Introduction

[jtay]

Hi, I am a new user here. I have recently aquired a used Techno Isel 50" X 50" cnc router. After a few weeks of experimentation with ENRoute 4 pro, I finally got a design done that I can market. I am cutting it in various hardwoods for appearance mostly using a 2flute 1/4" straight cut bit. I am using multiple shallow passes and have slowed the feed rate all the way down to 25 ipm but I still keep breaking bits at the shank a little way up into the collett. Maybe I need a new collett? This one looks a little worn but not alot.

I could use some advice here if anyone has any.

jtay

[ger21]

If they're breaking in the collet, there's a good chance that there's a burr or sharp area in the collet. You really should be using solid carbide spirals, at feedrates closer to 150 ipm. Although that depends a bit on exactly what you are doing.

[RandK]

What spindle/router are you using ? What RPM ? What depth of cut and stepover ? What wood ?

What's going on when you lose a bit ? Size of chips. Noise from cutting etc.

I have a small Techno machine with a 3hp HSD and with a 1/4" bit in mahogany I might be going 50IPM at 1/4" doc at 18krpm but in hard maple that would certainly break bits. A 1/2" bit will give you more than a 2x increase in cutting ability.

[ger21]

Originally Posted by RandK I might be going 50IPM at 1/4" doc at 18krpm but in hard maple that would certainly break bits.

It shouldn't. I cut stuff like that at 150ipm all the time, and never break any bits. What kind of bits are you using?

[RandK]

Vortex 1/4" spirals (they make good stuff, thanks). Doesn't matter, Onsrud are about the same. Low spindle hours, fresh collets etc. Not having a problem with it. Certainly not roughing at 150 with a 1/4" bit on my machine though, 100 with a 1/2" sometimes. Finish at 250 sure.

I have a whole tree (dry) of rediculously hard, very figured maple (sugar I think) that pretty much immediately dulls every carbide saw blade, router bit and tool it comes in contact with. Some of my favorite wood but F&S that work with other maples don't work on this stuff.

The techno machine has accelleration factors that can be adjusted but the defaults are fine for me. The OP may want to check those if it's a corner/turn thing when he's breaking a bit.

[jtay]

I am cutting in pecan w/a 2 flute spiral endmill. I am using 1/4 because of the detail and a 1/16 step over. I am going to go get a new collett set today.

[ger21]

Originally Posted by RandK Vortex 1/4" spirals (they make good stuff, thanks).

I use Vortex as well, and I think I've only broken a 1/4" bit once in about 8 years. I never cut slower than 100ipm. The only time I had a problem, I was cutting oak parts that were screwed down to a spoilboard from the backside. 3/4 oak, 3 passes at 150 ipm. On the last pass, as soon as the part would finish, the bit would break. After 3 bits, I figure out that the waste material was coming loose as soon as the part was finished, and the loose piece was getting pulled into the bit, snapping it instantly.

But other than that, I've never broken one.

Also, I spoke to someone a year ago that was cutting hardwoods at 600ipm with a 1/4" tool. I also know that people cut 3/4" particle board in 1 pass with 1/4" compression spirals at 1000 ipm.