3d carving problems

[williams_architectural]

I own a 2006 PRS Standard. The 2d seems to cut fine, with no position loss.

I'm carving three 6"Lx4.5"Wx1.125"thick moulding profile samples. I've carved several 3d carvings in the past with little to no problems. The level-Z roughing seems okay, but now I'm not so sure. For the carving I'm using a .125" roundnose bit with carving speed at 1.5-ips for xy&z and a step over of 20%. The wood is white pine. While carving on the first blank with the grain in X axis, it begins losing position after a few inches of step-over. It's subtle at first but continues to get worse. By the time it gets to the third blank, XY&Z are all off. I then tried separating the cutting files and carving it in the Y axis. I ran the file and immediately after it began cutting, it dives/plunges into the wood and quickly loses position.

Thanks in advance,

William

[Brady Watson]

Are you doing Z-level roughing with a square end tool (like an end mill) or are you using the ball ? Without seeing the design, it is hard to make a perfect recommendation, but I would guess that a 1/4" square end mill would be fine with a pass depth of .125 to .25" so that it closely follows the design. Use a 40% stepover value for this toolpath.

For 3D finishing, I would use your 1/8" ball, parallel with the grain at 10% stepover. It is imperative that the roughing tool do it's job to clear away the bulk of the material so that the ball can effortlessly resolve the final shape.

The conditions you mention DO seem strange to me. You should be able to power through that material with the 1/8" bit & it would snap before you would get positional loss. I am wondering if you have a 'tired' power supply.

If you feel up to it, get the volt meter out and test both power supplies. The ATX which gives 5 & 12 and the silver MeanWell which should give 44 to 48volts. If you have a 4G with toroid power supply, check the voltage outputs on that as well. It could vary from 48-65 vdc.

-B

[cowboy1296]

It hard to imagine doing 3-d in pine, it seems like you would get a lot of fuzzies. Now that said i have never tried it in soft wood. I use a 7-8 percent step over for finishing. Most of the time that i loose steps is because my brushes are worn out on the router. Recently i had that issue, the brushes were brand new and i blamed it on pushing a dull bit to fast.

[williams_architectural]

Thanks for the replies guys. I'm going to try and post a video of the problem, which will probably help figure this out. I've never had this problem until recently and I've carved several projects before with no problems.

I will message back again soon.

[Brady Watson]

William,
Post a screenshot of your VR fill-in sheet too when you repost. You can do this by bringing it up in SB3 and then press Alt + PrtSc (PrintScreen) - It will put it on the Windows clipboard. Then goto Start->Run and type in MSPaint. When you have it open, do a Ctrl + V to paste in your screenshot.

-B

[cowboy1296]

I have changed my brushes about 10 times since I have been doing this. Have you checked the brushes. What you are describing is the same thing that has happened to me when my brushes wear out.