As much as I hate bumping posts, I'd really appreciate some input on this. Thanks!
Using a Bosch Colt PRsomethingsomething00EV - the 1hp variable speed unit.
I toasted one lower bearing on this unit when the bit plunged nut-deep into a block of PS foam - liquefied the foam instantly and some of it travelled up onto the bearing surface...and into the bearing. It was fine for that job, but as soon as the router was stopped, the foam hardened, and thus the bearing was toast.
Replaced bearing w/ the Bosch OEM part, it's a press fit so nothing to get wrong...in the last couple days the router's been making some unhealthy sounds again at low RPMs and startup. Took it apart, sure enough, the lower bearing feels "gummy", not the least bit smooth. Additionally, when the router is turned off, the spindle comes to a very fast stop, clearly the bearing is impeding the spindle's free movement. Added a few drops o' 3-in-1, and it gets better for a little while, but gets worse after prolonged use.
The bearing was replaced ~3 months ago, and there isn't 50 hours of running on it since. I usually err on the side of under-loading the router, it's cut some mdf, a bit of PS foam, and a little bit o' aluminum since the replacement. And I bet it's seen less than 5 hours at full speed...I usually run it around 25,000RPM with shallow passes. At $8.00 and less than 30 minutes to replace, this dead bearing isn't a tragedy for me, but I would like to cure the problem once and for all!
My thinking is an $8.00 bearing can't be that long-living in a 35,000 RPM max router, so would it be reasonable to seek out a higher end aftermarket bearing? Ceramic, perhaps?
As the top bearing (smaller, no less) is still pristine, my feeling is junk is getting into the innards, and fouling things up. Any other ideas? Maybe a bearing with better sealing from debris, or an auxiliary seal beneath the bearing that attaches to the underside of the router?
As much as I hate bumping posts, I'd really appreciate some input on this. Thanks!
I don't think the user's of routers for spindles like to say much about the bearings, a lot just toss them & get another router, if they are using them alot, they fail all the time, even worse if they don't have good dust extraction
Yes a higher end bearing like ceramic will last better if you can keep the dust out of it
I was looking at the price for replacement bearings for Porter Cable routers the other day, and they're less than $10.
So I think that people just throw in new ones when they go bad.
Mach3 2010 Screenset
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)
P.S. Mine is getting bad, but I have several hundred of hours on it. I didn't know Mach 3 kept a maintenace hours running and inches per axis traveled log until recently, so I didn't know to reset it when I swapped spindles. On four spindles (3 are still good just not what I wanted) it shows 2300 hours. I run this Bosch Colt for continuous 6-12 hour jobs all the time, and have a few that run upto 30 hours. This Colt logged the most hours of the four though.
P.P.S. I think that VXB has a variety of ceramics in common sizes with seals to keep gunk out.
Bob La Londe
bearing life is dependent on
3) load / vibration / balance
a long length cutter or large diameter cutter will cause vibration and shorten bearing life as well as increase bearing temperature. high temperature causes bearing grease to dry out (oil separates from soap binder)
also some motors are made for intermittent use that is run for 5 minutes and let cool off for 5 minutes. if not rated for continuous use and you are using for long length of time you might need to think about additional cooling. also sometimes a hot cutter or bit is so hot from cutting the heat is traveling to the bearing and again cooking the grease.
I have a bosch 1617EVS modded with a SuperPID. Haven't had problems yet with the bearings thank God but I will say I don't baby the router either.
I've cut quite a bit of aluminum stuff the past 5-6 months, and I take deeper passes and faster feeds than some. I do use OneCNC high speed toolpaths which puts constant load on the cutter, and it does seem to make an audible difference.
Beterrn the HSM toolpaths, SuperPID, I think it's definitely helped my router, though I hope I haven't jinxed myself....
Bosch certainly makes good tools, I have several different types in my shop and hold them in high regard. That being said. . . .
You are using a palm router on a cnc machine. The palm routers are generally designed to be used by tradesmen to do things like trim laminate and other small jobs where they do not run for extended periods of time.
Every now and then a collection of parts will come together that for whatever reason will last and last. But you really have to look at what you are buying and how it was intended to be used.
I have a PC 892 that has at least 2000 hours of run time on it in my machine. Would I expect that same performance from a PC Laminate trimmer? No. I look at my PC Laminate trimmer and yes, it is well built, but there is nothing about it that says it was designed to be run continuously for 10 hours. It just does not "feel" heavy duty.
A similar example of this is when woodworkers build router tables, smart ones use a 3hp + router because it can handle the loads, the not so smart ones "save" some money and try to do it with a 2 1/4 hp router. They quickly wear out the smaller router.
Honestly, we should probably be building our machines with 3hp routers in them. But darn, that seems awfully big when I am doing .006 passes on sculpting work.
I would just replace it again, and ask the bearing guy to look up a good brand name high-RPM bearing to use. You might pay $15 to $20 for a good one.
Also it is possible if you are cutting carbon fibre that some CF might have worked it's way into the bearing?
It is tough to fathom that these machines we make can push a laminate trimmer far harder than any normal human could ever do. As mentioned, trim routers were designed mainly for "trimming" laminates and very light duty edge shaping work. I don't know how good the bearings are on them as far as axial loads; i.e. with repetitive plunging... I used to have a piloted bit with a point at the end for doing inside cuts with Formica and such, and I do have one with an extended base to do hinge plates...
That said, my first machine had a 1HP Craftsman palm router, and I didn't baby that one either.... I just got a new DeWalt palm router, rated at 1-1/4HP, that runs pretty smoothly, and might use it as a swap-out router on my CNC. Trend also makes a heavier duty small router that has a metal bearing housing, that would also make it easier to mount to a CNC...
Agree with everyone 100%
Having been inside the PR20's several times for cleaning, bearing replacement, inspections, etc., a few things do jump out at me which would certainly contribute to shorter bearing life.
- Lower bearing presses into a soft plastic bore, which is more prone to play and chattering. Both contribute to faster bearing wear. I suspect this is the weakest part of the PR20 design.
- Airflow runs through router body, introducing dust
- Upper body is plastic
I think the bearing bores were designed this way to work across wide temperature ranges, so the user doesn't need to warm up the bearings before use. Fundamentally, I feel this sort of router isn't ideal for our application, but for many people, this is the best/only option.
Which, if any, of these issues can be remedied in an economical manner?
Lower bearing bore can be redesigned in metal. I wouldn't expect this to be too tough, although it may require the bearings be warmed up prior to use.
Airflow exists in these to cool the motor - either it needs to be redirected away from the bearing, or alternative cooling needs to happen. Do the bearings benefit from cooling? Overall, I don't like air moving through the unit - dust is deposited no matter what.
Liquid cooling could be retrofitted, or an airflow deflector could be installed into the existing unit.
On the other hand, redesigning the housing in metal would solve the stiffness problem and make cooling solutions easier to implement. Liquid cooling would be easier to include, or a metal housing could incorporate a finned heatsink on the outer casing. I like the idea of a passive system. Overall, housing redesign wouldn't be worth it, IMO.
I think a router with the lower bearing supported in metal would run the bearing a lot cooler and be more suitable for long cycles of use. It's also a more rigid setup.
But you can still see your bearing shop for a good brand hi-life high-RPM bearing, it must last longer than a $8 bearing.