I have an application to attach a cup brush with a 1/2" arbor hole to a
plastic handle. The brush fits into a 3/8" deep flat-bottomed (2" Forsner
bit) hole, the handle is 3/4" thick. I hope to find a short, fat
washer-head screw that will hold well into the plastic with aggressive
threads. I imagine a tapered screw with a 1/4" to 3/8" root that tapers to
a point. Something we can power drive quickly and is rust resistant. Maybe
an automotive fastener for plastic. What would I call it to Google it? Any
advice?

Sort of like a LAG screw with a washer?

Dan

Tom Gardner wrote:

I have an application to attach a cup brush with a 1/2" arbor hole to a
plastic handle. The brush fits into a 3/8" deep flat-bottomed (2" Forsner
bit) hole, the handle is 3/4" thick. I hope to find a short, fat
washer-head screw that will hold well into the plastic with aggressive
threads. I imagine a tapered screw with a 1/4" to 3/8" root that tapers to
a point. Something we can power drive quickly and is rust resistant. Maybe
an automotive fastener for plastic. What would I call it to Google it? Any
advice?

I predict a lot of pain if you don't
pilot-drill the hole. That said, Mc
Master has SS truss-head Philips that
might meet your needs. Take a look
at 93406A296 or 93406A315.

If you're sure you don't want to pilot-
drill, McMaster also has a self-drilling
bolt with an extra-wide head. 92685A610
is 1/4-14 and 1" long with a flange
diameter of .610"

Sounds like a real problem application.
I'd start looking about in the fastener catalogs for a very coarse threaded
sheetmetal type screw in a length of about 1/2" for this. I'd probably also
want to back up the screw with some adjesive if possible as this will help
keep the brush in the handle. There are some epoxies that are good for
bonding to plastics that will help a lot in this application.
One of the big problems is that your central hole that is produced by the
bit is not a common taper for screw tips so you may end up with some
problems with holding the brush in.

--
Why isn't there an Ozone Hole at the NORTH Pole?

panhead sheet metal screw - panhead wood screw ...
panhead shoulder screw

maybe just panhead.

Hul

Tom Gardner wrote:
I have an application to attach a cup brush with a 1/2" arbor hole to a
plastic handle. The brush fits into a 3/8" deep flat-bottomed (2" Forsner
bit) hole, the handle is 3/4" thick. I hope to find a short, fat
washer-head screw that will hold well into the plastic with aggressive
threads. I imagine a tapered screw with a 1/4" to 3/8" root that tapers to
a point. Something we can power drive quickly and is rust resistant. Maybe
an automotive fastener for plastic. What would I call it to Google it? Any
advice?