Method: Pneumatics Recovery (hinges + cloth)

You are of course welcome to read through the entirety of the following post (I assume that’s why you’re here), but if you would prefer to watch a video tutorial on the same topic instead, then click here. I don’t plan on going into as much detail as Art Reblitz in his book (pp 52-78), but I will at least furnish a proper introduction, to give you a taste…

First, some assumptions, pertaining to teardown:

  • That the pneumatic has been carefully removed from its trunk (whether gasketed and screwed, or glued).
  • That the cloth was slit lengthwise between the bellows, and then peeled back and removed.
  • That your boards are sequentially numbered in pairs, for easy identification, on the inside face of each. (the inside board should also be marked on the exterior in a suitable place, if it happens that a particular pneumatic needs to be remounted in a particular location)
  • That the hinge was removed from both boards, and the old hinge glue lightly sanded away.
  • That any remaining cloth was scorched or smoothly sanded off, and the edges all sanded smooth.
  • That all sides are square and true, and each board is precisely the same dimensions as its mate.

Starting with these two prepped boards, we will remake a pneumatic!

Let’s begin with the hinge.

First, flashback: after having removed the original hinge (perhaps long ago), you found a source of identical but new material; likely something in the ticking or twill canvass line. It really must be 100% cotton. Having measured the old hinges, you recreate them by cutting first to length (to create a strip for a whole section). You have paid proper attention to follow the orientation of the weave, so you cut in the right direction. You then crease the hinge by folding and running a warm iron over the surface. The strips may now be cut to width to create the pneumatic hinges.

Ironing hinge material for bellows

Now, flashforward! Your pot of hot hide glue is at the ready. As are your pieces, organized and prepared. You may choose to insert a piece of wax paper in the hinge fold, to prevent gluing the hinge to itself.
Glue the end of each board where the hinge will attach. Pick up your hinge, place it on one board. Quickly take the other board and place it on top. Check positioning of the hinge (slight inset), and then clamp, with a medium spring clamp (I find large binder clips work well for this, and they are cost-effective!). Let dry, hinging is done.

Hinged pneumatic boards, waiting to be recovered

To verify the hinge, once the glue is dry gently try to wiggle the open ends to opposing sides. If there is noticeable play, you have failed. Remove the hinge and start again, until the ends travel freely and easily to open or close, but resist any sideplay.

John Tuttle has a video on this, with a slightly different perspective. Check it out here

Now, the recovery with cloth.

Again some assumptions: you have the proper bellows cloth, with appropriate thickness for bellows size, a measuring tape, you have a nice, sharp, pair of scissors, glue pot at the ready, and if necessary a jig to speed up accurate, consistent production (e.g. this)

Cut strips for your bellows, the width of which will be slightly oversize the span of the pneumatic in question.

To recover: Lay out the strip of cut cloth (inside facing up). Position the handy jig for spacing, if you have one, over top of the cloth, offset the centre. Glue first side of the pneumatic, by which I mean both edges of the left side.  Use enough glue, but not too much.

Pneumatics in process of being recovered
Detail of pneumatic recovery

Wait. Turn.  Glue end (open) edges. Wait. Turn again. Glue third side. Wait. Glue last side. Done.

This is a bit short on detail, but it is really meant as a procedural overview. There are other things to consider as well like carefully trimming the excess cloth from the finished pneumatic, to avoid knicking the cloth and wasting your work. Refer to Reblitz’s book or John Tuttle’s video tutorial for more in-depth information.

On to rebushing!

 

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