I am new to Inventables and using a cnc router. I have done a few straight forward projects that came out fine (basic lettering signs), now I am trying my hand at a plaque for my son. It is an “In Memory” plaque of his grand father. I am using birch plywood and used the 1.7 mm fishtail spiral to do the rough cut for design and lettering then switched to the 0.7 mm to do the detail.
On doing the detail I reduced the feed rate to 60% for the fine line areas but not too far into the project I keep breaking the bits.
Is there a formula that I can use to know what to adjust the feed rates to or am I using the wrong bits for this sort of project?
Any advise would be greatly appreciated.
Thank you
We really dont have much to judge by, care to share the project so we can see design/feeds and speeds.
What RPM?
What material?
Sorry first time using forum.
I think I saved the link properly to the design
If it doesn’t appear please let me know how to share properly.
Thank you
The detail bit is 0.7 mm not 0.1mm it is wrong in the program on file only not in job
https://easel.inventables.com/projects/VsvFIgabo65Y9GNrjzrNtw#
I’m also new to CNC but I have figured out that when I break very thin bits it’s because my 0,0 is not exact. When you switch from a rough bit to the fine detail you need to ensure 0,0 is exact. Easel will outline the roughed areas with the fine bit and if you are off even a little you will get bit deflection which will snap a very fine bit in a second. Just my experience as I snapped several in a single project. After I figured out what was happening, ive cut dozens of fine detail engravings with a super thin 1/32 bit to over .25 inch deep even in purple heart without a single break. Also for text that requires a very fine bit, like the font you are using, just cut the entire text with only the fine bit, then there is no alignment problems. Set the area that you don’t want cut to depth of 0 and cut the text, then switch that text to 0 depth and change bit and cut the rest. Hopefully this will help in some way. Good Luck
Thank you for your advice, I will definitely try this. I assumed I was starting at 0,0 because I clicked on use previous 0. I figured if I used set new 0 it would and could be off by even just a hair. As for using just the small bit for the finer fonts I did try on another project just to use the smaller bits and they snapped immediately that is why I went to a rough in bit down to small. It was going good until about 5 minutes into the project.
I will try with a new titanium bit I bought instead of the blue tipped ones and see how that goes.
Thank you again for taking the time to try to lead me into a better direction.
Just for reference, my settings using 1/32 bit are straight out of inventables defaults.
Federate 30 in/min
Plunge 12 in/min
Depth pass 0.015 in
This only applies IF the 2nd bit tip is at the exact same length out from the collet. Otherwise the actual tip is not where its computed to be.
For fine detail carving I really recommend V-bits or tapered end mills, they are much stronger than a thin flat bit. Most thin flat bits are also long, which cause bit deflection issues and increase risk of breaking.
ok thank you good to know I will look into buying some V bits