danielhv

danielhv

Well Known Member
So I was working on the Z brackets last night... and this is not the first time I have seen this, but I am getting more concerned about the amount of resistence the platenuts give when screwing in a bolt (or screw)... So, my dad suggested chasing the threads (running the same size tap as the threads to cut them to the right size I guess) with a tap and see if that helps. Thoughts?
 
Daniel,

The platenuts are supposed to have some resistance. That makes them self locking. If you tap them out, you are taking out the locking mechanism and they screws/bolts that go into the platenuts have the potential of backing out over time.

I didn't tap any of my platenuts out and I haven't had any issues.
 
They are supposed to be tight

If you look, you'll notice that the holes are slightly "squashed". This is what provides the locking function for the bolt or screw. You could chase the threads, but then you would probably need to use Locktite on them later.
 
Use a thread lubricant like Boelube

Platenuts are designed as a deformed-thread locknut. If you "chase" the threads, you will destroy the self-locking feature. A better solution is to use a thread lubricant to prevent galling of the threads.

Many on this forum have recommended Boelube in the solid push-up stick form for this purpose. Boelube is a wax-based lubricant that will prevent galling of the threads in a platenut, and is great as a tool lubricant, too.

Buy a stick of it now (ACS and others stock it) and keep it in your tool box to use when you are reinstalling all of the inspection covers during your phase 1 inspections.
 
Works great

I've run a tap through a number of platenuts to make installing the screw much easier. That pretty much eliminates the locking feature of the platenut, but in many places that is not an issue.
If you want the installation to be easier, but still retain a bit of the 'locking' capability, just lube up a screw/bolt (Boelube, oil,...) and run it in and out of the platenut a few times.
If the platenut is behind a thicker piece of material (like the Z brackets), be sure the platenut is aligned with the hole properly. If not, the difficulty may be due to the fastener binding in the hole as much or more as the resistance due to the platenut locking deformation.
 
Here's a hint.

When I know that I will be inserting and removing a bolt from a plate-nut several times, I add a washer stack to the bolt. This way the bolt doesn't go all the way through until the final assembly.
 
Nutplates

I am sure that Mel and someof our other esteemed DAR's can weigh in with complete accuracy on this matter, but I want to give MHO.
Nutplates have been in existance for decades, and there is a very good reason that they are manufactured with a built in locking feature. As many have been quick to point out, I did not build my RV so I may not be familiar with every bolt and screw that threads into a nutplate. The 8 years that I spent doing work on certiifed aircraft (early Mooneys and twin Cessnas being the worst for number of screws) makes me experieinced on nutplates. There may be some that one can get away with relieving the friction without negative consequences. However, if the screw/bolt is one that will not be removed once installed, then you want the friction. If it is one that is removed on a routine basis, it will be much easier on subsequent installations.
Our RV's endure lots of vibration during flight and also from the "hard charging" Lycomings providing the mojo that makes our planes so much fun.
This requires that all fasteners be able to able to retain their torque.
 
Chase threads

Put a little dab of water proof bearing grease on each screw or bolt before the first run. Really helps, and you can get it locally if you don't already have some on hand. AutoZone, etc. I believe that Van's only calls for chasing threads on the planenuts that hold the baggage compartment cover due to their proximity to the floor.
Mike H 9A/8A
 
jetjok said:
I am sure that Mel and someof our other esteemed DAR's can weigh in with complete accuracy on this matter, but I want to give MHO.
Nutplates have been in existance for decades, and there is a very good reason that they are manufactured with a built in locking feature. As many have been quick to point out, I did not build my RV so I may not be familiar with every bolt and screw that threads into a nutplate. The 8 years that I spent doing work on certiifed aircraft (early Mooneys and twin Cessnas being the worst for number of screws) makes me experieinced on nutplates. There may be some that one can get away with relieving the friction without negative consequences. However, if the screw/bolt is one that will not be removed once installed, then you want the friction. If it is one that is removed on a routine basis, it will be much easier on subsequent installations.
Our RV's endure lots of vibration during flight and also from the "hard charging" Lycomings providing the mojo that makes our planes so much fun.
This requires that all fasteners be able to able to retain their torque.
Click to expand...
I heartily concur!
 
