Repouring a Babbitt bearing headstock

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Ok, so I have an extra headstock that has had its babbitt removed, the fellow that owned it previously machined what appears to be bronze 2 piece bushings to sit in their place. It didn't work all that well from the looks of the scoring on them. So I'm toying with the idea of restoring the headstock with new babbitt bearings. Now I've seen quite a bit on youtube, and Keith Fenner has a couple of videos showing the process. That part doesn't appear to be terribly difficult or complex, though he does make things appear easy. The issue that presents the greatest challenge to me is how to secure the spindle or suitable core with the proper height and alignment to the ways.

One approach I saw, the fellow used the tailstock and the thread gears to lock the spindle in its proper location. Very good idea, however the issues here are, this headstock a. doesn't have a spindle yet, and b. doesn't have the original babbit in place to make the initial set up. Right now I'm leaning towards a bar turned to match the spindle, held in place between centers of my original headstock and tailstock. I don't like the idea of doing a pour over the bed, but I don't really see a way around it. One of the methods keith used doesn't strike me as being accurate enough for alignment to the bed. Another idea I had was to pour the bearings in go, with shims in place spanning the bearing entirely, and completely fill the area with a solid mass, then somehow mount the headstock to the carriage, or perhaps place it in the bed, and use the carrage to push it towards the headstock and bore it.

Not really sure of the most efficient way of getting it done accurately, so I'm looking for additional input and ideas. Thank you in advance.

Terry
 
Why not make timken bearings fit the housing instead of the babbit it should not be that hard at the very most maybe machine a sleeve or something to make them fit???
 
Not entirely sure that would be an option, as the geometry of the headstocks vary quite a bit between the babbitt and timkin versions, where the bearings are concerned. While I have read you can swap spindles with a bit of care, the only thing I've seen regarding a retrofit to timkin from babbitt includes replacing the headstock. Which I'm considering, but the challenge of redoing the babbitt is appealing too.

Terry
 
You could use aluminum it makes a good bearing surface but if you want to make new babbitt bearings you could make a mold out of steel we use to blacken the surface of the mold with a torch so the babbitt would not stick to the mold and then pour the mold with a silver bearing material. This way you dont have to machine them once thay are in place. Ray
 
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If you have a woodworker friend who has back issues of Fine Woodworking, They had an excellent 3 or 4 page article on re pouring babbit bearings. The article was in the early 80's - back when they were a serious magazine. I can look up the issue if you like.
Michael
 
At a shop I worked at few years back I did some centrifugal Babbitt casting. The easy part was heating it and pouring I in.... The hard part was to get itto stick and no crack when cooling. Pre-heating the base shell, using nasty chemicals to clean and flux and controlling the cooling .... No very fun.

If you are dead-set on Babbitt bearings maybe there are Babbitt inserts than you can put into custom bushing? Like rod or main bearing on a engine except perfectly round.
 
Check out www.rotometals.com for several different babbit alloys. I have bought metal from them before and was not unhappy with the service or the price. I think I would consider turning a mandrel to the diameter of the bearing journal or slightly undersize. long enough to be positioned by the tailstock and steady rest. I think the longer the better, so that any alignment error would be lessened (assuming the mandrel is straight). Once the mandrel is in position, go ahead and pour the babbit. If the mandrel is made undersize, it would allow for some extra metal to scrape the bearing to make some small alignment corrections when the spindle is re-installed. Just thinking out loud, so to speak....
 
SEK_22Hornet,

That was pretty much the idea I was having, taking a 3/4" bar to hold the spindle in alignment between the original headstock and tail. I've been looking at roto metals already, but I'm unsure as to which grade of babbitt would be the correct choice. I'm leaning towards the grade 7 'heavy pressure' choice, but I have zero experience in this area.

Terry
 
There is some interesting and potentially helpful information on babbitt alloys and selection on wikipedia http://en.wikipedia.org/wiki/Babbitt_(metal). A little note on McMaster's web site gives a tiny bit of insight, basically saying that lead based metal can work harden and crack under heavy loads and that tin based metals withstand higher rpm and heavy loads. That all being said, I would think that the high tin content with nickel and Monel of ASTM Grade 2 or the super tough grade 3 might be a good choice. I suspect that there are only subtle differences between all of the high tin based alloys listed. I do find it interesting that the Grade 7 is listed as "heavy pressure" and it is lead based. I suspect it might not like jarring loads like intermittent cuts, such as rounding a square shaft would produce.
 
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