Wood Router as Spindle

Ok, The Bosch Colts seem to be getting worse. The first couple I used easily ran over 750 hours continuous duty. I think I got over 1000 on the
first one. At the price I just replaced them. The last few have been running progressively less hours before failure, and the failures have been faster and more catastrophic with over heating bearings actually melting the nose out of the router case (nylon press fit busing) Each one seems to last less than the last with my most recent one failing at about 250 hours.
I'm looking for an affordable replacement.
Another similar, but better router. Maybe a PC 890?
One of the import 3 phase VFD controlled water cooled spindles?
A bigger router might be ok although I am not maxing out the horsepower of the Colt. Just wearing out the bearings. Yes I have replaced bearings on some, and the replacement bearings usually last longer, but once it overheats and melts out it can't be fixed again. Well, not economically. I did consider trying to remove the nylon bushing the bearing rides in and replace it with a home made aluminum one that would transfer heat better.
The VFD controlled spindles will have less down time (no brushes), but I am concerned that I'll have to redo all my calculations for lower spindle speed (max of 24K) and I still need to know if the bearings will hold up longer, and if they will fail in a less catastrophic and more predictable manner. They cost more, but if I get more work out of them it might be worth it.
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This just goes to show that those accountants who control the quality of products are worth every penny they're paid. Sadly, it's the destruction of a good name. They (manufacturers) just don't GAF anymore.
You could (I know, I've seen examples of your work) machine the router housing end/bearing support section out of aluminum and make the part so the bearing can be swapped almost effortlessly (well simply), and use quality bearings intended for high speeds (not 10-for-$1 skate bearings).
--
WB
.........


"Bob La Londe" < snipped-for-privacy@yahoo.com> wrote in message
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bad stuff....
Bob, et al,
I have a friend who owns a 5x9 CNC flatbed router. He chose from the beginning to spend $2200 on an Italian high-speed head and VFD.
He's got >12K hours on the machine now (seven years plus, 8 hours a day), and nary a glitch. It's still probably good for another 5 years, according to the manufacturer's specs. FWIW, it doesn't "sing" any more than it did the day he plugged it in.
LLoyd
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Are you driving them harder? ie, have you optimized production to the point where they work harder and die sooner, or are the programs /feedrates the same and they really are just making them worse and worse (believable, just asking...)

Not familiar with the Bosch colt, but if the design hasn't changed much since I bought mine, there's a reasonable amount of metal (and replaceable parts) in a good old PC690 - which I use as the spindle in my CNC, but it's wood CNC, mostly, so....if you are not maxing the power on a (web says) 5.6 amp colt, an 11 amp PC690 should be plenty of power, and likely costs somewhat less than an 890... No plastic in the nose of a 690, as far as I recall.
--
Cats, coffee, chocolate...vices to live by
Please don't feed the trolls. Killfile and ignore them so they will go away.
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wrote:

No, I have definitely changed the way I machine over the last year. I tend to cut deeper at a much slower feed rate. My end mills last longer, and I remove more material per hour that way. It is possible that I might by pushing them too hard when I run a .125 end mill, but I would think the smaller ones would be more likely to break than put too much load on the spindle bearings. My calculations still show low fractional horsepower requirements.

I believe they are not using as good of bearings. The ones I replace the bearings on BEFORE they cook I get much longer run time out of.

I have been looking at the PC 890, but atleast one person reported that they had more runout.

I looked at the 690 too. I'll have to change my relays though for any larger router. I have 10 amp 48 volt relays controlling my spindle and coolant pump.
Thanks for the feedback.
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Bob La Londe wrote:

How about putting better bearings in a brand new one, and logging the hours with a running time meter? If you can get a good idea of bearing life, change them as preventative maintenance when they hit around 75%. It's also possible that the nylon insert deforms, and makes the bearings gun hotter.
--
You can't have a sense of humor, if you have no sense.

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I had considered that. Time and distance is built into Mach 3.

and that I was trying to do, but they kept failing quicker and quicker.

I had not considered that.
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Bob La Londe wrote:

Failure analysis was part of my job at several companies so I try to find the reason why we saw common failures.
--
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Michael A. Terrell wrote:

If the problem lies with the plastic why not just machine an aluminum replacement. I would bet that since most of your failures are bearing related that if you made a replacement housing out of metal the bearings would last longer due to better heat dissipation and alignment.
--
Steve W.

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That is one of the things I am considering. I haven't got my mind around the problem entirely yet. Making the entire bottom end would be way to time intensive and difficult, but if I can get the insert out and press in an aluminum replacement it might be worth the time.
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I just started looking at high speed spindles on eBay. What drive do they need? I need to spin a 1/32" x 6" cut-off wheel to trim wire filled end brushes.
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Tom, most of them want a 0-400Hz VFD. Just match to the wattage of the motor.
LLoyd
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They use a VFD. Single phase in and 3 phase out at variable frequency from 0-400 hz. There are a couple outfits who sell them as packages with spindle and VFD control. Most of the VFDs can be controlled off Mach 3 or EMC 2 with just a little figuring out.
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Looking at a PC (computer) radiator and pump if I go that way for cooling my spindle(s).
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