1 Rough Cut and 2 Finish Paths - Please Advise

[xoneeleven]

Sorry for the confusion regarding the TBN, Martin.
It is actually a 1/4in Amana bit with a 1/16in tapered ballnose (1/32 radius)


https://www.dropbox.com/s/zpehqkiqs6h08 ... d.jpg?dl=0

I realise you can't post the file but can you post a picture or a screenshot of the job. Scott does tiny little jobs so uses small bits but this job is 24" square so I find it hard to believe you need to go as small as a 1/32" TBN to get the required level of detail. Or are you talking about a 1/32" radius which would be a 1/16" TBN to me

Have you compared different finish toolpaths as I would'nt think you would need to go smaller than 1/8" TBN

[scottp55]

Yep....a couple of screenshots would help picture it better, maybe the preview of the .5"BN cut,
and then maybe the 1/16" TBN done about halfway through immediately afterwards to see what's cut?

1/4" shank 1/16"D TBNs can cut a almost full CEL, PROVIDED the toolpath doesn't jump around.
Does that second Finish toolpath only have 1 cut and one retract line?
(Just wondering if you CAN skip the 1/4"BN)
scott

Martin,
JUST getting ready to do a HUGE 5.5X 8.25X2" 3D of "Mom's Harley" with possibly 4 Finish toolpaths
So it's Almost big

[martin54]

Scott, look forward to seeing that finished. I am just wondering if the OP needs to go as small as 1/16" since 24" square is a pretty bit model & I am wondering if the use of a 1/16" bit shows any more detail than 1/8" bit would.
The other thing is that TBN's seem to be pretty robust from the work I have done so you may be right about skipping the 1/4" first finish pass.

The other thing is I can't see what material this is being machined from which could make a big difference

[scottp55]

He mentioned it's Cherry Martin.
I was just looking at the model between surfacing backs of spalted Paper Birch I'm doing.

Awful small details in the center and a couple on the outside ring....
only a 3 brain cell day here, and trying to figure out a boundary(and sanding out witness lines easily),
but not sure about the ring radius's.

I might skip the 1/4" BN altogether to get a seamless result.

Imagine he's done the 1/8" TBN preview,
and then consecutively run the 1/16"(?) and opted the 1/16th(?)...all the rest is smooth.

Stinger3 with a 4 flute bit would be able to hum right along with an offset(usually use conventional).
(only thing I'd worry about is unsupported endgrain in Cherry is weak)
He'll be finished with it before I stopped dithering with it

Back to my mindless surfacing:)

[Leo]

The original toolpath setup was:
1: Roughing Toolpath - 1/4in end mill
2: Finish Toolpath - 1/8in tapered ballnose
Total cut time = 10:06:04

The new toolpath setup we are considering:
1: Roughing Toolpath - 1/2in ballnose
2: Finish Toolpath 1 - 1/4in ballnose
2: Finish Toolpath 2 - 1/8in tapered ballnose
Total cut time = 07:07:53

They key here is that the 1/2in ballnose removes material faster than a 1/4in bit.

OK, sure, that does make sense.

Still there are many ways to skin the cat.

Scott55 is really good at what he does and Scott makes some really awesome and small stuff. If you are using a 1/2 ball mill for roughing I think your project is large, or at least somewhat large.

I have used 2-3 finish toolpaths like Scott is telling about. That IS a valid approach for sure and a good one at that.

The Amana cutter is a good cutter, and I think can do the work to finish without the intermediate cutter, even cutting Cherry. Still depends on the machine and workholding.

So, on the 1/2 ball mill tool path, you can adjust feedrate, Depth of cut and stepover to save more time, then go onto the 1/8 TBN finish toolpath without the intermediate toolpath.

Maybe you did already, but can you tell us more about speed, feed, machine, size of project, and maybe a picture of the project?

edit in - OK I see the image.

Yes, I can see some significant ways to save a lot of the time in that project.

You do not need the 1/8 TBN on the entire project. The individual details can be done separately and the base can be done with a different cutter. Vector bountaries can isolate the details so they can be cut seperately, and allow a different cutter to cut the base. The 1/2 cutter can certainly be make to be cutting more efficiently.

What is the outside diameter, and what machine, spindle are you using.

[Leo]

OK - sorry.

I have just gone back to re-read this thread.

The Cammaster is certainly capable.

So, can you isolate the details with vector boundaries and use a flat 1/2 end mill to 2D rough/finish out all except the details. Next use a 1/4 end mill to 3D rough the details, then 1/8 TBN to 1 pass 3D finish the details. The rings can "maybe" be fluting with 1/8 TBN. I have never used fluting, but I think it would do a nice job.

Tongue in cheek - but I think that is a 3-4 hour job.

[Rcnewcomb]

To cut 3D projects efficiently you want to use the largest bit possible that still yields the detail required.

Rest machining allows you to go in and touch up certain areas with a smaller bit for better detail, but has the downside of potentially leaving witness lines that have to be sanded out.

To help you decide what size bit you should use on a 3D project, or to set up rest machining, have a look at the instructions in this thread: Rest Machining and Spring Wreath

It shows how to see exactly what additional detail would be cut by a smaller bit.