1944! Colchester lathe coversion

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Thread: 1944! Colchester lathe coversion

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    Default 1944! Colchester lathe coversion

    Hi,

    I've just bought 1944 Colchester lathe (a "pig in a poke", £50 on eBay UK, 113 euros transport to France where I live, it has very little wear for a sixty year old machine!), my intention is to"CNC" it. It came without change wheels, intend to use the Electronic Lead Screw being developed on the ELS yahoo group. The ELS will allow threading and taper turning, and for "real" CNC, I'll go over to EMC and Linux, this also gives me time to learn G code ans stuff! Mechanically I can cope with this project, but I need help with the maths involved. Thirty five years ago, when training as a mechanic, I learnt to check bearing preload on differentials (third members for our American cousins) using a piece of string and a spring balance. I've only ever done this once in my life, as fate has it I've never had to rebuild a diff since! Today I wound a piece of string around a 25mm diameter part of the cross slide screw, pulled it with a spring balance and obtained a read out of 800grams. Can anybody out there help me with the calcuations to transform this into stepper motor torque.

    Matthew TINKER (Tinker is my real name!)

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    No. I think it should be put on a pedestal with a sign underneath reading;

    "The Way Things Were. Oh For The Good Old Days".

    CNCing it is nothing less than sacrilege; like when people take 500 year old mansions, gut them and install all modern conveniences. Have you no appreciation of the finer things in life you, you, Philistine!!!!!! Splutter, spluttter.



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    I never said that I was making an ireversable change to a museum piece! I have no intentions of mutilating it! It's missing too much to restore, besides I appreciate the quality of the machine! It's easy to jude without knowing!

    Matthew


    Quote Originally Posted by Geof View Post
    No. I think it should be put on a pedestal with a sign underneath reading;

    "The Way Things Were. Oh For The Good Old Days".

    CNCing it is nothing less than sacrilege; like when people take 500 year old mansions, gut them and install all modern conveniences. Have you no appreciation of the finer things in life you, you, Philistine!!!!!! Splutter, spluttter.




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    I'm joking for goodness sake!!!!

    But I bet I will get support from some of the other old fogies .



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    Default Other antiquities!

    Goef

    Good!

    I also have in my workshop, an 1841 folding machine, on a pedistal "cos I use it lots"! It's a French made machine, that I saved from the slow boat to China. It was made the year after the French passed the law that obliged the use of the metric system, fourty years after it's introduction! It is beautiful to use, I can fold 2.05m lengths of 2mm steel with it by hand. I get a kick out of using it on stainless and alluminium, metals that didn't exist when it was made! It's quite an attraction in it's original drippy black paint, I just cleaned it oiled it adujusted it and use it!

    Respectfully, Matthew

    P.S. an one got a solution for my maths problem!



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    Quote Originally Posted by mattinker View Post

    P.S. an one got a solution for my maths problem!
    I would think a 1944 Colchester at least deserves servo's
    I would expect it is on the beefy side and not exactly a 'table-top'

    For Break-away torque, the method you describe, or similar would work, you can also get an idea using sizing programs like Kollmorgen etc, http://kmtg.kollmorgen.com/motioneering/app_engine/ . which introduce the inertia motor to load aspect (Free).
    Al.

    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.


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    Quote Originally Posted by mattinker View Post
    ...and alluminium, metals that didn't exist when it was made!....

    Are you sure?

    I found this when I went Googling.

    Some scholars have suggested limited production of aluminium metal may have occurred as long as 2000 years ago! In his famous encyclopedia "Historia Naturalis" Pliny the Elder mentions a familiar sounding silvery metal:

    "One day a goldsmith in Rome was allowed to show the Emperor Tiberius a dinner plate of a new metal. The plate was very light, and almost as bright as silver. The goldsmith told the Emperor that he had made the metal from plain clay. He also assured the Emperor that only he, himself, and the Gods knew how to produce this metal from clay. The Emperor became very interested, and as a financial expert he was also a little concerned. The Emperor felt immediately, however, that all his treasures of gold and silver would decline in value if people started to produce this bright metal of clay. Therefore, instead of giving the goldsmith the regard expected, he ordered him to be beheaded."

