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Tapered pin on nose gear...

comfortcat

Well Known Member
I've deceided to use the tapered pin to attach the nose gear to the motor mount on my RV-9A. Low cost, well tested mod (Jim Ellis rules) that looks MUCH easier during installation than adding later. Note that the cost is low if you do not screw up the taper when cutting the hole!

BruceH in Ramona is my guide for using a hand tool, LOTS of oil and patience. Do you really have to push that hard to get it to cut?

I bought the #3 tapered reamer from A/S and will attempt next week-end.

Tips? Comments? Warnings?

Just in case I'm a glutton for punishment, do folks use a tapered pin in the mains as well?

CC
 
David,

I think you start by drilling out to size "S" bit on the hole. That was the tough part. Almost burned up my drill motor on that one. The reaming can be done by hand. Once the reamer starts making chips, just keep it moving forward and it will go pretty easily as long as it is really oiled up. I helped another builder do his and it went MUCH easier than mine did. It helps to have a buddy and extra hands. Be careful when you get going not to go too far. It is easy to come up on the correct depth very quickly. We would pull out the reamer every few turns near the end, put in the pin and measure how far the threads on the pin were sticking out. Rinse (more oil), repeat as needed....

I think the main gear legs are fine with the provided AN5 hardware. Just be sure to measure the diameter of the bolts and use a correctly sized bit or reamer (not 5/32, which will be too big).
 
HE KNOWS

Do as Bruce says. He knows it well. He, with my assistance, did my nose gear. Came out perfect. Thanx again Bruce.
 
I followed Bruce's lead on my tapered pin installation as well. I bought a brand new "S" bit for the pilot hole, and I thought I'd never get that hole drilled. The material is VERY hard and it takes a lot patience, a lot of pushing, a lot of BoeLube, and a big powerful drill (I'd use the biggest electric you can get your hands on). But once the pilot hole is drilled, the tapered reamer takes almost no time, by comparison. I almost went too far! So be careful with the final reaming to depth.
 
S bit

Bruce do you know if the S size bit is needed for the 6A tapered pin install. My gear was already drilled from the factory so all I ordered was the pin and reamer. Never heard of having to drill out first unless this is something specific to the 7A or a un-drilled gear. :confused:
 
If you have the tapered pin, take a measurement of the small side diameter at the point where it is going to exit the weldment. Add on the depth of the required washer and measure from there. You want to drill to that diameter (or less). Then you can start the tapered reaming. I followed the instructions online at the Matronics wiki.
 
Question

Why does the gear leg bolt come from the bottom with the nut on top. I would think having the bolt coming from the top would safer. To me this just backwards.

Thanks Guys
 
Access

Why does the gear leg bolt come from the bottom with the nut on top. I would think having the bolt coming from the top would safer. To me this just backwards.

Thanks Guys

I think it might be more to do with removal.

The pin could be tapped (or hit harder..:)..) downwards, but there is no room for a hammer or other striking device hitting upwards from within the cockpit through the firewall hole.
 
clarifacation

matronics site states that for a AN386-4-13 taper pin we should use a#3 taper reamer. but elsewhere it's suggested that the first dash number of the pin is the number for the reamer....
so...which is correct?

that said,my #3 reamer isn't cutting anymore. guess I'll have to get another one.
 
Reamer Size

In this application either a #3 or a #4 reamer will work. The #3 will fit a little further into the predrilled hole before it starts to cut. Also it may be a little less expensive to purchase than a #4 reamer.
 
Done!

Well, last week-end we finally finished the taper pin for the nose wheel landing gear on my RV-9A, and thought I'd share my results.
Please note: I'm not a machinist, or A/P or anyone who knows anything about this stuff. Only sharing what I did.

I followed the Jim Ellis instructions pretty close but with some important additions (at least for me)
Jim's instructions are here:

http://www.matronics.com/wiki/index.php/Nose_Gear_Strut

First. I made sure the motor mount was secured to the work table. I used adel clamps and screwed it to the work bench:
2135eoj.jpg


NOTE Towels and plastic. I used LOTS of oil!

