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  1. #76
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    "My Lord, News" (Baldrick C1710)

    I have spent a couple of hours in the shed (much to the chagrin of my most beautiful lol). Below are my summarised findings after much manual chuck spinning;


    • the Whitworth/Metric lever DEFINITELY does not do anything other than select one or other of the dogs i.e. engage Shaft A or Shaft B
    • Shaft A and Shaft B DEFINITELY do not slide such that the back gears can swap positions
    • I lost another point, the tang on the dog shaft is indeed the key that connects the dog ring to the Shaft (A or B) - obvious now I see it derrrrrrr
    • reversing the 117T gear does not enable it to mesh with the 63T or any other gear unless I also reverse the 48T and 72T gears (which then achieves nothing)
    • the 63T is splined the same as the 72T so could manually swap positions
    • the 117T and 74T are one solid piece meaning the 74T can provide some compounding if it can be meshed with something else
    • I have a picture of the dog gear selector setup. I can confirm that moving the Whitworth/Metric lever clockwise (to the Whitworth setting) moves the Shaft A dog in thus connecting the QCGB gears (Xmas tree) to Shaft A
    • for interest my lathes slowest speed is 22 and fastest 1120 rpm
    • I analysed the impact of the Normal/Course lever on the Whitworth setting only (hopefully I don't need to do Metric as well as my arm hurts! lol)


    The Whitworth/Metric Lever setup;
    Whit_Metric_Lever.jpg


    The back gear setup;
    BackGears2.jpgBackGears1.jpg


    Any my gearing analysis (hopefully readable);

    Lathe Analysis.jpg


    Being hungry and having had my brain frazzled by counting tiny gear teeth over and over I have not fully decided what all this means. At this stage I am thinking that the 1:1 4:1 16:1 lever does not change the spindle to gearbox input ratio UNLESS the Course/Normal lever is on Course. This is displayed in 2 of the tables above.

    I am not sure any of this helps us unless we can determine from these ratios exactly what back gear ratio would be needed for metric threading. This might indicate which back gears need to go where.
    Attached Images Attached Images

  2. #77
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    Quote Originally Posted by BaronJ View Post
    How about "CML" Coarse metric lead:
    "NML" Normal metric lead:
    Baron you are the man!!!!!

    Looking at the original (and small plate), the 2 sections on feed rates say CWF & NWF i.e. course whitworth feed i.e. course setting, whitworth setting, feed shaft setting

    Under the Threads Per Inch section it says CWL & NWL i.e. course setting, whitworth setting and lead screw setting

    Under the Pitch In MM section it says NML & CML i.e. normal setting, metric setting, lead screw setting


    By jove that is a big bit of the puzzle for me - well done that man!

  3. #78
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    Well we can't see that

    Can we have a good picture of the imp threading chart please.

    Going ot take some time to get my head around those numbers but at first look they seem well strange

    *edit* I assume you have put the change gears back as they were in the picture in post #8?

  4. #79
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    *BURP* That was a tasty hat.

    So yup - the coarse lever is used in addition to selecting either 4:1 or 16:1 in order to get that factor of 4:1 reduction that is visible in the tables, which I was (and I think Stu was) assuming was intrinsically tied to the 4:1/16:1 selection itself. In other words, if you only select 4:1 or 16:1 WITHOUT also using the coarse lever, you should get pitches/TPI as described in the 1:1 column, but conveniently enough at a lower overall speed. (To the many - yes, you were right all along)

    *EDIT for Mk1_OZs morning digestion* And I just realised the table even tells us that last point. Obvious by its absence. Note that it just says 'NML' in those columns - absolutely no mention of 1:1, 4:1, or 16:1, because indeed you can cut those pitches or TPI in any of the 3. But under CML you have an additional restriction listed, because the coarse setting decouples the spindle speed reduction from the leadscrew (like Stu and I were assuming happened, as described earlier this morning). Should come in very handy when you get to finally cutting that 2.5mm thread, just set B4 NML, and 16:1 speed range to keep things moving nice and slow.

    Good news on the key - when you said it was moving, I was thinking it might be sheared, which would have been an issue come attempting a Whitworth thread. I haven't bothered keeping score, any time I gain a point I'll lose it 5 minutes later, lol.

    That close up of the change gear arrangement is a worry though. The existence of that slot at top left I pointed out way back when may suggest we need more gears than we have. But hopefully not.

    I'll have a bit of a look at the other numbers now, and see if I can figure something out.

