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Thread: Auto-Return for Super Surfacer

  1. #16
    I wondered if the overall drag of the drive/belt/and material drag on the table (pretty heavy down pressure) didnt act as its own brake in that the board never leaves the drive belt. Id imagine shutting your machine down mid-stroke as a test would probably result in an almost instant stop? Still doesnt address it all but just a thought.

  2. #17
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    Sounds good Malcolm! No hurry at all.

    Mark, the stroke is past the knife when it shuts down to return, so most of the resistance from pulling is gone. Their are a series of pulleys that slow the speed down at the belt.
    Bumbling forward into the unknown.

  3. #18
    Quote Originally Posted by Brian Holcombe View Post
    Sounds good Malcolm! No hurry at all.

    Mark, the stroke is past the knife when it shuts down to return, so most of the resistance from pulling is gone. Their are a series of pulleys that slow the speed down at the belt.
    Yeah, clearly past the knife but I assumed there would even be little to no wind down just with the drag on the table, head down pressure, drive train, etc. because the piece never comes out from under the drive belt so it can return. just a thought.

  4. #19
    Quote Originally Posted by Mark Bolton View Post
    Yeah, clearly past the knife but I assumed there would even be little to no wind down just with the drag on the table, head down pressure, drive train, etc. because the piece never comes out from under the drive belt so it can return. just a thought.
    Very similar to my thoughts; very low rotational inertia in the feed belt system — outside the motor itself.

  5. #20
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    This is a full auto Hitachi model that I recently got in the shop.
    The sensors are optical.
    one at the infeed and one at the outfeed.
    One set are mounted to the posts and are fixed.
    The other set opposite the posts are pivoted because these are open sided machines and the wood can be twice as wide as the blade, so the pivoted sensor will ride up on the wood and break the beam.
    The motor is a standard motor and gearbox.


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  6. #21
    Quote Originally Posted by Malcolm McLeod View Post
    Very similar to my thoughts; very low rotational inertia in the feed belt system — outside the motor itself.
    Id say Brian could check this by simply killing the power the instant a work piece leaves the knife. You'd see clearly if its a pretty much instantaneous stop. I know even on my 20" planer there is very little wind down when the power has gone out (gotta love a rural shop) in mid-stream. I can only imagine this is even faster with no cutter head inertia.

  7. #22
    Quote Originally Posted by Mark Hennebury View Post
    This is a full auto Hitachi model that I recently got in the shop.
    The sensors are optical.
    one at the infeed and one at the outfeed.
    One set are mounted to the posts and are fixed.
    The other set opposite the posts are pivoted because these are open sided machines and the wood can be twice as wide as the blade, so the pivoted sensor will ride up on the wood and break the beam.
    The motor is a standard motor and gearbox.
    Is that the same Hitachi that was being sold on the Canadian Woodworking forum in September?

  8. #23
    Quote Originally Posted by Brian Holcombe View Post
    Sounds good Malcolm! No hurry at all.

    Mark, the stroke is past the knife when it shuts down to return, so most of the resistance from pulling is gone. Their are a series of pulleys that slow the speed down at the belt.
    Spent a bit of lunch pondering.

    For the moment, if I go by the linked video and assume the available buttons and switches are:
    • POWER - pushbutton to enable the system; basically 'push' to arm it to run.
    • E-STOP - mushroom button (1 or more) resets logic and kills outputs.
    • SAFETY LSS - (1 or more on covers or guards :: all optional) resets logic kills outputs.
    • MODE SW - 1-PASS or CONTINUOUS.
    • START SW - Foot-switch as in video (basically, a dead-man SW); take your foot off and it kills outputs.

    I made no allowance for powered control of the belt/feed height, nor for pilot-lights, alarms, or status indicators - but they could be added.

    That leaves the process - or material - sensors. Initially I thought it would take 4 limit switches, but I now think it can be done with 3, whether they are roller-arm, proximity, or optical makes little difference from a logical perspective. They just have to be able to turn ON when a board is present. They are:
    1. Entry - material is present at the in-feed and ready to process.
    2. Cutter - material is present at the cutter (maybe just a bit past it?? 1/2" or so? ...depends on inertia.)
    3. Exit - material is present after the cutter.

    Based on the speed of operation, I'd SWAG there should be 6"-8" between the switches. I'll call them ZSS-01, -02, & -03 ('Z' = position; 'SS' = status sensor).

    These sensors mean you see 10 'States' or Steps of operation, with values in parenthesis as respective ZSS(#3/#2/#1) 'on' states (1=ON, 0=OFF):
    • 0 - (0/0/0) No Material present, not ready.
    • 1 - (0/0/1) Matl at entry; ready to START.
    • 2 - (0/1/1) Moving FWD / Cutting; matl has reached cutter.
    • 3 - (1/1/1) Moving FWD / Cutting; matl has reached exit.
    • 4 - (1/1/0) Moving FWD / Cutting ; matl clear of entry.
    • 5 - (1/0/0) FWD>(stop)>REV transition; matl clear of cutter, but still at exit.
    • 6 - (1/1/0) Moving REV / No Cut; matl has reached cutter.
    • 7 - (1/1/1) Moving REV / No Cut; matl has reached entry.
    • 8 - (0/1/1) Moving REV / No Cut; matl clear of exit.
    • 9 - (0/0/1) Stopping (or back to FWD, based on Mode); matl cleared cutter, but still at entry.

    At Step 9, depending on how the Mode SW is set, the system could either stop, or cycle again - as long as the foot switch is held ON.

    I see a need for 4 logic relays: POWER (ON), ONE-PASS (Mode), FWD, and REV. The latter 2 could feed either a FWD/REV starter coil pair, or a VFD. I also think each of the ZSS will need its own relay to allow multiple NO & NC contacts for each; so 7 relays total. A 4PDT ice-cube relay would be plenty with what I have so far. I wrote a ladder logic program to execute this, and it could easily translate to hard-wired relay logic. If the above seems reasonable, I'll find a way to get it in your hands.

    I'm not crazy about the error handling, but to keep it simple, if anything interrupts a cycle, you would have to just kill it, pull the material out, and start over. I am also not certain 3 ZSS's will do it; it might require a pair straddling the cutter, rather than 1 'at' the cutter? ...Thoughts?

    Hope this helps.

    *******
    I did consider just 2 ZSS's, one on each side of the cutter, but that introduces some type of time delay requirement - - I think - - since the material needs to carry beyond the entry ZSS and clear the cutter. I just don't know enough about the machine to have confidence it will do this.
    Last edited by Malcolm McLeod; 01-03-2022 at 3:33 PM. Reason: 2 ZSS?

  9. #24
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    This is very helpful, thank you! I’ll start looking into a few parts to make it happen.

    I think I’ll build out a completely new box and use the current on another machine.
    Bumbling forward into the unknown.

  10. #25
    Quote Originally Posted by Brian Holcombe View Post
    This is very helpful, thank you! I’ll start looking into a few parts to make it happen.

    I think I’ll build out a completely new box and use the current on another machine.
    Schematics are headed your way. Good Luck!

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