what material should I use to make shims for a babbitt bearing cap?
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    Default what material should I use to make shims for a babbitt bearing cap?

    Old camelback drill press top shaft. Runs in babbitt bearings. The bearing caps are shimmed up. The shims that came out were about 0.050" thick but disintegrated on removal. I don't believe this is a case where I'm going to need a sophisticated stack of thin shims so I can remove a few thou every now and again. This isn't some finicky old steam engine.

    I'm thinking about having the shapes waterjet cut because I think I can induce my buddy with a waterjet machine to do it for me and that would do a very nice job. So paper products that swell or come apart in water probably aren't a good idea. I grew up always making shims from cereal box cardboard. That worked amazingly well for me for many years but I am thinking of something a bit more sophisticated.

    McMaster doesn't carry much simple shim stock. If you want EFI safe gaskets for your rocket ship, they're the vendor for you.

    Suggestions?

    metalmagpie

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    Quote Originally Posted by metalmagpie View Post
    Old camelback drill press top shaft. Runs in babbitt bearings. The bearing caps are shimmed up. The shims that came out were about 0.080" thick but disintegrated on removal. I don't believe this is a case where I'm going to need a sophisticated stack of thin shims so I can remove a few thou every now and again. This isn't some finicky old steam engine.

    I'm thinking about having the shapes waterjet cut because I think I can induce my buddy with a waterjet machine to do it for me and that would do a very nice job. So paper products that swell or come apart in water probably aren't a good idea. I grew up always making shims from cereal box cardboard. That worked amazingly well for me for many years but I am thinking of something a bit more sophisticated.

    McMaster doesn't carry much simple shim stock. If you want EFI safe gaskets for your rocket ship, they're the vendor for you.

    Suggestions?

    metalmagpie
    Bought a "pack" of Bronze (a few are actually Brass ) shim stock sheets from MMC some years ago. IIRC, I'd have to stack two or three of the thicker sizes to hit 0.080".

    Or use some of the Micarta/Formica or FR4 / G10 I keep around.

    Or even "loominum, AKA "shiney wood".

    Doesn't sound like it is all that demanding a loading on the shim, and the phenolics ain't hard to sand a skosh, if need be, so what could possibly go wrong?

    Prolly hand cut and file them faster, naked, than I could find clothes, shoes, socks, car-keys, saddle-up to even make the round-trip journey to a waterjet guru's shop, let alone explain the shape wanted.. so..

    "JFDI" It's only shims. Not a Teller-43 Anti-Tank mine fuse or an Omega watch.

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    Quote Originally Posted by metalmagpie View Post
    I don't believe this is a case where I'm going to need a sophisticated stack of thin shims so I can remove a few thou every now and again. This isn't some finicky old steam engine.
    I don't believe that's the reason for a stack of shims. How are you going to get the thickness you want, try ten different shims ? If you use the stack method, you make one set on the jet then peel off until you get where you want to be.

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    Actually, I just measured the thickness of the old shims to get my desired thickness.

    metalmagpie

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    Quote Originally Posted by metalmagpie View Post
    Old camelback drill press top shaft. Runs in babbitt bearings. The bearing caps are shimmed up.

    Suggestions?

    metalmagpie
    You can get plastic shim stock assortments for pretty reasonable prices. Lots of different thicknesses, easy to cut, decent price...

    Shim Stock Assortment 5 x 20", Pk14 | Zoro.com


    Kevin

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    Almost anything you can cut with a tinsnips and/or gasket hole punch (for bearing cap bolt holes, if required) will work. My own preference is to use brass shim stock for this sort of application. Brass shim stock cuts easily and if it contacts a shaft journal, will not score the journal. I am fortunate in that I have a great deal of brass shim stock which was scrap or leftover from various alignment or erecting jobs I was on over the years.

    On some jobs, where shim stock was not too plentiful, and where heavier shims were needed, I cut them from any sheet steel available. I have also made shims by cutting up welding electrode cans and olive oil cans.

    A material which might work for your application, if you need a heavier shim, is aluminum. If you cut the shims from aluminum, a bit heavier than needed, you can 'polish' them down to required thickness. This can be done by rubbing on the shims on a sheet of coarse emery cloth or sandpaper laid on any handy flat surface (such as the table of your drill press). Mike the shim as you rub it on the emery cloth or sandpaper and keep going until you get the required thickness.

    I've also made shims from thin 'reinforced phenolic' (aka "Micarat" or "Bakelite") sheet material when I needed 1/16" and 1/8" shims.

    Some people have shimmed babbitted bearing caps using shims cut from manila file folders or thin cardboard such as some boxes are made from. Computer printer paper mikes at 0,004", and can be used as a shim as well. I've taken some old machinery apart and found shims made from things like 'time cards' (the kind you inserted into the time clock to 'punch in' and 'punch out' of work), and slips of paper.

    Another material that is plentiful is soft aluminum beverage cans. These cut with common scissors. In the book "Zen and the Art of Motorcycle Maintenance", the author (Robert Pirsig) is going to repair a friend's BMW motorcycle. The problem is the handlebars are loose in the mounting clamps and there is no takeup left. Pirsig wants to cut shims from a beer or pop can, citing how the thin aluminum is ideal for shim stock. Of course, the BMW owner, an academic sort, wants no part of having his motorcycle repaired using shims cut from a beer can. For the application on a camelback drill, shims cut from a beer or pop can would be fine if thinner shims were needed.