    While there is obviously no way of testing the truth behind this story (Pliny's Historia Naturalis is not known for its scientific accuracy!) the similarities are interesting. Indeed, almost 2000 years later another Emperor, Napoleon III, used aluminium plates and cutlery to serve the King of Siam at a state banquet. Aluminium was then a rare and precious metal and less important guests had to eat from plates of pure gold.


    I knew about the Napoleon link but not the Tiberius one.



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    The cross slide isn't heavy, I'll have to do the test on the lead screw. John Dammeyer on the ELS group did some calculations for me (since I posted here)and came up with a torque of 12oz.in so a minimum size 23 stepper at 55oz.in should be sufficient. He suggested belting it down 2 to 1as it's a 5 T.P.I.

    I'm on Mac and Linux (anti microsft!) so I'll have to find some body to try the
    program you propose.

    Thanks, Matthew

    Quote Originally Posted by Al_The_Man View Post
    I would think a 1944 Colchester at least deserves servo's
    I would expect it is on the beefy side and not exactly a 'table-top'

    For Break-away torque, the method you describe, or similar would work, you can also get an idea using sizing programs like Kollmorgen etc, http://kmtg.kollmorgen.com/motioneering/app_engine/ . which introduce the inertia motor to load aspect (Free).
    Al.




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    Geof,

    I allways thought that the first smelting of Alluminium was arround 1875 don't know where I remember this from, happy to be corrected! I know I'm right about the stainless!

    Respectfully, Matthew


    Quote Originally Posted by Geof View Post
    Are you sure?

    I found this when I went Googling.

    Some scholars have suggested limited production of aluminium metal may have occurred as long as 2000 years ago! In his famous encyclopedia "Historia Naturalis" Pliny the Elder mentions a familiar sounding silvery metal:

    "One day a goldsmith in Rome was allowed to show the Emperor Tiberius a dinner plate of a new metal. The plate was very light, and almost as bright as silver. The goldsmith told the Emperor that he had made the metal from plain clay. He also assured the Emperor that only he, himself, and the Gods knew how to produce this metal from clay. The Emperor became very interested, and as a financial expert he was also a little concerned. The Emperor felt immediately, however, that all his treasures of gold and silver would decline in value if people started to produce this bright metal of clay. Therefore, instead of giving the goldsmith the regard expected, he ordered him to be beheaded."

    While there is obviously no way of testing the truth behind this story (Pliny's Historia Naturalis is not known for its scientific accuracy!) the similarities are interesting. Indeed, almost 2000 years later another Emperor, Napoleon III, used aluminium plates and cutlery to serve the King of Siam at a state banquet. Aluminium was then a rare and precious metal and less important guests had to eat from plates of pure gold.


    I knew about the Napoleon link but not the Tiberius one.




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    Quote Originally Posted by mattinker View Post
    Geof,

    I allways thought that the first smelting of Alluminium was arround 1875 don't know where I remember this from, happy to be corrected! I know I'm right about the stainless!

    Respectfully, Matthew
    You are correct aluminum was not produced in commercial quantities until then but it was produced in small quantities a lot earlier; as my excerpt pointed out it was a precious metal.

    I think the statue of Eros, Piccadilly Circus I think, was cast in aluminum around the late 1800's.

    Perhaps I should also Google stainless just to be awkward.



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    Default Eros, layshafts and Maths

    Goef,

    what you only "think" Eros was cast aluminium, your slipping, your right, but....

    I think the statue of Eros, Piccadilly Circus I think, was cast in aluminum around the late 1800's.

