Can I cut prop shaft taper w/o taper attachment?
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    Default Can I cut prop shaft taper w/o taper attachment?

    I want to make an inboard boat prop shaft from some 1" stainless on my Heavy 10 lathe. I do not have a taper attachment. The taper IIRC is 1:12 or 3 degrees (may have to double check that).

    Just throwing this out here and see what comes back!

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    How long is the taper? If you have enough stroke with the compound maybe. I'd definitely mount an indicator and set the angle with the amount of drop/rise in a designated distance to set the angle, not the protractor scale on the compound. Then blue it in with the prop itself when you're done. Diameter will have to be somewhat accurate so the prop sets on shaft in the correct position. May take some doin but its possible.

    Brent

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    No worries ,I used to do them all the time on damaged shafts....Some stainless shafts were lovely free machining,very soft,then some of the very old ones were monel or something like....very tough going........i used to straighten them too,and rudders ........inboard boat owners are very rich,and you can charge them what you like.............one time I had a trailer load of cut up logs ,guy says ...whats that for?......simple ,says I ,I take em up to the bridge and toss em in the river......why would you do that ,he says.......doh.....bent prop and shaft.

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    Quote Originally Posted by FlyinChip View Post
    I want to make an inboard boat prop shaft from some 1" stainless on my Heavy 10 lathe. I do not have a taper attachment. The taper IIRC is 1:12 or 3 degrees (may have to double check that).

    Just throwing this out here and see what comes back!
    - Step cut it first since you have very scant metal-removal capability.

    - Set the compound. Plan to mate-up two goes with that - so don't change the angle, just re-position the carriage & cross.

    - File & abrasive finish it so it fits. No other choice. Hand-feeding the compound simply won't git you the prettiest of surface finishes.

    Even so - not as if you were DIY'ing Timken tapered roller bearing elements from scratch.

    It's only a sub-ONE INCH..(alleged) prop shaft.

    Ex Boss'es 73-footer Hatteras with twin Caterpiggle turbo's? Dif'rent class of "inboard".


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    Quote Originally Posted by thermite View Post
    Set the compound. Plan to mate-up two goes with that - so don't change the angle, just re-position the carriage & cross.

    I agree this would be best for setting the compound if the prop ID is in fair condition.

    Brent

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    In short, no you cannot. You should have a TA or a tracer attachment. Second, the fit must be correct or you risk loosing the prop and shaft. It is the taper that drives the shaft, it is not the key! That taper must be a lapped fit and the shaft keyway Must have large radius corners with a matching key. Sharp corners encourage shaft failure due to stress concentrations. If you don't have the right equipment, you need to send the job out.

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    Quote Originally Posted by yardbird View Post
    I agree this would be best for setting the compound if the prop ID is in fair condition.

    Brent
    Din't figure he had the 'sperience to do the whole deal with nought but a file, but it mought be faster.

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    Quote Originally Posted by steve-l View Post
    In short, no you cannot. You should have a TA or a tracer attachment. Second, the fit must be correct or you risk loosing the prop and shaft. It is the taper that drives the shaft, it is not the key! That taper must be a lapped fit and the shaft keyway Must have large radius corners with a matching key. Sharp corners encourage shaft failure due to stress concentrations. If you don't have the right equipment, you need to send the job out.
    I trust that ''In short, no you cannot. You should have a TA or a tracer attachment.'' and '' If you don't have the right equipment, you need to send the job out'' is being at least a little tongue in cheek.

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    Quote Originally Posted by Limy Sami View Post
    I trust that ''In short, no you cannot. You should have a TA or a tracer attachment.'' and '' If you don't have the right equipment, you need to send the job out'' is being at least a little tongue in cheek.
    Why tongue in cheek? it is clear the OP is inexperienced at least in this task. The OP has a 10" SB with very limited compound travel. Is he prepared to cut the radiused cornered keyway and with what? He didn't say. He threw the question out there for comments and advice. Prop shafts and props are expensive. Thermite is correct, the OP will never get an acceptable finish with the compound for a lapped fit. I think my advice is pretty much spot on.

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    Quote Originally Posted by steve-l View Post
    Why tongue in cheek? it is clear the OP is inexperienced at least in this task. The OP has a 10" SB with very limited compound travel. Is he prepared to cut the radiused cornered keyway and with what? He didn't say. He threw the question out there for comments and advice. Prop shafts and props are expensive. Thermite is correct, the OP will never get an acceptable finish with the compound for a lapped fit. I think my advice is pretty much spot on.
    Well... drive wheels for diesel-electric yard or mine-haul locos now and then class as "need to be right", also. While many OTHER shafts had their keyways cut on our K&T horizontal (cudda married that cooperative-sweet bitch..) with "wheel" style milling cutters, those requiring round ends I did with an endmill of appropriate size in a Cinncy Toolmaster vertical.

    Size of HIS shaft, the SB can pretend to be a mill, same way with but a stout angle plate Vee-block, shims, hasty clamps, and an endmill in - perish the though - a friggin' collet.

