Lost wax casting method LM Cox15 R/C

As I mentioned before, a speed control carburetor to Cox 15 Medallion program was performed today. The adapter piece is made from light metallic material that is used for a motor crank case. This procedure is done by Lost Wax casting method with precision. 2 pieces are made with sheet wax for the crank case and the carburetor promptly, they are combined together and formed firmly. It is set on the rubber setting mount following sprue setting. Then avoiding any bubble formation on the wax pattern, investing material is pored in the casting ring under vibrating condition. Casting would be done in 2 days.

L.M.Cox Medallion 15

I got LM Cox Medallion 15 motor from Yahoo Auction the other day. It has been giving me a strong motivation to set up throttle valve for speed control since half a century ago. Lightest crank case with machinery cutting and grinding method and Schnurle scavenging port type combustion design.
After disassembling this motor, an idea came up in my mind to make the red plastic part that is forming the carburetor construction with a light metallic material to set up throttle system.
This plastic part plays a part of just holding carburetor and has nothing to do with intake port timing. So, keeping splay bur in position with adequate fuel amount is the only duty for this. Consequently, under the condition of avoiding pressure leak, making up throttle body holder construction is my work.
In order to remove this part full disassembling task was required especially for removing a drive washer the precise oil press machine was indispensable, removing a drive washer with press machine is a key to do that. I'm going to show the steps here to make a one-off part with casting method in very near future.

OS 32F carburetor drum spring

In spite of careful checking in fuel pressure line especially the one way valve and fuel filter constructive screw tightening with O shape rubber ring, OS 32F motor with YS fuel injection regulator system does not run stable at high speed, how come? Deeper consideration about this inconvenience led me some conclusion that the tension spring in the carburetor drum construction that plays the part of keeping the drum position laterally for the secondary fuel needle closing point and preventing inconvenient lateral sliding movement caused by the pressure oscillation in 2 cycle motor crank case produced beneath the piston.
A tiny coil spring is designed to keep the throttle valve drum in an adequate position to measure the amount of fuel firmly at any speed, so the tension strength of it is decided at some very suitable value after researches and developing by the factory. Any change would not permitted into a weaker strengthened one by an user based on some happening idea, reducing rotating resistance just like I did this time. Beginner and layman would realize that how much efforts had been done by the engineers after this kind of stupid experiment. Remembering the past, 35 years ago, I had an experience about carburetor drum oscillation phenomena on OS7D carb while idling operation. equipped in OS61VF motor. I should remember about this fact before I did the similar manners on OS 32F motor.

OS FS20 in good condition

Very rare and seldom vintage model 4 cycle motor was obtained from Yahoo Auction at some reasonable price the other day, OS FS20 is one of the smallest one in the world. The seller dictated some disadvantage instead of relatively low price, lack of compression like nothing and dirty a bit, but I had some self confidence to repair it and survive as an actually useful motor for participating in the meeting of Golden Age & Old Timer held twice a year at Kyoto Uji.
Fully overhaul was done on it, disassembling and cleaning a parts for removing sludge piled between a piston grove and piston ring, valve guide and valve, cam shaft supporting construction, also replacing crank shaft supporting main bearing #6901.
Thanks to my desperate effort on this tiny motor, a miserable FS20 has been survived like a phoenix, strong compression that is indispensable for normal operation was regained.
This motor would be observed by some enthusiastic old modelers with big surprises burdening on the model airplane "Super Tiger 102" that had been designed in single channel period by Jumpei Kato who had been an elder brother of Masahiro Kato, famous for his champion ship at the very beginning of model airplane age about half a century ago.

Oil pressure switch in VW1302 Super Beetle

So long period of time have I been ignoring the motor oil leakage at the oil pressure switch portion in VW 1302 Super Beetle AD motor. Made up my mind to stop the inconvenient phenomena, most of my friend propose the opinion to replace the part into new one, because the material of adjacent part of it is made of plastic, it has shrunk by long time of thermal cycle over 40 years. Basically agree with the opinion, I tried to repair it by means of fulfilling the space with Alpha-Cyanoacrylate material.
As the original switching function is maintained after the experimental trial, I would like to continue this old part in position for the time being.
I have an intention that the original part should be maintained and continued so far as the designed physical property is in alive condition.

On the other hand, the opinion of my son is just like an opposite one, he says that  any long used and having any problem should be replaced immediately into a new part because he would be at a loss if his car should stop on the way with a distance.

As an another story, a washing machine for family use with the name "Gentle Lovely Wife" was deserted without notice by my Xanthippe in spite of the promise with me that I would repair firmly as usual after coming back from work. In addition, she payed some money for bring it out!  The machine could have been repaired and regained the original performance with relatively easy task for me.
She cried, "I don't like to continue this kind of old fashioned and ugly designed!".
I just had not enough energy to explain about her wrong opinion and I said nothing about that. Just old and out of fashion are the reason to desert a precious machinery, how come, said to myself?

As a conclusion today, any machinery has it's history and an enthusiastic intention by the designers and the engineers.

Minolta MD 75-200 in action

I make it a rule to use Minolta MD Zoom 75-200 mm to make snaps on the theater Japanese dance. It has no sophisticated mechanism like auto focusing and exposure measuring while iris opened condition, also anti camera vibration. Though the lighting condition was not so favorable today, relatively good transparencies were obtained, I would be able to satisfy the dancers without complaint. Hand holding exposure without a tripod device obliged me to endure some hard condition because of the weight of the device, Canon 7D camera body  and Minolta Zoom lens, also because of my age.
Here want I mention about the modification to use Minolta SLR silver salt film period fully manual lens onto Canon EOS mount. Original Minolta bayonet nails were removed and Canon EOS bayonet mount nails in genuine Canon body cap were adhered onto the flange with special acrylic resin material 4-Methane, but the critical discrepancy, flange-back value Minolta SLR 43,50 and Canon 44,00 was compensated by adjusting the mechanical constructive part that is prepared for factory production line convenience, moving the lens constructive barrel 0,50 mm forward could be compensated without problems relatively in easy way, the value was within the adjustment tolerance for lenses.
Consequently, I did the same modifications manners onto several Minolta SLR lenses, zooms, fixed focusing length ones including those for short distance exposure purpose, 50 mm macro and 100 mm macro. All of them supplies me some satisfactorily transparencies now.
As a not few of Minolta SLR lenses are sold at very cheap prices like nothing, I could obtain them without teasing my purse, it probably because of  critically shorter flange back value, almost of the people in the field must have thought it's no way to utilize shorter flange back lens to another longer f/b body. This is why the selling prices are so cheap, so I conclude. Though my modification at the mounting part might be some irreversible distraction, my attitude is not a braking of cultural resources. All the Minolta SLR lenses I obtain now could survive and re-born as a actually useful lens on Canon EOS body like a Phoenix.
Lens designing technology must have been established at the end of the silver-salt film period, because the designing of digital camera is not changed so fundamentally so far as I see on the catalog of SONY company, most of the researching and developing engineers were rehired by them after Konica-Minolta's absorption-type merger.