    Perhaps I should also Google stainless just to be awkward.[/QUOTE]

    Google away to your hearts content!

    Meanwhile, I'm going to start to cobble together a temperoy motor mount so that I can turn a new layshaft to replace the missing one that this "pig in poke" doesn't have! It's the only lathe I've got so it will have to stay working!

    Fortunately, I've had some mathematical help from elsewhere, but if anyone wants to add their 2cents, Euro, dollar, pence, whatever! I'm open!


    Matthew



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    Default The beginning!

    Well, if this is going to be a conversion log, maybe I better show you something of what the lathe in question looks like! tony@lathes.co.uk confirms that it's a standard 1930's Colchester lathe, this one was made in 1944 which explains why it's exposed flat belt drive. I have mounted the motor on a tempoary plate and have started turning a lay shaft it has to work before I can CNC it! Over a 40cm (OK 16") I have a 0,002" taper so I'm not touching the tailstock for the time being! For the time being I'm thinking mostly in inches, as the cross slide is calibrated in thous, this is going to be a bit scytsophrenic for me, as I've spent nearly thirty years here in France, so I have a metric tendancy despite my being brought up on the Imperial system! At least all those whitworth "spanners" (wrench allways sounds so violent to me) that I've been dragging around since I trained as a mechanic in 1972 are getting used! My unified stuff gets used on my Elliot M10 shaper (maybe a CNC shaper later!)

    I did a black and white version of the general view just for Geof!

    I still need help with the calculation of the stepper size for the lead screw!


    Matthew

    I don't seem to be able to attach the pics, I'll send this and try later!

    Last edited by mattinker; 04-11-2007 at 04:14 PM. Reason: spelling mistake


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    Default pics

    It worked this time.

    Attached Thumbnails Attached Thumbnails 1944! Colchester lathe coversion-black-white-jpg   1944! Colchester lathe coversion-headstock-jpg   1944! Colchester lathe coversion-tempmotormount-jpg   1944! Colchester lathe coversion-carridge-jpg  



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    Quote Originally Posted by mattinker View Post
    I don't seem to be able to attach the pics, I'll send this and try later!
    Ha Ha Ha

    I can.

    EDIT

    First try!



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    Default So can I

    So can I now, I'm an absolute begginer onthis forum!

    Matthew



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    wow you have a lot of work ahead of you!! this will be a beautiful combination of old and new tech!!

    love that "old" b/w pic!



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    Heck, I thought that my 1954 (or so )Pratt Whitney Tool room lathe was going to be the oldest manual converted to CNC (Manual to CNC lathe Conversion, Pics, here on the CNC Zone). I used 670 inch/oz servo motors with a 5:1 reduction, on both the Z and X axis.I did make some cuts before being hospitalized, and the finish is real good..unfortunatley I programed two tools incorrectly and and scrubbed the tail end of the part, but overall the part held .0003 to .0006 tolerance.

    Do not forget oiling, including a method to lubercate Z and X ways, and the ball shaft and nuts, it is really important, and will help holding tolerances. I also made and installed some way wipers using bronze and rubber to keep most of the trashy bits from getting under the saddle, also helps in retaining the oil too.

    Good luck on your conversion, its a real challenge, but you will enjoy making parts that are accurate,having the ability to thread and taper. Are you using a CAD/CAM system ? That really adds to the overall ability to make some really different parts !

    Adobe (old as dirt)



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    Default Over ambitious?

    Thanks for the encouragement!

    Adobe, I have read your thread very carefully, full of admiration! I'm not in your machining class!

    Lathe experience:-
    An old hand made " flexy chatterbox" with more chatter than a womens institute outing! It would on a good day hold tenths of a mm! Used it mostly to make Al pulleys for it's self. (home foundry)

    "Metal work" classes in school in West Wales aged fourteen, I made a centre punch and a screw driver!

    Fabrication, worked as a maintenance mechanic in a quarry, lots of "gas axe" and mobile stick welder. These techniques have stayed with me.

