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ljoe1969
10-16-2003, 10:06 AM
I was wondering why everyone is using roller skate bearings on there homemade cnc wood routers.

Are they sealed or unsealed bearings?

Also has anyone made a 24" x 36" wood router using a rotozip type tool as the cutting spindle?

anoel
10-16-2003, 11:54 AM
The inline skate bearings are a simple inexpensive source for a very high quality bearing. You can usually get ABEC5 or ABEC7 bearings for about $15-$30 for 16 of them. That's a killer deal on a quality bearing. That's probably the big motivator in using them.

I built a decent size router using inline skate bearings (18x32 cutting area) and use a Dremel Advantage as a cutting tool. it works quite well. (it's not going to compete with a Porter+Cable or equivalent full size router) But I definitely like the Advantage much better than the Roto-Zip. But I've cut hardwood and plastics with no problem. I tried doing some aluminum but that's a bit too much strain on the tool and my machine.

Mr.Chips
10-16-2003, 08:25 PM
Ijoe1969
As anoel has said they are a good bearings that can be used for a number of machines.
Please go to this link and look around, he has first rate plans plans that in most cases can be built with hand tools and parts from your local hardware store.
http://www.crankorgan.com/index.html

I highly recommend his plans.
Hager

DaSigntist
10-16-2003, 08:46 PM
Hi,
I bought mine from eBay yesterday for my upcoming machine (see URL below)
With shipping $25.00 bucks for 100 sealed bearings!

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=36624&item=3631258481

Heck I'll use less then half but it was cheaper then locally for 20 of the same.

Need half of them email me........
I'll use 36 of them max.

I'm going for the under $750. 4'X3" "budget machine"
And will go for all the chaepest materials and upgrade if need be.

Cheers

Thank you to all the CNCZone Gurus that are inspiring my poormans router!
Pictures to be in the future.

cbcnc
10-17-2003, 02:24 AM
Hi There,

I say that you should be a little careful of bearings that are sold as skate bearings. There may be good ones out there but there are some that are not so good.
I have heard talk of poor quality grease and rust on some. My own experience with some that I bought and used is that the seals are not that great. I get some leakage. Secondly I tried press fitting one into a bearing holder that I turned and found that the bearing became rough when it turned. So I had to go to a slip fit. It still works but the bearing could spin with enough force.
Also in working with them you should understand that they are metric sizes. 22mm x 8mm x 7mm (OD, ID,Th.). You can see the difference if you put one on a 5/16" rod. It will have some play. Then take a .001 shim and wrap it around the rod once. You should still be able to slip the bearing on but it will have considerably less play. 8mm = .3149", 5/16" = .3125".
I realize that if any of my bearings mess up they are inexpensively replaced. I just found that you had to take their limitations into account.

Good Luck,
Chris

ljoe1969
10-17-2003, 10:59 AM
Are the bearings sealed or open?

balsaman
10-17-2003, 01:29 PM
Generally sealed I would think but perhaps some are just shielded (metal shield instead of plastic seal.)

Eric

cbcnc
10-18-2003, 02:11 AM
IJoe,

The ones I bought are shielded and not sealed. That is the reason I have had some leakage. I have another bearing that is the same size that I removed from an old router. That one is sealed and of better quality. You can really see and feel the difference.

Chris

ljoe1969
11-07-2003, 08:36 AM
Would someone measure a skate bearing for me? I need the thickness, inside diameter and outside diameter.

thanks.

cbcnc
11-07-2003, 08:46 PM
IJoe,

22 mm OD, 8 mm ID and & 7mm thick.

Chris

HuFlungDung
11-08-2003, 05:41 AM
Originally posted by cbcnc
Hi There,

~snip~ Secondly I tried press fitting one into a bearing holder that I turned and found that the bearing became rough when it turned. So I had to go to a slip fit. It still works but the bearing could spin with enough force. ~snip~
Good Luck,
Chris

Press fit for a small bearing like that must be light and accurate, maybe .0002" max interference, so as not to remove the internal clearance. However, you can also use Loctite compound to lock the bearings to the shafts or housings with ease. :)

Take care that your housing shoulders and shaft abutments do not extend so far radially, that the rotating elements could contact the bearing seals and increase drag. This might mean machining a bit of a counterbore inside a housing, to create a little step that will just catch the metallic part of the outside race of the bearing, thus clearing the seals or shields.

xairflyer
11-09-2003, 08:46 AM
Been looking at bearings and noticed ceramic ones sold for skateboards quoting that they last 4 times as long.

Are they worth looking into