sintered bronze lathe bearing

Hello to all, short time lurker here....
I just got a craftsman 6 inch lathe, with worn out bearings. I've got access
to a cnc mill and manual lathe and have gotten the bearing material. Since
the lathe spindle is a little worn, I got oversized ID sintered bronze
bearings. I have done a few test pass cuts and think I can machine the new
bearings just fine. The issue is that I don't know how much "play" (for lack
of a better word) to leave between the bearing and the spindle. There are
three bearings, 3/4's 13/16's and 1 inch. The max speed of the spindle is
about 3000 rpm, if I read correctly.
any ideas how much bigger the ID of the bearing should be, in relationship
to the OD of the spindle. I am worried about heat, bearing expansion and
seizing....HELP!!!
thanks in advance.
bob in phx.
Reply to
Bob in Phx
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I've read that the Craftsman mills and lathes are actually repackaged Sherline mills and lathes. So you could definitely buy a replacement bearing from sherline or get it from
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Reply to
DammitCoetzee
sorry, I guess I didnt make it clear, this is a very old craftsman / atlas 618 lathe. made from wwII to about 1980, in various configurations. The first had babbit bearings, the next had plain bearings and the final had ball or roller.... I need help with the plain bearings, made of sintered bronze, with 18 to 20 percent porosity.
thanks
Reply to
Bob in Phx
Bob, Have you dismantled the spindle to look at the bearing? I had one of those little model 109 lathes as a young boy-----and recall that the bearing was split and adjustable. Could be wrong, though.
Clearance for running is critical if you expect your lathe to generate a true circle. Rule of thumb for bearing fits is .001"/inch. Size your bearing accordingly. Too tight and it will fail-----too lose and it rattles around. If in doubt, start out slightly snug----run for a while at slower speed and see how it behaves. You might find that the bearings are not in dead alignment, so starting out snug and allowing the bearings to wear on the highs may be a good thing. Hard to say--------
Luck, anyway.
Harold
Reply to
Harold and Susan Vordos
Not Sherline. Atlas or AA lathes, depending on whether the Sears part number is 101.xxxxx or 109.xxxxx
Make the bearing so that it can be split, at least in one position, then use peel off shim stock, or simply stacks of shims to adjust the free play to about 1.5 thou IIRC, tested by putting a rod into the spindle and alternately pressing down, then up (or vice versa) while reading the measurement with a dial indicator.
The really rough guide! If it skeaks its too tight, if it stays cold after a prolonged run at top speed, it's probably too loose.
Find a copy of South Bends book, How to Run a Lathe. Available almost anywhere. Don't pay more than $20, you should be able to get one for $10 or so.
Cheers Trevor Jones
Reply to
Trevor Jones
Is it really cylindrical? I can't believe (that much).
3000 RPM with a friction bearing? It really is on the upper end.
Nick
Reply to
Nick Mueller
From the sizes it sounds like he's got a variation on the 618 series, though I've not heard of one with sleeve bearings. All I've seen were babbit or tapered roller. The 109 series made by AA had a spindle OD of ~1/2"
Reply to
Rex
snip---
Did I mention how easy it was to bend that 1/2" spindle? :-(
Harold
Reply to
Harold and Susan Vordos
Why yes, Harold, I do believe that you did ! :)
And it's a rare 109 that has an original, straight spindle
Reply to
Rex
I wonder if a previous owner had taken a babbitt-bearing headstock and bored it out for sleeve bearings? That sounds like something I'd do, rather than pour new babbitt bearings.
Does your headstock have a single bolt to the front of each headstock journal, that closes down the clearance when tightened?
Reply to
Rex
If yours is like mine there is a big slotted screw on the near side of the spindle to tighten the bearings a bit. If yours is also like this, you can make it just a tiny bit oversized, and adjust it to remove play.
Larger older lathes used either poured and scraped babbit bearings, or machined solid bronze bored and scraped to size, with a stack of laminated shims between the two halves of the bearing, so you could peel off a layer of the shim stock to adjust for wear.
*Very* little bigger. The test is to run it for an hour or two at maximum speed, frequently checking the headstock casting near the bearings to check for overheating. They should warm up a bit, but not much.
You are thinking of the current crop of Craftsman tools, not the older 6" lathe, and the horizontal mill, which were (mostly) made by Atlas, unless this lathe has "109" as the first three digits of the part number, in which case it is a AA (Ann Arbor) lathe, IIRC -- a very underdesigned lathe. Both were made as 6" lathes, and the Atlas were also made as 10" and 12" depending on when you are dealing with.
In any case -- if the lathe is a 6" lathe, the Sherline spindles would be useless for the repairs.
Good Luck, DoN.
Reply to
DoN. Nichols
Yes, I have dismanteled the spindle and the back gear. If I read correctly on
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lathe had "plain bearings"
Here is an exerpt of what I read.
