Warning: I Started a Fire With My Maslow

Greetings,

I was recently cutting shapes from 3/8" bamboo 11"x14" cutting boards using a 2-flute 1/8" Bosch bit at 23000 RPM at a feed rate of 15 inches per minute and step down of .15". The bit must have become dull and the $7 bamboo cutting board may have been oiled. Either way, I had a genuine fire at a thin part of the design that required a fire extinguisher to put out.

Wow, this was scary as hell. I am glad I was in the room and nothing was damaged except the piece because it only took me seconds to put out the flames. I realize that I may have done some dumb things and I am sure the community will steer me straight, but even so, I would recommend to every Maslow owner that you keep a good fire extinguisher near by and never leave the Maslow unattended for a lights-out operation. I keep several in my shop always in arms reach and I know I won’t ever leave it alone like I have in the past.

I hope this helps someone.

-orzot

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Way too high speed, i dial mine down to to lowest setting at 15 ipm.

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^^ This!

How and why did you determine that RPM and feed rate?

Suggestion: Change topic title to “I started a fire with my Maslow”.

Your machine didn’t ‘catch fire’. Your operation of the machine caused a fire… .

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I will add that if you already have a fire extinguisher, Kidde is recalling a bunch of plastic-handled ones. This includes models that were sold under other names, so it would be wise to check this site: https://www.kidde.com/home-safety/en/us/support/product-alerts/recall-kidde-fire-extinguisher/

Here’s the CPSC webpage with list of models:

@orzot

Welcome to our group & that is awful there was a “Carbon Condition”. I’m glad you were diligent in monitoring your work. Gosh I can tell you I eended up in a gas station when my car caught on fire. It was a 69 bug and the fuel line ruptured. When I asked where the fire extinguisher was they told me they didn’t have one. As I was going back in for water a guy came out trying to read the side if the extinguisher and struggling with the lever. I yelled give it to me, I had just done a class, he hadn’t pulled the pin.

Long story sort it’s always good to be prepared and now all my cars have an Extinguishers.

All machines have a function and no ability to think for you. caveat emptor!

I find my Maslow to be a worthy investment but it requires my participation. I’ve seen the chain ball up in 3 seconds flat trying to feed out. Like any skill it takes time, patients and diligence.

I’m glad it was a minor incident.

Thank you

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Thank you so much for calling this to our attention. I have been so focused on the zillion details of trying to get this thing working, that the idea of a fire extinguisher nearby hadn’t occurred to me… I will get one tomorrow.

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With a username like Dustcloud, you better! :smile:

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Hello! I’ve got my admin hat on this morning and I wanted to let everyone know: I changed the title of this topic from “…My Maslow Caught Fire” to “I Started a Fire With My Maslow”

When I saw the original title I immediately pictured a flaming Arduino but the topic clearly is not that! If only to assuage a panic, I thought a title change was appropriate.

@orzot no offense was intended and I hope you don’t take offense to this change.

This is an excellent reminder of how important shop safety is and that you should never run any power tool unattended.

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I used MakerCam to set the feed rate and the dial on the Rigid router was set to 23 (which is 23000).

Here is the piece I was making…

Here is the one that caught fire after I put it out…

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Thanks for sharing. Just last week I paused a long cutting process to attend an after school play my daughter was in. I was giving some thought in how to use the G code turn off spindle command to shut off the router if I left future projects running unattended. After reading your post, I think I’m going to scrap that idea.

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Smart man. :slight_smile:

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When drilling holes if dwell time is long with compression bit, the saw dust does not leave. So it accumulates in the flutes and rubs against the wood. The friction can start a fire.

Better not drill with compression bit.
What I mean, you can drill, sink with a compression bit, but up-cut has better saw dust/chips clearing when drilling.

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Good point. Compression bits are really only useful when you can cut the full depth at once (plunge to full depth then move)

The issue of burning or creating a fire with a CNC is not limited to any particular machine. This can happen a basic CNC up to an industrial CNC.

Typically the reason for the fire is friction has caused the tool and material to heat hot enough to the material to burn. The question is why is the tool getting that hot? As other mentioned above the general cause is feed rate and rpm of the spindle. Too slow of a feed with high rpm creates friction resulting in the bit to get hot enough to burn the material.

Dwell time can also be an issue. If the bit plunges and pauses prior to moving or is used for drilling this will cause the bit to heat up quickly. General rule is to keep a router bit moving in the cut. If the bit is used for drilling, try using a pecking motion, where the bit goes into the material and retracts and the processed is repeated until the hole is drilled.

There are optimal feed rates and rpm for every type of bit. Yes this will involve math, yet today most manufacturers will give you a starting point.

An easy way to tell if feed rates and rpm are to slow is to check the tool. If run at a proper speed the tool should be clean and show little discoloration when the cuts are complete. Even a bit which has run its tool life should not be very discolored. The discoloration comes from the bit overheating and thus and issue with feed rates and rpm.

Dwell time can also be an issue. If the bit plunges and pauses prior to moving or is used for drilling this will cause the bit to heat up quickly. General rule is to keep a router bit moving in the cut. If the bit is used for drilling, try using a pecking motion, where the bit goes into the material and retracts and the processed is repeated until the hole is drilled.

Still, having a fire extinguisher is a good idea.

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The big problem we have is that the maslow moves so slowly, and the router turns
so fast, that we don’t come close to the recommendations.

I know this is an old post, but, what is the max travel speed for the Maslow? I would think 30 IPM (inch per minute) would be acceptable if you kept your RPM to a minimum. As an example, for a .250 inch bit (just as a guess) I would run at between 20 and 30 IPM at around 15000 RPM with a depth of cut of .100. I base these numbers off my CNC Mill (Hurco and HAAS) experience. Let me know if you guys think I’m close or if I’m way off. As a rule of thumb, at least for metal cutting machines, if it sounds good when cutting then its probably good. :slight_smile:

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