J

jdmunzell

Well Known Member
Hi all. I just finished hand squeezing one of the end ribs on my left fuel tank, complete with Pro-Seal. After cleaning it all up afterwards, I noticed that around 6 or 7 rivets along the top side of the skin stick out ever so slightly on one side or the other. The area is along the forward part of the leading edge of the tank where the skins curves a lot. I tried resqueezing the rivets to try and flatten out the flush rivet heads but to no avail.

I'm sure they are quite structurely sound, but wondering what to do about the fit and finish here on these rivets. Can I attempt a lit bit of pneumatic riveting to try and set these a little flatter or is it too late now? Perhaps the rivet has hardened making it much harder to change their shape.

Avery Tools sells a rivet shaver bit that can be set in a C/S cage. The shaver bit is 7/16ths across though, making it kind of big for my needs.

Does anyone have any experience with this tool or any other recommendations for how to handle my problem?
 
jdmunzell said:
...... wondering what to do about the fit and finish here on these rivets....... Avery Tools sells a rivet shaver bit that can be set in a C/S cage......
Click to expand...
I would not attempt to smash the rivets flatter in an attempt to seat them better. I have no experience with the Avery rivet shaver bit, but am quite familiar with a regular high speed rivet shaver. Fitted to a regular countersink cage I suppose the Avery is up to the task but again...I do not know first hand. I have used my high speed pneumatic rivet shaver quite successfully in many situations and specifically for the problem you mentioned. At least two local builders also used my shaver to enhance surface flushness and finish on their fuel tanks rivets too. The first photo may be a bit misleading to many builders because on some of the upper skin fuel tanks rivets, I INTENTIONALLY machine countersunk the rivet holes to a slightly undersize diameter....just shy of seating a regular flush AD426 rivet and later used the rivet shaver to produce maximum surface flushness. Of course doing so is not really routine or recommended practice but it IS after all, my airplane and 7+ years later am still quite pleased with the unique result.

 
I've tried the shaver-in-cage technique & wasn't totally happy with the result.

Also tried a small diamond wheel in a dremel tool, better but tends to 'dish' the rivet if you're not careful.

I've been happiest with a 2" scotchbrite wheel (old, with rounded corners) in a small air grinder. If you control rpm, it's not too aggressive & you can 'hunt' for proper position without doing damage.

FWIW,

Charlie
 
Shaving Rivets

I used a piece of .003" steel machinist shim stock with a hole punched in it with a clone Whitney-Roper metal punch just a little larger than the rivet head. This was placed over the high rivet head, then using a sanding disc on my Dremel tool, sanded the rivet until flush with the shim stock which protected the skin. Worked pretty good.

Rivet shavers in a microstop cage was tried but I was not very pleased as the shaver always tried to spin off the rivet rather than cutting evenly. There is a special motor for this similar to a drill motor with support legs which may work much better but I did not have one. I tried the rivet shaver in a variable speed electric drill, pneumatic drill and a cordless drill with the same problem. Also the depth of the cage had to be set very shallow or chatter became too severe to even control the tool.

Dick DeCramer
Northfield, MN
RV6 N500DD 300 hours
RV8 wings complete
 
I just experienced this last night for the first time while cleaning up my tank exterior. I found two rivets that were sticking up. I just used a grinder wheel on my pencil grinder to knock the heads down. I intentionally dished them out a very small amount, so that I can dab a little more proseal in there, then when it's time to paint, a little filler will hide it forever!
 
It sounds like maybe I should save my $$ from buying a rivet shaver specifically. I am a little worried also that the Avery one is kind of wide (7/16 inch), and I'm afraid of damaging the surrounding skin.

This also sounds like a universal problem. Rick, the area you show in your picture is exactly the same area I have my problem.

Hummm.... maybe the Dremel tool solution or even the small scotchbrite wheel is the way to go here.
 
jdmunzell said:
It sounds like maybe I should save my $$ from buying a rivet shaver specifically. I am a little worried also that the Avery one is kind of wide (7/16 inch), and I'm afraid of damaging the surrounding skin.

