[Silver-Fox]

Greetings everyone!

I just recently finished my new CNC machine and I've been having a blast learning as much as I can.

I've started to try my hand at making some Edge-lit signs for some friends. The first few runs were pretty good, but I wanted some more improvement so I bought a few new bits to try.

I decided to pick up the In-Groove Insert System from AmanaTools. Using their feed and speed chart I started engraving one of the signs. The first half of the cut looked amazing. The edges were crisp and I did not have any real issues with melting. Then I noticed that the bit was no longer cutting. I thought that the material thickness might be uneven but it turned out to be a broken tip.

I was cutting with a depth of .0156 using the RCK-360 30 deg bit. It's tip is .005. My RPMs were at 16,000 (my lowest) and my feeds were at 100 ipm.

I used a few of the other bits on different materials without any issues.

Then I used the RCK-362 30 deg bit with a .020 tip. My depth was .0156 at 16,000 RPM with a 120 ipm feed. The tip broke off on that bit too.

Both cuts were on scrap Lexan from Lowes. I'm not afraid to say that I'm at fault, but could someone help explain why this is happening.

The Speed and Feed Chart is found here and the tool info can be found here.

I'd appreciate any assistance.

Thanks

[victorofga]

use halfround bits...
cheaper and lot stronger..

those disposable blades requiring very careful uses..
also they are very expenses..

10XCARBIDE PCB Engraving Bit CNC Router Tool 60° 0 2mm | eBay

try this ebay store..
1 dollar per piece.. if you break, you wont cry really.. they will gives same sharp edges..

In-Groove? CNC Insert Engraving System -Toolstoday.com- Industrial Quality Engraving & Signmaking Insert Router Bits
let me dont make comment on these prices

if you break a few couple within making one sign, you migth estaplish 0.0 profit on the work...

well.. i checked chart... best you can do, buy a few dozen of blade and follow amanas chart..

i wouldnt use that chart.. for 0.2mm dia they are saying 150 ipm with 20K rpm... possible in foam it will work.. this is my private opinion..

[victorofga]

i found a video.. i dont know what speed they are using, for me looks lot less than 150 ipm..

[ame=http://www.youtube.com/watch?v=sr89_p5_OdM]Amana Tool's Ingroove Engraving System Demonstration - YouTube[/ame]

those inserts otherwise standard carbide inserts specially ground for these profiles..
a diamond wheel you can buy around 15-100 somewhere between..
and i think, if you want to stick with these inserts wellworth to learn to sharpening those blades..
i just hardly can imagine engraving work, using 40-60 dollar tool for each work..

when you try to figure feedrate, you have to count on the smallest cutting diameter on a v-bit..
and that is somewhere 0.1 mm
so counting on 10 percent stepover, or feed per rotation it will gives 200 mmper min at 20K rpm.. what is refer about 8ipm..

yet you can push amana suggestion for 120-150 ipm..

[Silver-Fox]

Thanks for the replies, I appreciate it. I've had better luck with the round nose insert. It cuts extremely well in the Lexan at 16,000 RPMs and 50-70 ipm.

Watching those videos again I noticed that the plastic was chipping nicely with their V-groove bit. I never had cuts that looked like that. I know 16,000 RPM is pretty fast, maybe that is part of my problem. I have a Super-Pid on order, hopefully that will give me some more options.

[victorofga]

for ballnose bits, you can use roughly the ball dia for cutting diameter for calculation...
means if its refer 1/16 or 1.59 mm then feed can be 0.15 per rotation, and at 16K
2400 mm close 90 ipm

also ballend on a taper a lot more better geometry for milling..

all advantage i see of this amana tool i could make my own profiles.. like low angle conical bits