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Countersinking Battery Box

T

transientair

Active Member
Fellow RV-14 builders, I need your help. I've come to the point where I need to machine countersink the FF-01403 battery box. I had no problem accessing the side holes, but the bottom row has me stumped. The lip extends beyond the point where I can get the countersink bit in straight (even without the cage and an extension used).

At this point, I am stumped at how to countersink these five holes.
 
I dimpled the whole battery box and mounted it. You could dimple the bottom row on the box and also that row on the firewall.
 
Battery Box Countersink

Here are a couple of suggestions.

1. right angle drill extension.
2. If you haven't riveted the bottom flange, there is still some flex in it and you can pull it out of the way.
3. Needle nose vise grips with countersink and turn it by hand.

Good luck, it turned out to be much more difficult than it should be.
 
The firewall can easily be dimpled at this location. Just take a solid something, heavy bucking bar, etc, and drill a hole in it to accept the female dimple. I think a #12 drill is the right size. I have drilled a hole in the wooden end of a large hammer handle to accept a die. The mass of the handle and head of the hammer provides adequate mass for this job.
Have a helper hold this, whatever you use, in place on the aft side of the firewall and strike the male die, using the set holder from your C frame, with a hammer and the dimple is set.
It took longer to type this then the job will take.
Far easier then trying to get a nice countersink by using vice grips!
 
I'm looking ahead now and my firewall is not assembled yet. Can the DRDT2 dimple the firewall holes at that location or is it not powerful enough? Does dimpling the firewall material ruin the dies? Lots harder than aluminum.... The battery box aluminum is easy enough.....
 
What PSI?

cajunwings said:
Cleveland Tool has a rivet set with a 3/16 hole in the end to hold the male dimple die so you can drive dimple with your rivet gun. Make a suitable holder with enough mass to hold the female die. Works good. Firewall stainless is fairly soft and dimples easily.
Click to expand...

Don, what do you set your air pressure to when doing this?

Thanks,
 
Air pressure

Like everything else in building these planes it depends. Assuming you are only dimpling the firewall stainless for a 3/32 rivet with a 3x gun start with 20 psi and see how it goes. Increase pressure in 5 psi increments if needed. It dimples very easily.

Don Broussard

RV 9 Rebuild in Progress
 
Jody just to let you know of my experience with the battery box there is one thing I would have done differently:
The stainless will deform noticeably as you set the rivets on the shop side i.e. It will dimple towards the manufactured head even back rivetting, worse when setting normally. If I was to do it again I would make a backing plate for the rivet line.
Others with a higher skill level may not have had this problem.....
 
If you are still looking to countersink I have a method I used. I went to an ace hardware and got a threaded rod that was the same threads as the countersink bit. I believe this was a 1/4"-28. Call Mike at Cleaveland tool to confirm as I shared with him what I made. Anyway I got the threaded rod, cut it down to I believe 7 inches. I also bought a rod coupling nut of the same diameter/pitch. Screw the countersink bit in one side and the threaded rod in the other. Chuck the other end in your drill and presto you now have a 7 inch extension countersink bit. Granted you don't have a cage so you have to watch depth and angle but mine turned out pretty good and I believe the parts were about $5.
 
I just ran across this issue. Since the bottom row is only the firewall, can you use a pop rivet simpler to dimple only the bottom row? Or was this the tool suggested above--I could not open the link.
 
Stockmanreef said:
I just ran across this issue. Since the bottom row is only the firewall, can you use a pop rivet simpler to dimple only the bottom row? Or was this the tool suggested above--I could not open the link.
Click to expand...

The material is quite thick and marginal for dimpling with normal dimpling methods, so pop rivet dimple dies wont do a very good job.
It is for this reason that (I think) the plans recommend machine countersinking.
 
Dimpling Tools

Stockmanreef said:
I just ran across this issue. Since the bottom row is only the firewall, can you use a pop rivet simpler to dimple only the bottom row? Or was this the tool suggested above--I could not open the link.
Click to expand...

Hey Ken,

Here is what the tool is. You put the male dimple die in the end, put it in your rivet gun and use something on the backside for the female die. Be careful not to have the pressure up too high, because it WILL break of the die inside the tool, which makes it unusable.

sz924h.jpg


Mike at Cleaveland shows this piece attached to a workbench and if you have a part that you could do that, it would work. This tool is also good for getting into tight areas if you are hand holding it.

2vsgbjd.jpg


Avery Tools used to have a "Block Set" which included a cylinder part that held the female die and also included the part for the male die from above. I couldn't find it on Cleaveland's site, but did find it on Aircraft Tool Supply, but the website wouldn't let me copy the picture, so try this link, http://www.aircraft-tool.com/shop/detail.aspx?PRODUCT_ID=4187.
 
Last edited:
Stoney--

Thanks for the tip. I do have both tools you show. I understand how to put in dimple with the rivet gun and attached tool. I have to figure out what to use on the back side to hold the female die.

I am not sure how I would use the second tool which attaches to the bench. Or would you hold it and put a bucking bar behind it?

Ken
 
Stockmanreef said:
Stoney--

Thanks for the tip. I do have both tools you show. I understand how to put in dimple with the rivet gun and attached tool. I have to figure out what to use on the back side to hold the female die.

I am not sure how I would use the second tool which attaches to the bench. Or would you hold it and put a bucking bar behind it?

Ken
Click to expand...

It's part of that set if you go to the link. It's a cylinder shaped part with a hole in the end to put the female die. It has enough mass like a bucking bar to hold on the other side.
 
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