent you from using an end mill like it does on other bits that aren't appropriate to a specific toolpath.

His rationale is that the surface is flat and a ball nose takes too long.

1 Does anyone do this?

2 Are there unique "actions/motions/limitations" to the finishing toolpath that would result in a resulting finish not as smooth as if he used a ball nose?

3 His step over is 40%

Thanks in advance
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Re: End Mill as Finish Toolpath

Postby martin54 » Fri Oct 06, 2017 5:24 pm

No reason not to use an endmill, if the surface is perfectly flat then a bottom cutting endmill would be my choice of bit as well, question is does he really need to use a 3D toolpath in the first place, often using a combination of toolpath strategies can speed up a job :lol: :lol:

Which cutters you use depend on the job you are doing which is where the preview screen comes in handy :lol: :lol:
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Re: End Mill as Finish Toolpath

Postby ohiolyons » Fri Oct 06, 2017 5:29 pm

He has 3d images "sticking out" from the flat surface
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Re: End Mill as Finish Toolpath

Postby mtylerfl » Fri Oct 06, 2017 5:35 pm

ohiolyons wrote:He has 3d images "sticking out" from the flat surface


Show us a screenshot, please.

Depending on the layout, it's possible an End Mill would not yield the best result. But...we don't know until we can see exactly what you're talking about.
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Re: End Mill as Finish Toolpath

Postby martin54 » Fri Oct 06, 2017 5:41 pm

Like Michael says a screenshot would help a lot but by using vector boundary's the flat area could easily be excluded from the 3D toolpaths, like I said combining different toolpath strategies can often help :lol: :lol:

Have a look at the tutorials on efficient machining of 3D parts from the 2015 user group meeting :lol: :lol:

http://support.vectric.com/tutorials/V8 ... Index.html
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Re: End Mill as Finish Toolpath

Postby mtylerfl » Fri Oct 06, 2017 6:07 pm

There is a real "danger" of a bad result if the flat areas are cut separately from the 3D toolpaths.

I've seen it a lot over the years from photos posted of completed projects...what happens is you get a halo effect around the 3D model. It's nearly impossible to avoid because it's nearly impossible to set exactly same z-zero between an End Mill and a Ball Nose. (Not to mention material movement alters the Z Zero point anyway.)

So why do people do it? To save time, that's all. Unfortunately, the outcome is often compromised. "Halos" around the 3D models are unattractive to me. :D
Last edited by mtylerfl on Fri Oct 06, 2017 6:19 pm, edited 1 time in total.
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Re: End Mill as Finish Toolpath

Postby ohiolyons » Fri Oct 06, 2017 6:09 pm

I don't have the file.

He is using a Resting toolpath on 3d artwork areas so the quality of the cut from an end mill in those areas isn't an issue.

To redirect my original question.

So as long as the surface is smooth enough a 40% step over on an end mill is OK as a Finishing Toolpath on a flat surface?

I'm just use to 8% step overs on ball nose.
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Re: End Mill as Finish Toolpath

Postby ohiolyons » Fri Oct 06, 2017 6:12 pm

I like your "Halo effect" versus my moat analogy.

Thanks
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Re: End Mill as Finish Toolpath

Postby mtylerfl » Fri Oct 06, 2017 6:14 pm

ohiolyons wrote:I don't have the file.


Ok. So, it would make more sense if he would post to the forum instead. I think it would be far more efficient and helpful for him!

Please ask him to do that and also include a screenshot of the toolpath preview. It would be BEST if we could see the actual file, but that might not be possible if there are commercial models included in his file.
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Re: End Mill as Finish Toolpath

Postby Xxray » Fri Oct 06, 2017 6:17 pm

40% is high for finishing, yes it will clear material I doubt if it would be very smooth - It would be, in effect, a roughing pass.
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Re: End Mill as Finish Toolpath

Postby ohiolyons » Fri Oct 06, 2017 6:27 pm

I agree.

New guy said "... worked well the last time...".

Just trying to up my knowledge since using an EM as a finishing toolpath never crossed my mind.
I'm even surprised the software allows you to use an EM as a finishing tool.

Hoping someone would have a special case I was unaware of so I could become smarter!
Last edited by ohiolyons on Fri Oct 06, 2017 6:51 pm, edited 1 time in total.
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Re: End Mill as Finish Toolpath

Postby martin54 » Fri Oct 06, 2017 6:46 pm

OK generally people will use a ball nose bit as a finishing tool because a lot of 3D models contain curves which simply won't cut very well using a flat bottomed endmill, if you had a model that was completely angular with all flat surfaces then a flat bottomed endmill would allow you to use a larger step over & still give you a very good surface finish, a small step over is required with a ballnose bit to avoid ridges which need to be sanded out.
40% is still probably a lot more than I would ever use for a finish toolpath but I would certainly experiment up to about 25%. Comes down to how much sanding you want to have to do really :lol: :lol: :lol:
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Re: End Mill as Finish Toolpath

Postby Xxray » Fri Oct 06, 2017 6:48 pm

Software isn't that selective, it assumes the operator knows what they are doing and is in no position to argue.
Of course, it will refuse to do certain things outside of defined parameters, or warn you that what you are about to do maybe is not such a good idea ,,,, But usually alot of leeway on tool selection. There can be and are legit reasons for using non standard tooling for certain situations.
As already noted, we are in the dark what the master plan here is, so are of limited assistance.
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Re: End Mill as Finish Toolpath

Postby martin54 » Fri Oct 06, 2017 6:56 pm

Michael, I don't want to hijack this thread & I am by no means saying you are wrong but some of us need to look at all the options we can to save time to be able to make any money :lol: :lol:
For those of us that don't have a reputation charging a bit extra to cover the extra time required is not always possible, yes I agree the job still has to be done to a high enough standard but I have been able to reduce the time some jobs have taken by following the advice given in the efficient 3D machining tutorial & achieved good results as long as I made sure to take care when setting up & tool changing :lol: :lol: :lol:
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Re: End Mill as Finish Toolpath

Postby mtylerfl » Fri Oct 06, 2017 7:21 pm

Agree that saving time is a good thing all around. One just needs to decide when and where we can get away with it.
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