Beveling edges seem to be offset

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gmm50
Posts: 46
Joined: Fri May 16, 2014 5:22 pm

Beveling edges seem to be offset

Post by gmm50 »

Hello:

Got a Shark about 2-3 months ago. Been learning a lot and just when you think you have it mastered......

We're making a block cut from HDPE. about 2.0" x 8.0" x 3/4 thick. We're using 1/4" up cut router bit and a 90deg beveling bit.

The cut out of the part is done in 2 passes with tabs. First pass we lie to the machine telling it has a 3/8" router bit and make a pass. Then we run the same outline but now saying it has a 1/4" bit. This has the effect of making one pass that's 3/8-1/4 = 1/8 away from the desired edge....Then the 2nd pass runs to the true edge. This looks good. We can run several times over the same spot with great results. (no wandering about).

We now insert a 90deg V bit and zero that bit.
We tell the machine we have a 1/4 inch router bit and then set the depth to give us the desired bevel on the edges.

The bevel is not the same on both sides of the part. We can rerun the V bit and get the same offset pattern.

So what's going on with this is the question....Any help would be appreciated.
George

4DThinker
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Joined: Wed Jun 27, 2012 9:00 am

Re: Beveling edges seem to be offset

Post by 4DThinker »

Are you profile cutting ON a vector outline, or outside a vector for your bevel cut? If outside (or inside for that matter) the vector must be closed or the tool path will not know which is the inside or outside and may flip to the other side of the vector half way around.

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gmm50
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Joined: Fri May 16, 2014 5:22 pm

Re: Beveling edges seem to be offset

Post by gmm50 »

We did run into all those issues. But in the latest run, we cut the outline using a 1/4 inch router. Then change to a 90 deg V bit and tell the shark it's a 1/4 bit.
So the tool path should be exactly the same used for the outline. We just pick a depth that gives us the correct amount of bevel.

It's just off in x and y a small amount.

We can then go back to the 1/4 bit and re-cut the profile with perfect results....so we didn't loose zero.

Perplexing to say the least.
George

Danwood
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Joined: Sun Nov 17, 2013 9:46 am

Re: Beveling edges seem to be offset

Post by Danwood »

There is another possibility.
If the bed is not perfectly level You might not notice the cuts with and end mill being off a little bit.
When you run a Vee bit to miter an edge the difference in width of cut becomes readily apparent.
I recommend you get a dial indicator and a way to mount in your router and check the bed for parallel to the gantry travel.
Danwood

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gmm50
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Joined: Fri May 16, 2014 5:22 pm

Re: Beveling edges seem to be offset

Post by gmm50 »

That was an issue 4 weeks ago.

We have fly cut the bed with the unit NextWave offers and that did make a big difference.

Sorry to be such a spoil sport.....Please keep these good ideas coming.
George

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gmm50
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Re: Beveling edges seem to be offset CONCLUSION

Post by gmm50 »

Conclusion::::::::

If we take a router bit (1/4 end mill) and drill a holes at 0,0,0. Then change to a 90 degree V bit, we're off in x and y. about 0.005" or so.
If we change back to the end mill we're spot on. +/- nothing the eye can see.

I've tried this with 2 different 90 deg V bits and the same results just different amounts.

We can make a correction and then bevel the job perfectly.
I'm assuming it's something the the manufacturer of the V bits. Not out of round but an error in concentricity or tilt.
Case closed as far as we're concerned
George

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