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  1. #1
    Join Date
    Apr 2019
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    Default Help Needed: Eriksen Lathe Thread Cutting

    I have had my Eriksen 180NE lathe for a few years and today I had a testing day........in all senses of the word.

    I have been making a mandrel to hold some sack truck nylon wheels that I need to take 4mm off the OD (for my machine trollies). This required me to try threading for the first time!!!

    20201003_165857.jpg20201003_165945.jpg20201003_165935.jpg

    The first pic shows the lever position plate for various metric threads and the next 2 show the levers I have available (note these are not necessarily still in the positions I threaded in). The one labelled 'Reverse Gear' doesn't actually say which position is reverse and I nearly had an expensive crash with it being in left hand thread position!!

    I need to create a thread for an M20 nut which is a 2.5mm [EDIT: I wrongly measured at 2.0 previously)] thread pitch. Now the fourth column in the lever position plate deals with Metric threads and as far as I can read it for 2mm I need;
    Spring Lever in 1
    Lever I in B (as at the time I was using a speed requiring the speed lever in 1:1)
    Lever II in Lead Screw
    Lever III in Metric

    Didn't get the result I wanted. This gave me a 4.0mm thread. I tried various other setting as below using a slightly higher speed and CML 4:1 (I have no idea what NML and CML mean but they are related to the speed controls);

    NML 4:1
    B1 = 3.5mm (should be 8)
    B10 = 0.875mm (should be 14)
    D1 = 0.875mm (should be 2)
    D10 = 3.5mm (correct!!!)
    A10 = 8.0mm (should be 28)
    C10 = 2.0mm (should be 7)

    None of this matches what I expected! If I move the lever Course Pitch-Normal Pitch to course I got some super big threads that had the carriage moving so quick I did not pursue using that setting.

    Am I reading the dials wrong???????

  2. #2
    Join Date
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    I can't read the threading chart at all, the resolution is too low. Can you post a close up of just the metric section?

  3. #3
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    Default

    Try this one....
    Attached Images Attached Images

  4. #4
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    Default

    For starters can you check

    NML 4:1
    B1 = 3.5mm (should be 8)
    B10 = 0.875mm (should be 14)

    That would seem to be backwards from both the chart and your D1 and D10 measurements. Pitch always increases as the number gets larger.

    Apart from the correct one, all your measurements are less than they should be. Something loose somewhere or a broken sheer pin?

    But then the ratio between A10 and C10 is correct...

    *edit*While you are out there a measurement of A1 and C1 might come in handy.

  5. #5
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    Quote Originally Posted by Stustoys View Post
    For starters can you check

    NML 4:1
    B1 = 3.5mm (should be 8)
    B10 = 0.875mm (should be 14)

    That would seem to be backwards from both the chart and your D1 and D10 measurements. Pitch always increases as the number gets larger.

    Apart from the correct one, all your measurements are less than they should be. Something loose somewhere or a broken sheer pin?

    But then the ratio between A10 and C10 is correct...

    *edit*While you are out there a measurement of A1 and C1 might come in handy.
    So is the ratio between B1 and D1, but the ratio of B10 and D10 is the wrong way round....

    For any given speed, the pitch given by 'C' is equal to 'A'/4, and the pitch given by 'D' is equal to 'B'/4.

    And yes, something odd is going on here. Perhaps some kind of slippage between the spindle drive and threading portions of the gearbox? Does it have a clutch arrangement for that part? I assume there are no change gears?

    Also wondering if the 1-10 pin is actually connected properly, or whether it's slipping on the shaft?

  6. #6
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    What do you get with the quick change on 1
    Lever 1 to B
    Lever 2 to M
    and Lever 3 to L ?

  7. #7
    Join Date
    Apr 2019
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    Adelaide
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    Default

    Nice work on recognising the ratios!

    Yes the lathe has a clutch but it is on the motor input so will not be the cause. As for slippage, it does seem that something weird is happening although so far the weirdness is consistent which may not be expected with a slippage.

    I do not think there are any back gears although not having a manual of any kind and not being able to find out ANY info on these lathes I have not pulled it around too much. I will have a look just in case somebody has messed with them (I did not get any spares with the machine).

