Brass Gears for the HP/Agilent 8640B Signal Generator
On offer are custom-fabricated brass gears for the HP/Agilent 8640B signal generator. A well known weak point of this generator is the gear train connected to the frequency range switch. The gears are made of Delrin with a brass insert. Over the years they have tended to shrink and split. You probably already know that if you have one of these beautiful generators!I had the original delrin gear from my ~1983 instrument 3D-scanned and reproduced in a machine shop using a semi-automatic process with custom jigs and fixtures. These are practically exact replicas of the original 1983 gears, and will work just as well with no more splitting or cracking!This set of 3 gears (2xCombo + 1xSpur) will replace all the 3 gears that suffer from this problem.As some of the machining process is manual, please be aware that there are very small cosmetic blemishes on the gears which are in fact barely visible and do not affect their functioning (see close-up photo).The set screws required are #4-40 (the same size as the original). I usually include 4 of them if you order a set; they are 1/4" in length (a bit longer than the original)Drop me a line if you need multiple of just one type such as Combos, or some other bespoke combination.Important notes:1. If you find the movement seems a tad stiff or squeaky with these gears, do NOT immediately try to enlarge the hole or reshape any teeth! Some stiffness is natural when metal meets metal - use a drop of machine oil on the shaft and/or teeth - this usually works wonders. Also make sure you read the "A9 Reassembly" section in the 8640B manual which has advice on what to do if the gear shafts bind causing movement to become stiff. Be prepared for 30+ minutes' worth of fine-tuning of the gear assembly before things hit the sweet spot.2. On occasion some gears may not slide easily onto the shaft at first shot. This is because of manufacturing tolerances and/or small burrs in the gear hole. If this happens, here is what works: just take some coarse sandpaper (#60-80), make a roll and run it inside the shaft for about a minute or two. Blow away the dust from the shaft and screwholes, swish it in some alcohol if you like, and it will fit perfectly.