My Nutplate Rules

1) First screw through a nutplate is always Boelubed!

2) First screw through a nutplate is frequently out of my box of Stainless Steel "workshop screws" that I use over again for just the purpose of running in new nutplates.

3) I never try and take the locking feature out of any fastener (OK, I would probably be OK with some floor fasteners...), after seeing what vibration can loosen!

4) For temporary assembly of components (floors, skins, etc) that have nut-plates behind them, a brass cleco (1/8" size) holds perfectly in a #8 nutplate. Why run a screw in until you need to?

That's how I do it - might not be for everyone....

Paul
 
Daniel,

When messing with nutplates, I did not chase threads. To ease with the attach-remove-attach-remove that you do with the nutplates (especially on the z-brackets), I used a stack of washers under the AN3 bolt to allow the threads of the bolt to catch the threads in the nutplate, but the bolt will bottom out on the washers before it hits the deformed threads. This allows easy installation and removal while test fitting (building), and does not wear out the self locking feature.

n12804481_34245527_3656.jpg
 
I use the same procedure as Paul, but I would add to not reuse any of the locking nuts. In fact I use the all steel lock nuts with new bolts on the control systems. New bolts are cheap and I reuse the old ones for temporary work or for project around the house.


Ironflight said:
1) First screw through a nutplate is always Boelubed!

2) First screw through a nutplate is frequently out of my box of Stainless Steel "workshop screws" that I use over again for just the purpose of running in new nutplates.

3) I never try and take the locking feature out of any fastener (OK, I would probably be OK with some floor fasteners...), after seeing what vibration can loosen!

4) For temporary assembly of components (floors, skins, etc) that have nut-plates behind them, a brass cleco (1/8" size) holds perfectly in a #8 nutplate. Why run a screw in until you need to?

That's how I do it - might not be for everyone....

Paul
Click to expand...
 
Ok, so my next question then. I bolted the Z brackets to the spar for drilling the top side... And of course didn't think to use a washer stack... Do I need to replace those AN3-4A bolts since they have been run through the planenuts or will they be ok?
 
No replacement necessary. As long as you can't screw the bolt in with you hand, it's fine.
 
danielhv said:
So I was working on the Z brackets last night... and this is not the first time I have seen this, but I am getting more concerned about the amount of resistence the platenuts give when screwing in a bolt (or screw)... So, my dad suggested chasing the threads (running the same size tap as the threads to cut them to the right size I guess) with a tap and see if that helps. Thoughts?
Click to expand...

Daniel,
As others have stated, you should never run a "cutting" tap through a nutplate. Your fuel tank nutplates call for AN3 bolts, which have a hex head. This makes stripping the head of the fastener almost impossible. However, on smaller sizes (4,6 or #8), you are often installing Phillips head screws. To avoid damage to your fasterners:

1 Apply a lubricate to the threads prior to installing the fastener the first time.

2 If possible, substitute a hex head fastener for that "first" insertion.

3 If no hex head fastener is available, do the following. Purchase a tube or tin of valve lapping compound from the local auto parts store. This is a very abrasive, gray paste. Dip the tip of your Phillips screw driver into the valve lapping compound prior to placing into the screw. This little trick will greatly increase the screw driver's grip on the screw. Also avoid using cheapo screw drivers here. The best ones are made by Snap On. You will only need a #1 and a #2 for use on your RV.

Charlie Kuss
 
Daniel:

If you look at my instrument panel and floor boards and anything else in my RV-8 requiring a number 6 or number 8 screw you'll find a stainless steel hex screw.

After literally "screwing up" enough phillips heads (always the ones in the hardest to reach spaces, of course) I was about throw the whole project in the trash. I decided there had to be a better way. Yes, the stainless hex screws are more expensive but they are so much easier to remove plus the driver can be at an angle and you can still get enough leverage to finish the job. A 1/2" or 3/8" length works fine just about anywhere.