Next I drilled out the hole first with a 3/16, then the S that Jim recommends. Use a powerful 1/2 inch drill motor and use LOTS of oil. Go slow and keep the bit clean and well oiled. BruceH said he had trouble drilling. I had none.

Next I started with the taper. LOTS of oil, only by hand, and take your time. Even though I had a brand new ACS tapered reamer, there seemed to be little cutting, and no good chips that I expected to see. I kept the taper clean and well oiled and still I made almost no progress. After 2 hours, we gave up for the day.

The point here is that the taper never made chips. The reamer looked sharp and was brand new, but after reading all the noise on this site, I figure this is just how it works.

Cruising on eBay, I found a shop that sold reamers for a lot less than I paid, and decided a backup reamer was in order. I talked to Jon at North Bay Cutting Tools and was able to get another taper for about $29 plus shipping. BTW: I screwed up my order and Jon helped me out with great customer service. I bought what I thought was the #3 taper, and it was smaller than my little pinkie!

Anyway, I got the new reamer, and was starting again with the old one. Little progress and no chips. So, what the heck, I'll try the new one.

HOLY COW!!!! What a difference!

It got right to work. So did I.

iw0u80.jpg


Follow the same rules: Go slow. LOTS of oil and keep the reamer cleaned out. I turned only a few turns and removed the taper and cleaned out the shavings. Wash, rinse, repeat.

Less than 30 minute later, BINGO. Beautiful.
scs944.jpg


Here are the added tricks I found:

Anchor your work
Drill twice (3/16 then S) and use a slow turning powerful drill.
Get a good taper reamer. Talk to Jon at
[FONT=&quot][email protected]
Use LOTS of oil
Ream by hand
Keep the tool clean and free of shavings
Use lots of oil
AND: Check the fit often! This was cutting a lot faster than I thought.

Dkb


[/FONT]
 
NFG reamers?

I got all my stuff from ACS and the reamer didn,t ream worth a hoot.
Brown&sharpe is the reamer ACS supplied.
I,ll get another reamer and try again
 
Hmm.. Me too. I bought 3 reams from ACS (broke 2 trying to get them to cut) and never got them to cut like is shown in the image above. After many hrs of hand reaming, I fixtured a leg in the mill so I could use the quill to provide downpressure on the back of the tap handle and still turn the ream by hand. No luck. I moved from tap handle to a 1/2" ratchet drive and cheater bar in order to turn the ream with the amount of pressure need to make it do anything (fine dust). Used 3 different oils, the last being sulfer based (the heavy stuff used for threading pipe). The reams snapped from friction loading, not chip load.

So, after failing miserably and left with gear legs that were unuseable.......:mad:

I wound up designing and fabricating fixtures to hold the legs in a wire EDM in order to cut the tapers. I finished by match reaming these legs to the weldments. The 3rd ACS ream cut the unhardened weldments just fine.

It was an expensive exercise but I got what I wanted in taper pins for all 3 legs.
 
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Cutting Oil?

For oil, I just used motor oil. Nothing fancy, and it seemed to work for me.

Kinda hard to see, but here is a picture of the cuttings. Long, not powdery. I kept the taper clean as much as possible.

2hwmel3.jpg
 
ACS reamer

I had my reamer from ACS cutting just fine when I started, but then it stopped cutting. I was able to very lightly dress the interior edges of the reamer with a very fine stone, and it was resurrected. The same reamer has been used by several other builders and continues to cut just fine.

I used lots of cutting oil from Snap-On tools. Stinky stuff, but essential. As David says, you can't use too much oil.
 
I hear ya' Bruce. I tried stoning the edges on my first reamer but maybe I made it worse. It does take the right tool and a bit of skill. I imagine the stinky oil you mentioned was sulphur based. When loaded via powertool cutting, it emits an aromatic :rolleyes: smoke.
 