    I will chew up some more metal and map out in more detail what is happening. This may give me a clue. Right back out to it..........

    EDIT: PS - I managed to get something thread like looking! It isn't as scary as I thought.

  8. #8
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    Had another play and am now totally confused. These are the results;

    4:1 (which is a slower speed)
    Lever III = Metric
    Lever II = Lead Screw
    Normal Pitch

    Lever I A B C D
    1 8.5 ~4.1 ~2.0 ~1.0 ~values seem slightly over those stated
    6 8.5 ~4.1 ~2.0 ~1.0 ~values seem slightly over those stated
    10 8.5 ~4.1 ~2.0 ~1.0 ~values seem slightly over those stated




    1:1 (higher speed)
    Lever III = Metric
    Lever II = Lead Screw
    Normal Pitch

    Lever I A B D
    1 scared 4.2 ~1.0 ~values seem slightly over those stated
    6 ~4.0 4.2 ~1.0 ~values seem slightly over those stated
    10 8.5 4.2 ~1.0 ~values seem slightly over those stated


    1:1 A was REAL fast and I barely had time to turn the threading knob before having to turn it back off. I do not have huge faith in the 1:1 A numbers.

    So these numbers are conflicting with what I did yesterday but I measured these better (the best I can with my eyes) and I feel todays numbers are more reliable.

    What I am seeing is quite clear. The quick change gearbox is doing nothing as it appears positions 1-10 give the same thread. Taking my quick change position 1 numbers with 4:1, I am consistently 1/2 what it should be. Quick change 1 and 1:1 I appear consistently double what it should be (taking measuring error into account).

    There appears to be 2 issues;
    1. something broken in QCGB - must be locked into a position (most likely #1?)
    2. there is an error factor involving the number 2



    I have opened the side of the machine and this is what I see;

    20201004_150510.jpg

    These are back gears? (Remember everything I know I heard it on my radio I mean on the internet) I wrote the z (teeth) and m (???) numbers on the picture. The 2 gears marked with a red X are not driven although both rotate (the left one cos its bolted to the big gear and the right one cos its on the end of a QCGB shaft).

    My totally uneducated guess is that somebody has played with these gears and got things out of whack for metric threading?

    Open to all thoughts and suggestions. I will have to take a deep deep breath and go into the QCGB.

  9. #9
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    CML and NML look to be coarse and normal pitch. Looking at the plate to get a 2mm pitch thread, I would guess that you need to have the coarse/ normal on coarse and on the 4:1 ratio.

    Michael

  10. #10
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    Now it's gotten REALLY interesting.... lol.

    I'd tend to agree with your conclusion about the pins 1-10, as I mentioned in the previous post I was wondering whether that was working properly. The fact that the 4:1 ratio seemed to be preserved between the letter pairs, but the actual pitches were screwy was why I was thinking of that.

    But actually having change gears in ADDITION to a metric/whitworth lever is what's got me going - I wasn't really expecting that although I probably should have. I had previously wondered whether you had rounded the pitch measurements, and it was actually giving imperial - looks possible.

    So the obvious question that pops into mind first - does it cut imperial threads correctly in that setup (at least in one position)? That'd be my first test from here out.

    Looking at that change gear arrangement, there's no compounding currently going on, so if the leadscrew is an imperial pitch, that might start explaining things. Not sure why the metric/whitworth lever, but being German, perhaps it makes a small further adjustment to get a more exact conversion? The 117/74 arrangement is a little odd, but I seem to recall reading of some odd compounding arrangements before.

    Second question - what does that 63 tooth gear mesh with? Is there another gear paired to the back of the 72 tooth?

    Looking at the boss on the 72 tooth, I'd suspect that it should be flipped around so that it engages the 74 tooth in order to convert to whichever pitch is not native to the leadscrew. But there are a few problems/questions around that:

    1. I can't see if there's enough range of adjustment for that to work.
    2. It's also possible that the 117/74 should also be flipped over, so that the 48 drives the 74.
    3. What goes in the machined slot to the left of the 48? Is there possibly some other gear that's supposed to interface between the 48 and the (currently) 117?
    4. What then is the point of the 63? It must have something intended to engage with it in some situation, otherwise there wouldn't be a gear on there - unless it's for 'storage'?
    5. (not neccesarily related, but has been bugging me all along) Why on earth is there a course/fine lever? It doesn't appear to be mentioned at all in the table, but there must be a reason for it. MichaelG's guess could well be correct, and I've wondered if that might be part of the answer before, but it didn't make sense on your previous numbers - maybe worth revisiting?