    But a quick guess, looking at that picture - taking the bronze bush off, flipping the 117/74 and inserting the bush from the outside in would engage the 74 with the 63. Relocating the 72 (or using a gear we don't have) to the currently empty slot could provide drive from 48-72, 72-117, 74-63. I'm guessing that the bronze bush is slightly longer than the gear, so it won't lock up....

  5. #80
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    Seems to me we/you guys are on the right track. Still doesn't explain how power gets to Shaft A when Metric is selected.

    I agree that the top left back gear slot does indicate a missing gear. Whenever I have read about metric threading on an imperial lead screw it seems to always involve 4 gears.

    This is the only other Whitworth threading chart pic (some is missing);
    Whitworth Plate.jpg

  6. #81
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    I'm calling that correct for imp threads(at least A nwl )

    Am I seeing things?

    From the threading charts I get these numbers
    1=4tpi
    2=
    3=
    4=5
    5=
    6=
    7=6
    8=
    9=
    10=7

  7. #82
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    Quote Originally Posted by Stustoys View Post
    I'm calling that correct for imp threads(at least A nwl )

    Am I seeing things?

    From the threading charts I get these numbers
    1=4tpi
    2=
    3=
    4=5
    5=
    6=
    7=6
    8=
    9=
    10=7
    I make those numbers on the chart too, just been stuffing around with A:1. Interested to see where you've gone with this, I'm second guessing myself a bit.

  8. #83
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    Quote Originally Posted by Stustoys View Post
    I'm calling that correct for imp threads(at least A nwl )

    Am I seeing things?

    From the threading charts I get these numbers
    1=4tpi
    2=
    3=
    4=5
    5=
    6=
    7=6
    8=
    9=
    10=7
    Those numbers are Pitch in mm not TPI

  9. #84
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    Quote Originally Posted by Mk1_Oz View Post
    Those numbers are Pitch in mm not TPI
    Pretty sure Stu is looking at the blurry original photo from the first post. Coincidentally (or not?) the numbers happen to be the same as the metric chart...

    *EDIT* Also, I'm waiting to see what Stu comes up with, but I have a feeling your gear counting days might not quite be over yet - I have a feeling to work out the metric properly, we might need 4 more gears counted....

  10. #85
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    Quote Originally Posted by Jekyll and Hyde View Post
    I make those numbers on the chart too, just been stuffing around with A:1. Interested to see where you've gone with this, I'm second guessing myself a bit.
    A:1 2 turns of the spindle per one turn of leadscrew. =2 turns to move carriage 1/2". times 2 =4 turns to move 1"=4TPI
    That what you mean?

    Quote Originally Posted by Mk1_Oz View Post
    Those numbers are Pitch in mm not TPI
    yes. they are the same lol, I gave up trying to get my head around that long ago.

    Quote Originally Posted by Jekyll and Hyde View Post
    * 74 with the 63.
    But is mixing modules allowed? I thought it wasn't, but what I know about gears wouldn't fill a small book.

    My hunch is, flip the compound as J&H says and fit the 72 tooth to shaft A
    Test that by hand in metric and see what you get.
    I say this because it seems someone has put a lot of thought into this setup, I'd like to think they managed to come up with a imp/metric swap that didn't involve yet another set of gears
    I'm guessing the extra slot in the banjo is for really strange pitches
    Last edited by Stustoys; 6th Oct 2020 at 11:12 PM. Reason: fixed about 1/2 doz typos

  11. #86
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    Quote Originally Posted by Stustoys View Post
    A:1 2 turns of the spindle per one turn of leadscrew. =2 turns to move carriage 1/2". time 2 =4 turns to move 1"=4TPI
    That what you mean?
    ******
    My hunch is, flip the compound as J&H says and fit the 72 tooth to shaft A
    Test that by hand in metric and see what you get.
    I say this because it seems someone has put a lot of thought into this setup, I'd like to think they managed to come up with a imp/metric swap that didn't involve yet another set of gears
    I'm guessing the extra slot in the banjo is for really strange pitches
    Yeah, I spotted that. So by my calculation, by the time you get to the drive dog on shaft A, you should be going 4 times slower than the spindle - which doesn't match what's been measured? Either the 48t is going the same speed as the spindle, or the drive dog at A should require FOUR turns of the spindle for one revolution?

    *EDIT* Unless 'spindle turns' in this table refers to the number of turns of the 72 tooth gear?

