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Thread: Carving Rotary Lithopanes in 4 Inside Diameter PVC pipe (4 Outside Diameter)

  1. #11
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    Click image for larger version. 

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ID:	78304Oh, the choices you might have

    Just to brighten everyone's day!

  2. #12
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    It would seem that the places on the Z-truck that touch the PVC could be ground off without damaging the machine.
    The need to change the touch-point would be addressed differently.
    Ken,
    V-1, 2, & 3

    When the People fear their Government, there is Tyranny.
    When the Government fears the People, there is Liberty.
    - Thomas Jefferson

    You must be the change you wish to see in the world.
    - Mohandas Gandhi

  3. #13
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    There is no need. It is an easy matter to make the jig plates 1/8" higher. Tape on some strips of wood (use some silver tape) and the machine would not know the difference. After putting some thought into this, I think it should not be difficult to carve 4.5" diameter stock. I have, however, not actually done it and may be speaking too soon!

    I will be interested to see if 200k has any problems.

  4. #14
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    May 2011
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    Mount Juliet, TN
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    Default How to carve 4 O.D. PVC Schedule 40 pipe using the LHR Rotary Jig

    Yes you can do it!

    In entry #1 of this thread I related that the LHR jig alone will not physically permit 4 ” diameter workpiece because it contacts/rubs on the bottom of the Y-truck. The solution was to raise the machine head height and hence the Y-truck. I cut a pair of jig end-plate caps out of ” Corian and taped them in place. (photo 1) When clamped in the machine, this relieved the problem of contact between the workpiece and the y-truck. (photo 2)

    Unfortunately when trying to run a carve the first thing that happened is that a warning showed at the beginning of the carve sequence even before it would measure the board - “Clear Board Sensor”. Hmmmmm. The Corian caps I put on the top of the jig ends came very close (but not touching) to the board sensor where it starts its transit across the Y axis. I guess if the board sensor reads a high enough number even before it starts moving across the board it can’t tell where the board starts and results in the fault message. I took the LCD-display-side Corian cap (left as you face the machine) back to the tablesaw and cut a notch down to the aluminum to give enough clearance from the board sensor so it could start its measuring transit with a zero read. When I put it back in the machine, it worked and I got all the way through all the bit calibrations and started the carve.

    Another glitch. It tried to carve the piece about ” above the surface – an air carve. OK, so I need to jog the bit to the actual workpiece to gauge the real surface. Another run through the menu and at the point where the bit descends to the left jig plate I hit STOP and then tried to JOG to position it to the workpiece. The menu will not let you do that. It says “hit STOP to jog to position” but when you do it just reverts to “ENTER to continue or STOP to abort”. You never get the chance to press 3 to jog to position. OK, so the machine is calculating the radius of the workpiece from the top of the Corian cap. Since the desired radius of the workpiece is only 1/8” greater than the 4 ” entered into the machine, I needed to make a notch in the Corian cap that added only that 1/8” on top of the aluminum – not the entire 5/16”. Back to the tablesaw. I also added a lateral groove to let the bit bypass the Corian cap at the start of its calibration sequence. (photo 3) (photo 4)

    With all the Corian cap grooves and notches in place, I tried again. This time it started to carve at the right depth. Success! The results of the first complete carve is shown in photo 5.

    There a couple of caveats I need to add. First of all the 4” Schedule 40 PVC I used was foam core not solid – hence the yellowish cast. It’s what I had on hand and this was just an experiment to see if it could be done. I strongly suggest using solid PVC pipe for lithopanes and not the cheaper foam core stuff. The latter doesn’t carve as nicely plus, when illuminated, it is always yellow no matter how blue your source light is. Look at the edge of the tubing and you can see. If it is white throughout then it is solid PVC. If it has smooth white inner and outer veneers and a coarse, softer yellowish core, it is foam core. I’ve found that around here Home Depot carries solid PVC and Lowe’s carries the foam core stuff. I hate that because Lowe’s is 15 miles closer to my house than the nearest HD, but what can ya do?

    Second, I stretched the pattern vertically by multiplying the original height by 1.0588235, which is the ratio difference in circumference between 4.25” and 4.5”. I did this because the machine was rotating the cylinder at the rate that was appropriate for each cut using a 4.25” diameter. The same number of arc degrees would be moved but a greater surface length would be covered. Stretching the height of the pattern would keep the length to width ratio equal in the final carve.

    Finally, the last photo looks like there is some severe cylindrical distortion in the carve but that is an artifact of my cell phone camera. Cell cameras have a very wide angle lens that gives a mild fisheye effect in everything. The actual carve looks very proportional in real life.

    Well that’s about it. I’ll now open the floor for discussion.

    Questions?
    Attached Thumbnails Attached Thumbnails 4InchID_PVC-E.jpg   4InchID_PVC-F.jpg   4InchID_PVC-G.jpg   4InchID_PVC-H.jpg  

    4InchID_PVC-I.jpg  

  5. #15
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    Good job. Nothing like doing it to prove it can be done!

    A few notes about the rotary may help. The depth touch is the touch on the top of the drive plate. The machine knows that the axle is 1.75" below that. One cannot touch on the dowel. (That is only when calibrating.) The shim had to be 1/8" thick. The sensor error was because your Corian cap was too wide. The board sensor encountered the edge too close to the keypad. My idea was just to put 1/4" wide, 1/8" thick strips on top of the plates and wrap aluminum tape around them to hold them on. Simply raise the effective height by 1/8". I think if one does that, the machine will operate as normal.

