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Toolpath that cuts wider than bit?

sjj530
Advocate

Toolpath that cuts wider than bit?

sjj530
Advocate
Advocate

I have a hobbyist CNC that is just not rigid enough for some of the operations I want to perform.   For example, if I am cutting out a part, I'll use a 2D Contour toolpath and with multiple steps to mill to the bottom, setting radial stock-to-leave at about 0.5 mm.  I then w run another 2D Contour in a single pass, full depth, with 0 stock-to-leave, as a finishing path.  

 

If the stock is greater than say 25 mm, I get destructive chatter on the finishing pass.   I've played around with speeds and feeds, but haven't hit on a fix.   

 

I'm wondering if there is a toolpath option that will allow me to mill a contour wider than the bit.  I remember I saw something like that once, where the bit described a small spiral as it moved around a contour, but I can't remember the setup.    

 

Any thoughts?  Thanks!

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seth.madore
Community Manager
Community Manager

Could you share some photos and a Fusion file so we can better understand what you're running into?


Seth Madore
Customer Advocacy Manager - Manufacturing
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sjj530
Advocate
Advocate

Thanks for the response.  

 

Attached  is the file I've been playing with.

 

What I'm trying to do is test  an idea for a piece of furniture.   I want to mill a tenon on a 3/4" stile, and an open mortise on a 1 1/2" rail.   The stile meets the rail in a curve.    The design is not complicated, but the execution isn't working.  The  2D Contour finish pass for the mortise at 7/8" deep chatters and in this case gouged out a chunk of the railCM1.jpgCM2.jpg

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programming2C78B
Advisor
Advisor
Accepted solution

You can still finish pass with Depths enabled, I recommend 1x tool Dia for now, and play around with 2-3x. You can do repeat finish pass if youre REALLY worried about the "Stepped" look you may get with your tool deflection. 

Please click "Accept Solution" if what I wrote solved your issue!
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engineguy
Mentor
Mentor

@sjj530 

 

Ouch, that really grabbed a chunk and ripped it out, surprised it didn`t break the tool :disappointed_face:

 

As @programming2C78B has suggested do your finish in steps although it is odd that the other Radius seems to have cut OK.

Have you tried doing that finish cut using "Climb" Milling ? I know that in theory it should be Conventional but might be worth a try.

I can see that the internal Radius prior to where the chunk is ripped out is also not good which could indicate that the flutes are getting clogged by the time it gets to that point and worse by the last Radius.

 

Just a thought :slightly_smiling_face:

 

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david.lundbergC7AM5
Advocate
Advocate

I've never milled in wood, but I'm kinda surprised that doesn't happen all the time, if your tool is anything but supersharp. At the first radius, with conventional, you're just "pulling" in the grain direction, but at the other two,

you're basically ripping the wood out of the stock. A change to climb milling wouldn't change that fact (?), or maybe some wood milling wizard could chime in here? I know there's a lot of you out there. :slightly_smiling_face:

/David

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sjj530
Advocate
Advocate

Thanks for all the responses!   I will do a little more playing around with climb vs conventional milling.  My guess is I'll have to do what programming2C78B suggested and take the finishing path in multiple steps also.   The finish won't be as good, but that's what sandpaper is for.     Thanks!

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