Well #3 for some reason had both "Z" style bearings. I dont remember doing that but maybe thats all I had when I built than one up. Going to load a short carve to break the "VV" ones in, 6 hours...
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Well #3 for some reason had both "Z" style bearings. I dont remember doing that but maybe thats all I had when I built than one up. Going to load a short carve to break the "VV" ones in, 6 hours...
It's been about seven months since you reported the bearing failure. How's the replacement working out? I've had my old quick change style chuck spin loose on my Carvewright and figure as long as I'm fixing it I may as well upgrade it to the er20 design. I'm just in need of a bearing that will last.Quote:
Originally Posted by bergerud
About that ceramic bearing, how did you go about pressing it into place? Are they fragile? Has anyone looked into an angular contact bearing?
Another thing, is it possible yours got too hot because you lubed it? The Teflon is self lubricating and should have been able to withstand the heat. Maybe the lube provided too much resistance at high speed causing excess heat?
I still like the design and if the bearing problem can't be solved maybe we should be thinking of a new Z axis truck design that will either support larger bearings or some kind of cooling if heat is the problem. Liquid cooled? Air cooled? Maybe design in the dust collection in the new truck to the vacuum can provide the cooling for the bearings? I've never been a fan of after thought style dust collectors. Just a little food for thought.
I'll be ordering a bearing or two in the next couple of days as my machines are both down. A few of my Christmas gifts are going to be a little late this year.
Brad
I am quite happy with the hybrid ceramic. It is a high quality bearing and I think it will last. Also, I think the VV bearings last ok as well. This is a case where one cannot go cheap.
I have also thought about designing a whole new truck with better bearings. I do not see, however, how to get the hose out for on truck dust collection.
The VV bearings have worked great for me. The only thing I would note is as we tested the different bearings I did have a couple tolerance rings go. I believe from taking bearings in and out so much. But other than that solid.
Did you go with VXB bearings again? One of my complaints with their site is they leave so many bearing specs out of the information. Heat ratings? RPM ratings? Those two factors are quite important to our applications. Any special requirements pressing those ceramics onto the spindle other than keeping things squared while applying pressure?
I'd really love to try an angular bearing but most of them are unsealed and won't work for our application.
I was thinking of a tube inside of a tube design for the vacuum problem. Think of the head and block of an engine with the water ports channeling water around the internal combustion sections of the motor. It may have to extend further out of the slot in the top of the Carvewright to allow a manifold or port to separate the drive shaft from the vacuum. The trick is to keep it compact and light. The closer we can get to the source of the chips the less vacuum we need and that helps to keep the hose diameter small. But you already know all that. Your dust collection designs make that clear. If we increase the diameter to move chips we can also build thinner and end up with the same strength. One of the limits will be side clearances within the machine itself.
Another possibility is a lightweight composite such as carbon fiber for dust collection around the central bearing supports which could remain aluminum to maintain keeping things rigid. I think the design could also be simplified by making the top and bottom bearings the same size. The downside of the composite structure is making things more complicated to manufacture. I'd rather start with a rough sand casting of aluminum machine it to size from there. A light weldment of chrome moly 4130 tubing as a starting point prior to machining may also be a possibility.
Bought them on ebay. That way I got a little more bang for my buck. I'll try to find the item numbers.
Your probably carving the longest carves on a regular basis and that says a lot. What VV bearing did you use?
I'll need to look them up. Just to be sure I don't misquote. And your right. I do 12 hour carves weekly. At least one or so. I have one machine that is all it does. Then another just for the short ones. The other two just sit as backups.
I read somewhere that the vv was a brand specific code that NSK uses. I found a 6804 vv bearing on ebay for $21.00 dollars American and ordered that to get me up and going again.Quote:
Originally Posted by unitedcases
I also ran across an "Enduro" brand "ZEROceramic" part number: C0 6804-VV Zero Ceramic Enduro Bike Bearing 20 x 32 x 7 that looks promising. My only concern is most bikes don't have the spindle speeds we do. The price would have been about double as it was listed in euro's. Still not a bad price if it proved to work for any length of time.
I was thinking Rectangular Metal Pipe.... Thought of grinding flat the front of the current truck to the top hat bracket and the bottom close to the spindle with a slide down after homing piece... since you mentioned it...Quote:
Originally Posted by bergerud
AL