I just finished my taper pin installation in my -7A. I bought my reamer from ACS, but after reading about all the problems on VAF with the reamer not cutting, I ordered a second one from Travers. Turns out I didn't need the second one, the ACS reamer cut the hole in 30 minutes of hand turning. The process was very easy.
 
30 minute tapered pin...

Great!

Do you have any pictures?

I saw a note about a nose bolt shearing, and was glad I did the tapered pin. After reading all the nightmares, I was not sure I wanted a tapered pin. But as it turned out, it was easy.

CAUTION!!! Your mileage may vary!

CC


I just finished my taper pin installation in my -7A. I bought my reamer from ACS, but after reading about all the problems on VAF with the reamer not cutting, I ordered a second one from Travers. Turns out I didn't need the second one, the ACS reamer cut the hole in 30 minutes of hand turning. The process was very easy.
 
Torque

Why does the gear leg bolt come from the bottom with the nut on top. I would think having the bolt coming from the top would safer. To me this just backwards.

Thanks Guys

This may be so you can properly torque the nut occasionally during inspections. Otherwise you'd never get a torque wrench on that nut from the top.
 
Guess I need some help! I have bought 2 reamers and they cut for a moment then just spin around in the hole while doing nothing. I am afraid the leg steel has hardened. I was able to resurrect one reamer with my dremel to produce some chips for a while. I only need to get the pin to insert about another 1/4". Would a machine shop be able to finish this off for me? I'm so tired of messing with it. Wish I would have left it alone and just kept the stock setup but now I have a tapered hole to deal with.
 
Patience Grasshopper . . .

Guess I need some help! I have bought 2 reamers and they cut for a moment then just spin around in the hole while doing nothing. I am afraid the leg steel has hardened. I was able to resurrect one reamer with my dremel to produce some chips for a while. I only need to get the pin to insert about another 1/4". Would a machine shop be able to finish this off for me? I'm so tired of messing with it. Wish I would have left it alone and just kept the stock setup but now I have a tapered hole to deal with.

I did this to my tail spike and had the same initial experience. I used a diamond hone plate to touch up the reamer every few rounds after the initial spin. 3-4 swipes on the diamond hone on each flute and ready for another cut. Your bar is still good and the non dremeled reamer is recoverable. Pitch the one you used a dremel on (or see below). Oil, firm pressure and three-four revs or less if it is not feeling like it is cutting. It takes longer to ponder than to do.

While any good machine shop can sharpen the damaged (dremel) reamer, it may cost more than a new one. Unless you have connections, and it is free. ;)
 
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Thanks Bill I'll get the sharpeners you linked. I was wondering if a metal shop could ream the hole quicker and better than i could. It may be my last resort if i can't get anywhere with it in my garage.
 
re-sharpening the reamer is necessary

I successfully reamed my nose and main gear for tapered pins.

Takeaways:
  • Sharpening the reamer with a stone was necessary and worked great. I have a Norton FF724 stone that looks like the one ebay calls "knife blade file sharpening" "stone" or "file". Should be ~$20.
  • Should have sharpened reamer sooner than I did.
  • Drilling was done with a hand drill but be carful not to overheat the drill motor.
  • Lubricated generously. I used a mix of engine oil and STP because I had it. Type of lubrication might not be critical; perhaps pipe thread cutting oil is a good choice, or BoeLube
  • Reaming was done with a T-handle mechanic's wrench with a 12-point 10 mm socket. I figure the t-handle prevents side force compared to a ratchet handle.
  • A large mechanics T-handle is important IMO (but I've seen photos where others used a tap wrench, which is smaller); it allows adequate force and torque to be applied versus a tap handle; the T on mine is 9" long.
  • Be careful not to go too far once you get close. Sharpening the reamer makes it move much faster than when it's dull and it could surprise you. 1/2" per foot taper means taking off 2.6 thousandths" on the diameter moves the reamer 1/16".

