Rivett 608 tailstock taper
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  1. #1
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    Default Rivett 608 tailstock taper

    Went to look at the "revised" rivettlathe website.....

    Had a brief "oh goodie" moment, when I saw the drawing of the tailstock taper shown on the list....... No cigar, though.

    Woopsie...... right on the drawing are two notations...... 1) a note of "approx" against the dimension of the small end of the taper. and ..... 2) a note of "to gage" on the taper itself!

    Obviously the Rivett folks had a master and floor use gages for their part, and those items have almost certainly been in the Maine landfill for 40+ years, very unlikely to be any help. Unless some Rivett-minded person saved them and kept them slathered with grease all these years.......NOT!

    Drat.....

    I do have a possible method of getting at the taper, assuming mine is standard and un-worn..... which is probably a total crapshoot. Fill the taper with the low temp "cerro" alloy metal I have, and then make a female gage to fit, probably of the "parallel surface" type, as opposed to a full female taper gage. probably there will be some errors in that, but hopefully it should be close enough to work.

    More work for "later".........

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    When i got my first Hardinge lathe, I tried to figure out the taper in the headstock spindle. I thought it used an adapter to hold a Morse taper center like the 12" Craftsman lathes I owned. I cast a plug of Cerrobend and got a very good model of the taper. Shortly after, I found out the lathe took 4C collets directly in the spindle, and the slow taper was just a transition from the fast taper of the collet cone to the straight bore for the collet body.

    My point is, the low melt alloy worked great. These days, I would use one of my Taper-Mikes to determine the taper from the plug. Or I could use my internal Taper-Mike directly in the bore.

    Larry

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    My main concern is with the bore being worn so that I won't be able to make a consistently fitting part. The one taper I have that fits looks like it was chewed to shape by a possum, I'd never tell if it fit right or not.... Time will tell.

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    Happy New Year JT.

    If the inside of the ram looks good, and is smooth and clean, there are a couple of things which might be worth a try....
    Ink up the taper that fits and run it in and give a gentle twirl or two and then see where the marks are on the taper (and if you can, in the ram). That might give you an idea of how good your taper is. Or it might tell nothing....
    If you are planning to turn a taper anyway, try the numbers from the blueprint. Worth a go if you have are not pushed for time I suppose. You can always ink that new one and see how well it fits in the ram. I know it all is a bit of trial and error rather than a direct route, but that might be how the factory made the originals "to gage" anyway, i.e., do it, then check against a standard, then correct, etc.
    Mind you, this is all advice from a complete novice, so take it as such.
    Michael

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    One of my Rivett's was owned by lets just a very old school type of machinist...... he was a 4th generation machinist and he was passing the family machinist's chest with an engraved silver plaque on to his son....... anyway he set up and tweaked his slide rest to cut some tapers..... they fit fine and in all the years I have used them I have never had one slip so he must have got it right.

    One thing kind of fun is he mounted up some Jacobs chucks that had been through that fire in the machine shop in Antarctica which is something kind of neat (or cool)....... not everybody has tools that were truly down under. He BTW spent 17 seasons down there...... every time I use one of them I think of him.

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    Several years ago when I restored my Rivett 608 I was faced with the same questions.
    At that time I sat down with a calculator and figured the taper per inch, based on several pieces of information I could gather.
    Although I don't have the specifics at hand right now, I do remember the taper being so close to a Jarno that the difference was insignificant.

    I posted the results on the Yahoo Rivett board, and some of the purists Poopoo-ed the thought, preferring to hold on the the belief of some mystical "Rivett taper".
    My experience with the Rivett has lead me to the conclusion that the designers were very good, pragmatic engineers who would use the best available information to build a terrific enduring design, and Jarno tapers were much more common in those days.

    On another project I used a similar method as described by L Vanice. I lightly greased up the bore of the spindle, jammed a wad of rag in the bottom and filled the taper with bondo. I let it get "rubbery" hard and then knocked it out. Once I let it harden fully I had no difficulty with measuring the taper.

    Happy New Year
    Pete

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    Well, I plan to do the Cerro deal. That's what the material is FOR after all.... and why I have several pounds of it. The variable is how good the existing taper is.

    The Jarno and Morse tapers are same for at least one taper (Morse 1), and that's near the Rivett size.... problem being that the DEPTH is totally wrong, the similar Morse and Jarno tapers don't fit even close as far as where the big end and small end are in the T/S bore.

    it won't matter much..... If I can make a gage, I'll be good to go for as many as I want.

    Too bad the taper is so different size-wise, or I could just grind an existing hardened center to a proper fit.

    It'll get done, when I have got to that point. Between vacations, plumbing, holidays etc, I have not got nearly to where I want on the refurbish and scrape-in job on the (formerly) filthy 608

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    Below are a couple clips from some threads on the Yahoo rivett board from about 4 years ago.
    I hope that the info is of some value.

    Pete

    "I have made some tailstock tooling for my 608 using the #4 jarno dimensions and
    they
    work nicely.
    I have looked at the adaptor route, (#1mt-#4jarno) but have decided against it,
    as #1 Mt is
    pretty whimpy, and the adaptor would have to be made as a special, and some of
    the
    headstock tooling is also #4 jarno."

    "I was hunting around for some information on tapers, and came up with
    something I found interesting.

    According to Rivett drawing LLE-771 the taper of the shank to fit the
    tailstock is 2*55'. Taking the dimensions off that drawing, the shank
    tapers .103" in a length of 2.062", or .04995"per in, or .5994" per ft.
    This is only .0006" difference in a ft from a Jarno taper which
    is .600" per ft.

