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IndustryArena Forum > MetalWorking Machines > Benchtop Machines > Rocky the Benchman with Homebrew ATC
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  1. #1
    Join Date
    Feb 2006
    Posts
    42

    Rocky the Benchman with Homebrew ATC

    I'm converting (yet another) Benchan 4000 VMC for use with Mach3, and I'm exploring the possibility of adding some type of tool changer. (The donor came with a rotary 4th axis, but no ATC.)

    My puzzle for the day is, how does the factory-ATC lock the spindle in place while loosening & tightening the drawbar? The donor has a hole in the left side of the spindle carriage, apparently for jamming in a bolt or some other object, to catch a hole drilled into the side of the spindle itself. I can imagine adding an over-center spring mechanism to insert (and withdraw) the pin, then giving the spindle a quick blip of power to rotate the shaft until the pin catches, but this seems ... inelegant.

    Is there anybody out there using a Benchman or Intelitek machine with factory ATC? Is there a clutch, or brake, or ???

    Thanks for your time.

  2. #2

    Re: Rocky the Benchman with Homebrew ATC

    The tool holder is pulled into the spindle, this is done via many methods, but with an ATC it's not usually threads (there are exceptions, Novakon being one). What you need to look up is how power drawbars work. There are a variety of methods.

  3. #3
    Join Date
    Feb 2006
    Posts
    42

    Re: Rocky the Benchman with Homebrew ATC

    Thanks for the insight, CMT!

    I've seem some interesting videos on the Tormach 3-stage power drawbar, and I've read through the manual for the thing. Seems very nicely engineered, arguably worth the $1300 as an accessory when you are shopping for a $15K+ mill. Unfortunately, I'm coming at this project from a low-budget perspective, and I'm hoping to find a solution based on an inexpensive air tool. HF impact wrench, or their pneumatic pop riveter. Lots of impact-wrench based devices those out there for Bridgeport mills.

    It's a pity that the Benchman is such a closed-box system, in all regards. FleaBay and Google images show me dark and gloomy photos of systems with rack-type tool changers, but I'm not finding much that shows me how they work mechanically. Online comments indicate that Intelitek has ZERO interest in providing drawings or manuals that describe the necessary details. I'm hoping that there's someone out there with a Benchman, ProLIGHT, or Intelitek machine in their shop who can shed a little light on this puzzle.

    =ALL= suggestions and insights are greatly appreciated,

  4. #4

    Re: Rocky the Benchman with Homebrew ATC

    I know absolutely zero about the specific technical specifications of the Benchman mill. So I can't help there. That said, I googled it, and it looks pretty cool.

    What type of drawbar does the machine use? What spindle taper?

    A HF impact gun method isn't a bad one, but I don't think it's really practical with an ATC. It's better suited to just using it as a power drawbar of sorts. There are number of reasons for that, but the most obvious one is that it's overly complex. Doing a spring actuated preload system and air actuated release means you effectively have one thing to control, that being the air cylinder. With a impact wrench, you know control the wrench in two directions, but you also have to hold the spindle, whether that's with a brake or with the spindle motor, it's still an entire different problem. So in reality, the budget option likely isn't the impact wrench system, not for an ATC anyways. I'm not saying it couldn't be done, the wrench could be controlled with a stepper, but you'd still have to write the macro's, figure out how to assure it get's torqued properly every time, how does the spindle run with a impact wrench permanently fixed to the spindle? It's a problem and there are cheaper and more simple ways of going about it.

    FYI, i bought a three stage 3" air cylinder for $160 on ebay. I already own a compressor, I own a milling machine to make the parts to mount the cylinder, all I have to do is setup a solenoid operated air valve, build a simple drawbar, and I'll have a power draw bar.

  5. #5
    Join Date
    Jan 2018
    Posts
    1516

    Re: Rocky the Benchman with Homebrew ATC

    I came across this design for a power drawbar.
    https://www.youtube.com/watch?v=Wr6S3SSgtTU
    I reckon you could get the air ram, valve & belleville's for not much money, make the mounting kit parts yourself. I reckon you'd be around the £100-£120 mark myself with this.

    For example:
    https://www.ebay.co.uk/itm/5pcs-DIN6...OUsdfKTKEoozrQ
    https://www.ebay.co.uk/itm/1-4-Doubl...n/323512588123
    https://www.ebay.co.uk/itm/40mm-Bore...kAAOSwSc5c56Xl
    Unsure if they're correct sizes needed but you get the idea

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