I’m cutting some signs in pine for my horse stalls. I keep getting uneven cuts in the bottom of the pockets. Not by a lot but enough to be annoying because it’s hard to get with sandpaper to clean it up. Is it the biting using or which one should I be using?
Thanks
Mike
It could possibly be that your Z axis and therefore your bit is not perpendicular to your X and Y axis… if it is even a little off of 90 to the X or Y or both then you will have uneven flats at the bottom of your pockets.
Another option is that the bit is slightly deflecting due to it being pushed too hard through the last pass. If you are sure that your Z axis is perpendicular then try adjusting your depth of cut so that there is a very shallow pass at the end that cleans up the pocket in question.
Have you checked that your waste board is perfectly level, you may want to surface cut it
Awesome, thanks for your help. I think the Z is perpendicular, I’ll check it again. The reason I think it’s perpendicular is one side of the sign turned out perfectly while the other was the problem. If it wasn’t perpendicular, I think the problem would be the entire sign.
I think the waste board may be the culprit. It’s a standard Mdf waste board. I had cut something earlier in the day that accidentally went maybe 1/32 into the waste board. I kinda scraped the edges it made but I never thought to really make sure it was perfect because I didn’t realize the consequences. I’ll try it again!
Are using v-carve by chance? The texture feature is a godsend. Plus it looks cool. I have to do a dozen signs for a resort in a week, and fortunately they love this texture in the background.
Thats super cool…I only wish. I feel like Im too old to understand a lot of these programs. I pretty much have learned inkscape and I load my files into easel. 
Im making stall signs for our horses.
I dont understand what all Vcarve does nor how or why to use it. I know nothing about G code lol and half of the things on these forums sound over my head lol. But Im trying.
Mike
There’s a lot to learn with these machines and all of the software that can go along with them. That sign is pretty damn nice looking so apparently you’re doing something right.
Thanks man!
Very nice. You can download v-carve and play with it. It is by far the easiest design software I have encountered… plus there are loads of tutorials. You could definately get most of those tool marks with a Dremel… but I wouldn’t sweat it. Pour some paint in there and let them fill up!
I am not sure but looking at your picture I am thinking that is being caused by the gantry twisting and or the Z axis flexing causing the bit to change angle. I am thinking that is the case because the uneven lines follow the couture of the carve.
If it was a case of the bit not being square to the waste board the uneven lines would be in the clear areas as well.
Have you done one of the stiffening mods?
Depth of cut seems to have a greater impact on the forces that cause this then feed rate. So reducing your depth of cut (not your speed) may make a difference.
I had been securing the wood to my wasteboard with 2 sided carpet tape. I never installed clamps because they seemed like they would always be in the way. This afternoon, I installed clamps and cleaned up my waste board. Its carving right now a sign for my other horse but it looks much cleaner. I think maybe the carpet tape had just a little give to it? Its clamped solid now so far looks good. Ill post a pic in a bit when its done.
Play in the fixturing definitely plays heck with carve quality. I also see this with plywood that has a slight bow in it and which I haven’t firmly clamped to the table. There is enough spring action in the wood to cause it to oscillate up and down. Maybe the 2x sided tape has enough give in it to mimic this behavior.
I clamped the second one down, came out pretty close to perfect. Im sure thats what it was. I need to make a new clamp now though. I set the bit at the home position when it took off to start carving, it cut right across the clamp lol.
I do have a question regarding the home position. When I originally starting setting it up, I tried to put the center of the bit on the bottom left corner of the material to be cut. I think to really get it accurate though, I think the bit actually needs to be just off the material on the x and y axis so that the edges of the bit are touching both axis. Does this sound accurate? I saw where a guy cut an eagle out of the center of a quarter so it got me thinking about how to set the home positon with that kind of accuracy
You’ve got a couple options available to you for locating the bit precisely. You could wire up a touchplate, which let’s the machine know where your work is located by closing an electrical circuit when the bit touches a metal plate of a known thickness and size.
You could setup limit switches and home the machine with them. That will set the bit to the same spot on your work table electronically.
You could also setup some type of mechanical stops on the slides and manually set the machine to the same spot every time.
The last 2 can be combined with a fixed fence on your table that place a corner of your work in the same spot every time.
Here’s one thing you can try too. Put a v bit in your router and jog your router so that the bit point is precisely on the intersection of 2 lines on your workable. Set that as zero, raise the router and carefully swap bits. Position your workpiece right on that grid intersection and clamp it. Set your z height zero and start your cut. You should be pretty accurate, assuming your grid lines are parallel to your machine axes.
I’ll give it a try. My grid seems to be dead on for everything else. Thanks!
