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  1. #1
    Join Date
    Jun 2008
    Posts
    56

    CHESTER MODEL B 3 IN 1 BOTCH JOB

    I thought I would post some pics of my build, I started at the weekend. I am going to try to do the job at minimal cost and time. Budget is below £200, I hope to finish first version in a month, then make improvements from there.

    I am a beginner, only metalworking as hobby for a year and most of my stuff is a botch (which I blame on the awful machine ))) .

    I hope to post some pics, video, and maybe some text about my ideas and what I have done.

    Don't expect too much, I am trying for an evolutionary approach, botch then improve.

    Very quickly what I did this weekend:

    1) wired up and installed variable frequency inverter for main motor.
    2) made stepper mounting brackets for X, Y, and rotary table from 100x50x5mm alloy extrusion.
    3) played with linux cnc emc ubuntu distribution.
    4) tested pacsci stepper that I got from ebay.
    5) tested some other stepper drivers.
    6) butchered all the atx PSUs I have lying around (have heard switching psus are not good for stepper drivers but thought I'd give it a try anyway).
    7) mounted most of the PSUs in an atx case.
    8) thought about how to remove backlash in the lathe
    9) butcher some HTD pulleys from a HP laserjet to connect steppers to lead screws
    10) took loads of pictures and some video

    May post some video when I get time though its not good so I may not bother.







  2. #2
    Join Date
    Jun 2008
    Posts
    56

    Some more pictures


    ATX pc case with 2 AT and 2 ATX PSUs stacked to give 48volt supply for stepper drivers, I had these lying around scrap.


    X axis mounted

    X axis mounted from above (this is just test fit further work needs to be done)

    X axis and the rotary table mount on the bench.
    X axis mount was made by hand (i.e. not on the lathe or mill) in about 30mins, cut section of alloy extrusion about 200mm long on band saw, mark out and centre punch mounting hole positions, used battery hand drill to drill 9 holes. It just seemed easier to do by hand than setup on the lathe as it would not fit in the vice.

    Rotary table stepper mount was machined on the mill, as the mount holes needed to be fairly accurate, took about hour and a half (though probably could do in 45mins second time, as I keep having to change drill bits).

    The drive pulleys for X axis came from a laserjet printer and were filed down.
    I may go to davall or RS for some proper HTD pulleys in the future depending how the scrap ones workout.

    The drive belt came from ebay for £1.59, HTD M3 10mm width belt

    The steppers came from supplier who gave best price they are old stock size 34 2Amp 3Volts unipolar and work out at £8 each (had to buy case of 6)

    The drivers I got from ebay 2 (2.5Amp 45volt) for £17(8.50 each), another 1 (3.5Amp 55Volt) for £18, and a pacsci 34 long series motor and driver (with 240volt ac supply) for £45.

    I feel I paid too much for most of the stuff I got from ebay (there always seem to be idiots with too much money bidding against me!). Most of the stuff is used and probably found by someone on a rubbish dump.

  3. #3
    Join Date
    Jun 2008
    Posts
    56

    testing pacsci stepper driver

    [ame="http://youtube.com/watch?v=AGnKpAKjaOA"]YouTube - stepper motor test[/ame]

  4. #4
    Join Date
    Jun 2008
    Posts
    56

    how to run a serial terminal link in linux cnc emc ubuntu distribution

    I had a little trouble working out how to access the serial terminal on the linux cnc live distribution as I had only ever used minicom and that was not available.
    So after a few googles I found some other serial terminal comms programs, went back to the cnc pc and tried each on the list. The only serial terminal prog that is available on the emc distro (as far as I know) is "screen"

    screen /dev/ttyS1 9600

    (access the ttyS1 at 9600 baud)

    So just a quick vid showing how I accessed the pacsci 5445 Microstep Indexer/Drive via the serial terminal in linuxcnc emc ubuntu live cd distro.


    More videos available once I have time to upload them to youtube.

    I think I have some vids of:

    a)points on the lathe mill that are total **** and the manufacturers should be embarassed of
    b)wiring a VFD to a three phase motor
    c)general workshop
    d)rotary table stepper mount
    e)?????

