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Thread: DIY Indexer

  1. #11
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    Jan 2004
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    Dave - thanks missed that.

    Tim - Here's your thread: first project on cheap indexer - I'd like to see pics of the head/tailstock you used as I am sure others would as well. Your pic strategically eliminated both from view...

    -B
    High Definition 3D Laser Scanning Services - Advanced ShopBot CNC Training and Consultation - Vectric Custom Video Training IBILD.com

  2. #12
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    Dec 2005
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    Pro Signs, Coal CIty IL
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    I have no problems fabricating whatever is needed on the mechanical side, it's the electronic side I'll have to be schooled on. I guess I already knew if there was a spare driver on the board, but I had to go look. Being a complete electronic illiterate, I'll need an indexer with tailstock, driver and cable. Everything else (electronically) is a matter of software/resistor adjustments, if I understand that right?
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  3. #13
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    Dec 2005
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    I should add, I do have a little idea how the 4th axis files are generated. I have a laser engraver with a chuck rotary and wheel rotary for engraving round jobs. However, it doesn't have a dedicated 4th axis drive, since there's no need for Z axis function during engraving on a laser. I unplug the y axis on the machine and plug the rotary attachment to the y outlet. Manually move the laser head to TDC of the workpiece and zero the z off the surface. Then I go into the menu and calculate the diameter of the piece to get the rotary dialed in. I've only done a couple rotary jobs so far. To check my calculations I've been putting masking tape on the part, and marking the start/stop positions say, 4" apart. Then I move the rotary 4" on the screen to see if it matches my start/stop points. I'm sure if I had more run time, the calculating would be an automatic process, but for now this is an ''engraving for dummies'' way to check my calculations.

  4. #14
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    Apr 1999
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    Rock Hill SC
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    Here is a like to what i bought. It has pics and specs.

    http://www.ebay.com/itm/CNC-Lathe-Ro...72.m2749.l2649

  5. #15
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    Jan 2004
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    Quote Originally Posted by pro70z28 View Post
    I have no problems fabricating whatever is needed on the mechanical side, it's the electronic side I'll have to be schooled on. I guess I already knew if there was a spare driver on the board, but I had to go look. Being a complete electronic illiterate, I'll need an indexer with tailstock, driver and cable. Everything else (electronically) is a matter of software/resistor adjustments, if I understand that right?
    If you have a PRT96, you need another G203V driver for that 5th slot. You'll need a current set resistor for the drive to limit how many amps it puts to the motor. With no resistor in there it puts out the full 7A...and will run like carp and super hot. Not a big deal you can read up on current set resistors on the Geckodrive site. Download the user manual PDF and there's a list to get you in the ballpark. The resistors have color bands on them...you can decipher what they are using an online resistor calculator - and find the one you need for the new drive after you know the value.

    Aside from this, you just need the motor, cable and connectors. In VI change channel 4 to B. Ch 5 can be whatever. Turn on 5 axes in SB3 in VD command and set your UV for the motor depending on the reduction ratio. Go as high as you can on reduction...while it is possible to spin it like a lathe, ZERO useful work can be done doing that, so you might as well gear down for torque and resolution.

    I have a couple of new straight gear 18:1 that work well as an indexer motor (has a little bit of backlash but ALL SGs do) but won't work if you get one of the units up thread. It's the same size as the rest of your motors.

    -B
    High Definition 3D Laser Scanning Services - Advanced ShopBot CNC Training and Consultation - Vectric Custom Video Training IBILD.com

  6. #16
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    Dec 2005
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    Thanks for all the info. Brady. So, it sounds like with enough reduction torque, amperage may not be the main consideration as the gear ratio would offset the smaller stepper?

    While typing this it dawned on me... I retired my first CNC (a 4'x4' Multi-Cam) when I bought the ShopBot. Lightning fried a chip in the control board and they stopped parts support for that machine. I was told it could be upgraded, but the cost was nearly what the Shopbot was new, and I really wanted to step up to a 4'x8' table. That CNC is tucked away in the corner of the shop. Do you suppose I could rob one of the steppers off that machine? They are belt reduction stepper motors, but I'd have to dig it out for any info beyond that. Are stepper motors pretty standard, as in, if I match the amps with a resistor it should work? Still have the chuck to consider, so it may not be worth the extra fabricating time.

  7. #17
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    Mar 2006
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    Go to the last page in this "Indexer" section (first page when it was started) and move forward and somewhere along in there is a section where several guys posted their own DIY indexers from $100.00 and up and that ought to give you some ideas.
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  8. #18
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    Dec 2005
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    Thanks myxpykalix. I'll check that out.

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