Brake Roller Track Rivets

[Keith]

Question: The new brake roller track rivets are or seem to be extra long in length. I am getting ready to hot rivet them into the backing plate and they extend about .350" out of the backing plate. Seems like allot to mushroom over while heating cherry red. Is there an ideal length that they should extend out? Keith

[Oldbluoval]

I’ve always had the rivets extend the same as the diameter of the rivet.
Was told that many years ago and always followed

[Phil Brown]

Originally Posted by Oldbluoval

I’ve always had the rivets extend the same as the diameter of the rivet.
Was told that many years ago and always followed

I was told that same "rule of thumb" as well, many years ago

[Keith]

Thanks for the feedback, I'll measure the old ones on the rear backing plates against the new ones that extend through the front Keith

[BRENT in 10-uh-C]

Keith, what Phil and Bill are suggesting about the length vs. diameter is correct if you are making a Button-head rivet, ...however that is not really what the original rivets were. Originally the rivet heads were more resembling of a Pan-head rivet which requires a tad longer shank.

One other thing to note, you have a margin of five-thousandths of an inch (-or about the thickness of a human hair either way! ) to play with on getting the A-2017 Brake Centering Bracket riveted into the correct position on the Housing Plate. It has been my experience that if you miss the measurement, then the shoes will not be located in the center of the brake drum which means you won't have optimum brakes. Therefore make sure these brackets are correctly located when you rivet them.

.

[rotorwrench]

Sponsored Links (Register now to hide all advertisements)

The aviation rule for a flat face buck tail is 1 and 1/2 the diameter of the rivet shank. The buck tail will be 1/2 the diameter after bucking is completed.

A lot also depends on the thicknesses of the parts being joined and the hardness of the rivet material. The hole size is another factor when rejoining parts that have been drilled apart and the holes may be a bit larger. The more the rivet has to fill, the shorter the driven buck tail will be. Ford likely had a big foot operated squeezer to drive the rivets originally. It would have been a very quick process for each backing plate assembly.

I have driven all sorts of rivets due to the wreck rebuilding process on helicopters I was involved in at one time. Driving aluminum rivets (AD universal and flush head types) worked well at 1.5 D as long as the holes were still tight but on monel rivets, they would try to fold over due to the hardness of the rivet in the thin titanium sheet metal. I had to use 1 D for them so that they wouldn't nail over or club foot. The buck tails were less than .5 D but all of the original factory ones were too.

I used a hand operated pneumatic belt sander to adjust for a length that would work when the rivet cutter didn't get them quite right. The cutter would cut them to correct fractional size but that doesn't always work. It takes a lot of riveting experience to get a feel for what works and what doesn't. I don't like to drill out freshly driven rivets that didn't drive right.

I was fortunate on the last backing plates I did. I just welded the tracks up and ground them back to specs. Eventually the spring grooves wear out so that doesn't happen as often as I'd like.

[Keith]

I read all of your comments and suggestions. Yesterday I hot riveted both tracks in the backing plates. Everything came out fine. I used a map torch (Yellow) which worked but an Oxygen-Actelene would have worked better. Keith Again thanks for all the feedback

[BRENT in 10-uh-C]

Originally Posted by Keith

I read all of your comments and suggestions. Yesterday I hot riveted both tracks in the backing plates. Everything came out fine. I used a map torch (Yellow) which worked but an Oxygen-Actelene would have worked better. Keith Again thanks for all the feedback

Well good. A MAPP gas torch will get it hot too but it just takes an extra minute or two.

BTW, how did you verify the tracks are in the proper location?

[Keith]

I did not drill out the old rivets. I used a die grinder and ground flush to the backing plate and then punched them out. I then used a gauge pin in the second hole and bolted the tracking plate through the brake wedge hole. I then measured using your PDF sketches sent with an edge finder on a Bridgeport. Now thinking this through I should of had to old ones welded and milled in on the Bridgeport. Keith

[BRENT in 10-uh-C]

Originally Posted by Keith

I did not drill out the old rivets. I used a die grinder and ground flush to the backing plate and then punched them out. I then used a gauge pin in the second hole and bolted the tracking plate through the brake wedge hole. I then measured using your PDF sketches sent with an edge finder on a Bridgeport. Now thinking this through I should of had to old ones welded and milled in on the Bridgeport. Keith

.........