    Have not looked at it all yet and most is probably poor quality (I always seem to end with two option doing a poor quality job or never having time to finish the job)


    [ame="http://youtube.com/watch?v=oddZfUhk-DA"]YouTube - screen tty to stepper motor driver[/ame]

  5. #5
    Join Date
    Jun 2008
    Posts
    56

    rotary table mount

    [ame="http://www.youtube.com/watch?v=VU0EUd_JKtY"]YouTube - stepper mount for rotary table[/ame]

  6. #6
    Join Date
    Jun 2008
    Posts
    56

    This weekend I have been mostly botching.....

    So total fiasco this weekend I was hopeing to get a couple of axes test fitted and run the motors using linux cnc.

    But after a quick look at the system I decided the original plan was a bad idea, and felt it would be more productive to blow four channels of my parallel post.

    So to achive the new goal I had to carefully drop a screw driver on to the stepper drivers so that the 36v stepper supply shorted to the step and direction lines to the parallel port.


    Anyways I found out a little about linuxcnc axis gui and setting up the parallel interface.

    Made a pretty much complete assembly of the Y axis (mounting bracket, motor, pulleys, belt, and tensioner).

    made some changes to X axis for longer belt as I realised I did not have suitable M3 HTD pulley for fitting the leadscrew so used a smaller belt.

    Made a 5.25" drivebay bracket for two stepper drivers and alterations to the wiring.

    Tested the stacked PC power supplys and found that they did not work..... FFFFF.

    Machined pulley for X axis.

    Some pictures below....


    X axis bracket

    X axis bracket

    X axis bracket

    Y axis bracket almost complete

    Y axis bracket almost complete closer

    Y axis different angle

    the steppers, 5.25" drivebay bracket, and wires, foil wrapped motor wire to cut EMI noise.

    box of scrap drive components

    tapping holes that were drilled for stepper mounting bracket.

    offering up the stepper bracket to mark holes to drill.






    May add some more latter.

    I get the feeling I take too many photos though.

  7. #7
    Join Date
    Jan 2008
    Posts
    458
    I used to read a car magazine printed in England. Whenever they found some long lost classic, the article invariably began with " It was pulled from a garden shed which had long since collapsed around it"

  8. #8
    Join Date
    Jun 2008
    Posts
    56
    Quote Originally Posted by smallblock View Post
    I used to read a car magazine printed in England. Whenever they found some long lost classic, the article invariably began with " It was pulled from a garden shed which had long since collapsed around it"
    I think england may be a collapsed shed but there are still a few old classics in it?.

    I knew an old stegasaurus that worked at the company, used to go round taking pictures of that sort of thing (think it was for practical classics?, maybe not the same magazine though).

  9. #9
    Join Date
    Jun 2008
    Posts
    56

    Weekend number 3, progress is slowing.......

    I have made very little progress as I am considering how to get a decent power supply (that will run possibly 6 axes at 3.5A 40V per axis) with very very little money.

    I made a few more vids and started trying to edit down the larger ones so I can post them.

    Adjusted made minor mods and tested the X axis as shown in the vid below:

    [ame="http://www.youtube.com/watch?v=_PiI-it32Po"]YouTube - cnc axis test max speed 400mmpm[/ame]

    Will maybe post another vid showing the stepper stalling (test showed max speed of about 400mm per minute), making and assembling the stepper mounting...

    Few more pics taken, but I am still behind in posting what has been done as I have not shown a lot of work that was done last weekend. Some pics and posts are not going to be in chronological order.

    Considered what the plan for future work will be:

    1)Get all steppers and axes assembled and tested.
    2)Workout power supply system
    3)Look at covers and guards to ways/slides and leadscrews.
    4)dismantle and clean all components
    5)Final reassembly and fitting fixing backlash problems.


    I hopefully have found a way to fix any backlash problems in the leadscrews with very low expense and no machining or special tools. But I think backlash adjustment will be the last thing to do.

    Will post more when I get a round to it.

  10. #10
    Join Date
    Jun 2008
    Posts
    56

    video of test stepper stalling

    [ame="http://www.youtube.com/watch?v=Fcvbn8DAZAI"]YouTube - cnc axis test max speed 400mmpm[/ame]

  11. #11
    Join Date
    Jun 2008
    Posts
    56

    wiring an imo vfd inverter to three phase motor

    Just edited this video, was actually done a few weeks back.