Procedure:
  • Cleaned up the hole in the gear leg with a 5/16 drill bit which removed paint and burrs.
  • Cut and scraped powder coat from the edges of the bearing surfaces of the gear leg with a razor blade.
  • Cleaned powder coat from the upper bearing ID of the engine mount using MEK and Q-tips where the powder coat blew thru the bolt hole.
  • Cleaned up the holes in the engine mount with a 5/16 drill bit in assy with the gear leg. Both had powder coat and one was small.
  • Drilled the engine mount and gear leg assy with an 11/32 bit. Inserted a 5/16 AN bolt from the opposite direction to line up the assy; the drill bit pushed it out as it progressed. Use lubricant, run the drill slowly, and push hard so it’s always cutting to prevent heat hardening the material. My understanding is a cobalt bit is best and run it at 300-400 rpm.
  • Reamed the hole thru the assy of the engine mount and gear leg until pin shoulder protrudes 1/16" when it's pulled down with the nut. Cleaned chips out of reamed hole with Q-tip. Counterbore in taper pin washer is 1/8".
  • Removed, cleaned, relubricated the reamer frequently. It cut well at first with the assy on a bench attached to a wall, pushing up to maybe 30 lbs (much less at first before the cone is developed), then it stopped cutting. I put the assy on the floor so I could push harder, over 100 lbs I guess, and it cut. It stopped cutting when I was almost finished so I stoned the reamer and then it cut so fast I had to be careful not to go too far. I went back and forth about 3/4" with the stone eight times on the inside of each flute which worked great but I'm thinking fewer strokes would have worked.
  • You can hear when the reamer is cutting and of course you get chips.
  • I've read turning a reamer backwards will dull it prematurely but I have done it when I couldn't otherwise pull it out.
  • Cleaned the chips out of the hole, inserted the taper pin, special washer, and castle nut, tightened the nut just enough to get the slack out, more than finger tight but less than snug. Then went to the next flat that lined up the nut slot with the cotter pin hole.
  • Removed .016 from the AN320 nut bearing face with a vixen file to get the the cotter pin in, because I didn't want to ream too far. Slid the nut on the stationary file while rotating frequently rather clamping the nut and moving the file. Figure eighted the nut face with sandpaper and broke hex edges with Scothchbrite wheel. Maybe an AN310 nut would be better but having some regular and thin washers on hand would be good in that case.

My photos here

My notes here


PS: dwranda was having trouble reaming the nose gear hole ref posts 23, 25, and 29. I lent him my tools and he successfully finished reaming the hole.
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Well I gave up and took it to a machine shop. They didn't have a reamer that size so they tried to use mine. They couldn't get it to cut any deeper either. What are my options? I have a reamed hole that's not deep enough for the pin. Should I drill the hole to the size of the larger end and get one of the close tolerance bolts others have described on VAF? I have bought 2 reamers and don't really want to invest a bunch more in this. I just want to move on!!!! Help!!
 
it can be done at home

Well I gave up and took it to a machine shop. They didn't have a reamer that size so they tried to use mine. They couldn't get it to cut any deeper either. What are my options? I have a reamed hole that's not deep enough for the pin. Should I drill the hole to the size of the larger end and get one of the close tolerance bolts others have described on VAF? I have bought 2 reamers and don't really want to invest a bunch more in this. I just want to move on!!!! Help!!

Feel free to call me, I'd like to see if I can help, I can loan you my reamer and stone if that helps, I don't assume my reamer is special though. If the material of the leg or engine mount had hardened you would have ruined your drill bit. Cutting with the reamer will not harden the workpiece. I assume the reamer reworked with the dremel is ruined. Sharpening my reamer with the Norton FF724 stone was amazingly quick and effective. My notes are in post 26 of this thread.

seven five seven ate one two one niner oh niner
 
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Feel free to call me, I'd like to see if I can help, I can loan you my reamer and stone if that helps, I don't assume my reamer is special though. If the material of the leg or engine mount had hardened you would have ruined your drill bit. Cutting with the reamer will not harden the workpiece. I assume the reamer reworked with the dremel is ruined. Sharpening my reamer with the Norton FF724 stone was amazingly quick and effective. My notes are in post 26 of this thread.

seven five seven ate one two one niner oh niner

Thanks John! I'll call this evening.
 
