I spent the weekend puttering with the Korona, shimming and building a new lensboard. I worked on the focus pinions first. At some time in the past someone had managed to snap the knobs off the lefthand side of the camera leaving nubs just big enough to know something used to be there. I disassembled by removing the stop screw at the end of the bed and working the standards off the ends. Unscrewing the brackets I found a strip of spring steel tensioning the gear rod against the rack gear, rather ineffectively I might add. More about this later.
I decided the best solution was to braze a washer onto the end of the shaft to allow a stop for the lockdown knob to pull against. Lacking a properly dimensioned washer I has to drill a disc out. First of I though a penny would do until I hit it with the brazing torch and watched it wither and fall to the bench like a dead leaf. Wierd! Forgot that pennys were now made with zinc! Poking around located some knockouts from an electrical box. Marked and drilled they brazed on pretty well with only a little popping and flaring from the zinc plating on them.
While fitting them in I decided a little attention to the fit of the gears to the rack was due. Found out the notch the gear shaft was set in was way too deep and allowed the gear to jump over the rack teeth. Simple solution was a wood shim set on each end of both shafts between the gear and knob ends taking a little under 1/8th inch out of the depth with no binding. I put it all back together and looked it over. Messing with the geared front rise I notice it is jumping teeth too. Now I have to take the front standard off again.
This gives easy acess to the plate that holds the gear shaft in. Removing them let me roll the board up and out of the frame. This time I find the trouble is too loose a fit between the inner and outer parts of the rising front.
Since all I wanted was some slack removed at the gear I opted to use an iron on oak veneer strip I found at Home Depot a while back for another project. I cut a slip with the grain about 1/2 inch by 1/8th and used my tacking iron to seal them in place at the bottom of the inner part of the front. This made a fit that got rid of the slippage with no aparent binding.
The lensboard was neccesary because the one that came with it was a Burke & James board. Same 6 inch square but the flange is much thinner than a Korona needs. The Korona dimensions need a 1/4 inch thick flange cut slightly more than 1/4 inch in on my 3/8th thick board or you might just use a simple 1/4 inch board. I think the thicker board gives a better light trap.
Hopefully this will make the camera easier to use with some of the rattles eliminated.