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Thread: Edgefinder question

  1. #1
    Join Date
    Mar 2014
    Posts
    94

    Default Edgefinder question

    Hey again SBotters,

    I have successfully run 2x 4.5" bores through 1" aluminum plate with a nice interference fit for receivers that I am setting a jig into. So far so good!

    I am now looking to pick up the edges of 8 aluminum parts on my jig and I will need to do them all separately with accuracy. I would like to use an edge finder to accomplish this feat for now (I will be looking into writing a routine similar to Z-zero w/ a circuit and Dowel Pin).

    I've read posts about laser finders and the like, but really need to accomplish this with an 'old school' edgefinder for now.

    I need help with the controls on the ShopBot to get it to move small distances efficiently. For those who have run CNC's, this would typically be done with an incremental dial.

    Could someone who has experience with edgefinding on a ShopBot give me a hand?

    Thanks in advance,

    Brandan

  2. #2
    Join Date
    Feb 2008
    Location
    Miller Marine Products, Ridgefield Washington
    Posts
    877

    Default

    Hi Brandan,
    I have a laser edge finder and also a wiggler. The laser is quick but not supper accurate I use it when I am looking to find the edge of a sheet that I am going to machine and the parts are not laid right to that edge. I use the wiggler on my CNC bed mill all the time it is more accurate and repeats to about .003" or better.

    If I were to use the wiggler on the Shopbot I would bring up the SK screen and change the default setting to move .001" I think default is .100" or .010" I am not at my shop right now to check. Then a tap will move the machine .001" and should work fine for your edge finder.

    If I remember right there might be a button to click to put it in incremental mode so that it moves you specified increment.
    Mike
    WWW.MillerMarineProducts.com
    Proto Trak DPM CNC Bed Mill
    Brand X Industrial router
    Sharp SVL-2416SE-M VMC

  3. #3
    Join Date
    Dec 2000
    Location
    Thorp, WI
    Posts
    2,845

    Default

    There are two files in your SBParts folder that you could use to find the centers of the holes using an input connection just like your Z zero plate does. Those are sample_Center_inHole.sbp and sample_Center_inHole_wZtest.sbp
    Scott




  4. #4
    Join Date
    Jan 2004
    Location
    iBILD Solutions - Southern NJ
    Posts
    7,986

    Default

    Quote Originally Posted by srwtlc View Post
    There are two files in your SBParts folder that you could use to find the centers of the holes using an input connection just like your Z zero plate does. Those are sample_Center_inHole.sbp and sample_Center_inHole_wZtest.sbp
    X2 to that.

    PLEASE err on the side of caution with a conventional edge finder. They are probably not rated for the lowest spindle RPM possible on a ShopBot (5,000) and unless you have a Super PID, a Porter Cable won't go lower than around 9,000. They are meant to be used at low RPM on a mill...I imagine it would not take much to make one of those fly apart in a router - so be cautious! (Safety glasses, flak jacket etc)

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

  5. #5
    Join Date
    Feb 2008
    Location
    Miller Marine Products, Ridgefield Washington
    Posts
    877

    Default

    Brady has a good point. When I use the wiggler on the mill I do it at 1000 RPM it would fly in pieces @ 5000 RPM I suspect.

    I have never used my wiggler on my SB but I put my spindle on as an after market item and with my VFD I can run mine down to 100 RPM and often drill plastic at 2500 RPM. The spindle is rated for 24000 RPM max.
    WWW.MillerMarineProducts.com
    Proto Trak DPM CNC Bed Mill
    Brand X Industrial router
    Sharp SVL-2416SE-M VMC

  6. #6
    Join Date
    Oct 2011
    Location
    Colorado
    Posts
    453

    Default

    There is a very simple way to find the edge of a part, or locate the edge of a part. We install a 1/4in dowel pin (or the broken shank from a bit) in the collet and then move the router to the correct position on the table and clamp a part stop to the table. You can then locate the part very accurately repeatedly. The code below is the program I wrote to accomplish this. It locates part stops at the center of the part along the short side and two additional stops on the long side on the side farthest from the operator. This could be altered to your needs and machine setup very easily.

    MSGBOX ( Have you installed a 1/4in pin and zeroed it to the table?, YesNo, Ready?)
    if &msganswer = No then end

    BEGINENTRY:
    INPUT "Enter X value for origin offset:" &_x_offset
    INPUT "Enter Y value for origin offset:" &_y_offset

    INPUT "Enter X length of rectangle:" &_x_length
    INPUT "Enter Y length of rectangle:" &_y_length

    JZ,1
    J2,&_x_offset,&_y_offset
    MSGBOX ( Is the machine over the corner of your desired origin?, YesNo, Ready?)
    if &msganswer = No then goto BEGINENTRY

    J2,&_x_offset+0.125,&_y_offset+(&_y_length/2)
    MZ,0.1

    'Position end stop!
    PAUSE
    JZ,1

    J2,&_x_offset+(&_x_length/5),&_y_offset+&_y_length-0.125
    MZ,0.1

    'Position edge stop!
    PAUSE
    JZ,1

    J2,&_x_offset+4*(&_x_length/5),&_y_offset+&_y_length-0.125
    MZ,0.1

    'Position edge stop!
    PAUSE
    JZ,1

    JH
    END

  7. #7
    Join Date
    Feb 2008
    Location
    Miller Marine Products, Ridgefield Washington
    Posts
    877

    Default

    Another method used by machinst is to use a piece of paper or tape bewteen the bit and the work piece. Move up slow with the spindle turning until it tears the paper or tape. Measure tape or paper with a mic and that will get you as close as an edge finder and better than a laser edge finder. I like blue painters tape best.
    WWW.MillerMarineProducts.com
    Proto Trak DPM CNC Bed Mill
    Brand X Industrial router
    Sharp SVL-2416SE-M VMC

  8. #8
    Join Date
    Mar 2009
    Location
    San Diego CA
    Posts
    318

    Default

    yup, old school is to use paper (thermal paper i.e. receipt is almost universally ~ 2 thou) set your increment to a thou and edge up till the shank of the bit (not spinning) compresses the paper, z out, and the set your zero for x or y at +/- radius of the bit +/- a thou and you are pretty dead nuts on.
    Do not follow where the path may lead. Go instead where there is no path and leave a trail.

