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  1. #71
    [quote]
    I can only imagine the ruin it's doing to those dainty fingers...
    [/QUOTE

    The middle one is very dainty, do you want to see it......

    Just ordered some delrin as a last attempt to salvage the leadscrews. Think I've got a worn 10mm lead, ballscrew kicking around that came with a motor I bought. Probably would be easier to rebuild that with new balls than mess around with delrin and leadscrews......

  2. #72
    More questions if I may.........

    Made the 2 delrin nuts no probs, mounted one each side of the connector block (what was the original nut that I trashed).

    The problem I have is that although the backlash is almost gone the resultant friction caused is making the screw difficult to turn. Theres still a bit of alignment to do which will hopfully reduce it a bit and Ive also got the gibbs set to tight. However I noticed that the last bit of backlash/play is actually the delrin flexing. Is this correct or have I made a mistake some where?

    Once the alignment and gibbs are set correctly there should be no play under no load conditions.... But I cant help think that under load this problem will re-appeer and cause problems.

    Has anyone else experienced problems between static/no load measurements and actual machining measurements? or am I worring about nothing

    I've looked around on the net and some people seem to swear by leadscrews and delrin and some only use ballsrews...
    From what I can see the only way to reduce flex in the nut is to use a metal one with delrin as the antibacklash, but surley this will only "smooth" out the play as ultimately the delrin will have to compress for the metal nut to make contact with the screw during change of direction to increase the strength......

    Hope this makes sense. pretty much finished the x axis motor mounts so changing to ballscrews will be a major redesign.

    I cant make up my mind If an accurrate small small mill (ie ball screws) will still be usefull after its built the bigger machine....

  3. and Ive also got the gibbs set to tight.
    Just like the nut, there should be a tiny amount of play in the gibs (you can always tweak it once it's up an running, so leave them a little slack). If they're too tight it'll cause you as many problems as too loose.

    Does the table slide freely now? There'll be an initial stiction (about 40lbs worth on my drill/mill) but, once moving it should move easily.

  4. #74
    Just like the nut, there should be a tiny amount of play in the gibs (you can always tweak it once it's up an running, so leave them a little slack). If they're too tight it'll cause you as many problems as too loose.

    Does the table slide freely now? There'll be an initial stiction (about 40lbs worth on my drill/mill) but, once moving it should move easily.
    Thanks Bill, that was the advice I was after. Ive found that if I use both hands then the tables moves easily once the inertia is bult up, but this is too tight for the screw. I have readjusted it so that if i try to push it with a finger it wont budge, bit more force and it flys to the other end. with it set like this there is a small amount of side ways movement but I can only see it when there is oil on the ways.

    Maybe I will stick with the leads and see how it performs with the motors. As much as I want to get it finnished I also want to get it right. Its been fun learning on this tho...I seem to only be able to learn when I've tried it and F**ked it up for myself:heehee:

  5. #75
    Quote Originally Posted by Ross77 View Post
    I seem to only be able to learn when I've tried it and F**ked it up for myself:heehee:
    Best way of learning.....!

    If I made a list of all the things that I have fucked up I would need a lot of paper, 2 catogories, minor and major f**k ups. I am pleased to say that as you get older you don't add as many things to the list.

    My best major f**k up was ripping the cross slide clean off my newish CNC lathe because I did not set the chuck pressure high enough, the part came out of the jaws when I was screw cutting and got jammed between the chuck jaws and the toolholder at about 1000rpm. I was standing right next to it when it happened and I can tell you it went with a bit of a bang, had to add a new pair of pants to the repair bill!

    Repair cost - 8,000 - thank god for insurance!

  6. #76
    Quote Originally Posted by HiltonSteve View Post
    I am pleased to say that as you get older you don't add as many things to the list.

    That's something to look forward to then :heehee:

  7. #77
    Nice to know Im not the only one then

    readjusted the antibacklash nut alignment and its much better now, so it seems perseverance is key. Spent ages the other nite trying to work out why it was binding, next day I spotted the problem in 5 mins.

    Thanks again for all the advice. Its ok reading from a book or off the net, but being able to ask specific questions when you get stuck is brilliant. Definetly wouldnt have got this far on my own.......

  8. #78
    Had to put this on hold for a while and then when I got started again last week I crushed my finger whilst honing the ways.........

    So decided to move on to the electrical side and sort out the stepper controller, after hours of trying to bypass the optos and feed the chips direct the L6203's (H bridge) decided to put on an impressive firework display.... @ 40V these things sure go bang.:whistling:

    So all in all things arnt going to well.

    Any body make curcuit boards for L297 + 2x L6203's with diode protection so I can transfer the remaining parts over to a less complicated board?

    After a lot of serching on the web I think I've found out why I couldnt get it to work, There is an enable pin on the L297 that has to logic high! Am I right in thinking that will stop the chip from working?

    Ive got another board to try, but not to keen to fry that one as well

  9. #79
    I have 2 dead boards and 2 good ones....all to go in the bin and good riddance to the worst 700 I ever spent.
    You dont rate these as drivers then? Your not throwing away the good ones are you. :whistling:

    Just want to get this thing running. Nearly finnished the x-y axis
    Just the spindle, motor and z axisto do....

  10. #80
    Never put them in the bin pass them on..........Ross check for signal on the output of the Opto's if none is found when you fire the circuit up it maybe because they require some voltage. I've built a few opto isolated circuits for interfaces to my radios, every time they do not work is because they need power to one of the pins??? check the spec of the ic you are using with the manufacturers specs
    If the nagging gets really bad......Get a bigger shed:naughty:

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