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Table saw fence and guide

Discussion in 'Other Builds' started by Marc Gingras, Apr 10, 2017.

  1. Marc Gingras

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    Marc Gingras published a new build:

    Read more about this build...
     
  2. Mark Carew

    Mark Carew OpenBuilds Team
    Staff Member Moderator Builder Resident Builder

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    Well done @Marc Gingras this is a great concept guide and to have the ability to motorize the position is such a nice addition! :thumbsup:
     
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  3. dave_robinson_022

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    This looks like great work! I have been working on a similar concept with the priority being automatic motorised positioning. I looked at MGN12 Linear Guides as well as C-Beam as I have a C-Beam machine and even just a 2020 slot with mini gantry as I have spare.

    I also looked at lead screw or belt driven but was concerned about holding strength when ripping.

    I have even considered rotary encoders to add closed loop control to stepper motors.

    The trouble is a new set up would cost $600 New Zealand to do 1m.... that is with motors both ends of the fence as I thought this would make alignment and holding better.

    What are your thoughts from your build? How much is enough and what is overkill?

    Dave
     
  4. Marc Gingras

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    Hi Dave,
    I found the C-Beam fence compares really well with off the shelf products that retail here for well over 500$ that do not have automatic positioning "potential". It should cost under $200 to build it with off the shelf Openbuilds components eg. 500mm x 500mm C-Beam fence & rails (3 c-Beams, 2 c-beam gantry kits + odds and ends). The fence holds square without the positioning option if it rides free (ie. is not tied to a screw or a belt). The toggle clamps one at each are secure (500lbs per clamp). It will not move during a rip, I suspect the beam would bend before it slips. I found that adding the "positioning" optional lead screws and/or motors actually complicate alignment.
    I just started the "optional" motorized positioning option part last week. I am new to robotics/cnc/motorized positioning and am pretty rusty/incompetent with programming in general. I have bought most of the parts (smoothieboard/ power supplies/ stepper motors/controllers) and hoping to test out the bugs with bCNC on my windows tower before deciding on what I will be using in the sawdust. As an aside, I though it was going to be an easy first step.. it is not. Installing bCNC on a win7 64bit non-root drive along with it's recommended ancillary programs (python, numpy, scipy, Visual studio, matplot, pillow, pyserial and opencv) has been a frustrating exercise to say the least. I ended up loading everything into Anaconda, all except for bCNC which I have not been able to load/recognize as of yet :( This is starting to remind me of the stone-age when I was trying to get selectrics to kern & snake with rs232C's and CP/M kludges. Anyhow...
    The fence is part of a much larger build which is far from complete and is a "design as I go" project. The "optionaI" screws on the rails that you see in the pictures were chosen for build symmetry and don't add strength. The fence sits on a floating zero clearance work table (work in progress). I am using lead screws for strength on the table, since I was concerned that the table might fly out if I used belts and they snapped during a sloppy rip. I secure the work piece to the table and slide the work table over the blade.
    I am not familiar with rotary encoders.
    Motorized positioning for a table saw fence & table ... overkill perhaps, ... if things go as expected with minor modifications the fence with positioning should also be able to double as a sphinx platform. :)
    Hope this helps
    marc
     
  5. HOBOPHOBIA

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    What is the name of the red handled clamp you are using?
     
  6. Marc Gingras

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    To secure the fence to the side bars at the correct stop distance I used two Samona 80827 500 lbs toggle clamp I had lying around. They sell for under 10$ and happen to be pin compatible with C-Beams. Samona 50827, Vertical Toggle Clamp 500 lb - 50827
     
  7. Marc Gingras

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    Hi Dave,
    Just an after though on my previous answer... You could reduce costs further by replacing both gantries with Robert Nee's Y Axis trolley build. The costs would fall by another $100 and basically be the cost of C-beams.
     
  8. DMas

    DMas New
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    Could use lasers bouncing back and forth to feed you the numbers. So two lasers an inch or so apart pointing to other end. They would need to match distance before locking? Of course that would just be x axis. Do stepper motors have such fine control to be able to move .001?
     

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