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  1. #11
    Quote Originally Posted by Clive S View Post
    Just for clarity do you mean carve or cut with plasma by rotating the cylinder?
    very sorry...i would like to cut with the plasma.......................

  2. #12
    Quote Originally Posted by warwick View Post
    very sorry...i would like to cut with the plasma.......................
    Well in that case I think it would be fine.
    ..Clive
    The more you know, The better you know, How little you know

  3. #13
    There's better way to do this than having wide gantry making for large foot print if only want to cut cylinders which are less than width of machine.?

    Make the Top rails longer so gantry over hangs the end. I do this with routers so 4th axis can be added or Panels cut on there ends. IE: Hindges or Dovetails etc. Take less space and easy to do.

  4. #14
    Quote Originally Posted by JAZZCNC View Post
    There's better way to do this than having wide gantry making for large foot print if only want to cut cylinders which are less than width of machine.?

    Make the Top rails longer so gantry over hangs the end. I do this with routers so 4th axis can be added or Panels cut on there ends. IE: Hindges or Dovetails etc. Take less space and easy to do.
    that was my initial thinking,but the y axis is 3m long and the longest rails i could find were the 16mm supported rail that are 3.2m ...i have 2m of r&p spare and some long lengths supported rail so i figured the only option was to side mount.....i would like to be able to get the x axis gantry completely out of the way so i can load an 8x4 sheets on my own with out to much worry of damage to the machine......the size of the machine and space isnt an issue where we are for now......id like to have an engraver along side the plasma torch so i can scribe parts for folding and numbering etc.is this going to be possible???

  5. #15
    Marking and scribing etc will be no problem provided you have enough resolution. What kind of ratio and pinion size are you thinking to use.

  6. #16
    Quote Originally Posted by JAZZCNC View Post
    Marking and scribing etc will be no problem provided you have enough resolution. What kind of ratio and pinion size are you thinking to use.
    think the pinions are 20t and was hoping to use a 60t for 3/1 gearing....as for resolution i havent a clue as of yet..have just been taking advice from a very nice fella locally and building it in stages..right at the start of my craving for cnc i was totally over whelmed so now im just doing stages and moving to the next part of the build....

  7. #17
    Quote Originally Posted by warwick View Post
    think the pinions are 20t and was hoping to use a 60t for 3/1 gearing....as for resolution i havent a clue as of yet..have just been taking advice from a very nice fella locally and building it in stages..right at the start of my craving for cnc i was totally over whelmed so now im just doing stages and moving to the next part of the build....
    Ok well lets work it out for you. I'll assume Mod1 pinion. So the Diametric pitch (basicly diameter) will be 20mm because Mod1 =1mm times the #teeth.
    Apply \pi and the affective pitch is 62.832mm which is huge and why you need ratio. So then divided by the ratio to give pitch of 20.95mm per rev.

    Working on motors full step value then Full step resolution will be 20.95/200=0.104mm per Step.

    Now this is the smallest amount you'll move if the drives where set to Full step. Which you won't want to do otherwsie they'll run like bag of marbles. But take it thats your worst case scenerio.
    In real use you'll have the drives set to something like 800 or 1600 micro steps. Going above this is pretty much wasted and just stress the system for very little gain.

    So Best case will 20.95 / 1600 = 0.013mm thou don't get excited because you won't get that in reality but will fall some where between 0.1 and 0.01 which i'm sure you'll be pleased with.

    But again don't too giddy because thats only resolution and it means nothing in accuracy terms if the machine bends like banana.!!

    Now you'll want to know the speed you can expect.? So lets work on 900rpm which is realistic figure for stepper using R&P provided run on enough volts. (60-70v)

    20.95mm x 900rpm = 18855mm/min or 18.85mtr/min which is just about spot on for decent sized plasma machine.! . . . . Well Done . .Lol

    Edit: Opp's I forgot the ratio.!!
    So it's 20.95 x (900/3) = 6285mm/min or 6.3mtr/min which is still ok for cutting but on the slow side for rapids on large machine.
    In practise provided all is setup well and correct voltages etc I'd estimate 8mtr/min or more will be quite do-able.
    Last edited by JAZZCNC; 18-11-2016 at 08:11 PM.

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  9. #18
    HELP!!!!!!
    im just coming to the stage to order my pulleys for reduction on the x and y axis.......dean kindly worked out the 3-1 reduction with mod1 rack and pinion.........
    iv actualy used mod1.5 with a 24t pinion spur gear..............if i order t5 60 tooth and 15 tooth will this be ok to get me back near the mod1 calculation in the above post???

  10. #19
    It's easy to work out if you know the Dp (Diametric pitch) of the pinion which for 24T Mod1.5 is 36mm. Then times this by pi to give the Linear pitch before ratio which in this case is 113mm.

    Now you can work out ratio you'll need to give the desired linear Pitch. 15t/60t will give 4:1 ratio so 113 / 4 = 28.25mm. For Plasma this would work ok.

    Ps: Word of warning before ordering make sure 15t pulley will fit your motor shaft because there won't be lot of pulley left for grub screws etc after it's bored.
    Last edited by JAZZCNC; 28-11-2016 at 04:30 PM.

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  12. #20
    hi, just a few questions. is 100mm deep enough for a water table? and is there a prefered spacing for the slats??

    many thanks

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