|February 2000 Tech Feature||www.virtualindian.org|
|Home / Features / Flywheels / Part 4|
Now we really open the door for adamant opinions with the Preparation stage. This is perhaps the most important sequence of steps, as all subsequent Inspection and Assembly depends upon its thoroughness. (Machining usually leads to more Prep.)
I think we all will
agree (except for the EPA and environmental groups) that a preliminary
solvent wash is in order. Here in Illinois the cheapest practical solvent
is mineral spirits, available sometimes as cheap as $2 a gallon. My equipment
is simple: My vessel is an old double laundry tub on wheels, with rounded
bottoms and spigots so I can regularly decant to wipe out sediment. The
metal lid is hinged with a fusible link to please my evil insurance company.
Aside from a turkey baster, deep-fry baskets, and a variety of brushes,
only the air compressor adds any efficiency. My water scrub station is
similar, although I use a siphon gun to steam off
Here's where will shall diverge in dogma: Almost everything I prep gets run through a blast cabinet at some time or another. I have a 'coarse' cabinet with Aluminum oxide or the mineral media called "Starblast", and a second one with the next-to-finest grade of beads. (I look forward to affording some of those cheap plastic table top cabinents for walnut hulls, steel shot, etc.) Often pieces will be treated in both. It goes without saying that judicious choices are to be made with each piece to be blasted, such as masking, etc. We all know of the hazards here from embedded and trapped abrasives. I firmly believe that cleansing is possible as long as every trace of gummy carbon has been removed. Ferrous materials will not imbed grit, assuming proper pressures, however Aluminum does readily with aggressive abrasives like the AlO2 or silica. External surfaces are Adalox brushed at my shop (a soft nylon impregnated with AlO2, not steel, see top picture on this page) while internal areas are vigorously water-scrubbed and then encapsulated with Glyptal (a solvent resistant bakeable enamel available in quarts from Eastman ). One cannot emphasise attention to scrubbing at this point. Most motorcases will be scrubbed several times, depending upon the sequence of prep, machining, re-prep, thread chasing, honing, prep for assembly, etc. I obtain the most professional results by even blasting out the oil passages as opposed to masking: it is the gum retained that most often retains the abrasive, and no masking is 'tight' enough.
I think I'll let you all explode with dissention at this point.
From: "Marc Gunderson"
One thing I learned
years ago about reconditioning engines is that you need to clean the parts
properly before assembly. Something like Kerosene or Petrol/ Gasoline is
not good enough to remove all the dirt and grime.
PREPARATION 2nd installment: equipment
My blast cabinets are undistinguished; a cabinet is a cabinet, plumbing is as expected, etc. I do, however, use an intermediate 5 gal vaccuum canister as a cyclone before dust is hosed to a 16 ga vacs fitted with gargantuan 10"x16" filters bought from a salvage house. Separate vacuum systems are used for each cabinet. The lights are shock resistant floodlamps, and I buy the expensive (!) carbide tips for the aluminum oxide. My first gloves were sewn from raincoats, but cheap ones are occasionally available from outfits like Harbor Freight.
The pressure-washing (Hot!) stall is adjacent, and SimpleGreen has proven to be the most cost-effective surfactant.
The Adalox (impregnated nylon) brush I mentioned is a 16" wheel pulleyed down slow. This is a safe brush that will not burnish the soft case surfaces, yet gives a bright cleanliness as opposed to the dull mill profile that will collect fingerprints and other dirt. Small 1/4"shank versions of these are available at retail outlets. I use a nominal 2" bore brush for a final plateau finish on the rod races after honing. A similar brush is used on finished wristpin bushings or to gently crosshatch serviceable installed bushings. At this point, the Prep and Machining stages overlap, but microfinishes are important.
Mounted wheels are
effective on the ferrous hardware. All that is needed is a half-horse (or
bigger!) motor mounted on a benchtop with a hardware store arbor to hold
wheels, probably from the same store. Here, the peening action of a stiff
wire wheel concieveably affects the 'skin' of forgings much as shotblasting.
Rods should be 'polished' lengthwise for this reason.
Accessory appliances for prep work are infinite in variation, but blasting and wheeldressing account for the bulk of mechanical cleaning processes in my commercial circumstance. Chemical processes include not only the detergent and solvent scrubs, but paint strippers, carb digestives, even baking soda or acid etches may the order for unique circumstances. (Here in Illinois, the early black-top paving was tarred pea-gravel called 'bitumenous', and its removal from headfins can be a tedious surgery.)
The unsung workhorse
behind all of the prep equipment is the air compressor: Too big still isn't
From: "Moen" <firstname.lastname@example.org>
From: "Cotten" <Liberty@npoint.net>
From: Keith <Packardv8@aol.com>
From: "Moen" <email@example.com>
Blast cabs & wire wheel rack
|To Part 5: Balancing||