    But looking at the train from the drive dog out to the leadscrew, by eye speeding back up by a factor of 2 looks plausible, so I'd be more inclined to go with the 48t output being correct?

    Which brings me to the problem I have with the metric - without counting the A-D slider, the gear it meshes with in position A, and the gear on the leadscrew and it's mate, I don't think we can work out how much of that 2x increase is still present in the metric config? Or maybe it doesn't matter?

    *EDIT* Actually, eyeballing it, might end up as a further reduction in metric?

    And try banging the numbers on my 'guess' configuration - I don't think it's anywhere near correct, from what I was getting out of the quackulator earlier....

    And as far as mixing modules? I don't even know what you mean here, so no point asking me! Mechanical drivetrains I get, numbers I get on a good day, so that's the bit I'm tackling - the details are up to you, lol.

    *Yet another edit* Oooookay, now I get it - I missed that the 63 tooth is an m1.5 - but NOTHING else is.... Better hope it's allowed - or that it's a typo, couldn't find if you've asked that before?

  12. #87
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    Quote Originally Posted by Jekyll and Hyde View Post
    *EDIT* Unless 'spindle turns' in this table refers to the number of turns of the 72 tooth gear?
    Nope......spindle turns means chuck turns.

    It is so late that I don't think you 2 are talking English anymore!!! I will re-read tomorrow at work and digest......I am constantly researching/learning and trying to keep up with you!

  13. #88
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    Quote Originally Posted by Mk1_Oz View Post
    Nope......spindle turns means chuck turns.

    It is so late that I don't think you 2 are talking English anymore!!! I will re-read tomorrow at work and digest......I am constantly researching/learning and trying to keep up with you!
    I don't think anyone has ever accused me of speaking English at any point in time....

    And hmmm. If that is indeed chuck turns on both tables, I'm stumped now. Obviously doing something very wrong.

  14. #89
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    I'm not sure I understand your last post either. But then I'm not looking at the gear ratios at all. All I have done it checked that the "turns of the spindle" to "lead of the leadscrew" give the pitch as per the threading chart. Which it seems to do. After that I am happy to assume for the minute that all the other imp pitches will be correct(though checking some more would be nice).

    I still dont have my head around exactly whats going on.



    p.s. with the spindle speed set to 22 rpm, in course pitch and 16:1 does the spindle still turn at 22 rpm or 1.375rpm?

  15. #90
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    [QUOTE=

    Lathes UK says there is 68 metric threads from 0.5 to 11.2 mm

    The thread chart shows some gaps for the spring gears at positions 3, 6, and 9.
    The pitches for the two right hand columns follow the number of teeth on the xmas tree gears. These gears just have to be involved in the pitch selection.
    The decimal point seems to be missing; ie the pitch is 11.2 and not 112
    The two columns on the LH side appear to be almost irrelevant. The RH side seems to cover the pitch range of 0.8 to 11.2.

    The pitch of 40 of the pitch selections is related to the number of teeth by a factor of ten. Just not sure where this factor is generated.

    I am still unsure of the lead screw pitch. Just seems to be very coarse. 6 turns over 12 inches is coarse by my reckoning. Lathes UK says pitches of 2 TPI or 4TPI were used.
    From Lathes UK:
    [FONT=Times New Roman]Screwcutting was by a Norton-type quick-change gearbox with a combination of tumbler and lever control on the face of the box and headstock - with one lever available to select coarse pitches. Interestingly, on lathes with the standard speed range, the leadscrew had a pitch of 1/4" while on those with the high-speed option it was 1/2". The box, driven in the usual way by changewheels, was arranged such that, when the leadscrew was in use for threading, the sliding and surfacing feeds drive shaft did not turn - and vice versa. The box was able to generate 80 English (Whitworth) pitches from 1/4" to 56 t.p.i., 68 metric from 0.5 to 11.2 mm and 52 module from 0.25 to 28 MOD - with all common pitches of all types available without recourse to altering the changewheel drive. Eighty rates of power sliding and surfacing feeds were provided, the former from 0.0006" to 0.1356" per revolution of the spindle and the latter from 0.0004" to 0.0959".
    Rather unusually, a single apron-mounted lever - rotating around a cylindrical boss cut with a slotted gate - was used to select and engage not only the power feeds but also the opening and closing of the leadscrew clasp nuts; the actions were, of course, interlocked to prevent the use of more than one motion at a time.
    [/FONT]

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