    An old bro of mine has had a saying that I've heard for the past 35 plus years that I have known and worked with him: "The solution to most problems is within 15 feet of them". Hence, if you go to your recycling container and fish out a couple of aluminum cans or find an empty welding electrode can laying around, consider it as shim stock. It's worked for me many times over and plenty of machinery has been levelled on sole plates shimmed with whatever was at hand, and plenty of babbitted bearings have had their clearance set with shims cut from similar materials.

    I have brass shim stock down to 0.001" thick, which is basically a thin foil. That was from turbine alignment jobs and similar. It's rare that I use the 0,001" stock. I think the last time I used some was setting the clearances on a plain bearing lathe headstock. A rule to remember with shimming: if you wind up with a stack of many shims to set a bearing's clearance (or to level a piece of machinery), you have essentially built a 'spring pack'. Once you have determined what is needed to set a bearing's clearance, it is a good idea to try to reduce the number of shims to one or two heavy ones and perhaps 3 or 4 thin ones. The thin shims let you fine-adjust the clearance. After a shaft journal 'beds into' a babbitted bearing, the clearance sometimes opens up a bit. Having a thin shim or two in the shim pack on a bearing cap lets you take up for this 'bedding in'. I usually leave shims of 0.010", 0.005" and 0.003" as the thin shims and try to get the balance of the shims made up as heavy as possible. Cutting shim stock with snips or scissors usually leaves a burred or 'crinkled' edge. I bring a piece of flat steel bar that has been polished with emery cloth and a piece of maybe 1/2" OR 3/4" drill rod with me when I am cutting and fitting shims. I place the shims I have cut with the snips or scissors on the flat steel surface, hold one end down with my fingers and press and draw the drill rod over the shim. This 'irons out' the crinkling. For heavier shims as may be cut from sheet metal (like 16 gauge), I take a ball peen hammer and lightly hammer along the cut edges with the shim laid on the steel flat bar. This works down any wrinkling or slight burring. It does not take much to create a 'soft' shim stack if there are burrs or wrinkling on any of the shims. Over time, this will cause a looseness in the bearing cap and open up the clearance.

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    If you can find it, you can also use 100% rag content paper. It is actually very tough, won't score a shaft ,is easy to work with and will not dissolve in oil. I once had a pile of banknote paper (made for some 3rd world country that didn't pay the bill) but you can also look up "Crane's" writing paper. They are one of the few companies that still makes it.

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    Quote Originally Posted by metalmagpie View Post
    Actually, I just measured the thickness of the old shims to get my desired thickness.
    You're not going to use plastigage or something to set the amount of clearance you want ?

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    For checking the bearing clearance on something like the OP's camelback drill press shaft, it is not necessary to use 'Plastigage'. Typically, clearance is checked on this sort of shaft/bearing using a pry bar and dial indicator. On the OP's drill press shaft, I would imagine it is somewhere around 1 1/4- 1 1/2" diameter. Babbitted bearings with oil lubrication running at fairly low speeds of this size on something like this drill press might have maybe 0.003"- 0.004" of clearance. The dial indicator will measure this clearance. The shaft is pushed down into the bottom half of the bearing, and the contact point of the dial indicator is set to touch the shaft at 12:00 position. With the shaft pushed down hard into the bottom half of the bearing (and the belt to the cone pulley on the shaft 'thrown off' so belt tension is not working on the shaft), the indicator is zeroed. With the pry bar, the shaft is forced up in the bearing. The clearance is read on the dial indicator.

    On larger diameter shafts and babbitted bearings, if access allows it, another method is to force the shaft down into the bottom half of the bearing, and try inserting feeler gauges at the 12:00 position.

    I always associated 'Plastigage" with checking clearances on automotive 'insert' type bearings. In 50 years around powerplant work and erecting work and machine tools, I do not recall ever seeing 'Plastigage' used for checking bearing clearances. On some of the larger babbitted bearings on hydro turbines, we used a 'Porta Power' jack and dial indicator to check bearing clearances. On some other large babbitted bearings, we slid in long feeler gauges to get the clearance readings.

    Another little trick: rolling papers such as 'Zig Zag' mike an even 0.001". For setup work or other places where a shim of 0.001" is needed on a temporary basis, a rolling paper comes in handy.

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    Quote Originally Posted by Joe Michaels View Post
    For checking the bearing clearance on something like the OP's camelback drill press shaft, it is not necessary to use 'Plastigage'.
    Not necessary, just easier The stuff you are talking about weighs tons ! He's got a stinky little drill press. Pop off the caps, stick a squirch of gage in there, squeeze down on the caps, measure the clearance, adjust. Easy.

    (Which totally ignores the question of how wonderful is the babbit in this assembly but oh well, nip and tuck and hope she'll be good until the next owner comes along, cap'tn !)

    Of course there's a hundred different ways to do this but me, I'm lazy


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