Raster vs offset

[Dclifton2]

When I cut with offset I get a deeper cut then with raster. Why and is there a place to change it.
Thanks
Don Clifton

[zeeway]

You can change it on your toolpath settings - near middle of dialogue box, I think.

Angie

[Dclifton2]

I think that's the boundary offset this is in the Z.
Thanks
Donald Clifton

[Rcnewcomb]

Does the toolpath file show a deeper Z with an offset strategy vs. a raster strategy, i.e. is it a:
- software issue (file shows a deeper Z)
- machine issue (Z doesn't always move the same amount)
- material issue (material is cupping or bowing differently depending on the machining strategy)?

[Dclifton2]

We did a test, We cut a dished shape with the raster profile but before we did we zeroed the bit and then sent the bit to G0z0.00 and the bit just touched the work surface and afterwords we did the same thing. we ran the offset profile using the same zeroing technique and it cut deeper.
Thanks
Don Clifton

[esteeme1]

Can you give some more details? What is the depth difference? What is the bit diameter? Do you have offsets set? Is your model above the surface and protruding above the dish? A pic would really help.

[Bob Reda]

Are you using Mach 3? Seems like alot of people using that have to change some settings. If not I believe it would be more a machine problem than a software issue. Is your table flat? Alot of wood have variations that would make it seem like there is a difference. Just some thoughts.
I just ran a test on a 6" negative circle and measured the depth with the mouse and they are both the same depth on my screen. Whatever that means.
Bob

[Dclifton2]

I'm going to do some more testing as soon as it warms up outside. And yes I'm in Florida but it's cold.
Thanks
Don Clifton

[dond52]

Hello Don,
You do not mention how much difference there is in z height from the start to the finish of the project. I just completed 13 Candle trays for Christmas gifts. The trays are 1/2" thick. The center is 3 3/4" diameter pocketed out 1/4" deep. The trays started out as flat as I could get them. Each tray finished up with about a .032" convex bow on the back after I unclamped them. The wood is kiln dried oak. I have also made some from 3/4" thick oak with the same results.
Are you sure your wood is not bowing because of the stress relief caused by the cutting of the dish ?

[Dclifton2]

The wood is never unclamped. I'm just changing from rough to finish and was changing bits from 1/8 to 2mm ball nose but rezero ing after tool change from the same point on the work surface. I'm now cutting both rough and finish with the same 2mm bit but I don't think thats it. It will take a while to see if it makes a difference with the 2mm.
Thanks
Don Clifton

[esteeme1]

Hi Don,
Have you tried to recalculate each tool path for the model you are working with? Is it possible that you made changes to the model, like adjusted the cut depth or model height in between calculating the existing toolpaths? If not is it possible that you didn't save the current tool paths after recalculating them?
I would go back to the beginning and check your cut depth. I would also make sure the model is not higher than the dish is deep. After you check that I would recalculate your toolpaths for offset and raster. Make sure to resave the new toolpaths. I can't think of any reason related to the software other than the above stated as to why you would have a depth difference.
Are you running different speeds between the two bits? Is it possible that you are losing steps because of it?
There are many question that are going unanswered. Could you provide some more details? We still don’t know how gradual or drastic the difference is between the two toolpaths.

[Dclifton2]

I ran it again without bit change and it came out perfect so I guess it was something in the tool change. I normally use Ger's 2010 screen set in mach3 but didn't this time or when it messed up. If you haven't used the screen set it has a simiautomatic tool changer that works really well. Thanks everyone for all the help.
Thanks
Don clifton

[ger21]

Don, are there G43 Hxx in your code? It sounds like your seeing some length offsets being applied, which is causing the different depths.
I'm leaving right now, but I'll send you a modified post later tonight that doesn't use G43.
And it's 28° here. That's cold.

[Dclifton2]

Thanks Ger, I think I'm using a PP that I changed. Would like to try your. Your screen set is working great but I have been training my son in using the router and didn't want to throw that in yet. He just got out of the Navy for 14 years. It wasn't that cold compared to the rest of the country but for a Fla boy it's cold.
Thanks as always
Don Clifton

[Dclifton2]

Ger, I was using the simple tool setter from your screen set but not the tool changer.
Thanks
Don Clifton