How I almost set fire to my garage...

[GEOFFREY]

Not wanting to teach my grandmother to suck eggs, - but you should Never leave a router cutting wood unattended. If the spindle manages to pick up on a piece wood and rotates with that piece on the cutter, when making the next Z down move can cause a fire in no time due to the friction of the rotating wood rubbing on the job. Matters can be even worse with a vacuum bed as the vacuum can cause the sacrificial board to smoulder, and perhaps burst into flames hours later when the machine has been abandoned for the night. I think you have indeed had a lucky escape!!!G.

[cncJim]

I would be concerned for the spindle bearings. From your photo is looks like things got hot enough to discolor the collet? If so then I expect the bearings would have got very hot as there's not much distance between the collet and the bearings.

The bearings on my spindle do have seals, although due to being high speed bearings they rely more on the labyrinth seal. These pictures should give you an idea what to expect:

Attachment 11359Attachment 11360Attachment 11361Attachment 11362

If this had happened to me I'd definitely dismantle the spindle and have a look at the bearings. It's not too difficult to disassemble the spindle - the only difficult bit is removing the nut on the collet end. You might be fine as it is, or you might find the oil/grease has burnt away and the bearings fail in a few months.

Thanks Jonathan, I am in two minds about opening it up. Part of me wants to open it up and check it out but then I think stuff it, keep running it until I have problems, and deal with the bearings then.?

[Jonathan]

Thanks Jonathan, I am in two minds about opening it up. Part of me wants to open it up and check it out but then I think stuff it, keep running it until I have problems, and deal with the bearings then.?

If you leave the bearings and the grease/oil is no longer present they're not going to last very long, then you'll need new bearings - i.e 7005 matched pair for about £50-£100. Compare that to a few £'s on the right lubricant. However you might find that there's nothing wrong...

Just looked at the photos again, and it looks like the spindle itself has blackened? Is that just soot? I hope it's not got hot enough to anneal the collet taper, as that would clearly be a big problem.

[cncJim]

If you leave the bearings and the grease/oil is no longer present they're not going to last very long, then you'll need new bearings - i.e 7005 matched pair for about £50-£100. Compare that to a few £'s on the right lubricant. However you might find that there's nothing wrong...

Just looked at the photos again, and it looks like the spindle itself has blackened? Is that just soot? I hope it's not got hot enough to anneal the collet taper, as that would clearly be a big problem.

I didn't realise you meant I could potentially grease/oil them up again, I thought I would be opening it up to see if the bearing needed replacing or not. I also didn't realise new bearings would cost so much!

On reflection I think your right and it's worth a look.

You mention it getting hot enough to anneal the collet taper, forgive my ignorance but why would this be an issue?

Thanks.

[Jonathan]

You mention it getting hot enough to anneal the collet taper, forgive my ignorance but why would this be an issue?

The spindle shaft is machined from a grade of steel which can subsequently be hardened and ground. This is necessary to ensure that the wear caused by changing the tool/collet doesn't wear the taper out (much), which would lead to high run-out. If yours has been heated above a certain temperature (which depends on the grade of steel), it will be softened and will wear out much more quickly. The temperature range is quite wide though, and we've not really got much idea how hot it got, although the colour can be an indication of that. Either way it's hard to tell...

[JAZZCNC]

Jim I'd strip it just to be safe better spending 60mins and £1 worth of grease than 2 weeks waiting and £150 for new spindle or even £80 on bearings.
Like Jon says there's nothing to it other than plucking up the balls to do it.!!

Wouldn't worry to much about the annealing has while it could have I doubt it did because it didn't fire up and the amount of heat required to anneal would have set the wood on fire.!!

[Jonathan]

Wouldn't worry to much about the annealing has while it could have I doubt it did because it didn't fire up and the amount of heat required to anneal would have set the wood on fire.!!

Yeah, to be fair I think you're right. According to wikipedia(!) the annealing temperature for steel is between 260°C and 760°C, depending on the grade, so if you compare that to the autoignition temperature for oak, which is around 250°C applied for 5 mins...it's probably fine.

[JAZZCNC]

Yeah, to be fair I think you're right.

It has been known from time to time.!. .

[JAZZCNC]

Back to the Potential fire and E-stop then I've seen Larger machines use a Rope E-stop with rope that runs around the machine that can be pulled from anywhere on the machine and activate the E-stop.!!

Oh by the way I'd already seen these pics fews weeks ago and asked Jim if he'd please post because it's important to show just how powerful and potentially dangerous even small machines can be.
I see it often people saying " Not botherd about E-stop because the steppers will stall or spindle will stall " or " I'll just switch it off at the wall" but they don't realise the full power even medium torque steppers can have when attached to ballscrews or how like a startled rabbit your froze on the spot for what seems like minutes but is nano seconds and by the time your brains recovered from the shock and told your arm to do something it's all just too late.!!
It's not until you actualy have some thing like this happen or see stationery 12mm cutter punch a hole thru 30mm of bed like it was punching butter do you stand back and say "OH SHITE".!!

So thanks for sharing Jim and Boy's he deserves some Thank's so get clicking. .

[cncJim]

I have a bathroom isolation switch pull cord running the length of the back wall which will shut off all power to the garage and an RCD box just for the garage by the door next to the fire extinguisher.

Not needed either yet but I like the "plan for the worst hope for the best" approach.

I am in the process of turning the garage into a "proper workshop" with a mill and lathe and top of my list is to sort the electrics out. I like the idea of an isolator by the door, piece of mind knowing all power is off when I shut up for the night.

How about a smoke detector connected to a contactor to turn of power to router etc. ..Clive

Well I have a stand alone smoke detector in there now. The house alarm box is close by so I thought I might hook the smoke detector into one of the alert inputs. That way if there is any fire issue in the garage, I would know about it all over the house. I already have a raspberry pi hanging of the house alarm ready to send me an email if the alarm goes off!