Van's engineer, Rian, asked me about them during LOE when he was looking at my panel. I got the impression that Van provides some hex screws now in the kits but are looking to do more and was curious about what I used and the length. I guess they get tired of the phone calls asking how in the $%*& do you remove a phillips that is stuck 90% of the way in and now has no slot left to grip, and who the heck designed this thing anyway. But I digress.

Thanks for reminding me about those pleasurable evenings spent with nutplates :rolleyes:-- a very appropriate label considering what they do to your psyche.

Chris
 
danielhv said:
So, my dad suggested chasing the threads (running the same size tap as the threads to cut them to the right size I guess) with a tap and see if that helps. Thoughts?
Click to expand...

I agree with Dad. Paint overspray, construction dust, debris, ect., gets in the threads and really gums them up. For sizes -6 & -8 I put a tap in a battery drill, spray it with WD40 and clean them all out. If they are designed to lock the threads I have never had one come loose after cleaning them out. Much easier to get the screws in and out after that.
 
chrispratt said:
Daniel:

If you look at my instrument panel and floor boards and anything else in my RV-8 requiring a number 6 or number 8 screw you'll find a stainless steel hex screw.

Chris
Click to expand...

Chris,

Do you have any pictures/part numbers of what you used?

Thanks!!
 
RyanM said:
Chris,

Do you have any pictures/part numbers of what you used?

Thanks!!
Click to expand...

Ryan:

I will have to take some photos for you next time I'm at my hangar. I know I bought mine at a local Tru-Value hardware store (Elliott's in Dallas). They are not the ones that mike109g6 is showing in the post after yours. Mine have more surface area for the driver.

Chris
 
chrispratt said:
Ryan:

I will have to take some photos for you next time I'm at my hangar. I know I bought mine at a local Tru-Value hardware store (Elliott's in Dallas). They are not the ones that mike109g6 is showing in the post after yours. Mine have more surface area for the driver.

Chris
Click to expand...

I'll take some pics too Chris! I don't think I've ever seen your panel. :eek:
 
OK here I go again, hope I don't regret this posting.

Running a roll tap in a plate nut is fine. It is no different then running a screw or hex bolt or allen head in as others are stating. A roll tap does not cut.

Another option is to run a very dull tap in, if chips are coming out it's not dull enough. The key is not to cut, your just trying to ease the deformation so you can run the screw in without stripping the threads or head of the screw.

The plate nuts have a locking feature by deforming the last few threads. On the smaller threads the amount of drag created by the deformation can be more than the strength of some of the screws going into the threads. This can strip the driving head or the threads. It is really only needed on #6 and #8 threads. Once you get into #10 and larger there is enough material area in the screw and it is usually a hex head that it does not cause a problem.

I personally use a roll tap in a slow turning battery powered drill and Boelube.

The tips from Charlie Kuss are excellent. Use of valve grinding paste on the tip of thescrewdriver for a better grip works very well. There is even a product marketed as a driver gripper that I think is just a coarse valve grinding paste. The use of a good screwdriver is also required Snap-on, Mac, etc. are all good. Another option is a driver with replaceable hex tips. Some of the tips available are cobalt and will last a long time before deforming.

Use of hex head or allen head are another option especially on non structural areas.

I've seen where alot of people are switching to the 100 degree torx head stainless screws. These are bad news for a couple of reasons. One the 100 degree screws are usually being used in a structural area ie. fuel tank mounting. These screws do not meet aircraft specs. The vender link on this thread is a hardware company that caters to "hobbiests". Although many consider our airplane building a hobby, it's still an airplane carrying people. It should be built using materials designed for this application. Not trying to start a war on the experimental concept and the freedom to do as we want.

The other problem with the torx head and 100 degree design is their is not enough area in the head of the screw. The phillips head profile is in a vee and does not remove as much area of the screw head. The torx head profile is straight in and will run very close to the bottom of the screw head. This give less area of material to do the holding.

If you look most screw manufacturers do not offer a torx head with a 100 degree head. There is a reason for this. The only supplier for them I've ever found is the link refferenced on this thread.

My two cents worth.

