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Multiple rod turner

November 22, 2010

For some time I turned my rods for varnishing wraps , one section at a time, on a gizmo I made with a spitbraai motor (braai is the South African equivalent of barbeque and almost a national sport ). The motor’s  gears gnarled and gnashed their way into the ears of the family, driving my hardwon popularity stakes for washing dishes etc. down the drain of irritation. And then I would have to do the next section. And then the next section. And then the next of the 5 coats. And ….you get the picture. I was ‘persona non grata’ every time I approached the final stages of a rod.

So whilst looking for a much needed replacement  motor at a kid’s science expo shop I stumbled across some plastic gears that  were begging to be  linked together into some sort of gadget. The begging crystallized into “please can we be a multiple section rod turner”, which is what is shown here.

The dimensions of the device and the spacing  of the gears, position of the motor, cradles etc. are all determined by the sizes of the various components so it is not possible to dimension these meaningfully here without those dimensions. I can however describe the construction and assembly process.

motor holder stand

 

support stand

 

rod holder

motor gear

SEQUENCE OF CONSTRUCTION

  1. Calculate the spacing for the 6 ‘holder gears’, the ‘motor gear’ and the motor. Bear in mind the motor gear can be placed alongside any of the gears.
  2. After determining the basic layout make the two timber T-stands
  3. Measure and drill holes for the 6 gears and for the bushing for the motor arbor into the motor stand. The gear holes should be the same size diameter as the machine screws.
  4. Measure the position for the holes for the cradle pit son the supporting stand and drill these. The pit hole size should accommodate the felt lining thickness and the rod section.
  5. Cut slot openings from the edge of  the supporting stand to the cradle pits. Make sure the throat at the mouth of the pit is wide enough to accommodate the felt lining and the rod section
  6. Cut felt to size and glue as a lining into cradles
  7. Fit the arbor bushing into the motor stand. The bushing is not essential but nice to have – you could simply drill a very slightly oversize hole
  8. It may be necessary to make up an arbor that is threaded on one  end and shaped to fit the motor on the other unless the arbor that comes with the motor is useable as is. Insert the arbor through bushing and into the motor.
  9. Fix the motor to the stand.
  10. Fix the motor gear to the arbor. I epoxied and bolted the motor gear to the arbor
  11. Turn the maple rod holders to size and cut to length.
  12. Drill a hole just larger than the machine screw diameter through each maple holder .
  13. Increase  the hole diameter of one end of the maple holder to a dimension large enough to take the largest female ferrule you envisage using  ( mine is approx 3/8”) . This hole must stop short of the end of the maple holder by 3/8” or so.
  14. Tap sideways through the maple holders  to receive the holding bolts. Position the tapped hole so that the holding bolt will meet the shortest ferrule you envisage using allowing the ferrule wrap to be outside of the holder.
  15. Glue and screw the gears to the maple holders
  16. Slide the machine screw with a washer into the large hole of maple holder. Slide a washer onto other end and fit a nut. The nut should tighten the washer up to the gear but leave just enough play so that the gear and maple holder turns freely on the machine screw. The nut can be locked in place with nutlock.
  17. Fit washers so that the holder gears line up with each other and with the motor gear.
  18. Slide the end of machine screw through the stand, slide a washer onto the other side and tighten on a nut. The nut should be locked in place with nutlock.
  19. The holders should have their gears enmeshed with the holding bolts orientated so that they won’t bump into each other as the turner rotates
  20. That’s it ready for action

NB : The maple rod holder component  should be turned on the lathe to a diameter where the fastening bolt will not bump against the adjacent maple rod holders as they all rotate. This should be worked out with the fastening bolt screwed in to the maple component to  a point where it just does not enter the hole in the maple ( the hole that will receive the rod) . Be careful to accommodate the motor size itself in planning the height of the stands and the location of the gears.

The device should be bolted together so that the parts that are attached are held firmly and the parts that are required to rotate are allowed to rotate freely but with minimal play.

Hopefully the drawings provide  an adequate explanation.

OPERATION

When turning the rod sections  I first wrap the ferrules in layers of masking  tape to the approximate diameter of the hole in the maple before inserting them and tightening the holding bolts.

The stand that supports the other end of the rod sections must be moved to a point where all wraps on all sections are well clear of the felt lined cradles. The pit of the cradle itself should really be made a little deeper than shown here to avoid having a rod section attempt to climb out and escape from the cradle as it rotates. I currently prevent the possibility of this unacceptable behavior by wedging short  dowels into the cradle openings.

As a last word of advice, unless you have a dedicated space far from sensitive ears, try to get the quietest motor you can.

It is a real treat to be able to varnish wraps on all sections of at least one rod (two if they are 2/2 rods) at the same time. You can of course increase the number of gears and holders ad infinitum.

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