Nigel, which size of Vertex do you have? I pulled a tiny 4" one apart a year ago to clear out the (manufacturers) swarf and adjust it and was able to adjust out most of the backlash, but that is no longer to hand and I seem to remember the blurb suggesting that the bigger ones had proper bearings.
On Thu, 24 Mar 2005 16:53:32 -0000, "Andrew Mawson" wrote:
No direct help with your question, but my experience confirms that 'proper bearings' are an important consideration.
You may have seen my postings over machining & gear cutting a big flywheel (150Kg+), I started off trying this on a 14" MECA table which I'd picked up for 40 quid at a steam rally tool stall. It seemed logical to use the biggest table I could lay my hands on The stepper motor, via belt reduction, would drive the table round OK with no load, but wouldn't even look at it at any speed with the flywheel on. This is a table of reputable make, no idea what sort of bearings though & probably not been maintained beyond a few drops of oil since it was new, which was probably a few years ago. I then turned to my 'good' MECA 12" table, a classy bit of kit which has oil bath for the gears etc., and is listed on the Meca website where I could check that the load was within its ratings. This looked a bit small for a 23" dia x 6" deep flywheel, but it did the job with no trouble at all, and would run at any speed my setup was capable of even with the 150Kg load. This setup was done mainly for this one job, but in the expectation that there may be more to follow (2 more already ). Prior to that I had converted a 6" CH dividing head for more general use as a 4th axis, I'd been looking out for one with a decent CH so as to be able to us a reasonable sized chuck, this one looked the part at the right price. It's of East European origin, I think, the quality of machining etc is high, it had apparently had very little previous use, but it was obviously built down to a price. This means that friction levels are higher than they would be in the likes of a Hofmann or Victoria, for instance, which usually have oil bath lubrication etc. It works, but a lot of the torque avilable from the stepper moter is used in overcoming the friction within the head. If I was starting to do the same job again, I would wait longer/save more pennies until the 'right' dividing head came along.
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