This also sounds like a universal problem. Rick, the area you show in your picture is exactly the same area I have my problem.

Hummm.... maybe the Dremel tool solution or even the small scotchbrite wheel is the way to go here.
Click to expand...
While not having experience with the Avery shaver this is what I suspect: The 7/16" wide Avery bit is not the problem at all, my dedicated rivet shaver uses the same size bit. You avoid damaging the surrounding skin by setting up the proper depth on the tool which in the case of the Avery bit is the countersink cage you fit it to. And as with my shaver, you should always TEST the setting on a piece of scrap FIRST. The real problem with the Avery as I see it is SPEED. Most drill motors are not capable of the very high RPM's needed to make the shaver work efficiently. I'm not saying the Avery will not work but I am saying a real rivet shaver will make shaving rivets as easy as drilling #40 holes.

If it were me and finding and using a relatively expensive pneumatic rivet shaver was not a possibility....I'd likely go ahead and buy the Avery bit, fit it and its countersink cage to a die grinder and practice, practice, practice before turning it loose on my airplane.
 
Rick is right on the money here. The problem is not the width of the Rivet Shaver Bit, it is the speed and technique used to operate that bit. Carbide Tipped Rivet Shaver Bits were never intended to be operated at the relatively slow speed of a standard drill motor (2500 ? 4000 rpm), rather they were designed to most efficiently operate and cut at much higher speeds (18,000 ? 24,000 rpm). In a perfect world with an unlimited budget, you should use a true pneumatic rivet shaver to shave rivets. The pneumatic rivet shaver is adjustable in increments of .001? and when set up properly will shave rivets to near perfection without damaging the surrounding skin. Stabilizing arms are standard on most rivet shavers and add to the reliability and ease of use of the tool. Rivet shavers are used extensively in aircraft factories and repair stations and they offer superb results when used correctly.

With all of that being said, reality kicks in, and for most people a pneumatic rivet shaver is not in the budget. Once again, I would agree with Rick, you can set up a ?poor man?s? rivet shaver by using a HEAVY DUTY Microstop Countersink Cage and a high speed die grinder with a ?? collet (heavy duty cages by definition are rated to operate at 10,000 rpm and feature much heavier duty bearings than a standard microstop which is usually rated at 3000 rpm). The key here is practice, practice, practice and it is imperative that you set up your ?shaver? and test it out on scrap material.

Just my two cents and as others frequently say...your mileage may vary!

Michael Brown
Brown Aviation Tool Supply Co.
1-800-587-3883
www.browntool.com
 
Got the T shirt

Been there, done that.

Had exactly the same problem. I made some scrap parts and practiced fixing the problem before attacking my tank.

Tried the Avery shaver. - Results not good.

Wound up with the following procedure which worked perfectly!

Got some stainless steel tape from JC Whintey. Very thin (around .002")
Got 3" surface finishing disks and 1.5" mandrel from MSC. The ends of the disk flop over to give more flexibility.

Here is the right page from MSC: http://www1.mscdirect.com/CGI/NNPDF...T4NO=0&PMITEM=03363264&PMCTLG=00&PMT4TP=*LTIP
The disk is flexible and looks like red scothbrite pad.

I mounted it on a small pneumatic 90 degree die grinder.

Tape completely over the offensive rivet. Yes, cover the whole thing.

Grind on the rivet head through the tape. The tape will peel off perfectly around the rivet head leaving only the rivet head exposed but completely protecting the alcad.. Carefully buff down until you see the tape hole becoming imperfect. This is you indication that you have gone far enough. Peel the tape off and clean mastic off with Lacuer thinner.

Results are PERFECTO!!!

Again, I highly recommend building scrap parts. Purposefully underdimple or undercountersink the holes to create the same problem and practive fixing it until you have perfected your process.

Your mileage will probably not vary.
 
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Many thanks to all of you who responded. That is the beauty of this forum! Several good ideas on how to tackle this problem. It looks like practice, practice, practice in order to use a rivet shaver properly. I 'll let you all know how it all turns out, and which procedure I elected to use.
 
whifof100ll said:
Got some stainless steel tape from JC Whintey. Very thin (around .002")
Got 3" surface finishing disks and 1.5" mandrel from MSC. The ends of the disk flop over to give more flexibility.
Click to expand...