[rotorwrench]

I only drill the head and then drive the shank out but have noticed that the holes were slightly oversized just from the bucking or squeezing process. The pressure expands the rivet shank and can expand the hole as well. Ford may have punched holes instead of drilling them. From reading some of the documentation on the model A frames, they made the holes a fair bit larger so that the rivets would fit in at manufacture. In aviation, we drilled the holes about .003" larger than the rivet shank for the same reason. Number drills were used for the hole and clecos would still fit. When drilling out an old rivet, we used the fractional size of the rivet shank to drill and a pin punch of the same size to break the head off and drive the rivet out. If the rivet won't drive out then is has to be drilled further until it will drive out. On thin metals it's easy to deform the metal if a person beats on it too much.

[dmar836]

Whats the best way to align the backing plate for milling the welded tabs?
Is there a datum that I indicate from or sweep to ensure the are milled parallel on each side?
D

[rotorwrench]

I use a file for the most part. The Les Andrews manual has a drawing with a dimension on it but I don't have it handy. I use an O/A torch and RG45 rod to weld the worn spots.

[dmar836]

Thanks for the response. I have already tig’d my tabs and just need to mill them flat. I used to have Les’s book but no longer. He has surely helped the hobby a lot but I sense there are some areas where I’d be better off following my OCD by choosing the factory drawings over his instructions. No offense to him as I’m sure his way is better than leaving them damaged and is surely more attainable than machining. However, indexing off of bucked rivet heads doesn’t sound too precise when I will be using a mill. I like benchwork but I doubt I could file that accurately. I guess I’m wondering if indicating off two of the backing plate mounting holes would be precise enough to establish parallelism of the tabs for milling. Distance from the center of the axle hole is easy enough.
I’m sure filing would get me close but just so I can relax and hope for self-centering, I am planning to replicate the factory drawing tolerances.
D

[BRENT in 10-uh-C]

Originally Posted by dmar836

Thanks for the response. I have already tig’d my tabs and just need to mill them flat. I used to have Les’s book but no longer. He has surely helped the hobby a lot but I sense there are some areas where I’d be better off following my OCD by choosing the factory drawings over his instructions. No offense to him as I’m sure his way is better than leaving them damaged and is surely more attainable than machining. However, indexing off of bucked rivet heads doesn’t sound too precise when I will be using a mill. I like benchwork but I doubt I could file that accurately. I guess I’m wondering if indicating off two of the backing plate mounting holes would be precise enough to establish parallelism of the tabs for milling. Distance from the center of the axle hole is easy enough.
I’m sure filing would get me close but just so I can relax and hope for self-centering, I am planning to replicate the factory drawing tolerances.
D

Les' has helped many, many hobbyists with his publications, so they are definitely an asset however as you eluded to, his book has dimensions that are incorrect. As you were asking, I have included the correct dimensions taken directly from the factory prints.
,
.

[dmar836]

Thanks Brent. I saw those drawings you had posted on another thread and it perfectly illustrates the dimensions so many ignore.
I suppose I will create a jig using the backing plate mounting holes.
Much appreciated,
D

[BRENT in 10-uh-C]

Originally Posted by dmar836

Thanks Brent. I saw those drawings you had posted on another thread and it perfectly illustrates the dimensions so many ignore.
I suppose I will create a jig using the backing plate mounting holes.
Much appreciated,
D

Yes, it sounds like you have a Bridgeport, so pilot off of the round hole in the center and just locate off of the two lower mounting holes. Then use a DRO to find the correct location on the Centering Bracket. If you do that, you won't even need to use the centering fixture that pilots off of the spindle to check if the shoes are centered.