Guitar neck Mastercam struggle

poolrod2 · Dec 2, 2017

Hi everyone, I'm running Mastercam X6 and can't get a great finish between my head and heel radius. Smooth on the top, but as it works down, pretty choppy. I'm using Surface finish constant scallop to rough it, and Surface finish shallow to finish.

Hazzert · Dec 2, 2017

A close up picture of the area you’re unhappy with would sure help. As it stands no one can tell you if it’s something as simple as your stepover or toolpath selection.

Generally the flatter the area the finer the stepover for a desired smoothness.

huskermcdoogle · Dec 2, 2017

You will want to look at flowline, morph, or scallop to help manage step-over in steep areas. Morph is in the multiaxis suite. If you aren't familiar with it, but have multi-axis, I would gladly help you out, and config up a file for you if you send it over via email. PM sent with that.

G00 Proto · Dec 2, 2017

I almost never use any of the parallel surface finish routines. They leave a fairly large scallop depending on the angle or the surface. As you are seeing, it is good on steep areas and poor on shallow areas... or vice versa (depending on the routine). I am prone to using a lot of flowlines because of the economy of code, or constant scallop for more complex surfaces. Shallow surfaces, I use more bull nose and even flat endmills for surfacing. Some of the new hybrid routines alleviate some of these concerns. I can help if you run into issues.

litlerob1 · Dec 2, 2017

poolrod2 said:
Hi everyone, I'm running Mastercam X6 and can't get a great finish between my head and heel radius. Smooth on the top, but as it works down, pretty choppy. I'm using Surface finish constant scallop to rough it, and Surface finish shallow to finish.

I am playing ignorant here, the space between the Head and Heel or the Neck of the Guitar is just flopping around in the cut out. I would change the "Leave Tabs" settings to leave them more frequently. It will require a bit more hand work to get rid of the blemish but I would guess that is the problem. The toolpath is not the problem.

Looks good BTW.

R

atomarc · Dec 2, 2017

poolrod2 said:
Hi everyone, I'm running Mastercam X6 and can't get a great finish between my head and heel radius. Smooth on the top, but as it works down, pretty choppy. I'm using Surface finish constant scallop to rough it, and Surface finish shallow to finish. View attachment 214359 View attachment 214360 View attachment 214361 View attachment 214362

Doug Fir or SYP????????? Or were those just trial runs?

Stuart

poolrod2 · Dec 3, 2017

I will take a picture when I get back to the shop. Currently using a 3/8 ball with a .007 stepover and surface finish shallow. It is both sides of the radius, but smooth on top.

poolrod2 · Dec 3, 2017

Model sent, thank you.

poolrod2 · Dec 3, 2017

I'm using junk wood right now and bouncing between 5/16 with .06 to .09 rad endmills, and 3/8 ball endmill. I just don't want to gouge real wood when I start the real deal. I'm using pocket on all flat surfaces, just having trouble with the long radius on the neck on the areas shown.

poolrod2 · Dec 3, 2017

Hi, it looks like it, but I cut the back side, neck rad first, for rigidity. So not a lot of vibration.

poolrod2 · Dec 3, 2017

Hi Stuart, just junk wood for test.

atomarc · Dec 3, 2017

While I don't know a thing about Mastercam I worked next door to a guitar shop that made thousands of necks a year on a CNC using that same program. What I do remember is that they used a huge ball (carbide) end mill..probably 7/8" although I'm not 100% sure.

The company is still there and I'm friends with the programmer. If you can't find a solution I could possibly put you in touch with him..If he didn't have the correct answer then no one would.

Stuart

litlerob1 · Dec 3, 2017

atomarc said:
What I do remember is that they used a huge ball (carbide) end mill..probably 7/8" although I'm not 100% sure.

This is probably right, I don't know as I am not a wood worker. But I would think .007" step over is way too small for wood. So bigger tool will allow you bigger step over with a similar finish.

But I would also guess you are NOT going to get a perfect finish right out of the machine. Ask the tool makers how much they know about sanding and buffing. The pictures look good to me, with a little care.....

R

poolrod2 · Dec 4, 2017

That would be great if you could ask what his rough and finish process is. My router will only go up to a .5 ball.

poolrod2 · Dec 4, 2017

Thank you, R, A ballnose at any size has very little contact on the surface though also. Hand work is always needed on this fun stuff, ha ha.

Mtndew · Dec 4, 2017

Use Surface Finish Flowline, you'll get the best results.

D Dubeau · Dec 4, 2017

poolrod2 said:
That would be great if you could ask what his rough and finish process is. My router will only go up to a .5 ball.

Use as big of a ball as you can. Look into router bits, such as a 1"or 3/4" ball with a reduced 1/2" shank.

http://www.leevalley.com/en/Wood/page.aspx?p=30169&cat=1,33084,46168,69435,46171&ap=1

12g87 · Dec 4, 2017

A screen shot of your Finish shallow parameters tab would help. I do a lot of wood, ren board, and plastic. I would say you .007" is too small. I usually will run wood somewhere north of .012" with a 1/2" ball. depending on part wall angles. From what I can see from you photos I would probably be using a surface blend for the middle section. Some secondary finish passes in small areas will probably be needed on such a part.

G00 Proto · Dec 4, 2017

Mtndew said:
Use Surface Finish Flowline, you'll get the best results.

I mostly agree (it is Monday morning). I would do a flowline in the same direction that you have the lines drawn on the screen shot above (lengthwise). This will give you the least amount of code (multi-axis transitions), which will run faster and leave fewer witness lines on the final product. You are going to have some discontinuities at the end of the surfaces where it radiuses up into the flat piece on the end. I would probably leave a check surface on those and finish them with a pencil cut, or surface those afterwards with a scallop or hybrid.

I have no idea what sort of machine you are running, but I would probably start with a 1/2" ball endmill (bigger is better, but much more expensive and has a larger zero SFM tip that tears fibers). I would do a scallop height of .0002 and a total tolerance of .001. Use 60/40 on your arc filter (for the transitions). Guessing on the speed, but if your machine can handle it I would like to see 300 IPM. Since you are only picking two simple surfaces and going the long way, it should not stutter and should achieve full IPM.

You could rough using anyone of the MC routines, but in this case I would just rough with a flowline with .050 scallop height, and leave about .050" finish. My guess if you do this you will have minimal sanding to make a good finish. Over time, you can adjust the stepover to get the time you would like.

If you get stuck, send me a PM and I'll program it for you. Should only take five minutes.

huskermcdoogle · Dec 4, 2017

With a 3/8 Ball, surface stepover marks of about .050" is very easy to sand out, not much purpose in going any finer than that. 1/2" - .060"-.075" is pretty good, the key is constant stepover.

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