    According to the information I found on wwwshopswarf.com, the Rivett
    taper is very likely a Jarno #4 taper."

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    JST, I'm gonna make an heretical statement right now.

    1) remove the original ram from you 608 tailstock.

    2) gold plate it, put ribbons on it, and mount to a nice wall plaque.

    3) fabricate a brand new tailstock ram with a suitable taper inside, probably
    MT2 if that'll fit.

    4) install and use same. Periodically glance up at the piece of history hanging
    on the wall, and pat yourself on the back that you preserved it for posteritiy.

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    Thumbs up

    Jim,
    That's what I should have said!

    Pete

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    It should be pretty easy to measure the taper by mounting a DTI on the carriage and measuring the offset over a given length. Use a dial indicator--or better, a DRO if you have one--to precisely measure a distance of travel and then use some simple trig to calculate the taper angle. Remember that your calculated dimension will be half of the total included angle of the taper...

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    I hadn't intended to get into it this deep...... I was more amused that here was a nice Rivett drawing preserved on teh revised site, of the most controversial part of the machine that I have so far seen, (and as evidenced by this thread ), and when you look at the drawing for the horses-mouth taper information that anyone might *expect* to find on it, IT ISN'T THERE!

    There is a sort of delightful irony about that which appeals to me....... like the murderer who pleads guilty, but the plea cannot be accepted because he is insane......

    Here we have *THE* official Rivett drawing, information directly from the Rivett engineering department, showing EXACTLY how to make the tailstock ram........ EXCEPT FOR the one critical dimension which everyone really wants to know!

    What we really need is the drawing for that gage........ except it will probably reference yet another Rivett special part that we don't have.

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    Almost makes you wonder how many customers sent tail stock tooling they bought after they got their lathes from Rivett back because it didn't fit?

    Or maybe over in a corner of the Rivett factory was a grinder set to grind these tapers..... it had a big sign on that said "Don't you dare touch any adjustments on this machine!" and had it's gibbs dowel pined by Mr. Rivett because he liked "That" taper!

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    Quote Originally Posted by JST View Post
    The Jarno and Morse tapers are same for at least one taper (Morse 1), and that's near the Rivett size.... problem being that the DEPTH is totally wrong, the similar Morse and Jarno tapers don't fit even close as far as where the big end and small end are in the T/S bore.
    Have you compared it to a Jarno-Reed taper?

    Bill

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    Quote Originally Posted by JST View Post
    There is a sort of delightful irony about that which appeals to me....... like the murderer who pleads guilty, but the plea cannot be accepted because he is insane......
    Yossarian would understand that.

    The way I heard it was that he murdered his parents and asked for clemency because he was an orphan.

    Bill

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    Quote Originally Posted by thermite View Post
    Have you compared it to a Jarno-Reed taper?

    Bill
    Discussing the taper itself.......

    Reed was my main contender, but I did not have a reference on the actual Reed taper.... Most google references come right back here to PM..... without any more info.

    Finally found one ref in Google books.

    http://books.google.com/books?id=o9A...0taper&f=false

    While this generally agrees with the *taper*, it does not include the size of machine we want.... all the tapers are too long. I still don't know if any actual Reed tapers are identical.

    However, the Rivett LLE-769 drawing shows a "close to but bigger than Jarno" taper of about 0.6025 per foot. Could be that is just an allowance for fitting to gage.

    Another Reed Taper ref seems to finish off the Reed taper idea..... even the 10" lathe has a 3" plus taper length

    http://books.google.com/books?id=uH4...per%22&f=false

    So measuring and copying seems to be the best plan.

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    Quote Originally Posted by JST View Post
    Reed was my main contender, but I do not have a reference on the actual Reed taper.... Most google references come right back here to PM..... without any more info.

    Finally found one ref in Google books. We'll see if this works. Nope, no cigar, link instead

    American machinists' handbook and ... - Fred Herbert Colvin, Frank Arthur Stanley - Google Books
    I have two sets of the Jarno-Reed spec & story here somewhere .. lemme search...

    .. back with the first one. here's the link:

    The Standard Tool Company's Standard Taper Shanks

    Here's a firm which 'may' make them:

    B-J Industries, Inc. - Shanks/Cavities

    I have one more - really comprehensive table - but cannot locate it just now. The Standard Tool Company source, table under F.E. Reed, may tell the tale..


    Bill

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    the first reference doesn't go anyplace..... comes up with blank pages.....

    May have to register, which I don't plan to do....Thanks anyway

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    Quote Originally Posted by JST View Post
    the first reference doesn't go anyplace..... comes up with blank pages.....

    May have to register, which I don't plan to do....Thanks anyway
    Ah.. Windows? ISTR that has come up before.

    Unix JF opens and displays it, so I've taken a screenshot to PM to you.

    Will Windows open a .png?
    If not, let me know what graphics it CAN handle, and I'll convert it.

    Bill

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    I've no idea what the list is of acceptable formats in Windoze........ I know jpg are obviously OK, IIRC gif and tiff it takes, also.

    Thanks, but no need to go to any great effort, after all I have the prototype here, and can take a cast from it, plus the Reed dimensions seem to be different from all the other info so far.

    Maybe if F E Reed made an 8" machine, they might have used a center as small as 2" long. The smallest Reed in any list so far was a 10", using a taper 3"+ long.


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