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  1. #1
    Heres some pictures of a prototype machine I built last year which I am re-developing and building again.












    The cutting head in the picture is just a mock up so ignore that bit, what I want to do is make the 2 axis run off a plc or simular. It is basically a lathe to reduce the diameter of the tyre. It needs to take around 4mm off in .5mm cuts.
    Ive found a company on ebay that sells the rails, bearings and ballscrew/nuts at a reasonable price, can anybody recomend a uk company thats as cheap?
    The main issue I need help with is the plc/cnc side of it. Ive been working cnc's for about 14 years now, but I havent got a clue how that side of it works? I already have orders for machines and need to get cracking asap, and bring it in as cheap as possible.
    So any ideas are very welcome.
    Thanks
    Jason
    www.jpcnc.co.uk
    Last edited by jpcnc; 26-07-2010 at 09:03 PM.

  2. #2
    Aside from your quest,isn't it illegal to reduce a tyres wall thickness and retread it if the thickness is reduced?

  3. #3
    Im not re-treading it, its for track tyres, they come new with 8mm of tread but for optimum performance track-dayers / racers will drive hard in practice to reduce them to around 4mm, but they can easily wreck the tyre in the process

  4. #4
    Doesthis work? ie I would have thought it would be far to hard to skim rubber without it becoming rough in the process.

    There are two places for cheap drivers and motors and cnc components and thats.......

    Zapp Automation who's linkyou find here on the site.
    The other is ArcEuro Trade,however this site only sells Steppers and their drivers but are cheap.

    I wouldn't buy off ebay for mechanics of the build as I thought it was cheap once,its not unless you mean China?

  5. #5
    Tom's Avatar
    Lives in Nottingham, United Kingdom. Last Activity: 11-11-2023 Has been a member for 9-10 years. Has a total post count of 176. Referred 1 members to the community.
    The machine looks good.

    2 axes of motion, plus a motor driving the tyre.
    For linear guides you could probably look up the IGUS linear guides. Cheap, and drylin W especially has little play with the low forces you'll be using to cut.
    Drylin N http://www.igus.co.uk/wpck/default.aspx?pagenr=1969
    Drylin W http://www.igus.co.uk/wpck/default.aspx?pagenr=1994

    The more interesting part of the project is the need for the machines to be operated by unskilled people (by that I mean people that didn't build the machine). A PC running mach3 is unlikely to be robust enough.

    You'll need:
    1) Safety (guards, big red e-stop buttons, etc)
    2) A black box to store the program, give step and direction commands to the motor drives, and interpret operator button pushes (go, stop, jog cutter, etc).
    3) Some drives to drive the motors.
    4) Motors (probably steppers).
    5) Power supply.

    1) You can do.
    2) This is the most interesting bit.
    A Siemens LOGO PLC is too simple (slow) for your needs.
    http://www.automation.siemens.com/mc...s/Default.aspx
    But this Galil PLC may be over spec (still only 300USD tho)
    http://www.galilmc.com/products/rio-47xxx.php
    You can find a PLC somewhere between the two. The main constraints are probably the amount of I/O (for buttons, etc), and the need to find one fast enough to send step pulses for the motor drives.
    3) Easy once you know what motor sizes you need.
    4) Easy once you have an idea of the cutting forces involved.
    5) Easy once you know what boxes you've bought to do all the above.

    Hope it helps. Basically you need a PLC. lol Give me a shout if you need a hand getting something up and running.

  6. For something this simple a PIC based box, like Steve's rotary controller with different firmware would be the answer.... simple display with ability to program in the number of cuts and depth and some constants such as tyre acceleration etc...

  7. #7
    Given that you will always have a know centre for the wheel a simple touch off to catch the diameter would mean your depth of cut will be accurate with Irvings idea also?
    If the nagging gets really bad......Get a bigger shed:naughty:

  8. yes, i was thinking one of those cheap digital angle protractors would work as an arm to measure the outer diameter, easy enough to read the angle and convert to a radius as all the lengths are known and its just a case of doing the math. You could put an index pulse on the tyre spindle to measure speed directly...

  9. #9
    Ross77's Avatar
    Lives in Devon, United Kingdom. Last Activity: 2 Weeks Ago Has been a member for 9-10 years. Has a total post count of 759. Received thanks 27 times, giving thanks to others 52 times.
    Sticking with the PIC idea couldnt you just have limit switches at the end of each side? you could even ditch the cnc bit and just have a mechanical advance at the end of each travel, simple

  10. #10
    No need to advance into the CNC side,a wide belt sander will alleviate all the headache. :-)

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