Glazing Points & Point Drivers

[johnleeke]

On mine that is .200" or just a 'shade' over 7/32", or a 'little bit' over 3/16"

[johnleeke]

The new CRL PD9 sets the points right on the glass. This is the type of point driver that has the reputation of breaking glass as the tongue inside the driver wears out or if poor quality points are used. I have one that I just got a couple years ago and it works fine. The old Fletcher #5 sets the points with a space. Back in the 1880s George Hubbard invented the point driver. (His invention is exactly like the #5. You can see his patent models and invention papers at the American Precision Museum in Windsor , VT) He made the driver so it sets the points up off the glass to solve the problem of the points becoming a stress on the glass causing cracked glass. To hold the glass in place with the space, use a putty knife or glaziers hammer to bend the point of the point down to just touch the glass.
With the flurry of hand glazing in recent years, and Fletcher no longer making the #5 with the space, there's been a lot of points set right on the glass. In the past 5 years I've been on three projects that were recently reglazed where more than a third of the panes have glass that developed cracks after sash installation. All caused by points set on the glass. This is the problem that Hubbard was solving 130 years ago.

[johnleeke]

If you are trying to get your point driver to drive the points in further:

The good old No.5 cannot drive the points in any further than the hammer tongue will push them. By grinding down the little tabs (on the sole of the guide block that stick out forward) you can gain up to another 3/32" of drive. Hubbard's original development and patent notes for his invention of the point driver in 1880 describe the length of these tabs as the way to control how deep the point is set. We saw this on Hubbard's original development papers and patent models that are in the collection of the American Precision Museum in Windsor, Vermont. (See page 18, Windows on Preservation, published by The American Precision Museum.)
None of my green Fletcher No.5s (made in the 1950s to 70s) have an adjustment screw showing on the end of the hammer block's rod inside the spring. See the No.5 point driver part names on this parts list from Fletcher-Terry:
http://www.google.com/url?sa=i&source=i ... 7454848437

[johnleeke]

Glazing Hammer Sources:

Glazier's Hammer, rotating head

[img]http://saveamericaswindows.com/forum/download/file.php?id=145[/img]

Lee Valley Tools: http://www.leevalley.com/us/Garden/page ... =1%2C43293


Pickard Glazing Hammer, beveled head
[img]http://www.hammersource.com/images/products/preview/p21401.jpg[/img]
Hammer Source: http://www.hammersource.com/Specialty-T ... od-handle/

[johnleeke]

Setting points with a woodworking chisel:

[attachment=0]GlazingAudels-WIN_20200123_11_33_31_Scan.jpg[/attachment]