Anyone able to tell me what I could be doing wrong?

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mkittle
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Anyone able to tell me what I could be doing wrong?

Post by mkittle »

I have had the Piranha for about year and have used it only a hand full of times and this is the first time something didn't come out as expected. I am fairly new to all of this but past projects have worked just fine. On this one, the result doesn't match the preview. I assume I have something set up wrong but don't know enough to know what is wrong. I have tried different depths and different bits and I get the same type of results. I have used a 22 degree and 45 degree MLCS bits from Eagle America (https://www.eagleamerica.com/product...groove_forming). I have attached photos of some of the results and screen shots of the tools I used. I would appreciate any tips or help that anyone can provide.
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IMG-1056.JPG
Mission.JPG
Capture.JPG
Capture2.JPG

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adze_cnc
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Re: Anyone able to tell me what I could be doing wrong?

Post by adze_cnc »

Your preview appears to use a 90-degree v-bit. But the two screenshots you show are for 45-degree and 22-deg v-bits.

Seems to me to be a mismatch between what you asked the program to use to create the v-carve (90 degree) versus what you are actually using to cut the job (45 or 22 degree).

mkittle
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Re: Anyone able to tell me what I could be doing wrong?

Post by mkittle »

I also read the post about checking V bit angles and did that test. It didn't seem to work like it should either. I did have to alter the file since my machine can only do 12"x 13" and changed the angles to test the 45 degree bit.
Test.jpg
IMG-1061.JPG

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Re: Anyone able to tell me what I could be doing wrong?

Post by mkittle »

Here is a screen shot from VCarve. I think I have that set to use the 45 degree bit.
Capture3.JPG
Last edited by mkittle on Tue Feb 05, 2019 6:06 pm, edited 1 time in total.

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Leo
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Re: Anyone able to tell me what I could be doing wrong?

Post by Leo »

There are lots of things that could be happening.

1) I don't like using oak for that sort of project. The grain is not really all that strong and it chips out in small and thin areas - I see that in the first pic.
2) It looks like you are just changing the cutter and running the same tool tool path - you cannot do that. You need to program for the tool being used
3) It looks like there is a rigidity issue. Something is loose.
4) Perhaps your cutter is sticking out of the collet too far. DO not clamp ON the flutes, but do get the flutes as close to the collet as possible. Stubby short setup.

If you post the Vectric file - NOT, toolpath, we can look at your settings.
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mkittle
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Re: Anyone able to tell me what I could be doing wrong?

Post by mkittle »

I am creating a new tool path when I change to try a new bit. I originally wanted to use the 45 degree bit. I tried to upload the file but it is over 3 MB so wouldn't upload. I have it saved in my google drive and have provided the link to it there.

https://drive.google.com/open?id=1xnEd5 ... bbIIE3hYC9

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Re: Anyone able to tell me what I could be doing wrong?

Post by mkittle »

I also switched over to a different project and tried it and it came out as I expected using the same 22 degree bit I tried on this project.
IMG-0505.JPG

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Re: Anyone able to tell me what I could be doing wrong?

Post by mkittle »

Sorry, I shared that link from the wrong account. Here it is from my personal google drive.

https://drive.google.com/file/d/17zQ_fJ ... sp=sharing

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Re: Anyone able to tell me what I could be doing wrong?

Post by Adrian »

Nothing wrong with the file that I can see. The preview looks as I would expect. The screenshots just look like there is too much movement in the machine and/or it's being pushed too hard with the tool settings you're using.

With the first small machine I had there is no way I could have cut at 100ipm in Oak. I was running at more like 40ipm but I have no idea what your machine is capable of and it probably wouldn't be getting to those speeds anyway on a small piece like that.

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Re: Anyone able to tell me what I could be doing wrong?

Post by Mobius »

Oak is much harder than the spruce or pine that you used in your Bob Straugh test project. It looks to me like then the bit is cutting deep, it is causing the machine to flex. Then when it becomes shallower you can see how it goes back to where it should. This is evident in your bit angle test.

You need to set up your pass depth on your tools to something less than the full depth of the cutting edge. That way it will make several passes before getting to full depth, and should help your problem in harder woods.
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mkittle
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Re: Anyone able to tell me what I could be doing wrong?

Post by mkittle »

Thanks for the tips. I will try slowing the feed rate down and decrease the pass depth and see how it turns out.

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Re: Anyone able to tell me what I could be doing wrong?

Post by Leo »

Oak is difficult to work with and not just because it is hard. It is brittle and chips out very easily.

I find Maple to be a GREAT wood for this stuff. It is about as hard as oak, but a lot more stable.

Poplar is an OK choice of woods

Cherry is my favorite wood, not quite as stable as Maple, but it is an awesome wood to work with.

For just testing Poplar is relatively inexpensive.

In my opinion the softwoods like pine are not a good choice to test with as it chips out really easy and is just too soft.

Looking at your V-Carve file I see the same thing as Adrian sees. It all looks OK. Saying that - you then need to focus on other things like machine, slides, holders for the spindle, screws and lots of mechanical things. Seems like something is loose
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Re: Anyone able to tell me what I could be doing wrong?

Post by Bob Reda »

In the first one you are going against the grain and as Leo said it is getting a lot of chipout. The other you are going with the grain and will get a smoother cut.

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