Spoil Board Fire

[pread]

We have been running our shopbot for about 2 years and over the course of this time I have had a number of spoil board fires. The problem occurs when the feed rate drops for tight circles or corners. I mostly use poplar anywhere from 1/4" to 1 1/2 thick. The fires only have happened in material 7/8" and thicker and with holes between 1/4 and 3/8". The feed rate greatly drops from the std 3.4ips to the point that friction and the saw dust start the fires. The RPM's are 16k, we mostly use Whiteside 1/4" down spiral bits with 2 cutting edges and 1/4" Onsrud compressions spiral and the plunge is 1/4". Any ideas on how to stop this would be greatly appreciated.

[ken_rychlik]

Compression bits are the worst thing for drilling. Down spiral second worst.

Slow down the spindle and or increase feed rate will help.

Plain old straight bit will help.

[beacon14]

peck drill to help clear the chips, also use a spiral plunge to make a hole at least a little larger than the bit diameter.

[Gary Campbell]

Adjust ramp speeds to keep slowest and smal circle speeds higher. Lower rpm.

[aaasigncom]

When i purchased my first shopbot, it came with a large burn hole like yours. My solution was to mount a cheap smoke detector near the spindle. On this machine its on the e-chain. I also use a video baby monitor with sound to view its progress when i am away from the shop. It also lets you know if in the middle of the job if the bit gets dull and starts to burn in the tight corners. Then i can stop and change the bit to save the job. I have twice as many detectors in the shop than normal. One is mounted in the window opening to make sure the sound can be herd outside. I hope this helps you. Tony in indianapolis

[harryball]

Has anyone every put a smoke detector inside a Fein? I'm wondering if that would work as an alert smoke is building?

/RB

[aaasigncom]

There is no reason to put the smoke dector inside. Putting it at the exhaust does the same thing and would be more effective and not muffle the sound. Tony