Choosing correct T.P.I, make your own air saw blade

In the previous blogpost some ventilation openings was created. The work began with drilling holes from which the opening was widened with the air saw. The blade used was usual hacksaw blade cut to a suitable shape in the bench shear, Image 1. Note the very slim blade used, slim enough to permit sawing from a 4 mm hole if done carefully.

Image1 Hacksaw blade cut to suite more extreme sawing.

Since long I make my own saw blades for the air driven machine using hack saw blades, incidentally Bahco Sandflex, probably the very best hack saw blade on the market. It is much cheaper to make own blades, a 12” blade is split into 4 short ones, Image 2. The direction of the teeth is important, they point to the left in the picture

Image 2 Splitting a hack saw blade.

Hacksaw blades come with 18 or 24 or 32 T.P.I (teeth/inch). The choice of T.P.I has been described in the book but one thing of special interest is the problem with sawing aluminium sheet. The aluminium often smears to the blade. But, if the blade is dropped into coco nut fat, Image 3, the problem will vanish.

Image 3 The saw blade is smeared with coco nut fat.

In Image 4 the box section has been put into place. In the nearest end a recess for a cooler tube has been made. During the fitting process the box was hold in place by screws and washers through the hole for the anti roll bar.

Image 4 The box section with its recess for the cooler tube.

After the box section was welded the cooler was temporarily fitted in the upper end rubber bushings. With the cooler hanging vertically the cooler profile, see Image no 3 in blog post 3, was held in place with three self tapping screws, Image 5. After welding the profile to the beam the work with the vertical walls started, Image 6.

Image 5 The cooler beam temporarily fitted with self tapping screws.
Image 6 The walls are during welding.

In the next step the remaining part of the front valance was the issue but first the repaired area was painted, first with a primer followed by a layer of red colour. The painting was done with matched colour, Image 7. With the paint applied the front valance could be carefully fitted and the welding. The work was finished with fitting the new lower part of the front valance, welding and lead filling before transportation to the paint shop, Image 8.

Image 7 Upper part of front valance is reused. Note the painting of the underlying structures just painted.
Image 8 The new front valance welded and leadfilled.

Panel Beating Doctor Bengt Blad

At this point in my life when I was about three quarters through the medical schooI I discovered the English wheel and the Eckold machine, and, one thing leading to another - no more time for med school.

More about the book

This book, with around 1,500 pages of reader-friendly text and about as many illustrations, is a summary of 40 years of working with vintage, collectors' and racing cars.