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----- Original Message ----- From: "Dave King" <email@example.com> To: <firstname.lastname@example.org> Sent: Friday, April 12, 2002 7:55 AM Subject: Re: To David Soderman: A Little Test > ----- Original Message ----- > From: "Ernst Dinkla" <E.Dinkla@chello.nl> > To: <email@example.com> > Sent: Thursday, April 11, 2002 5:40 PM > Subject: Re: To David Soderman: A Little Test > > The scan movement can't be done with the gear-teeth and a gear > > wheel. The only workable solution possible that includes the gear > > teeth of the carriage could be a belt that fits in the gear teeth > > over a longer stretch and the belt itself driven by friction or > > very fine teeth on the inside. But most likely the carrier is > > clamped between some wheels and relies on friction movement only > > for the scan movement. > > If it still has to move the uncoupled gear wheel then that in > > itself could be a source of vibration. > > > > The weight difference between the carriages is considerable, > > their length varies as well so a rack and pinion kind of movement > > with teeth of that size isn't an option. I have seen better gear > > solutions on 19 th century canal locks. I'm tempted to open the > > scanner as my plan to make another type of glass carrier should > > be compatible with the scan mechanism in all aspects. Maybe > > tomorrow. > > > > Ernst > > > If you do get in there could you also have a look at the mirror(s) > positions? Wondering if they're user accessible for the inevitable day they > need cleaning. Taken off the steel cover and resisted my desire to take it further apart. First, there is most likely just one mirror that bends the light from vertical to horizontal and so to the rear of the scanner where the lens and the CCD are located. Cleaning that mirror and the lens that must be horizontal at 1/3 from the rear of the scanner is not a DIY job. There's a cilinder like shaped chamber made of I guess glassfiber reinforced thermoplastic (looks more like a Bakelite but I doubt that is true) that holds the lens, mirror and at the rear end the CCD. Not something to take apart and put together without the right calibrating tools. The carrier is inserted in a traction unit that positions the carrier for scanning etc with the gear teeth at the side of the carrier. For scanning the whole traction unit glides on two rods with a traditional 3 point brass bearing setup. That movement is done with a finely machined screw spindle (don't know the right English term for it). So far I do not see any flaws in the mechanical design but maybe one; I can't see how the carrier is locked in the traction unit. From above some flat springs keep it down but if it is only arrested by the gear wheel on any lengthwise movement and sideway movement then I fear that it is difficult to keep out all vibrations on all the carrier models with their different weigths and lengths. Remember that the carrier is 'locked' in two extreme positions in the traction unit when it scans the first and the last image. The brass bearings are capable enough to keep the whole unit straight for a long time. But if a Nikon tealady (KME) did design the clamping of the carrier in the traction unit then there may be a problem there. A good vibration meter on the carrier will tell a lot. I think it must be in the CCD arrangement what causes the banding but I will take the cover off once more to see how the carrier is clamped down. Ernst - Turn off HTML mail features. Keep quoted material short. Use accurate subject lines. http://www.leben.com/lists for list instructions.