Getting ready for the fun...

Resurrecting this thread... I recently found some play in the nose gear on my 6A and decided to go with the tapered pin repair. I just ordered the parts and they should be here later this week. Hoping to get it done the following weekend.

My question is what is the easiest/fastest way to do this on a flying aircraft? My initial thoughts were to unhook all necessary hoses, mounts, wires, etc. then hook an engine hoist up, unbolt the engine mount from the firewall, and move the assembly far enough forward to access the hole and complete the job from underneath. Does this sound reasonable or am I going to need to remove the mount from the engine and clamp it to something in order to get enough force on it while drilling/reaming?

I was hoping the entire job could be accomplished in one long day, but maybe I'm crazy... It seems like a lot of folks have gone this route during their builds but I haven't been able to find a ton of info on the best way to accomplish this on a flying aircraft.

If only this could be done from the top without removing the engine or mount!
 
Nose gear taper pin

Done this on a 6A & 9A. Don’t see how it could be done without removing the engine. Might be possible to do this job on a long day with some good help and no snags. Both times I left the prop & baffles installed and only disconnected things that were necessary to free the engine.





Don Broussard
RV9 Rebuild in Progress
57 Pacer
 

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Done this on a 6A & 9A. Don’t see how it could be done without removing the engine. Might be possible to do this job on a long day with some good help and no snags. Both times I left the prop & baffles installed and only disconnected things that were necessary to free the engine.





Don Broussard
RV9 Rebuild in Progress
57 Pacer

Would you recommend removing the engine first and then the mount or can it be done by freeing the mount from the firewall just enough to allow room to complete the job?
 
Cole, you may save yourself a lot of work if you try a longer bolt first. The stock bolt measures under size right near the threads. This causes the mount to have only one fitted surface and that is near the head of the bolt. This will cause play in the gear to show up.

Replace the stock bolt (20A) with a 21A. Going by memory, I think I installed one washer under the head of the bolt, and two under the nut..... This procedure takes about 30 minutes and may solve your problem.
 
Would you recommend removing the engine first and then the mount or can it be done by freeing the mount from the firewall just enough to allow room to complete the job?

Both times I left the mount in place on the firewall and reamed from the top down. It took a lot of inward pressure on the reamer to get it to cut. If you wanted to ream from the bottom up I think the mount needs to be off the engine.

Don Broussard
RV9 Rebuild in Progress
57 Pacer
 
Cole, you may save yourself a lot of work if you try a longer bolt first. The stock bolt measures under size right near the threads. This causes the mount to have only one fitted surface and that is near the head of the bolt. This will cause play in the gear to show up.

Replace the stock bolt (20A) with a 21A. Going by memory, I think I installed one washer under the head of the bolt, and two under the nut..... This procedure takes about 30 minutes and may solve your problem.

Do you happen to have the specs so I get the right one from ACS? I already ordered the taper pin but if this easier fix works I can always return the other stuff. Is this a bolt I could find at Fastenal or only from ACS? My only fear is this fix will be good for awhile but I might have to do the taper pin option down the road as it wears more... I may order the NAS6605 as well and see which works best. I have the same question for Walt on which NAS6605 series part number is correct.
 
Both times I left the mount in place on the firewall and reamed from the top down. It took a lot of inward pressure on the reamer to get it to cut. If you wanted to ream from the bottom up I think the mount needs to be off the engine.

Don Broussard
RV9 Rebuild in Progress
57 Pacer

How were you able to torque the nut reaming from the top down? I'd prefer that route but didn't think it was possible.
 
Taper pin

On the 6A there was enough room. On the 9A I used the end of a wooden broom handle to form a small rounded dent/depression in the stainless firewall at the nut location. The material is pretty soft so easy does it. Didn’t take much, maybe 1/4 the size of a golf ball. I seem to remember having to cut the tip off the reamer so it wouldn’t contact the firewall.