    [ame="http://www.youtube.com/watch?v=L2qfGe6H8d0"]YouTube - imo inverter wiring for emc linux cnc lathe conversion[/ame]

    I get the feeling there will be no work done this weekend as I'm feeling ill, but that should give me some time to edit and post old videos.

  12. #12
    Join Date
    Jun 2008
    Posts
    56

    rotary table fitting of stepper motor

    [ame="http://www.youtube.com/watch?v=aQQoy905ej0"]YouTube - rotary table, cnc, stepper motor, mounting bracket, fitting[/ame]

  13. #13
    Join Date
    Jun 2008
    Posts
    56
    [ame="http://www.youtube.com/watch?v=fuwjUZKGCGY"]YouTube - rotary table, cnc, stepper motor, mounting bracket, fitting[/ame]

  14. #14
    Join Date
    Jun 2008
    Posts
    56

    Total fuct schedule!!!!!

    Well it seems I have succumbed to the usual diy cnc problem of everything grinding to a halt as the true scale of effort required to complete a machine is realised.

    I have probably spent 50 hours now working on the machine (probably 30 hands on grease and grime work and 20 thinking researching and working out how to solve problems). Its a month since I started, originally hoping to have a working first version running this weekend.

    I think it would have been a possibility if not for:

    1) power supply (hoped to make a stacked set of scrap atx pc psu, but the psus were scrapped for a reason, they were failing probably due to undervoltage shutdown circuits which means they run for a while then totally shutdown and need to be reinitialised, I may try using some caps to smooth and store power but I now think I will have to bit the bullet and buy something that works!!!)

    2) blew the parallel port on the PC I was testing the steppers with and I am so skint I felt I could only afford a usb parallel converter (on ebay a £3), now i have discovered the linux cnc emc2 does not support and does not want to support these usb devices. So I will have to pay out £9 for a pci parallel card from ebay. I may be developing some interface to control the system by usb parallel and have wasted some time looking into this??

    3) The Z axis is a major problem in terms of getting accuracy and I have had to look into some work around which means quite a lot of work.

    4) lazyness, illness, and lack of money

    Basically the X and Y axes are done and initial tests have been done of driving them, the rotary table has been mostly completed though I think I want to change some things about it.

    So I am now waiting to get a power supply and a pci parallel card. And have to workout the Z axis so that it will work to my required accuracy, and add some bracing to improve rigidity of the mill head.

    Work on the Z axis may get started tomorrow. I now think probably another two or three weekends to get all the axes running (if I get the parts and no unforseen problems occur). Then another week or two of tuning tweeking and setting up to get something working to a reasonable degree (0.2mm accuracy is my guesstimate).

    I still have loads of video and photos of work on the machine which I have not posted yet, may get round to posting if I can edit it and find something worth saying about what I have done?

  15. #15
    Join Date
    Dec 2007
    Posts
    413
    Hope this doesn't throw too much water on your campfire, but what do you expect to have after all is done? That machine would be passable as a lathe and could do some basic stuff under cnc, but as a mill it will be essentially worthless- You will never get around the issue of backlash in the Z axis because of its basic design and the milling envelope is practically zero. Adding to that is the lack of rigidity in the mill head hanging on that up and down adjuster. However, if its just a project to see if you can build a cnc out of miscellaneous parts, it may be worth the time and money.

  16. #16
    Join Date
    Jun 2008
    Posts
    56

    What I hope to achieve?

    Well I hope to achieve a cnc machine that I can use and improve upon.

    I hope to build with what I have available, as I cannot afford to spend out on a new machine and don't have space for more machines anyway.

    I hope to learn about cnc at minimal cost.

    I hope create something that makes the machine that I originally had easier, quicker, and more flexible to use.

    Its really a hobby and pastime.

    As far as the quality of the mill is concerned, it is when it comes from the factory appalling. That said I think I will be able to improve it with some work and parts that I have lying around. This afternoon I stripped the mill head and started installing a dovetail slideways for the Z axis which I hope will give the required feed accuracy, and some bracing angle iron for the mill head should improve rigidity. I have attached photo of the stripped down mill head (the dovetail slide I am going to bolt on is on the bottom right of photo).