Ted
 
Geico266 said:
....I put a tap in a battery drill, spray it with WD40 and clean them all out. If they are designed to lock the threads I have never had one come loose after cleaning them out. Much easier to get the screws in and out after that.
Click to expand...

No doubt that they are much easier to install!! If you removed any material from the nut, then you have weakened it's ability to carry the load.:eek:
The best comment so far was the person who advised to use the lapping compund and good tools.:)
 
when I did my tanks, the most I would do is take a test bolt and run it through all the platenuts. That way they would be broke in a little for the real thing. They still had some good grab, but they were way less trouble to get together on final assembly.
 
RyanM said:
Chris,

Do you have any pictures/part numbers of what you used?

Thanks!!
Click to expand...

Ryan:

Here are some photos that may help. I don't have a part number. As I mentioned in a previous post, you can get these from a good hardware store in the Fastener department. Look for number 6 and number 8 size. You can usually find them sold by the piece and in boxes of 100.

The first photo below shows the screws. They are stainless and come in a variety of sizes and lengths. The ones shown are #8. I used mostly #8 of 3/8 inch length plus a few of 1/2 inch length. I used a few #6 in the instrument panel as determined by the instrument (EI gauges for example). A shorter screw means fewer turns so use 3/8" as much as possible. (I had started with 1/2 inch since Van's screws are 1/2 inch, but found that to be longer than needed in most places.) The screwdriver-like tool shown has a hex-shaped shaft plus the tip is rounded so that you can still turn the screw from an angle. This really helps when the screw is next to the sidewall or longeron. There is also a little stubby looking insert which is a hex insert that can be used in a small ratchet tool or power drill. You can find these at Sears, Lowes, HD, etc.


Click on photo to enlarge

The next few photos show where I used these screws. I only used them in the INTERIOR of the aircraft. They are perfect for places that need to be removed each year for the condition inspection (side panels, floor pieces, baggage compartment) and to secure the panel instruments as shown in the close up. I also used them on the covers near the gear towers (RV-8) such as where the fuel valve to switch tanks is located.


Instruments held in place with hex screws


Lower left panel behind gear tower - instrument and panel are held by hex screws


Rear seat side panels held on by hex screws for easy removal

I like these screws in place of phillips head screws because they provide a good gripping surface for the tool with less likelihood of rounding off the edges. These can be removed and reinstalled with a battery powered drill or ratcheting screwdriver. Yes, you can SNAP OFF THE HEAD of one if you force it into a nutplate. And since it's stainless, it's a bear to remove when this happens. I only did this once.

For the interior places where I used these screws, I did run a tap through the nutplate first. Shame on me, but I haven't had a single one back out even a little in 275+ hours. And the areas where I did this are not structural.

You'll notice these screws are not countersunk. They stick up about a 1/4 inch from the surface. No big deal in my opinion.

So that's my approach. Hope it helps or gives you food for thought.

Chris
 
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Working on my QB fuselage, there were some screws into platenuts, screwed in by the factory, that were almost impossible to remove. I don't know how they got them in there without messing up the screw slots. I had to use vice grips to get the screws out as the screwdriver wouldn't stay in the slots. Even tried valve grinding compound on the screwdriver tip, which I had heard would give the bit a better grip.

So I ran the tap in about 1 turn after it began to bite. Screws still have resistance and they aren't going to back out.

Maybe I did the wrong thing, but it seems OK to me.
 
#6 & 8 screws stripping out

Any hardware stores in my area do not carry a 100 degree cs head. Watch what you are getting.
To solve the grip problem in the phillips head, go to your local Lowes
lumber yard and get a ten pack of Bosch phillips head bits.. They are
grooved on the very end and work much much much better than
the vaunted "SnapOn" brand.
The Bosch bits grip a SS screw so well you cannot get the bit out of some of the screws.. Try em you will be a believer.
 
Along the same topic...

I can't seem to get the bolt started into the plate nut for my rudder. It seems to catch, but just doesn't want to continue and pops out. The problem appears to be the threads on the plate nut. Do I need to drill out the rivets and put in a new plate nut? Any suggestions?

Thanks,
 
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