Dale Whifof100ll
I tried your solution to trimming down proud flush rivets; worked like a charm.
I had a roll of metal tape with a peel off backing (I think it is a tape that is used on HVAC ductwork joints, and I had a 2" round arbor burnishing kit with some assorted scotch brite pads from HFreight. I used a right angle pneumatic die grinder first with a red abrasive disc and then finished with a blue fine. Took a couple of minutes to do four rivets in a row on the bottom side of the left elevator at the first inboard rib at the trim activator. No issues and easy. Thanks for the good description.
 
I bought an Avery rivet shaver and was disappointed at first when trying to shave down a few rivets on my canopy fairing. After going back to it several times I started getting the hang of it and actually it works pretty good now. The cage turns a little and makes a little mark but soon all of the skin will be etched for painting and It will blend in fine.
 
Reverse thread on HD cage

For anyone purchasing the Zephyr heavy duty countersink cage from Brown tool, note that the locking ring and the adjustment body are reverse threaded compared to regular countersink tools. Traps for young players I guess. I think I may well use Dale's tape method anyway and report back.

Tom.
 
Rivet Shaver Bit from Avery.

YES, I bought the rivet shaver bit and it works great. It takes a little finesse. Be careful with it. You can see what I did here. http://www.mykitlog.com/users/displ...n&project=607&category=3818&log=66691&row=188




jdmunzell said:
Hi all. I just finished hand squeezing one of the end ribs on my left fuel tank, complete with Pro-Seal. After cleaning it all up afterwards, I noticed that around 6 or 7 rivets along the top side of the skin stick out ever so slightly on one side or the other. The area is along the forward part of the leading edge of the tank where the skins curves a lot. I tried resqueezing the rivets to try and flatten out the flush rivet heads but to no avail.

I'm sure they are quite structurely sound, but wondering what to do about the fit and finish here on these rivets. Can I attempt a lit bit of pneumatic riveting to try and set these a little flatter or is it too late now? Perhaps the rivet has hardened making it much harder to change their shape.

Avery Tools sells a rivet shaver bit that can be set in a C/S cage. The shaver bit is 7/16ths across though, making it kind of big for my needs.

Does anyone have any experience with this tool or any other recommendations for how to handle my problem?
Click to expand...
 
Hi Guys,
I seem to be unable to to find the stainless steel tape (heaps of aluminium but not stainless steel) on either the JC Whitney or MSCDirect sites. The only stainless steel tape I can find is a role on Amazon, but it is 0.0038", not the 0.002" recommended by Dale. Has anyone been able to find 0.002" thick tape online, or is the Amazon tape OK for this application even though it's a little thicker?
http://www1.mscdirect.com/CGI/NNPDF...T4NO=0&PMITEM=03363264&PMCTLG=00&PMT4TP=*LTIP

Cheers,
Tom.
 
tgmillso said:
Hi Guys,
I seem to be unable to to find the stainless steel tape (heaps of aluminium but not stainless steel) on either the JC Whitney or MSCDirect sites. The only stainless steel tape I can find is a role on Amazon, but it is 0.0038", not the 0.002" recommended by Dale. Has anyone been able to find 0.002" thick tape online, or is the Amazon tape OK for this application even though it's a little thicker?
http://www1.mscdirect.com/CGI/NNPDF...T4NO=0&PMITEM=03363264&PMCTLG=00&PMT4TP=*LTIP

Cheers,
Tom.
Click to expand...

The thicker tape would work. You're using the tape as a sacrificial layer. Keeps sanding the area until the tape wears through. Once you start removing tape around the rivet, go a little bit easier/slower and you should notice when the steel is gone and you are into the adhesive layer. At the first sign of this, you stop.

Larry
 
Cool. Thanks Larry. I've gone ahead and ordered the stuff from Amazon. This should be an interesting grinding experience.
Cheers.
Tom.
 
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