    The lathe/mill was originally £500 new (as far as I could find the cheapest new machine of this size available in this country??), the parts for cnc conversion so far total roughly £150 (a rough guess).

    I am a newbie to engineering and cnc (just under a year since I first used the mill/lathe). I really don't know ****e, but as far as I could tell the stuff I got is pretty crap but at the same time is probably good value for money??.

    If I consider it a learning experience its probably good value??.

    If I consider it a hobby its probably good value?.

    If I consider it as a commercial enterprise I have no idea, probably its not cost effective.

    I have seen people spend 3-4 times the total price of this project on a model steam engine hobby project, I don't know really what is achieved, seems i'm just filling in the time between birth and death with something that interests me?. There are many other things I desire or find more interesting, but I am constrained by budget, ability, time, and imagination.

    I hope the mill should be comparable with an X3 (6"x12" table travel, MT3 spindle) once finished.

    I am probably wrong but thought it was worth a try and an interesting project.

    Maybe I should have asked in forums what others recommended for a budget of £1000 for a mill and lathe???
    Attached Thumbnails Attached Thumbnails P1100123a.jpg  

  17. #17
    Join Date
    Sep 2006
    Posts
    607
    Mung, I think you are doing a great job. If you spend some time figuring out the weak points of the machine, and learn how to avoid them or remove them, you might end up with a pretty good machine. I would even do that same conversion if I had the chance. Though I would use higher quality parts. Keep up the good job.

  18. #18
    Join Date
    Jul 2008
    Posts
    3

    Keep Going

    Hi, Keep going at least you have started building i am still in the planning/lurking/looking stage. Can you tell me where you got the stepper motors please. The cost of CNC stuff in this country is stupid!!!
    Thanks

  19. #19
    Join Date
    Jun 2008
    Posts
    56

    Not much done but I thought I would update

    Well I have been a bit put back as I have been waiting to find a decent power supply, but it looks as though I should get one by this weekend?. Of course I am only guessing that it will be a decent PSU, I should know by saturday once i have tested it.

    I ordered one of these:

    http://cgi.ebay.co.uk/NEW-UNUSED-50V...QQcmdZViewItem

    I have done some other stuff since last post:

    1) stripped down and cleaned pretty much the whole lathe and mill head.
    2) made up some dovetail mounts for the new z axis mill slide.
    3) drilled and tapped holes for dovetail mounts.
    4) made and fitted some ways covers.
    5) started making stepper mount for new z axis.
    6) though about wiring
    7) thought about writing a device driver for usb parallel port for linux emc2

    I hope to get most stuff partially finished this weekend, and the first test next weekend (of course something is bound to cause problems so probably 3-4 weekends to get first test?)


    CNCconfused asked about where I got steppers from, i'm afraid I have lost the details but basically I saw some on ebay that my bid lost and asked the seller if he had anything else available that was cheap. I was told the steppers were slightly off spec but would work OK. Basically I have spent the last year lurking on ebay waiting for bargains, and sometimes asking sellers if they have anything else on auctions I lose.
    I think arc euro are probably the cheapest for steppers in UK if you don't want to waste hours searching ebay (let me know if there is anywhere cheaper).
    Attached Thumbnails Attached Thumbnails P1100414_1.jpg  

  20. #20
    Join Date
    Jun 2008
    Posts
    56

    Forgot to mention I made an experimental antibacklash nut

    Yes missed mentioning in the last post the antibacklash nut I made.

    Made the nut from a low temperature thermoplastic called polymorph (I did a little video showing how I formed it that I may upload?). Added a spring that I found in the scrap box and forced the thing together. Don't know if it works, but I will get round to testing it at some point.

    Basically the hardest part was getting the nut loose enough so that it did not cause too much friction, which I did by reducing the number of threads from 6 to 4 and by heating the leadscrew to soften the thermoplastic and waggling it gently to enlarge the threaded hole size.


    The result is shown below:
    Attached Thumbnails Attached Thumbnails P1100365_1.jpg  

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