[mattinker]

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!)

[Geof]

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.

[mattinker]

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

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.

[Geof]

I'm joking for goodness sake!!!!

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

[mattinker]

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!

[Al_The_Man]

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.

[Geof]

...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.

[bigbunny5]

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,

Gee I never knew it was illegal to use Civilized units of measurement in France I always just thought you guys Hated Americans for some reason I think I have some Metric Tools out there in the shop. If I remember Right, their hiding behind my Whit-worth tools I had to get for that old Triumph Motorcycle I had.

[Adobe Machine]

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)

[mattinker]

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

[mattinker]

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

[Adobe Machine]

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 )

[mattinker]

Adobe,

thanks for the encouragement and advice which haven't fallen on deaf ears! As I've said before, my experience is extremely limited. Although I've been sharpening drill bits by hand for years, my machine tool sharpening is very limited, I have an Elliot M10 shaper, for which I've made tools with reasonable success, I've now got to go back to sources on lathe tool sharpening. Sometimes by chance things cut well! I've had reasonable results with high speed steel tools which would seem to suite my purposes better than carbide. Any hints on sharpening or web sites about sharpening would be greatly received (The Shireline site was useful).

I hope no news about your health is good news. Matthew

[mattinker]

Finally some photos. Now that I' writing this, I realize that I was thinking in French when I named the pics!


Tour1: -This is the holder that I made to retouch the inside of the chuck jaws. I haven't yet made the blocks to go between the jaws so that it's locked closed when I true it up.

Tour2:- The lay-shaft, a piece of hot rolled 25mm bar, turned down to 20mm at the ends and sleeved up to 1 1/8" to take the flat belt pulley. I'll change the belt as soon as I can! The "V" step pulley came from another project, it just happened to have useable sizes!

Tour3:- The cross slide ball handle was damaged in transport, so I amused myself turning this from a blank that I'd cast some spares for another project thinking "that'l be useful one day".

Tour4:- The very temporary nature of the half horsepower motor mount!

Tour5:- Shows the second phase of the drive train, the frame for the lay-shaft is as it will be except that I will be adding a tensioner for the flat belt. The half horsepower motor held on with "G" clamps is not the final one, but it had a pulley which will allow me to bore out the motor pulley to fit the 25 mm shaft.

Well that's it for now.

Matthew

[awemawson]

You're getting there !

I doubt that that air pistol drill will really spin fast enough for that internal grinding wheel - at that diameter you need a few thousand rpm to avoid more wear on the wheel than the object being ground.

[mattinker]

I thought about this before I started, I was a bit disappointed at the speed that this drills turns at, I've known them much faster. I will be running the spindle as fast as I can so the speed of the drill will be added to the spindle speed. Mathematicly, I don't know how this works, but I think that the surface speed of the grind stone relative to the speed of the moving jaws should be the sum of the two surface speeds. This is what I'm hoping! More later when I've made the blocks to go between the jaws.

Matthew

[mattinker]

Well, I was surprised by the results that I got from "that air pistol drill", it took the metal off reasonably well, but the chuck is the one that Noah had on his ark, so worn, now it has an acurate spot around 35mm in diameter whereas it had run out every where before! Ok so I'll have to replace it!

You're getting there !

I doubt that that air pistol drill will really spin fast enough for that internal grinding wheel - at that diameter you need a few thousand rpm to avoid more wear on the wheel than the object being ground.

I've finally got myself a digital camera so I'm getting the pictures sorted.

Pictures tomorrow.

Matthew

[mattinker]

Well, there not very exciting!

The first one is just things I got through the post. The pump is a fountain pump(cheap solution). I've been using a similar one on my band saw for the last three years with very little trouble. It's 220 volt(yes 220) double insulated everything in my workshop runs through 30milliamp trips, so a current leak of about 1,5volts trips them. All I'll need to complete things is a bit of plastic pipe and a plastic jerry can. I made a very efficient magnetic filter for the band-saw just by taping a large magnet to the outside of the jerry can where the coolant runs down the side on its return. I have had very little trouble with filings in the pump.

I changed the old and rotting flat belt for a continuous synthetic one, I miss the flap-flap of the connector going by, but it doesn't slip so much.

The primary drive is in place along with the Chezck 1,5 HP motor. unfortunately, the pulley was an early casting, it has faults in the smallest diameter is breaking up all ready! I must find or make a new crucible, I've got lots of things to cast.

I've put in a series of photos of a fixed steady rest that I'm making as I'm going to need one soon. It's a low budget steady, using roller skate bearings that I had left over from some thing else, all thread, nuts and spring washers and 15mm thick plate. The body is made from a piece 200mm wide. I cut it hexagonal to get a maximum inside diameter. I used a plywood jig to cut out the inside circle with my plasma cutter. It's surprising how little the plywood burns.

I'd like to know whether you think these non CNC things which are part of an overall scheme are of interest and worthwhile.

Regards, Matthew

[Nzoldun]

There is an extremely good series of three articles in the UK magazine "Model Engineers Workshop", issues 102, 103 and 104, in 2005, which cover the basics of the choice of steppers, sized to match the expected loads. Although the articles are expressly written around the conversion of an X3, I am using them as the basis for converting my GL-45 Mill-Drill (Similar to X3 but about twice the size) If you are unable to source from your end, I could scan and e-mail the relevant bits.

Hope this helps!
My e-mail is [email protected]

[mattinker]

Hi,

I would be very interested in anything about choosing steppers. I've been using a spring balance (fish scales, no not the things you scrape of fish before cooking! the things you use to weigh them!) and a piece of string wound around either the lead-screw (I used a 100 tooth change gear otherwise it was off the scale!) or the cross-slide screw, you pull on the balance and it will read out ounces or grams of pull for a given diameter. This is a start, but not enough! So any additional information would be use full. I have no idea how to begin trying to get the three back numbers.

Thanks Matthew

There is an extremely good series of three articles in the UK magazine "Model Engineers Workshop", issues 102, 103 and 104, in 2005, which cover the basics of the choice of steppers, sized to match the expected loads. Although the articles are expressly written around the conversion of an X3, I am using them as the basis for converting my GL-45 Mill-Drill (Similar to X3 but about twice the size) If you are unable to source from your end, I could scan and e-mail the relevant bits.

Hope this helps!
My e-mail is [email protected]