    This is the start of a new era in rotary lithos. Good one Steve.

  6. #16
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    In it's most basic form, the only thing you need to do this kind of carve is an addition to the top of each end (front and back) of both jig plates of about 1/4"+ on the outside inch or so - the part that the rollers actually press on, and the addition of 1/8" in the center for the depth touch. I tried all this with the 1/2" dadoed Corian because the jig end plates are only 1/4" thick and it seemed too small to just lay a 1/4" x 1/4" strip on top of the plates, tape them down and then crank the head down hard. It shouldn't move... but if it did, it might do something nasty while the machine is running.

    I plan to make something less complicated on the lines of this rather than the Corian strips I used in the experiment for long term use.

  7. #17
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    Here is something you might be interested in. When I was beta testing the CW rotary jig, I made some prototype "add ons". One of these was some braces for the top of the jig. I was worried that the jig might need to be held in place by more than the tabs at the bottom and I was also worried about the small surface area for the rollers on top of the jig plates. Something similar to these, but more easily removable, might be an idea.
    Attached Thumbnails Attached Thumbnails Front Brace.jpg   Rear Brace.jpg  
    Attached Files Attached Files
    Last edited by bergerud; 10-17-2015 at 09:34 AM.

  8. #18
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    I took my results of yesterday and stripped them down to the bare essentials.

    What is left is five very small pieces that all can be taped to the LHR jig with blue tape, making easy removal for other projects. I kept the ” x ” Corian with a dado of ” x 3/16” so the machine head is raised 5/16”. The difference is that instead of covering the entire length of the jig ends, it’s now cut down into two pieces of 1 ” long that stay are the ends where the rollers compress. For the middle where the bit touchpoint is raised I simply cut a small piece of 1/8” thick aluminum to length of 1” and a width of ” to match the thickness of the jig ends. All these parts are simply taped to the jig with blue tape. (See photos). BTW, the aluminum foil ducting tape is in the photo because that’s what I was going to use to affix the pieces, but I decided that blue tape would be sufficient and much easier to remove.

    I haven’t’ tried to carve with this setup yet just because it’s Saturday and my wife has “plans” for my day. I did get to Home Depot and bought some solid 4” PVC so I can do a proper finish carve. I’ll post the results.

    Dan, your braces are nice (as is pretty much everything you design) but even though they give a broader surface for the rollers upon which to rest, they don’t raise the head above its normal level. Of course that could easily be changed in a matter of a couple of minutes in Designer. But it looks like you have made them attach to the jig on the threaded rod which would require more time to bolt and unbolt than applying just a bit of tape to my little pieces. That said, I like the idea of a greater surface area contacting the rollers than just a little ” wide flat piece at each end. To know whether it makes a difference would need further experimentation but unless my little blocks have problems staying in place, I won’t pursue it just now.

    Edit# 1: I just realized I will need to file a shallow vertical groove on the side of the aluminum shim for the bit bypass. Not too much, maybe 1/16" deep, because that is the same place the bit checks for board height and I don't want it to miss. The original aluminum end plate already has a groove that is worn in there by the bits themselves and I imagine it can't be good for the bits to have them pushed sideways as it descends in the beginning of the bit check. Easy fix. Two minutes.
    Attached Thumbnails Attached Thumbnails 4InchID_PVC-J.jpg   4InchID_PVC-K.jpg   4InchID_PVC-L.jpg  

  9. #19
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    Great job 2000K and thanks for sharing. I just got done buying some 4" PVC to try this out as I am very interested. To me the way it sounds I could just put the 1/4" wide, 1/8" thick strips on top of the plates. Would I need to make the indentation where the bit touches during calibration? I just want to make sure the depth during carving is correct. Again great job.
    Bergerud, Couldn't we take your jig and add the 1/8 strips into the design so they lay over the top plate? What do you think?
    Heather

  10. #20
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    Quote Originally Posted by sunmiztres View Post
    Great job 2000K and thanks for sharing. I just got done buying some 4" PVC to try this out as I am very interested. To me the way it sounds I could just put the 1/4" wide, 1/8" thick strips on top of the plates. Would I need to make the indentation where the bit touches during calibration? I just want to make sure the depth during carving is correct. Again great job.
    Bergerud, Couldn't we take your jig and add the 1/8 strips into the design so they lay over the top plate? What do you think?
    I think that is right. 1/8" strips taped to the tops of the plates should be good. The strips do two things: raise the head to give clearance under the y truck and raise the bit touch point. The touch point has to be 1/8" higher because that is how much larger the radius of the 4" pipe is. (4.5-4.25)/2.

    The machine will carve thinking it is carving a 4.25" diameter. This will result in the pattern being stretched by 4.5/4.25 = 1.06 in the x. (The pattern which is sized in Designer to wrap around the circumference of a 4.25" diameter will be stretched when it is fit around the circumference of the 4.5" diameter pipe.) To compensate for that, one could stretch the y of the pattern in Designer by the same amount. That way, the pattern will end up one to one again. (It is, however, only a 6% difference and maybe it does not matter too much.)

    Maybe 200k will chime in with some tips since he is the one who has done it.

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