Neck bolt bar dimensions

[kiwigeo]

Trevor,

When you discuss the neck bolt bar and the mortised hole for same you use imperial and metric dimensions for the former and latter respectively...ie and 3/8" square brass bar (first para section 14.6) and 10mm hole (second to last para of section 5.3.1).

Am I ok to use both a 10mm metric bar and 10mm mortiser bit?

[Trevor Gore]

Simple answer, yes.

The detail is, as ever, more complicated. The easily available dimensioned bar stock is 3/8" in brass and 10mm in aluminium. The easily available mortisers are 3/8". Due to manufacturing tolerances etc. none of these options will provide a fit - you won't be able to get the bar in the hole. The simplest route is to reduce the bar a little (file, belt sander, drum sander, whatever) and the easiest material to work (unless you have a milling machine) is the brass. So relieve the brass a little and all is good.

If you can get a 10mm mortiser bit, you should be good to go straight away with the 3/8" brass (9.5mm). You'll likely find the 10mm aluminium too tight a fit.

Word of warning, though: Just because someone advertises a 10mm mortiser doesn't mean it's not actually a 3/8" one, so make sure you're buying what you think you're buying.

[kiwigeo]

Thanks Trev.

[Allen]

While metal might come specified as a certain dimension, it's best not to assume it will be either. You only have to buy some from different sources and put a set of micrometers on them to find that there can be an astonishing degree of variations to what you thought you bought.