" The catalog specification for the lathe included a backgeared headstock spindle fitted with a 60-hole plunger indexing device, a 17/32" hole and a 1" diameter 10 pitch NF thread, running in plain bronze bearings contained within a headstock casting with a prominent frontal bulge - whilst that badged by the makers under the Atlas name was fitted with Timken taper rollers and had a much smoother, flatter front to the headstock. Despite this move to "cheapen" the Craftsman version the same excellent speed range of was claimed for the plain-bearing model as for the "genuine article". The countershaft of the standard lathe was a separate unit that bolted to the bench behind and was fitted with both a motor platform and a neatly-designed swing head to adjust the belt tension. A stand was offered in the form of cast-iron legs joined by a substantial timber top with sufficient room to mount the maker's countershaft and motor assembly. Although the Atlas-specification roller-bearing headstock was a much more expensive proposition than the plain-bearing Craftsman version, during the 1940s and 1950s some Craftsmen 6-inch lathes were sold with what amounted to an Atlas headstock - a result perhaps of shortages of plain-bearing headstocks (though, oddly, the castings were not exactly the same). However, by 1959, the Craftsman was being listed with Timken roller bearings as standard -"
In addition, the lathe is a 101.xxxxxx not a 109. The bearings are not split, but are bronze with no oil hole, yet they have an oil filler, so I beilve that is was made to have sintered bronze bearings.
I was thinking and reading that .001 is about right, but is that number total play side to side (and up and down of course), or is it that the ID ofthe bearing should be .001 total difference from the shaft?????? thanks for the help.
Bob
Reply to
Bob in Phx
The lathe is a 101.xxx series and these are not Babbitt bearings. They appear to be sintered bronze and from what I have read were standard on this lathe.... I have also read that these lathes indeed have weaker spindles then they should have, so care must be taken.... Thus the reason that I don't want to just turn the spindle down to a convient "standard" size....
thanks
bob
Reply to
Bob in Phx
Yes, the headstock casting does have a single bolt for each size that clamps down on the OD of the bearing. There is not much of a split in the casting, so I don't think I can put much force on the bearing in order to sort of shrink the ID. I think that the clamping action is to hold the bearing from spinning, because a press fit might change the ID due to compression of the bearing or a bad installation (like with a hammer and a drift)... but that's just my thoughts... bob
Reply to
Bob in Phx
Trevor,
I understand the concept of what you saying... make a cut from the OD of the bearing, through the body, into the ID of the bearing. Then make a shim to open or close the cut, in order to change the ID of the bearing. But wouldn't this idea make the bearing a bit (I know it would just be a tiny tiny bit) out of round on the ID of the bearing. I am thinking that this would lead to a hotspot of bearing contact. In addition, with this cut and shims (I am inmagining steel shims) cause the oil not to migrate into some parts of the bearings???? even though the oil reserve is on top of the bearing, I think that the oil uses heat and capillary action to keep the shaft lubed....
what are your thoughts???/
bob
Reply to
Bob in Phx
Nick, Here is the spec that I found on the net... "the original "round style" Mk. 1 versions, a remarkable 16 speeds between approximately 54 and 3225 rpm.
Of course with the spindle and bearings pulled out I cant test it....But I will as soon as its back together!!!!!
as for the tolerence, when I go the lathe we measured the play in the spindle, at the outside of the chuck and it was almost an 1/8 of an inch up and a little less right to left. The forward and backward play was almost nothing, due to a roller bearing working as a thrust surface....
Bob
Reply to
Bob in Phx
Do you know the bearing part number? Unfortunately the only 101 manual I have is for the Timken bearing style. I'm pretty sure the Clausing replacements are dirt cheap.
Reply to
marc.britten
I learned something today. I always thought those were babbitt, like the 10" lathes. Replaceable bronze bearings makes them more desirable in my eyes. At any rate, mine has the Timken, but I'll not pass up a plain bearing model in the future.
As for the Spindle, there's nothing particularly weak about them. As any precision turning, you need to be careful with them while they are out of the headstock, and never pound on them etc, but nothing special behind ordinary care is required.
Call clausing and price the bearings. Might as well fix it right. If they don't have them, it should be a simple matter to have some made. Or use those hardware-store stock bearings to get the lathe working, then make up some new ones to the correct profile, flanges etc.
Reply to
Rex
Yup. It'd make it a tiny bit out of round. Point contact would go away on its own accord, then be adjusted out. I doubt you own measureing equipment that would give you an accurate measure of the differences between tight and loose fita, as far as roundnes goes. Esp. if the bearing is made to size, and the split in it is used only for enough movement to adjust free play.
The shims are used on the bearing caps, not on the split in the bearing itself.
Given the number of South Bends and others that are running a hard steel spindle in plain cast iron, with only a single split in the bearing to accomodate taking up the wear, I have no trouble at all beleiving that this is a sound proposal.
But you have to do what works for you.
Cheers Trevor Jones
Reply to
Trevor Jones
The shaft is a little worn and undersized for stock bearings from Clausing or the hardware store would be way loose. So I got some that are oversized on the ID and OD.
bob
Reply to
Bob in Phx

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