Fabricating hinges? Conflicting plans diagrams.

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skeeter_ca

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Ok, looking at my plans of my Volmer VJ-22. I noticed a discrepancy in fabricating the hinges. They are like the Aeronca hinges on the rudder and elevators. The plans state several different sizes. .375 od x 060 wall, .380 od x 060, 375 od x .250id. All 4130. And it states to "ream to fit" after welding. After converting the numbers over I come up with uncommon sizes. Best I figure is it looks like 3/8" OD x .065 wall with .245 ID would be my best option and then ream to fit a .250 hinge pin. Would you say this would be correct?
 

Hot Wings

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The plans state several different sizes. .375 od x 060 wall, .380 od x 060, 375 od x .250id. All 4130.
All the same - it's just the kind of thing you find in "old school" plans were the designer expect a level of fabrication skills and experience that was more common among the builders in the past.

3/8" X .065" should work just fine and will ream to fit a .250" pin - which may vary in diameter a few thousands from .250"
 

Riggerrob

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The other advantage of "ream to fit" is that if you don't weld the hinges on perfectly straight, you have a second chance to straighten the hinge alignment with a reamer.
 

skeeter_ca

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Also, How do I "ream to fit" after I have welded the hinge tubes to the stab and elevator? There is not enough room to get in there with a drill. The reamers are only about 6" long. One side would be easy to get to but the other is about 12" from the edge of the stab.
 

ekimneirbo

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Ok, looking at my plans of my Volmer VJ-22. I noticed a discrepancy in fabricating the hinges. They are like the Aeronca hinges on the rudder and elevators. The plans state several different sizes. .375 od x 060 wall, .380 od x 060, 375 od x .250id. All 4130. And it states to "ream to fit" after welding. After converting the numbers over I come up with uncommon sizes. Best I figure is it looks like 3/8" OD x .065 wall with .245 ID would be my best option and then ream to fit a .250 hinge pin. Would you say this would be correct?
Most likely you will fare better if you obtain an adjustable reamer. I'm not sure what you are using for pin or hinge plate material but drill blanks can be had in different diameters by .001 increments if you need to fine tune your fit. Also, while I know builders want a good fit to help avoid play in the controls, you also need to insure its not too tight where it might gall or rust together.Are there any readymade stainless hinges from the marine industry that might work for your setup?
 

ekimneirbo

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Also, How do I "ream to fit" after I have welded the hinge tubes to the stab and elevator? There is not enough room to get in there with a drill. The reamers are only about 6" long. One side would be easy to get to but the other is about 12" from the edge of the stab.
You should be able to make an extension shaft which would hold the reamer. Drill the end of the extension shaft a little smaller than the reamer end.Use a lathe to drill the hole to insure concentricity. Then put the reamer in the lathe with the shank facing outward. File and polish until you are about .002 bigger than the hole in the extension. Remember, drill bits often don't drill an exactly round hole. So fitting the reamer will be a trial and error situation. Get an old drill bit or pin of some kind and file it until it is a slip fit in the hole. Then mic it to determine its size and file your reamer shank until it .002/.003 larger than the test pin. Next put your reamer in the freezer. When the reamer is good and cold (30 minutes) Use a torch to heat the end of the extension shaft and slide the reamer into place. This has to be done quickly. Hold the extension shaft vertically in a vice with the hole facing up. Heat the extension shaft and grab the reamer for insertion. Have a small wooden board to place on the top of the reamer and tap it with a hammer to insert the reamer if necessary. If it resists your efforts, file/polish another .001 from the diameter of the reamer shank, and refrigerate again. The reamer probably needs to be inserted a couple of inches at least to insure concentricity. You can usually find either a "letter" drill or a metric drill that will make a hole slightly smaller than the standard size of the reamer shank. :) OR, you can look on Ebay for "Drill Bit Extension" and see if any ready made one will fit or easily adapt to your needs.:ban:
 
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