Making WWI Rotary Engine Cylinders

Discussion in 'Tips, Tutorials & Tools' started by Gil, Apr 2, 2007.

  1. Leif Oh

    Leif Oh Member

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    This is really good, particularly since it doesn't involve exotic materials. (Even if I have not come across Teflon tape yet, I now have a reason to keep my eyes open...)

    The result is magnificent. And I am happy about the vellum paper and PVA glue bits - those I should be able to handle!

    The cylinder top bit is ingenious.

    One thought - it might even be possible to make taped cylinders this way, shouldn't it? If you make the original slightly oversize, a wedgeshaped cut could yield a tapered part of the cylinder, married to a straight part, right?

    Leif
  2. Gil

    Gil Active Member

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    Some Dialogue...,

    Hi Leif,

    Glad that you like the result. Amazingly enough it still looks good even with the magnification from the macro. I've been debating about the best way to proceed to obtain the transitions in the fin diameter along the cylinders length. One way would be to use a method like you describe. The "fitting" seams required to obtain the contour, as you describe, really shows up well (unfortunately) defeating the original purpose. And yes, several variations were tried.

    I am currently trying a slight variation of the fin forming technique that will incorporate the tapered section as part of its construction. The aim is to form the taper as part of the crushed corrugation. The image below shows an interim form used to emboss the corrugation into the vellum cylinders. The wire used to wrap the cylinder is 30 gauge and is too small. Next I'll try it with 24-26 gauge wire which is better suited to the purpose. As you might have already realized this technique depends a great deal on materials and their geometries. Getting all the parameters within a working range is the stuff of experiments and the most wonderful teacher of all time, the trial and error development method.

    Teflon plumber tape is used to seal pipe joints and can be found in any home improvement or hardware store World wide now. A strip of plastic wrap can be used instead. I've found that relaxing the corrugations by stretching them out makes removing the tape a much easier task. This is the original reason I went to teflon tape but now that I've found an easier way of removing it it's not really required any longer.

    Best regards,

    -Gil

    [​IMG]
  3. Gil

    Gil Active Member

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    Some Dialogue...,

    Hi Leif,

    Glad that you like the result. Amazingly enough it still looks good even with the magnification from the macro. I've been debating about the best way to proceed to obtain the transitions in the fin diameter along the cylinders length. One way would be to use a method like you describe. The "fitting" seams required to obtain the contour, as you describe, really shows up well (unfortunately) defeating the original purpose. And yes, several variations were tried.

    I am currently trying a slight variation of the fin forming technique that will incorporate the tapered section as part of its construction. The aim is to form the taper as part of the crushed corrugation. The image below shows an interim form used to emboss the corrugation into the vellum cylinders. The wire used to wrap the cylinder is 30 gauge and is too small. Next I'll try it with 24-26 gauge wire which is better suited to the purpose. As you might have already realized this technique depends a great deal on materials and their geometries. Getting all the parameters within a working range is the stuff of experiments and the most wonderful teacher of all time, the trial and error development method.

    Teflon plumber tape is used to seal pipe joints and can be found in any home improvement or hardware store World wide now. A strip of plastic wrap can be used instead. I've found that relaxing the corrugations by stretching them out makes removing the tape a much easier task. This is the original reason I went to teflon tape but now that I've found an easier way of removing it it's not really required any longer.

    Best regards,

    -Gil

    [​IMG]
  4. Leif Oh

    Leif Oh Member

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    OK - got it. In order to get the taper you make your own screw, so to speak, with different diameters. Ingenious!

    L.
  5. Leif Oh

    Leif Oh Member

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    OK - got it. In order to get the taper you make your own screw, so to speak, with different diameters. Ingenious!

    L.
  6. Ben Gal

    Ben Gal Member

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    Tire Treads

    Gil:

    I stupidly overlooked your link to this that you put into my E.ll thread. I still haven't got to making up the U.1 engine, but I will do it this way.

    As I am also doing the P51D, I looked at this method for tire treads - using embossing on the scored handles of the tools we use everyday gives a nice tread pattern. I still haven't figured out how to get it on the wheels!

    Thanks for this work.

    Keith
  7. Ben Gal

    Ben Gal Member

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    Tire Treads

    Gil:

    I stupidly overlooked your link to this that you put into my E.ll thread. I still haven't got to making up the U.1 engine, but I will do it this way.

    As I am also doing the P51D, I looked at this method for tire treads - using embossing on the scored handles of the tools we use everyday gives a nice tread pattern. I still haven't figured out how to get it on the wheels!

    Thanks for this work.

    Keith
  8. Gil

    Gil Active Member

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    Quiet! Thought Processes at Work...,

    Hi Fin Fans,

    I've found that interspersing periods of thought along the development process is one of the best techniques for making the next logical step in the sequence. This is especially true after a series of abject failures. The above screw embossing form didn't work quite the way I had envisioned it. The following items have now become very clear:

    - Wrapping the screw thread embossed paper with plastic wrap maintains the outer circular "ring" structure such that it folds or crushes along the outer most profile. Conversely a close fitting inner shaft supports the inner "ring" structure such that the fold or crush is along the inner most aspect. The keywords here are "holds it in place" so that the collapse or fold is along an expected or controlled fold lines.

    - The above implies that the paper needs to create it's own diameter when collapsed thus collectively creating a contour. This means that the inner shaft needs to be kept at a constant diameter otherwise the telescoping or collapsing along the inner fold lines cannot be accomplished.

    - The outer extent of the paper "thread ridge" sets the diameter difference along the longitudinal length of the structure. The plastic wrap being the flexible "containment structure" allowing it to collapse along the intended fold line ("thread ridge").

    - The collapsing technique, paper type and preparation doesn't need to be changed. It works well (although the use of 100% cotton bond 24# might be tried).


    I am currently building the third generation embossing jig for the next and hopefully last phase..., Words & pictures if it's a success, onl words if it's not...,

    -Gil

    P.S. Keith: You might want to try tulle netting. It can be found at any yardage store. It stretches easily and can be stretched slightly to form a diamond shape and glued to the tire surface. I've tried it experimentally and it looks pretty good.