    Marginal practice, and uglier than watchin' the hogs eat my little Brother - ever damned bit of that sort of SB kludge, yes. But WTH, ONE INCH shaft. Don' need no steenkin' LeBlond Heavy Duty and a K&T for that.

    Yah run what yah gots, not what you WISH you gots, or NO job ever gits DONE.

    Prop falls off, you fits a replacement. That shit happens all the time, specially yah hits sumthin' with it. Which happens all the time.

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    If his SB has a 1"+ spindle bore,he will have no trouble cutting the taper from his topslide,especially if his shaft is one of the soft free cutting stainless that are generally used.......ive seen badly scored tapers cleaned up with a linisher ,new brass key,and working perfectly............Two points ,never use a SS nut,use brass,and use a brass key,or when the key shears,you will never get the prop off......we re talking ski boats,not the Titanic.

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    Quote Originally Posted by john.k View Post
    If his SB has a 1"+ spindle bore,he will have no trouble cutting the taper from his topslide,especially if his shaft is one of the soft free cutting stainless that are generally used.......ive seen badly scored tapers cleaned up with a linisher ,new brass key,and working perfectly............Two points ,never use a SS nut,use brass,and use a brass key,or when the key shears,you will never get the prop off......we re talking ski boats,not the Titanic.
    Ski boat?

    I'd have thot a sailboat's auxiliary, given his 'inboard' is way below outboard power ranges.

    Any serious "inboard" ski boat I've been around would make a one inch shaft resemble a twist-drill in short order!


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    Taper was short, lathe was 16/18 1/2" actual swing, so more compound travel

    Setting Lathe Compound For Tapers

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    Isn't there anyone left who remembers offsetting the tail stock and running between centers, driving with a faceplate and dog? You use the power carriage feed just like normal lathe work so you can have as fine a feed as is available.

    Bill

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    Quote Originally Posted by 9100 View Post
    Isn't there anyone left who remembers offsetting the tail stock and running between centers, driving with a faceplate and dog? You use the power carriage feed just like normal lathe work so you can have as fine a feed as is available.

    Bill
    Came here to say this.

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    Quote Originally Posted by 9100 View Post
    Isn't there anyone left who remembers offsetting the tail stock and running between centers, driving with a faceplate and dog? You use the power carriage feed just like normal lathe work so you can have as fine a feed as is available.

    Bill
    It's a nice technique but I don't see a prop shaft fitting between centers on a SB!

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    I have all sorts of one-off centers and tools that I have made without a taper attachment on my 10L with Morse #2 tapers to fit the tailstock. It’s simple to set up especially if one has an exemplar taper, and most of them don’t even need much in the way of lapping. You are limited by the travel of the compound to about 2.75 inches, but if you want to set it up several times, you can make it as long as you want to.

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    jonok thanks, so how is that set up to do that?

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    Quote Originally Posted by yardbird View Post
    How long is the taper? If you have enough stroke with the compound maybe. I'd definitely mount an indicator and set the angle with the amount of drop/rise in a designated distance to set the angle, not the protractor scale on the compound. Then blue it in with the prop itself when you're done. Diameter will have to be somewhat accurate so the prop sets on shaft in the correct position. May take some doin but its possible.

    Brent
    On a 1" shaft the longest the taper could be is 6". Assume that there is a substantial bolt to hold on the prop, bigger than 1/2" the taper will be shorter than 3". Mesure the ID of the prop on the short end, subtract from 1" divide by 2 multiply by 12 and that is the length of the taper. Most likely the entire length of his taper is in the range of his compound travel.

    dee
    ;-D

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    Quote Originally Posted by jonok View Post
    ..if you want to set it up several times, you can make it as long as you want to.
    One still "sets up" the compound exactly ONCE.

    Thereafter, it's just;

    - cut the first portion the range of the compound provides

    - retract the top slide of the cross to clear

    - unclamp and move the carriage

    - lock-carriage again

    - run the cross back in to bring the tool into engagement

    - traverse another increment with the compound

    - clear chip, check results, repeat until full-length is complete.

    - Use High Spot (or lipstick!) to check, then file(s), abrasive(s), and/or time-saver paste.. and you have your fit.

    Compound remains at the same angle until done-done.

    Angle changes each step only by difference in wear on the bed between the two positions of the carriage.

    Which exists, but may be negligible, any given lathe.

    If you have to do this a LOT?

    Seek a gearmotor and powerize the compound. Need not be CNC. Ignorant gearmotor with any stable form of variable speed will do [1]. DC, VFD, Variac.. etc..

    Been done. More than once. There are examples on .. ta da..PM... "of all places?"



    [1] For a "onesie", I might pull the compound's handle, use a right-angle cordless Milwaukee M12 variable-speed power drill I have handy, and just take more cuts, but lighter ones, each increment. Make a keyed adapter first. Drill chuck will bugger the compound's shaft, otherwise. Count on it.

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