Graziano SAG14 Change Gears
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  1. #1
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    Default Graziano SAG14 Change Gears

    Hi, I recently got myself a neat SAG14 lathe and am fairly new to the conventional lathe world. Itís a fairly simple machine to work on and Iíve been trying to figure out how to properly change the gears so I can select finer thread pitches for the feed box. I originally had a 20-40-80 gear set up and according to the plate I would require a 31-58-47-64 gear set up for the finer thread pitch selection. I was lucky enough to find 3 of the gears, and had the 64 tooth one made on my CNC mill. I put everything together as shown in the diagram on the front plate. The feedbox has not gone slower to accommodate the 92-TPI as shown on the plate (my selection was W-A-10). I believe Iím doing something wrong here, but not sure what. The 64 tooth gear I made has the same gear pitch and approximately 132mm OD.

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    Hi GinoS,

    I think you are looking at the charts on the right hand side, which are for "Module" and "Diametral Pitch".

    I don't understand what those charts are for, but the '92' you are looking at is evidently not T.P.I.

    I would like to know what those charts on the RH side mean too!

    BTW, the 'standard' 20-40-80 gears give a reduction of 4:1, whereas the compound gearing 31-58-47-64 only gives a reduction of about 2.5:1, so it cannot give you a finer thread than the 'standard' gearing (assuming the other lever positions being the same)

    The TPI chart on the LH side shows 46 TPI as the finest, however the metric chart shows a pitch of 0.375mm which is about 67.75 TPI, FWIW...

    The manual shows 48 TPI, but with different gears.

    Another thought - could you just use the feed chart and select .011" feed, (90.90 TPI) or .010" (100 TPI). Not sure if you are wanting an actual thread or just a fine feed....
    Last edited by Peter S; 02-07-2020 at 05:01 PM.

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    Quote Originally Posted by Peter S View Post

    I don't understand what those charts are for, but the '92' you are looking at is evidently not T.P.I.
    They are used to cut worm gears on a lathe and so correspond with gear nomenclature.

    Nobody ever seems to make worms and is why I have a 2 sets of virgin Mod and Dia change gears from 30 and 40 year old lathes I recently purchased.
    Last edited by Doug W; 02-07-2020 at 01:11 PM.

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    yes, for cutting worm gears, module is the metric gear system, diametral pitch the inch system. ('comon, you knew that?!)

    also, Peter if you could post a decent picture or scan of the manual page(s) that covers the application of the change gears for threads not covered on the plate that would be fantastic. It would really help those of us with gears and no manual, SAG 17 in my case, but I think the threading is the same as the 14? Thank You!

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    Quote Originally Posted by cyanidekid View Post
    yes, for cutting worm gears, module is the metric gear system, diametral pitch the inch system. ('comon, you knew that?!)

    also, Peter if you could post a decent picture or scan of the manual page(s) that covers the application of the change gears for threads not covered on the plate that would be fantastic. It would really help those of us with gears and no manual, SAG 17 in my case, but I think the threading is the same as the 14? Thank You!
    I know that module and DP apply to gears, but the question is why these terms are found on a lathe. OK, for making a worm. Not something I know anything about either - I have used lots of worm gearboxes, but never made one. Maybe some have multi-start threads?

    The Sag 14 manual can be found here, hopefully:

    https://onedrive.live.com/?cid=547FE...%21164&o=OneUp

    The "special pitches" are on the last page.

    The photos of the lathe charts are too dark for me to read.

    I have a photocopy of another manual, will see if it is any clearer.

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    GinoS,

    Good news!

    If you have the correct gears that is...

    I had a look at my Sag 14 manual and found it is slightly different to the digital copy manual above (I think my manual is a slightly later version).

    It has 2 x pages showing how to get a wider range of metric pitches and TPI.

    It doesn't include 92 TPI, but I am pretty sure you could get 92 TPI by using the same settings as 80 TPI, but putting the 1-10 selector on '10'.

    It requires these gears: 20, 52, 26, 80. These would have been included in the original spare gears supplied with the lathe.

    BTW, you mentioned the gear pitch and OD of the gear you made, but the only relevant figure in these calculations is the number of teeth.

    Click on the thumbnail, then click on the image for further enlargement.

    If you would like a higher resolution, send me an email or PM.


    sag-14-pg-73-change-gears-special-pitches-red.jpg sag-14-pg-72-change-gears-special-pitches-red.jpg

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    For any Sag 14 owners interest - the manual I have is slightly different to the on-line digital copy, and has a more readable image of the screw-cutting/feeds charts.

    There were two options for these charts, my guess is that a lathe with metric dials would have this chart:

    sag-14-pg-71-screw-cutting-feed-charts-metric.jpg


    And the lathe with 'inch' dials would have this chart:

    sag-14-pg-71-screw-cutting-feed-charts-inch.jpg

    Both versions use the same leadscrew, so the charts are the same except the feed rates are given in metric or inch and the layout is slightly different (metric pitches at top for metric lathes, TPI at top for inch lathes).

    Both charts were taken from this page:

    sag-14-pg-71-screw-cutting-feed-charts.jpg

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    Quote Originally Posted by Peter S View Post
    GinoS,

    Good news!

    If you have the correct gears that is...

    I had a look at my Sag 14 manual and found it is slightly different to the digital copy manual above (I think my manual is a slightly later version).

    It has 2 x pages showing how to get a wider range of metric pitches and TPI.

    It doesn't include 92 TPI, but I am pretty sure you could get 92 TPI by using the same settings as 80 TPI, but putting the 1-10 selector on '10'.

    It requires these gears: 20, 52, 26, 80. These would have been included in the original spare gears supplied with the lathe.

    BTW, you mentioned the gear pitch and OD of the gear you made, but the only relevant figure in these calculations is the number of teeth.

    Click on the thumbnail, then click on the image for further enlargement.

    If you would like a higher resolution, send me an email or PM.


    sag-14-pg-73-change-gears-special-pitches-red.jpg sag-14-pg-72-change-gears-special-pitches-red.jpg

    Peter,

    My manual is an earlier version and it only has the gear change chart for metric pitches. Even the metric chart in my manual is different than the one that you've posted. Could you email the higher resolution charts to me. It would be greatly appreciated. I will PM my email address to you.

    Thank you

    Ted

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    GinoS,

    How did you get on. Was any of this information helpful?
    Also wondering why you would want to cut 92 TPI...

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    Not everyone does not never make worms on their lathe. I find the circular pitch, DP and module choices quite use full at times. I currently have a 1.5 module worm to make so. . . . . guess ya only need it when ya need it, like lots of other things!

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    Quote Originally Posted by Peter S View Post
    GinoS,

    How did you get on. Was any of this information helpful?
    Also wondering why you would want to cut 92 TPI...
    I'm always amazed at how many people come on this forum asking for assistance and never respond after having received some good feedback from other members.

    And....having said that, I guess I should say that Peter did in fact send me the charts that I requested in my post above. Thanks again Peter.

    Ted

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