    I've been structural metalworking ever since!

    First job is to get it to run at a reasonable speed at the moment, it's doing about 130 RPM with the back gear engaged. The first part of the lay-shaft is in the black & white photo!

    CAD/CAM is going to be much later, I intend to use ELS, an electronic lead-screw being developed by John Dammeyer on the Yahoo ELS group, this set up allows threading, metric UN and Whitworth, tapers, with the most common machine tapers programed plus the possibility of one off's. Once I've got that far, I will then set about CNC proper, as from what I can gather the ELS will act as a breakout board for the serial port, allowing computer control. I'm going to use Linux on a "bumpster grade" portable that my sister gave me using EMC to control things. The early version which would be light enough to run on this machine doesn't do threads, but there's the ELS!

    Adobe I keep checking on your thread to find out how you are, I was pleased to hear from you, as I know that you've been in hospital, I hope that your being able to spend time contributing to this thread is a sign that you're on the mend!

    I lived five years in a 3/4 adobe house (the other 1/4 was stone) great insulation and ecological! I feel that it's a noble material, not just "old as dirt"!

    Matthew



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    Default Progress is slower than I thought possible!

    I've been hanging on to have some photo's to post, still haven't got any, but I thought better post without photos than no post at ll!

    Progress is extremely slow, work and other obligations getting in the way. Since my last posting, I've made a lay-shaft that has the original flat belt pulley and a four pulley conical "v". The "v" pulley came from a previous project, it's a little on the light side! This set up allows spindle speeds of 40 rpm to around 2000 rpm. Tony Griffiths (tony@lathes) on his http://www.lathes.co.uk/ site describes the gear-head version of this lathe as having triple drive belts which are difficult as they tend to fight each other. He recommends using one belt if one's not doing heavy work! If one belt isn't enough, and I'm asking a lot on the smallest diameter! I shall go over to a toothed belt primary drive if I can afford it!.

    To continue working with the lathe as well as on it, I've been building a tool post holder for a small air drill to "touch up" the inside of the chuck jaws. I need the chuck to be accurate as I'm going to bore out the the motor pulley to fit the 25mm shaft of the ancient 1,5 hp Chzeck made motor that came with the lathe. (I suspect that Chzeck hoses are about twice as big as Chinese ones!) I can't bore the pulley right the way through as there wont be enough metal left to have any strength!. An interesting side affect is that the same tool-post holder will also take my big Makita hand drill, which will allow certain dividing head type operations using the 40 tooth shaft gear. OK , sixty would be better, but I'll be adding a 48 tooth pulley to drive (1 to 1)a small lay shaft for the optical encoder. This way I can keep the 1 1/8" - 32mm through the shaft bore. 48 teeth and 40 teeth give quite a reasonable number of angles.

    Matthew



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    Matt: Glad to hear of your progress...It is much better to work slowley and correctley, than rushing in , only to find haste has ruined a good project.

    I have operated a lot of flat belt machines, with bronze bushings in the head. Correctley set up and lubercated, the finish is actually better than a gearhead. I did find you can not push those machines as you would a large heavy geared head production machine, but for small production runs, prototyping and hobby use, they can not be beat.

    Tony Griffith also preaches correct set up and the proper tooling to reduce cutting forces on those type of machines, which relates to accuarcy and finish.When I first started in a machine shop while going to College, the owners ( a family ) demanded that I could grind tooling correctly, before I could use any of the machines..I spent a lot of time being yelled at because I did not grind a tool the way they wanted..but they were right every time, even my machine shop instructor in school, who had a PHD in Mechanical Engineering , along with his knowledge of tooling, was amazed at some of the tools I brought in from work,as they really made the product look good , along with accuracy.

    Keep up the good work, and post some more pictures !


    Adobe (old as dirt )



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1944! Colchester lathe coversion

1944! Colchester lathe coversion