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Sled change to avoid fires

I’m not sure this has been suggested before, but I thought about what happens when the router slides out of the z-axis arm and slams to the plywood due to the bungie tension and thought that it probably could be prevented with a slight tweak to the sled. The idea is basically put ‘wings’ on both sides of the center hole and install a couple of wooden dowels so that if the router body does pop out and heads toward plywood, it would hit these stops first before the chuck hits the plywood. Not to scale. The two small holes are where the wood dowels get installed.

I’ll probably try this out when I build my new sled.


So the fire was caused by z-axis failure with the router bit holder rubbing against the wood? I assumed that router stopped moving and the bit caused the fire.

Alternatively idea you might consider is using a large $2 hose clamp (6-8"?) on the router body to stop it going to far down. Might be less effort and cheaper to implement.

e.g. Clamp it in green area in pic below.

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That’s what has happened. I like your idea

remember that the stick-out of your bit is going to vary, and it still needs to
be able to go the full depth through your workpiecee.

so what depth do you set the limit to that doesn’t prevent you from making the
cuts you want, but still prevents the bit from going too far if it slips?

I don’t think there is such a value.

David Lang

I think the way you do David. I will never feel comfortable leaving the Maslow alone to do it’s own thing. I think I’m going to get a cheap IP camera so I can watch it from my TV chair. :wink:

You’re referring just to the clamp idea, correct? I don’t think the dowel stops have that issue.

Well, now that I think about it more, I’m not sure either have the issue. I think by lowering the router so the chuck is just above the workpiece and setting the clamp to be against the router “frame” and tightening it down really, really well, you’d be ok… regardless of the size of the bit (assuming you aren’t actually trying to extend the chuck into a cavity to get ‘extra’ depth). But, as always, I could be wrong.

@madgrizzle Funny this came up… last week was cutting a drawer divider right in the middle of the work area and I did a no no. I went inside for about 10 minutes, thinking I would hear a pitch change if anything went wrong :grimacing:
Well in fact in that little time Murphys Law occured. On a small pocket operation, the router plumetted into the piece and I walk out to a smoldering ember from the chips that had fallen to the pocket below :fearful:
Plain and simple, I should have paused. I now am in hyperdrive trying to get a cbeam zaxis up and going.


That would keep the chuck from rubbing, but not the bit (which is what srarted
the fire)

David Lang

Oh, I’ve not experienced a flame up from a bit staying recessed into the workpiece… I did experience one from the chuck hitting the board though when it released from the arm and that’s what I was trying to avoid happening. Fortunately I was there for that. Maybe can put a contact switch on it as well that can trigger a spindle off.

It should be possible to install a switch that only activates when the Z-axis slips down too far. The hard part is wiring it up to your router in a manner that allows it to cut the power in a safe manner.

Ideally, the maslow board would have an output that could control mains voltage. This way it could trigger the router to turn off if a limit was hit or if the maslow detected that the sled was no longer moving. This would reduce the risk of fires caused by a stuck bit or by a z axis failure.

The z-axis adjustment has limited travel which in my case is further reduced by the bushing fix. This leaves a good 1/2" on the router body above the router base that is never used. The hose clamp should comfortably fit there. In the pic with green line you can see dark gray marring where the router body rubs. This marring indicates the max clearance travel I have used and does not extend into the highlighetd green area.

To calibrate travel I adjusted the router down all the way then locked the bit in place with it extending 7/8" below sled base. I at max will only use 3/4" stock so this ensures it will cut through without bottoming out. Finally adjusted zero level. This leaves about 1/2" travel above stock for clearance. Set clearnace heights in Fusion360 to be max 1/4" and was good to go.

Thanks for the pics @clintloggins. This is what I was worried about with the router bit starting the fire which is much harder to avoid.


had the beginnings of what this looks like with ours the other day,was caused by a small dia bit doing a heap of cutting in12mm ply and it simply got blunt which caused it to get hot and was starting to char the cut .


After having mine pop out repeated times this is what I’m gonna try out tomorrow. Gotta get all shavings cleaned up and give it a trial run. Hopefully I didn’t just create another problem for myself lol. Sucks I’m voiding warranty but I prefer it over potential fires.


Hey @Cbolt360 did you dill and tap the router body or just the z-axis arm?

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I drilled larger hole in arm and drilled and tapped router body. 1/4" bolt about 1" long as that was smallest tap I had otherwise I would have went smaller so I didn’t have to cut a chunk (just left of bolt) of router sleeve for bolt clearance. Still haven’t had chance to test though as something came up yesterday.

Update: At first I had to loosen bolt a few turns so it was barely touching z axis arm otherwise it was causing binding. After that though it has worked fine through a few dry tests. True test though is getting through a cut.


Is there anything inside the router body to watch out for when drilling? Look forward to new on how it works/breaks.

No I didn’t run into anything drilling in that location. At first I had a bit to long of a bolt that threaded into body about 1/2 inch without hitting anything but I changed it out for a shorter bolt. I’ve cut a few projects with it no problem since.