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Ron B.

Well Known Member
I see we need a 0.311" reamer , 5/15" is 0.3125" and obviously not what Van's wants us to use. Van's also calls this reamer a 7.9mm. Avery tools has there 5/16" reamer listed as under size 5/16" @ 0.3115" I do believe , should be OK.
 
Hi Ron.

Be sure to check out McMaster Carr. I think they have a depot in Ontario because their shipping to our neck of the woods is incredibly fast for the price. Haven't been able to stump those guys yet for tools/bits!
 
I see we need a 0.311" reamer , 5/15" is 0.3125" and obviously not what Van's wants us to use. Van's also calls this reamer a 7.9mm. Avery tools has there 5/16" reamer listed as under size 5/16" @ 0.3115" I do believe , should be OK.

In the world of precision machining and drilling, .0005" can mean a lot.
That is why reams are available in that size increment, and why the one specified is specifically .311 (or 7.9 mm which at the level of precision we are working to is the same size)

More specifically, if you measure a typical AN5 bolt it does not measure 5/16". They typically are .311 (vs .3125). That is one and a half thousandths smaller than 5/16". In an instance where a tight fit is desired (landing gear leg bolts for example), a hole that is .0015 over sized will be a rather loose fit for the bolt. Even .0005 larger could be undesirable depending on the actual diam of the bolt being installed.
 
Size Matters

In the world of precision machining and drilling, .0005" can mean a lot.
That is why reams are available in that size increment, and why the one specified is specifically .311 (or 7.9 mm which at the level of precision we are working to is the same size)

More specifically, if you measure a typical AN5 bolt it does not measure 5/16". They typically are .311 (vs .3125). That is one and a half thousandths smaller than 5/16". In an instance where a tight fit is desired (landing gear leg bolts for example), a hole that is .0015 over sized will be a rather loose fit for the bolt. Even .0005 larger could be undesirable depending on the actual diam of the bolt being installed.

I looked on Avery's website and they show .3110 as the size, not .3115. Normally when the plans call for a tool that we probably don't have, it is listed on the front page of that section at the bottom. I didn't see this reamer listed. I like that feature because I usually look at all of the 1st pages, so when I am ordering tools, I can order them at the same time and hopefully get a cut on freight and it's more convenient to have it when you need it. Thanks.
 
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These types of tools are available in almost every medium sized town in North America. There is no need to pay for shipping and experience time delays for these reamers/drills. Check out your local industrial area, there will be a tool shop there that probably stocks these drills and reamers.
 
I looked on Avery's website and they show .3110 as the size, not .3115. Normally when the plans call for a tool that we probably don't have, it is listed on the front page of that section at the bottom. I didn't see this reamer listed. I like that feature because I usually look at all of the 1st pages, so when I am ordering tools, I can order them at the same time and hopefully get a cut on freight and it's more convenient to have it when you need it. Thanks.

An attempt has been made to do that, but may have been missed in some instances.
What plans section did it call for the .311 reamer, and was this the first instance in the plans that it was needed?
 
Reamer

An attempt has been made to do that, but may have been missed in some instances.
What plans section did it call for the .311 reamer, and was this the first instance in the plans that it was needed?

25.2, the first section in the fuselage. I ordered one from Avery and on there site, it says it is, .3110. I received it today and the package says, .3115. So, Scott, will it make a difference that I should return it to Avery? Thanks Scott. Just received my kit and there are a cagillion parts. I can't wait to get started. Thanks.
 
Posted by me previously...

In the world of precision machining and drilling, .0005" can mean a lot.

I received it today and the package says, .3115. So, Scott, will it make a difference that I should return it to Avery?

I can't really answer that with a level of certainty. As already mentioned, AN5 bolts tend to be right around .311 in diam, but they have a tolerance, so if the ones you have to use are slightly larger it would be fine.
If it were my kit, I would use a .311 just to be sure.
 
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Reamer

Posted by me previously...





I can't really answer that with a level of certainty. As already mentioned, AN5 bolts tend to be right around .311 in diam, but they have a tolerance, so if the ones you have to use are slightly larger it would be fine.
If it were my kit, I would use a .311 just to be sure.

I really appreciate good customer service. I called Bob about the reamer and he actually has both, the .3110 and the .3115. The website listed both as .3110. He fixed the website and is sending me out the correct one, 7.9mm with a postage paid envelope to return the other one. Great customer service.
 
I just had a customer call about this thread. For years the plans have said the same for the RV-10, but Van's tech support says 5/16" is fine at .3125". That is on the landing gear bolts. We are measuring to .00005" every day, so I feel like .0015" is a ballpark, however I know what it .0015" actually feels like in a hole, and while it's not a drive fit, it's not off by much. If you assumed a pinned joint vs. a fixed joint, and you assumed the wing length is roughly 6 times the spar to spar length, the wing at the tip may wiggle .009" back and forth. That's with the bolt loose, so it's not an alignment issue. Will it cause the joint to 'work' with motion or vibration should be a question Van's can answer (hopefully once and someone can post the answer), but for alignment it's closer than you can measure at those distances. I just took wing spar bolts out of an RV4 that were drive fit, made me want to cry by the time it was over... I can't imagine driving in the bolt in the confined area of the rear spar attach point. Perhaps if you could drill, ream, and bolt without ever unclamping or disassembling it would not be bad??

I stand corrected, see next post. It looks like I had bad information years ago that has continued until today. Thanks for quick and official clarification.
 
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I just had a customer call about this thread. For years the plans have said the same for the RV-10, but Van's tech support says 5/16" is fine at .3125". That is on the landing gear bolts. We are measuring to .00005" every day, so I feel like .0015" is a ballpark, however I know what it .0015" actually feels like in a hole, and while it's not a drive fit, it's not off by much. If you assumed a pinned joint vs. a fixed joint, and you assumed the wing length is roughly 6 times the spar to spar length, the wing at the tip may wiggle .009" back and forth. That's with the bolt loose, so it's not an alignment issue. Will it cause the joint to 'work' with motion or vibration should be a question Van's can answer (hopefully once and someone can post the answer), but for alignment it's closer than you can measure at those distances. I just took wing spar bolts out of an RV4 that were drive fit, made me want to cry by the time it was over... I can't imagine driving in the bolt in the confined area of the rear spar attach point. Perhaps if you could drill, ream, and bolt without ever unclamping or disassembling it would not be bad??

The official answer from Van's engineering is to use the size tool specified in the construction manual.

ANY amount of movement in a fastener joint like the rear spar attach or landing gear legs is undesirable. The goal of using the .311 reamer is for a tight interference fit. You shouldn't need a 3 lb hammer to drive the bolt in, but the goal is for it to be a close fit. When looking for a close fit, .0015 is not ballpark. It is the difference between fitting tight, or easily rotated in the hole with your fingers.
 
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