Thread: Router explodes in service

Glad you are ok. Now go and change your undies

what influenced your decision to not turn it off first I ask this as I am not familiar with the router.
Here is a parts diagram hope it helps Hitachi M12SA2 Parts List and Diagram : eReplacementParts.com

is there anything that is broken metal wise that looks like it has fatigued or snapped under pressure.

It has been several months since I have used this router, and I was not entirely comfortable with it, esp being a left hander, hence switching off at the powerpoint, before the spinning bit hit a live cord or anything.

I like to have the router firmly and sitting on a bench or workpiece when starting, to overcome the startup torque, and then plunge it on to the workpiece, and lock the height with the lever. I usually reverse the procedure for shutting it down. But first I have to release the height locking lever, which is what I was doing when the base and the router separated.

in hindsight, I should have released the locking lever while the router was on the workpiece, unplunged it in a controlled manner holding the router firmly, then switched it off and put it down on to bench. But I was actually trying to get the router offf the workpiece in this instance before risking damage to the workpiece.

My edit above shows the link to a parts diagram

My guess would be that the nuts/screws holding the base have vibrated loose and the sudden jolt made them let go...
If you closely inspect, you should be able to get some idea. Check nuts or bolts for worn/sloppy thread.
Is it still under warrantee?
TM

To me it looks like item 46 from Pacman's parts list has broken by your 3rd photo. From what I can see, that is the only thing that prevents the body separating from the base.
Did you have the router suspended when you released the locking lever with nothing to prevent the base from coming to a sudden stop when reaching the end of its stroke?
If so, you should always have the base supported even if just on one side, say over the edge of your bench, then release the lever and slowly lift the router body until the end of stroke is reached.

No sign of any broken metallic parts or fatigued parts. It would appear the only thing normally preventing the base from separating from the router body is that broken bit of plastic. It has to withstand the force of the springs expanding suddenly when i released the height lock lever. I think most of the noise was the base hitting the yellow workbench.

Thanks for the exploding parts diagram, packman - for a minute there I thought this was exactly how my router looked immediately after the incident.

Glad to hear you came out of it with everything intact! That had the potential for being a costly exercise.

I have come close - I think - to similar happening with one of my old B&D routers. It wasn't moving as freely when raising/lowering and I assumed the springs were loaded up with dust and needed cleaning... so I disassembled it.

It turned out that one of the plunge bolts had come undone! (The equivalent of parts 40 and/or 87 in PacMans parts diagram)

Now it was only because I had a spare moment that I pulled it apart for a "service" - it was still working fine beyond the stickiness - that I discovered that it was actually in need of a "repair."

If similar has happened to you... then only one bolt is holding everything together and as one bolt worked itself loose then the odds are the second isn't far behind it...

I'd carefully inspect the relevant sections of thread for damage before reassembling. Just so's you know, y'know?

Same router here in market place a couple of years ago with some good what its s'pose to look like photos.
As treecycle has said once the locking mechanism is release the tension would rapidly push the base down and over time ?fractured part 46 and then base pops off.

Originally Posted by TermiMonster

My guess would be that the nuts/screws holding the base have vibrated loose and the sudden jolt made them let go...
If you closely inspect, you should be able to get some idea. Check nuts or bolts for worn/sloppy thread.
Is it still under warrantee?
TM

Dengy

I would go along with TM's general thoughts.

I had a large GMC router do a similar act with me except I was not particularly subjected to fast rotating pieces. I had bought it cheaply after the GMC demise. My attitude was "Oh sh*t. That's it then."

On the strength of that when a work colleague was selling a large Makita, I snapped it up. As I went to throw away the GMC I realised that I only had to screw things back on. They had vibrated loose and possibly were never tight. Who knows? It has been working ever since .

Regards
Paul

Yes, Treecycle got it in one! The small plastic part no 46 took the sudden full force of the highly compressed expanding springs between the body and the base once the locking lever was released while the router was held in the air, prior to putting down on the bench.

while its apart it would be a good time to go over the threads as per TM and Skew

I also wouldnt be drilling in the brick wall as per your other post, youve had your luck for today me thinks.

That router doesn't look too old. Do they still not have soft start on those?

I got caught without the softstart feature when I bought it off eBay - I thought it would have had it too

Pacman, I spent the morning drilling holes in the wall, didn't hit the wiring. Was setting up the router to finish off a bedhead 1800 x 600 board that was to be hung off a frame attached to that wall.

Am having the rest of the day off - no point in pushing my luck too far. That router incident could have been a lot worse.

I think the sequence is basically
Unit is fully plunged by the sound of it (maximum energy stored in springs)
Plunge lock released with the base well clear of work so release is sudden and uncontrolled.
The only thing stopping the disintergration is a poor piece of plastic that shatters on impact leaving the rest of the plunge mechanism, base etc to continue on its way. Glad my old Mak 3600BR has a metal nut operated by a long reach placky handle to retain the base and plunge springs.

I am not normally a big fan of accessory foot switches for routers, but in your case I might make an exception and suggest one as a way to improve you access to power controls, but if you go that way remember that the sequence would be.
Check inbuilt switch off.
Position router for job.
Turn on inbuilt switch ( move han if needed then replace)
Depress footswitch to activate router, make cut including plunge as required, release plunge, release footswitch to power down
Lift router from job
Switch of inbuilt power switch.