  9. #9
    Join Date
    Jun 2013
    Location
    Pasadena, CA
    Posts
    986

    Default

    I have used paper for this purpose but lately I bought some 3/1000" spring steel shim stock (McMaster 9503K13). It is thin enough to be cut with scissors and a piece (I use a 1.5x3" strip) lasts very long. I hold it with a magnet on the gantry to have at hand when needed.

    I use it for edge finding but mostly for z-zero setting. I do have a zero-plate but I can do it just as fast with the steel strip by hand without a cable device.

  10. #10
    Join Date
    Mar 2014
    Posts
    94

    Default

    You guys are the greatest and super helpful!

    Quote Originally Posted by bradywatson View Post
    X2 to that.

    PLEASE err on the side of caution with a conventional edge finder. They are probably not rated for the lowest spindle RPM possible on a ShopBot (5,000) and unless you have a Super PID, a Porter Cable won't go lower than around 9,000. They are meant to be used at low RPM on a mill...I imagine it would not take much to make one of those fly apart in a router - so be cautious! (Safety glasses, flak jacket etc)

    -B
    @Brady, I thought of this exactly; I can't get my spindle lower than 4k RPM, and was a bit of a showstopper for me for a conventional edge finder or wiggler...

    So then I was thinking about an electronic edge finder or laser, but I have no experience with these:

    Quote Originally Posted by gundog View Post
    Hi Brandan,
    I have a laser edge finder and also a wiggler. The laser is quick but not supper accurate I use it when I am looking to find the edge of a sheet that I am going to machine and the parts are not laid right to that edge. I use the wiggler on my CNC bed mill all the time it is more accurate and repeats to about .003" or better.

    If I were to use the wiggler on the Shopbot I would bring up the SK screen and change the default setting to move .001" I think default is .100" or .010" I am not at my shop right now to check. Then a tap will move the machine .001" and should work fine for your edge finder.

    If I remember right there might be a button to click to put it in incremental mode so that it moves you specified increment.
    Mike
    @Michael I don't know if you need to to spin and LED edge finder. If anyone has experience with it please let me know. The laser seemed like my best option, but still dialing in the position seemed tedious with the .001" increments from the control. Would be more effective if there was a dial on ShopBot similar to CNC (from my OP).

    @Sean So then I started thinking about a program similar to the z-zero plate. I would expect this to be the most simple and efficient. Using a dowel in the collet seems reasonable and could run simply. Thanks for the helpful code!

    Quote Originally Posted by donek View Post
    There is a very simple way to find the edge of a part, or locate the edge of a part. We install a 1/4in dowel pin (or the broken shank from a bit) in the collet and then move the router to the correct position on the table and clamp a part stop to the table. You can then locate the part very accurately repeatedly. The code below is the program I wrote to accomplish this. It locates part stops at the center of the part along the short side and two additional stops on the long side on the side farthest from the operator. This could be altered to your needs and machine setup very easily.

    MSGBOX ( Have you installed a 1/4in pin and zeroed it to the table?, YesNo, Ready?)
    if &msganswer = No then end

    BEGINENTRY:
    INPUT "Enter X value for origin offset:" &_x_offset
    INPUT "Enter Y value for origin offset:" &_y_offset

    INPUT "Enter X length of rectangle:" &_x_length
    INPUT "Enter Y length of rectangle:" &_y_length

    JZ,1
    J2,&_x_offset,&_y_offset
    MSGBOX ( Is the machine over the corner of your desired origin?, YesNo, Ready?)
    if &msganswer = No then goto BEGINENTRY

    J2,&_x_offset+0.125,&_y_offset+(&_y_length/2)
    MZ,0.1

    'Position end stop!
    PAUSE
    JZ,1

    J2,&_x_offset+(&_x_length/5),&_y_offset+&_y_length-0.125
    MZ,0.1

    'Position edge stop!
    PAUSE
    JZ,1

    J2,&_x_offset+4*(&_x_length/5),&_y_offset+&_y_length-0.125
    MZ,0.1

    'Position edge stop!
    PAUSE
    JZ,1

    JH
    END
    @michael and @chris The paper/tape method is what I am using now. Problem being that I will have a lot of parts to setup in a single Operation rapidly and may eventually lead to another ShopBot. I need to find a solution better than what i am using .

    Quote Originally Posted by gundog View Post
    Another method used by machinst is to use a piece of paper or tape bewteen the bit and the work piece. Move up slow with the spindle turning until it tears the paper or tape. Measure tape or paper with a mic and that will get you as close as an edge finder and better than a laser edge finder. I like blue painters tape best.
    Quote Originally Posted by shoeshine View Post
    yup, old school is to use paper (thermal paper i.e. receipt is almost universally ~ 2 thou) set your increment to a thou and edge up till the shank of the bit (not spinning) compresses the paper, z out, and the set your zero for x or y at +/- radius of the bit +/- a thou and you are pretty dead nuts on.
    So think for now I will continue with the paper/tape method until I require capability report for the machine. Once I do I will use the Zero-Plate method extended to X/Y edgefind.

    Thanks ever so much for all your valuable input, with such a great community, it's difficult to go wrong!

    Brandan Smith

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