When it stalled I couldn't stop everything fast enough so it bent the 8mm steel bar that I was using to extend the length of the cutter - shows how powerful the steppers are to do that!
Anyway, I think I'll get this one from this seller:
It's the cheapest I can find. He's not got much feedback though...
Maybe get a 2.2Kw one:
Or is that overkill?
Does anyone here have a dimensioned drawing of one of these spindles? What does the 180mm length correspond to exactly - as in does it include the chuck/wire etc?
My guess is centrifugal force took over and bent the bar not the power from the stepper,there is a reason that the cutters are not too long, and that is for safety/stability reasons. I'm sorry if i seem to be having a go at you personally but you seem an accident waiting to happen.
So this rant is also aimed at the people who think machines running at high speed are safe, they are not especially when you modify them to be even more dangerous.
The last thing people on here want to hear is of you having an accident or anyone else for that matter.
Sorry I was ambiguous. The 25mm length of the extension piece that was in the router is 8mm, and that's what bent. The rest of the bar was 12.7mm. It wasn't centrifugal force...what happened was the router stalled and started only spinning at a few rps whilst gantry was still moving at cutting speed. That meant the cutter holder was basically bent by the X axis motors against the face of the MDF it was cutting ... naturally it bent at the weakst point. I hit the stop buttons pretty quickly, but evidently not quick enough. I underestimated how much extra force it put on the cutter having it 50mm further out.
I've used the same 'extender' in the milling machine lots of times before, admittedly at a lower rpm - yet similar feedrate so probably similar cutting force. If it wasn't for the router stalling I think it would have been fine - I wonder why the router did stall? It had only been going about 30 seconds. I've dismantled the router and checked the brushes/bearings and they all seem fine.
I was wearing saftey glasses and ear defenders - got the latter for Christmas! I agree that one should be conscious of saftey with these things (hence my recent thread about dust extraction!)...I once witnessed someone at school on a lathe (identical model to yours incidentally) put a long piece of 1" steel tube in the chuck to face the end, but didn't support the other end. As you say, centrifugal force took over and bent the steel tube to 90degrees, and smashed the cover off the lathe headstock that protects the autofeed gears shearing a couple of M10 (ish) bolts in the process. The teacher was NOT happy! We had health and saftey in the workshop drummed in to us since the very beginning - using lathe when I was 12.
'accident waiting to happen.'
Is there something else I've said that makes you say that?
My rant over...
Last edited by Jonathan; 02-01-2011 at 10:40 PM.
50mm extension is just way too long and are you are gonna admit its made of soft steel
Here is a pic of an extension i made for a Makita 2HP router , on the left is the original nut and on the right is the extension, the extension is the same diameter as the shaft so SAFE anything less is dangerous.
New rant over.
It was made from 316 stainless steel (not nice stuff to machine, work hardens), though I'll admit that was mainly because that's what I had at the time. I made it 8mm as that's the biggest collet the router can take. The nut and collet are separate parts on my router, so it would be tricky to make a mount like yours.
The safety things I won't have much idea is where there's a difference between manual and CNC machines since we only had a very small CNC router/engraver at school...
Last edited by Jonathan; 02-01-2011 at 11:20 PM.
Ask Trend Routers if they make an 8mm router cuter that projects 50mm from the collet and see what they say. I have had a few close shaves myself so i know what i am talking about.
I'm sorry if in my last few posts I've appeared to think I know more than I do about this. I do value your advice as you clearly have a lot more experience than I have. This discussion has made me think more about what went wrong than I would have otherwise. Still I think there was more to it than the tool extension, since had the router not stalled then I think it would have been fine - it was cutting fine before it stalled.
Maybe the extension put a larger bending moment through the router spindle, effectively trying to twist the inner race out of the bearings and they overheated? Seems plausible if the motor is running ok but the spindle is out of whack.
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