Discussion in 'Woodturning Discussion Forum' started by Bill Luce, May 6, 2011.
"Of course I'll respect you in the morning."
I have been thinking how it would be great if some machinist type turner started a small side business of replacing the old style twin front bearings for folks with pre 2005 2436's (or whenever exactly they stopped using that bearing) who decide that their bearings needed ners it would not cost anymore overall than going the OW route for their new bearing
IF A COMPANY COULD BUILD A NEW BEARING FOR THIS LATHE ,WOULD REPLACING THE BEARING VOID THE GUARANTEE ON THE LATHE, I AM SURE THAT SOMEONE COULD GET THE PARTS TODAY TO ASSEMBLE NEW BEARING RACE FOR ANY SPINDLE [EXCUSE THE CAPS]
That is not a realistic idea from a business, engineering, and manufacturing point of view.
From an engineering design and manufacturing perspective, tolerances stack up -- both fabrication and assembly. Adding one more interface element between a spindle and headstock that has to account for dimensions of those elements being anywhere within their tolerance range is only going to make tolerances significantly worse. If you are thinking of machining existing components to a different size, then there will be a very large expense in tooling set up for high precision machining. Needless to say, there will be no factory support from the OEM for maintenance and repair after that. That responsibility would fall on the owners shoulders.
From a business point of view, there is nothing to support the notion of a potential market from such a tiny sector. But, supposing that there were a handful of people who wished to have their lathes modified, the business manager would have to spread out the NRE and other one-time costs over a realistic projection of total sales within a certain time frame. He, of course, would also have to include the actual costs as well as a reasonable profit. While the businessman might be in a charitable mood towards woodturners, his employees, landlord, utilities, the businesses that he buys his tooling and machinery from, etc, are not very likely to be of the same mindset. Even a one-man operation still has to run his business as a business and not a charity if he wants to put food on the table. The businessman is taking on a potential liability even if he tells his customers that he doesn't warrant his non-reversible modification to be fit for any particular purpose and the customer must accept what he gives them "as is" since the lathe came to him in an unknown condition that was unsatisfactory to the customer. In the end, an imagined "simple" modification may run about half the cost of a new lathe.
On the other hand, you could take a set of engineering drawings and specs that you created to a specialty machine shop (maybe one that work for Indy cars) and have it done for much less. If they do the work to your drawings then that is that and not their problem if you decide you don't like the design change after all.
I think that someone else mentioned welding to build up the spindle for further machining. That's a bad idea because it almost guarantees warping the spindle as well as destroying the heat treatment tempering. This could snowball into an expensive proposition and probably be much cheaper to machine a new spindle from raw stock.
(Left side of keyboard, third key up from bottom -- make sure that it is off)
Never did hear back from Kevin with any info or a tracking number like he promised, but a new spindle did finally show up.
Not as bad as the last ones in terms of runout, but not within the max runout spec I asked them to check for and he agreed to (a max of .002 runout inboard on an insert only). I wish they had just sent me back my original spindle, as it was fine (just like my older 2436). Overall I feel actually I have gone backwards over the 8 months with this lathe having received three funky spindles in a row (4 if you count the defective one they accidentally returned to me).
Inboard shoulder and registers measure flat/round on this spindle with a DI (as has been true with all of them), haven't verified what the actual issue is with it yet to cause the runout on the insert.
I would be interested in knowing the sequence of how they machine the spindle,and I suspect the threads and the area between the registers are last step and they are having some sort of issue they don't recognize.
For example the surface between the two spindle registers on this spindle has a surprising amount of runout exactly in the direction of the runout of any inserts threaded onto the spindle show.
I am guessing that this material is removed at the same time (same fixing) as when the inboard threads are cut. I realize the surface between the registers does not need to be accurately machined, but mention it in case it reflects on the process of machining the threads.)
Bill B, Indeed it would be a small market. I spent I think about a grand having a new spindle made for my OW. Since he gave me larger shoulders for faceplates and chucks to settle on I would have to buy two new end caps should I wish to put back in the old spindle. But he said he modified nothing else on the inside.
Bill L., I did take a look inside and he does have the thing that adds pressure and holds all that in place. So he did not take it out. I may pull the thing apart to loosen up stuff to see just what kind of pressure he put on the bearings. Since when I really crank on the tailstock I can tell its putting straight in stress on the bearings. But the work was done many years ago so I am in no hurry.