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What you did today/shop-made tool/gloat combo

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  • What you did today/shop-made tool/gloat combo

    Threw this together over the past couple months. It's intended to do isolation milling of PCBs. I piddle in electronics some and this should be handy. It could also mill some small parts in softer materials and of course do engraving.



    Machined almost all the parts from stuff pulled from the "scrap" pile. The bought stuff comes in at around $100 (driver board, power supply, various hardware). The linear bearings and steppers were also in my spare parts pile, scavenged from stuff which was pulled out of service.

    The table is just flat because for what I intend to use it for I'll either be using CA glue/acetone or double-sided tape.
    Last edited by tyrone shewlaces; 02-27-2011, 04:08 PM.

  • #2
    Very impressive work.

    I can't tell which motor runs which axis.

    Is the motor on the left pillar for the z-axis with a keyed shaft, or is it for side-to-side using a leadscrew ? And I take it the fore-aft motor is hidden from the camera.
    Richard

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    • #3
      Yea it's a gantry style.
      Top of left post is the X-axis motor. Y-axis is way low and behind the table, but you can see the lead screw sticking out from under the front of the table (just 5/16-18 threaded rod throughout). Z-axis motor is mounted on the back of the block which slides L-R on the gantry rods - belt and pulley to transfer motion to the Z-slide on front. I hid it back there to keep things compact.

      Working envelope is ~ 8"x8" X/Y and 3" Z



      Last edited by tyrone shewlaces; 02-27-2011, 04:40 PM.

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      • #4
        That's a neat set up, any plans to scale it up to do larger projects?

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        • #5
          If you stretched the design a bit T/S, you could process 6' x 3' sheets. Might have to use 3/8" leadscrews though.

          Regards Ian.
          You might not like what I say,but that doesn't mean I'm wrong.

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          • #6
            That's a neat little thing.
            I bought a Techno Isel router a while ago with no motors or electronics, been robbed to keep other going.
            Real fun machine, I'd like to spend more time on this but other things keep getting in the way.
            .

            Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



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            • #7
              Cool,I like it! One thing for sure you shouldn't have any trouble with those columns flexing under load
              I just need one more tool,just one!

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              • #8
                Any pics of the parts yet?

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                • #9
                  Looks to be perfect size for average PCB machine, certainly anything short of major motherboard construction.

                  What size steppers, and which driver did you choose?

                  Are the lead screws driven 1:1 off the steppers or are they geared down somewhat?

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                  • #10
                    Nice job! I've long had my eye on making one of those.
                    What are you using for the stepper drivers and software?

                    Thanks for posting!

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                    • #11
                      I'll try to give answers.

                      Did this last night. Have to tweak the generating of the code - traces ended up being too narrow so must be cutting wider than it's supposed to. Not a big surprise. It will take a little T&E to work out the method. Isolation was done in three passes (6 between adjacent traces) so traces can definitely widened up with a simple parameter adjustment in the PCB-GCODE step (see below).



                      Machine can obviously drill the holes too, but I didn't need to test that as much as the trace milling, so maybe I'll show that a little later.

                      Stepper driver - about $33 + shipping from eBay:
                      http://cgi.ebay.com/ws/eBayISAPI.dll...m=270706351680
                      (They've upped shipping $10 since I bought mine. Uugh)

                      Power supply (24V 6.5A) was about $15 + shipping from MPJA:
                      http://www.mpja.com/prodinfo.asp?number=16854+PS
                      (Now out of stock. Uugh)

                      Softwares:
                      Eagle for PCB design. It's free for small boards, pay for unlimited (?) size files. Seems to be the industry standard for most folks I run into.
                      http://www.cadsoftusa.com/

                      PCB-GCODE for generating G-code from the Eagle file for both isolation milling and hole drilling. It seems to work pretty well. And it's free !
                      http://www.pcbgcode.org/
                      This runs "inside" Eagle and it's easy to deal with.

                      Gsuite for optimizing the code generated from PCB-GCODE. Basically eliminates a ton of rapid moves from what PCB-GCODE generates for whatever reason and does a very good job of it. For a slow stepper motor machine, it's a godsend. It has a couple other handy utilities as well. Pretty neat. Also free.
                      Gsuite v1.3

                      Mach 3 for running the machine. About $150 but all I'm doing is running the G-code to the machine and for that EMC2 would work just about as well (some say better) for free. I think Mach 3 is a little overboard for this, but I bought a copy a while back so I'm using it.

                      That's it. If you want to make parts or do engraving, you may need to use some kind of CAM software for generating the G-code depending on how complex you get into. So far I haven't looked into that, so you're on your own.

                      Steppers are NEMA 23 and 1.5A, so about as small as this frame gets I think. For the force required for an engraving bit and those little bitty drills, these are more than adequate.

                      Lead screws are 1:1. Just 5/16-18 threaded rod. I was finicky about picking a pretty straight one and it wasn't too bad. Seems to be plenty accurate enough for the purpose, and dirt cheap. 200 Steps per revolution on the motor (which is typical and easy to find) and 18 tpi gives a nominal positional accuracy of .00028 per step, so more than adequate for me.
                      I machined the nuts from delrin (yer basic drill & tap) and that makes for a free-turning but close fit. Of course wear & tear will probably loosen things up over time, but they are easy to make and at the moment it indicates zero backlash.

                      And finally, no the columns are definitely not the weak link. Nice and roomy for routing wires through too.

                      Oh yea. Downloaded the board file in Eagle from here in case you are curious what it is:
                      http://arduino.cc/en/Main/ArduinoBoa...alSingleSided3
                      Last edited by tyrone shewlaces; 03-04-2011, 08:45 PM.

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                      • #12
                        Originally posted by tyrone shewlaces
                        I'll try to give answers.

                        Did this last night. Have to tweak the generating of the code - traces ended up being too narrow so must be cutting wider than it's supposed to.
                        My money would be on the Dremel tool quill as the source of the problem.They aren't at all ridgid,I've always wanted to make a better quill and use the Dremel to drive it through a flexible coupling for that reason.
                        I just need one more tool,just one!

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                        • #13
                          No doubt the dremel is running out and cutting wider than the tool is supposed to. But that can still be modified in the software chain to still make a working board. The quality of the milling is workable, but the code called for too wide a channel to be milled and that can be reduced for sure.

                          A better spindle is on the drawing board and it was from the beginning, but a dremel was an easy way to get it working quickly. It's a quick bolt-on plate which can easily be switched out to install a good spindle (or laser, or extruder hehe, etc.)

                          Actually, here's a pretty darn good deal for a decent spindle if a guy didn't feel like making one from scratch:
                          http://www.cnconabudget.com/

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                          • #14
                            Originally posted by wierdscience
                            My money would be on the Dremel tool quill as the source of the problem.They aren't at all ridgid
                            Yup, Dremels suck for precision work.

                            I ran into the same problem with my cobbled-up CNC for r/c making model airplane parts. I quickly switched to a little Porter Cable trim router. MUCH better. A real collet, good bearings and will howl away all day with nary a whimper. When I say howl, there's the rub. Dey do make sum racket!

                            edit: Oops, Tyrone's got a handle on it already!
                            Milton

                            "Accuracy is the sum total of your compensating mistakes."

                            "The thing I hate about an argument is that it always interrupts a discussion." G. K. Chesterton

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                            • #15
                              You can take the Demel tools apart,and add packing around the ball bearings to tighten up their spindle wobble. The bearing housings are just cast into the plastic,and do not fit the bearings very well.

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