We use cookies to personalize content, interact with our analytics companies, advertising networks and cooperatives, and demographic companies, provide social media features, and to analyze our traffic. Our social media, advertising and analytics partners may combine it with other information that you’ve provided to them or that they’ve collected from your use of their services. Learn more.
I was amazed at how thirsty the wood was, it soaked up the oil in a mater of minuets. Dry to the touch in less than 5 minuets for the first 2 coats, less than 10 for the third.
(The wood was one of the larger planks from the $6 box of “firewood” that has been sitting in my garage for months now.)
There are 3 versions of this clipart shield. This version tapers to a very thin edge so I am concerned about the points breaking off if it is roughly handled. Next time I will use one of the other versions of the shield which had a thicker edge.
This was made as a wall hanging. I may mount it on another board to help protect the thin edge.
The thing is this rippling follows the couture of the cut lines from the ball nose bit on 3d carves. I don’t get it when using the end mill for pocket cuts.
So I am wondering what is causing it?
Looking back at the other photo is it part of the initial carve so it is not the stain making the wood swell. I guess I just don’t see it until the stain makes the ripples higher contrast.
I am trying to figure out if this is some kind of chatter related issue?
My best guess is that the ripple is caused by the bit deflecting and or the gantry twisting just enough to change the z depth ~.1mm or so?
What is throwing me off is the way to follows the cut lines, seeming to happen in the same place.
Maybe it is related to the compressed dust that builds up on the V rail?
Making a “bump”?
I am using GWisard to calculate my feed and speeds as well as my depth of cut to minimize defection. And this did minimize this effect when I was working with redwood.
V Wheels, pullies and belts are checked before each cut.
And the V Rail dusted off. (but that builds up again during the print)
Other earlier carves I did didn’t seem to have this.
So I am thinking it may be a wear, slippage issue?
Maybe it is something as simple as a dulling bit? It only seems to happen with the ball nose bit. but then again I only 3d carve with the ball nose bit…
It might be related to the grain in the wood. The hardness of the wood changes as the cutter passes the grain lines. The machine may not be rigid enough to overcome the cutter deflection as it goes across the grain.
*Feed Rate: 4392.1mm/min (173 in/min)
*I realized that RPM should have been at #6 but still was at #1 from the rough cut - oops.
Depth of cut: 0.7mm (machining allowance from rough pass)
*climb cut
(*Feeds and speeds calculated by GW)
I have been a little hesitant with the feed and speeds numbers that GW has been coming up with but have been getting good results so far. Other than the ripple issue of course. My results have been pretty good. And much improved from some of the random numbers I was throwing at the XC.
Using the Dewalt router? I usually do my finishing passes with a ballnose at 1.5 or 2 on the speed dial. And for feedrate usually about 120 IPM, I’ve never gone that fast with mine. In oak, I would go even slower about 85ipm for a smoother finish.
Yeah that was more in line to what I was running before but I have been running test with the GW calculator and scanning CNC cookbook.
And these are the more conservative numbers.
Example: at the most aggressive, GW says I “should” be able to run my 1/4" endmill, 24"deep at max feed (5000mm/min 196inch/min).
(Though it does want a slower RPM that the dewalt can do.)
Maybe I am pushing the machine too much.
But the rest of the carve comes out great. If the whole carve was affected I would not think twice and just adjust the numbers.
This is so dam subtle, and it is not happening in the more challenging areas of the carve. (Where the depth is a bit deeper because the roughing bit could not clear it, or a knot hole, etc.)
This ripple seems to happen in the smoother areas (consistent thickness) and if anything in the areas of softer wood.
Ultimately the answer may be “cut slower” but even so I would like to know what causing this. I was hoping someone would see it recognize what was causing it:
“Oh yeah you got your (blank) set way too high”, etc.
I get the same ripples when I go too fast. I had a belt that got caught by the smooth idlers once and it caused that, and damaged the belt. I ended up replacing and tightening the belt.
Yeah same thing, and in the relatively smooth are of the carve.
Brainstorming…
In the more detailed areas there is more Z movement. The Z axis plunge speed is significantly slower so could it be slowing down the whole cut? Reducing the average feed speed in that area?
The areas on mine that are affected are spots where the is little to no z movement, so max feed speed?
They also seem to happen in corners of the spiral pattern.
Maybe the change in direction is loading the bit more?
So things for me to try,
do a control carve,
carve one with raster rather than spiral pattern.
carve one at 90% feed speed.
Can someone make a tutorial on how to make a 2.5D carve? I can’t seem to find a good tutorial anywhere and a dragon would be a great starter project!
