Only a rather small hole is required to tighten the screw so they work well in an almost blind hole. A bolt and nut based mandrel using a very small bolt would not be nearly as rigid as these expanding mandrels. > -----Original Message----- > From: modeleng-bounce@xxxxxxxxxxxxx [mailto:modeleng-bounce@xxxxxxxxxxxxx] > On Behalf Of Tony Wells > Sent: Sunday, April 22, 2007 12:18 PM > To: modeleng@xxxxxxxxxxxxx > Subject: [modeleng] Re: How do these work please? > > Thanks Ken, and Peter of course. What puzzled me is that while it looks a > bit like a pin chuck, to grip inside a hole, it would only be of use with > a > through hole, for access to the set screw adjuster, where a nut and bolt > might be just as easy. > > Tony. > ----- Original Message ----- > From: "Ken Strauss" <ken.strauss@xxxxxxxxxxxx> > To: <modeleng@xxxxxxxxxxxxx> > Sent: Sunday, April 22, 2007 3:16 PM > Subject: [modeleng] Re: How do these work please? > > > > They're very simple. Just a cylinder of steel (?) that has six slits > along > > the axis to make fingers. A central hole is drilled and tapped. > Inserting > > a > > flat-head screw expands the fingers. It is easier to see the design if > you > > click on "View larger picture" on the eBay listing that you referenced. > > > > > MODEL ENGINEERING DISCUSSION LIST. > > To UNSUBSCRIBE from this list, send a blank email to, > modeleng-request@xxxxxxxxxxxxx with the word "unsubscribe" in the subject > line. MODEL ENGINEERING DISCUSSION LIST. To UNSUBSCRIBE from this list, send a blank email to, modeleng-request@xxxxxxxxxxxxx with the word "unsubscribe" in the subject line.