Don B
 
Do you happen to have the specs so I get the right one from ACS? I already ordered the taper pin but if this easier fix works I can always return the other stuff. Is this a bolt I could find at Fastenal or only from ACS? My only fear is this fix will be good for awhile but I might have to do the taper pin option down the road as it wears more... I may order the NAS6605 as well and see which works best. I have the same question for Walt on which NAS6605 series part number is correct.

I ordered five AN5-21A bolts and measured all of them for the best fit. You need to add at least one washer under the head for a good shank fit, and two under the nut. The nut used was MS21045-5. The washers AN960-516.

The bolt went in from the top with the washer, and you add washers and the nut as the bolt is exposed out the bottom or you will not get the nut on.

When ready to torque, measure the drag of the bolt, the tighten the nut to the point of needing the torque wrench and add the drag torque to the bolt torque spec.
 
How were you able to torque the nut reaming from the top down? I'd prefer that route but didn't think it was possible.

The plans for the 6 have you cut a hole in the firewall to get a socket on the nut. You then make a small cover and adhere it with proseal/RTV or pop rivet it on. As Don mentioned, you probably can make a depression deep enough to get a wrench on it. I used a metric M8 bolt to get a couple more thou and it made mine tight. Once the bolt is tight in it's bore, I don't believe you will have further wear. MIne is at 750 hours and still tight.

A 5/16 bolt (excluding close tolerance bolts) is usually a couple thou under .311. I believe the range is .307-.310. A metric bolt will be much closer to .311 (.310-.313), though there is a tolerance range so bring your calipar and pick through the bin to find the largest one. You want a fit just snug enough that light taps with a brass hammer are required to get it in. Be aware that the bore in the leg can be tight, but the bore in the sleeve still loose and that will require more work to get right. Both must be snug fits.

As mentioned, be sure the bolt has the FULL OD at the entry and exit point. Note that some bolts have a relatively long taper just before the threads. Just use extra washers. No issue busting the 3 washer rule here.

Larry
 
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The plans for the 6 have you cut a hole in the firewall to get a socket on the nut. You then make a small cover and adhere it with proseal/RTV or pop rivet it on. As Don mentioned, you probably can make a depression deep enough to get a wrench on it. I used a metric M8 bolt to get a couple more thou and it made mine tight. Once the bolt is tight in it's bore, I don't believe you will have further wear. MIne is at 750 hours and still tight.

A 5/16 bolt (excluding close tolerance bolts) is usually a couple thou under .311. I believe the range is .307-.310. A metric bolt will be much closer to .311 (.310-.313), though there is a tolerance range so bring your calipar and pick through the bin to find the largest one. You want a fit just snug enough that light taps with a brass hammer are required to get it in. Be aware that the bore in the leg can be tight, but the bore in the sleeve still loose and that will require more work to get right. Both must be snug fits.

As mentioned, be sure the bolt has the FULL OD at the entry and exit point. Note that some bolts have a relatively long taper just before the threads. Just use extra washers. No issue busting the 3 washer rule here.

Larry

Ah, I wondered exactly what that hole/cover was for. I may try this route first and if it doesn't fix it I've still got everything I need to go the taper pin route.
 
Ah, I wondered exactly what that hole/cover was for. I may try this route first and if it doesn't fix it I've still got everything I need to go the taper pin route.

Hole in firewall not needed..... Bolt pointing down is much easier to remove and install. Open end wrench works just fine.
 
fixed!

I had access to an NAS6205-25 bolt through work (I know it wasn't the 6605 series but it was the closest I could get) so I decided to give the easy fix a try. I knew it would be close but wasn't quite sure there would be enough threads to get the nut on. It took a few taps of the hammer to get it in, but it fit and removed all play without the nut on. With one washer under the nut I ended up with just enough threads to get the nut on with a safe buffer.

Thanks to those who encouraged me to try this easy fix, I think it will be a long lasting solution.
 
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