    Not sure, but get the feeling some parts could be missing. Pity a manual for this thing is unobtanium, because we could really use it right now. Might be worth trying to reach out to some German forums, see if someone has the same machine.

    *edit* Just realised the 48 looks like it's intended to be flippable as well, might lend some more weight to the idea of it driving the 117/74 via something else? Certainly introduces another possible layout even without.... My head is starting to hurt, lol.

  11. #11
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    Default

    The way I read it for a 2.5mm Pitch you should have the following set up:
    Position: 4
    Lever 1: D
    Lever 2: Metric (hard to read)
    Lever 3: Lead Screw
    Coarse Pitch
    Ratio: 4:1


    It looks like you can also have it in 'B' & Normal Pitch with a 1:1 Ratio but if it's that fast like you say I wouldn't bother.
    It is quite possible that someone has messed with the change gears.
    Good luck
    All The Best steran50 Stewart

    The shortest way to do many things is to do only one thing at once.

  12. #12
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    Just read through the page on Lathes.co.uk. Now I have found some things on there before that don't seem to match up with what the owners manual says for other machines I've been researching, so this should be taken with a grain of salt, but:

    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.

    So it suggests that the leadscrew is likely an imperial pitch, and also suggests that the change gears should not need to be rearranged for the table (only for oddball special pitches). Which doesn't preclude them being set up wrong at the moment, and if the leadscrew is imperial, I'm seriously wondering about that 117/74 gear (despite the whitworth/metric lever). Question is, how to figure out what they should be...

    *edit* Just banged some numbers in the calculator to see - as it's set up, the overall ratio from the 48 to 72 I make a 1.5 reduction.
    Flipping the 72 so you have 48 driving 117, 74 driving 72, would give a reduction of 2.372.
    Flipping the 72 and the 117/74 (doesn't look like it will actually fit though) would give a ratio of 0.949 - a slight increase.

    So if my brains not upside down, the 2.372 option should result in a finer pitch, due to the spindle doing more revolutions than the leadscrew (compared to current), and the 0.949 option would make slightly coarser pitches? Probably not overly useful until we figure out what's going on with the 1-10 pin selector though, and know which position it's actually in.

  13. #13
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    Does this lathe have an imperial leadscrew? If so there should be a 127 tooth gear in the equation for metric threads.

  14. #14
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    Quote Originally Posted by Michael G View Post
    CML and NML look to be coarse and normal pitch. Looking at the plate to get a 2mm pitch thread, I would guess that you need to have the coarse/ normal on coarse and on the 4:1 ratio. Michael
    That did cross my mind but I could not work out what the ML stood for. I will investigate that tomorrow and suspect you might be right on this. When I have put the lever into course the pitch was huge but I cannot remember if I had it in 4:1 or 1:1.


    Quote Originally Posted by Jekyll and Hyde
    So the obvious question that pops into mind first - does it cut imperial threads correctly in that setup


    I will take a look tomorrow. I did not think to use the imperial gauges today.

    Quote Originally Posted by Jekyll and Hyde

    so if the leadscrew is an imperial pitch, that might start explaining things


    I will measure it tomorrow and see if I can tell if metric or imperial

    Quote Originally Posted by Jekyll and Hyde

    Second question - what does that 63 tooth gear mesh with?


    This meshes with nothing making me think it might be a spare of changing things.


    I have previously searched the German forums for information on this lathe (using google translate) but still came up with nothing. Anybody speak/write German who could sign up with a German forum and ask a few questions??

  15. #15
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    Quote Originally Posted by Snapey View Post
    Does this lathe have an imperial leadscrew? If so there should be a 127 tooth gear in the equation for metric threads.
    I will measure and find out. There are no 127 tooth gears however.

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