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  1. #1
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    Default Bluing a tapered shaft

    Gents,
    I need to bore a taper in an aluminium hub to fit a 6mm diameter crankshaft with a 5 degree taper (see pic). In an ideal world I would have turned both pieces without disturbing the top-slide setting, but that wasn't an option.

    I've been told I need to blue the crankshaft to test the fit in the bore when setting up the top-slide angle. I assume that means spotting blue or bearing blue (the stuff that doesn't dry)? If so, I don't have any. However, I do have a 20g packet of ferric ferrocynide, which I think is Prussian Blue. There was a thread a while ago in which some posters were mixing it with either oil or grease to make their own spotting blue.

    Can anyone recommend a good mix for this job?

    Chris
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  2. #2
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    Default Texta Blue

    Chris,

    the other day I was at a mates who is building a solar car using lots of different donor parts. He was not sure if the steering rack ball joints off one car where mating correctly with the steering arm off another car. So I cleaned up the male ball joint and covered the mating area in texta color and then inserted the two parts and rotated them slightly. When it was removed all the texta had been wiped off indicating the two tappers are the same size.

    hope this helps.

    cheers

    piers

  3. #3
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    Thanks Piers. I have blue layout dye, so I'll give that a go.

  4. #4
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    Quote Originally Posted by jack620 View Post
    Thanks Piers. I have blue layout dye, so I'll give that a go.
    Hi Chris,

    No... I don't think layout blue is going to help you much, for the blueing recipe, try sending a PM to Phil (Machtool), but I think it's just a case of mix up prussian blue and some suitable grease.

    Regards
    Ray

  5. #5
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    Ueee is offline Blacksmith, Cabinetmaker, Machinist, Messmaker
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    From memory the mix was one sachet to 100g of grease. I think it was discussed in the 2nd Melbourne scraping class thread. A search for shell alvania may find it for you.
    1915 17"x50" LeBlond heavy duty Lathe, 24" Queen city shaper, 1970's G Vernier FV.3.TO Universal Mill, 1958 Blohm HFS 6 surface grinder, 1942 Rivett 715 Lathe, 14"x40" Antrac Lathe, Startrite H225 Bandsaw, 1949 Hercus Camelback Drill press, 1947 Holbrook C10 Lathe.

  6. #6
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    I have some translucent blue bearing grease I use on my boat trailer's bearing buddies. That should colour up nicely with a bit of Prussian Blue. I couldn't find any ratios in my searches, so I'll just add the PB to some grease till I get a decent colour.
    Chris

  7. #7
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    Ueee is offline Blacksmith, Cabinetmaker, Machinist, Messmaker
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    Here you go Chris. http://www.woodworkforums.com/f65/2n...ml#post1491559 I was on the phone before but now i'm on the PC i found it.
    1915 17"x50" LeBlond heavy duty Lathe, 24" Queen city shaper, 1970's G Vernier FV.3.TO Universal Mill, 1958 Blohm HFS 6 surface grinder, 1942 Rivett 715 Lathe, 14"x40" Antrac Lathe, Startrite H225 Bandsaw, 1949 Hercus Camelback Drill press, 1947 Holbrook C10 Lathe.

  8. #8
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    Thanks Ewan. The 20 in 100 looks good in the picture. I will start with 10 in 50 and take it from there. Looks like a bit of thin oil is also required to offset the stiffening effect of the powder on the mix.
    Chris

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    I can understand some guys who are doing quite a bit of scraping may be keen to experiment with better properties and different colours etc, but in this case I wouldn't dick around with it personally Chris. A tube of bearing blue is cheap and will last you a long time. https://www.bolt.com.au/bearing-blue-25gm-p-101967.html

    Pete

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    Quote Originally Posted by Pete F View Post
    I can understand some guys who are doing quite a bit of scraping may be keen to experiment with better properties and different colours etc, but in this case I wouldn't dick around with it personally Chris. A tube of bearing blue is cheap and will last you a long time. https://www.bolt.com.au/bearing-blue-25gm-p-101967.html

    Pete
    If I'm doing these sorts of fits I just use a big Pentel pen, as someone else has already stated. Why screw around with anything more complicated?

    Last job was to get 4 stainless steel pins to fit snugly into 4 stainless steel sockets - stern gate on my boat where the gate drops in (2 pins per side) and I do not want it to accidentally come out, nor do I want it to corrode immovably into place. So a nice fit but not really a precision fit. Pentel pen & files worked fine to deal with the welding distortion.

    Incidentally that little TIG welder has seen a fair bit of use on various stainless fittings, mainly pipe.

    PDW

  11. #11
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    Default Bluing a tapered shaft

    Thanks Pete, I didn't realise it was so cheap. Will try to find some locally.

    We seem to have two schools of thought on testing fits:
    Texta=OK
    Texta= not OK

    Since I have loads of textas, I'll give that a try first.

    Chris
    Chris

  12. #12
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    Where did you see it said that a marker doesn't work Chris? I use them all the time, constantly in fact, for both making small patches on work so I can better see my scribe lines and also for testing fits. I've just blued a project with proper marking blue a few minutes BC*, but only use the "proper" marking fluid when it's worth messing about with it, otherwise it's a marker every time, and the same thing when fitting. About the only time I've had problems with doing that is when fitting close tolerance shafts, where the thickness of the marker ink is too great, but that will often be the case with many marking mediums.

    The bearing blue is handy stuff to have around, but for what you're doing, if you just want to get the tapers the same, run 3 or 4 lines with a marker up the male taper and shove it relatively firmly into the female taper. You'll be able to see quite clearly where the marker gets removed when you pull them apart again. Since the angle isn't critical, I find it easier to adjust the taper angle of the male side to suit the female.

    Pete

    *BC; Before Cuppa

  13. #13
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    Default Bluing a tapered shaft

    Pete,
    Ray said layout blue probably wouldn't work. I took that to mean any drying type ink, including a marker pen. Maybe I misunderstood (likely).

    I don't have the luxury of turning the male to fit the female as the crankshafts are already made. I'll remember that for next time. I'll try a texta when i tackle the job later. First I need to grind a ridiculously small boring tool.
    Chris

  14. #14
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    You wouldn't normally use layout blue, but in this case where it's aluminium and you're just trying to match a taper I think you'd be fine with anything that will be scraped off. I seem to recall watching my Dad even use soft pencil on hardened steel tapers, but that was a long time ago and I guess there's no chance to ring him up and confirm that now! I may have missed what you're fitting to the crankshaft, but from my understanding, in cases like yours you're looking more for material being removed when it hits the incorrect taper rather than being transferred between the surfaces, hence why it doesn't really matter what you use. Anyway, that's how I do it, but ### would I know.

    Pete

  15. #15
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    Quote Originally Posted by jack620 View Post
    Pete,
    Ray said layout blue probably wouldn't work. I took that to mean any drying type ink, including a marker pen. Maybe I misunderstood (likely).

    I don't have the luxury of turning the male to fit the female as the crankshafts are already made. I'll remember that for next time. I'll try a texta when i tackle the job later. First I need to grind a ridiculously small boring tool.
    If the female part you're fitting is already machined (except for the taper) with lots of work sunk in it, use a dummy part to get the taper right. Then you only have to worry about the depth of insertion when machining the real thing, not the taper angle as well.

    WRT the fit, I also use 4 lines down the male part then insert, twist slightly and take it out to check the fit. A soft hammer to tap the compound is useful, you can keep the bolts on the firm side and lessen the risk of moving too far.

    PDW

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