What does over dimpling look like?

[jcarne]

Originally Posted by rvbuilder2002

The rubber hammer is likely your problem.

We use a hard plastic tipped (replaceable tips) metal hammer in our shop. It still requires hitting quite a bit harder than if a steel hammer were used.

Another big influence is how solid the surface is that the tool is on.
If you put the tool on a concrete floor the force required to get a proper dimple is reduced greatly. When doing large dimples such as for screws (the ones most likely to not be fully formed by lots of builders) I often move the tool to the floor or switch to using a steel faced hammer.

I have experienced this problem early on because I was dimpling on my table and it was flexing. Now I do all of my dimpling on concrete and the dimples come out spot on! Not fun kneeling for the whole process but beauty is pain.

[rv7charlie]

Scott & Jereme match my experience. I did use a big (3" dia x 4" head) rubber mallet for all my C-frame work, but I swung it like I was driving big 3" framing nails; 1st a medium blow to start the dimple, then a really hard hit to finish it. My work table is a section of maple bowling lane; it looks like a giant butcher's block, but made with 1" maple strips on edge and over 2" thick. The top is ~ 3' x 5', and it's so heavy it's difficult to pick up one end without help. I'd be surprised if one could build a simple plywood work surface stiff enough to allow good C-frame work.

Charlie

[airguy]

Originally Posted by rv7charlie

Scott & Jereme match my experience. I did use a big (3" dia x 4" head) rubber mallet for all my C-frame work, but I swung it like I was driving big 3" framing nails; 1st a medium blow to start the dimple, then a really hard hit to finish it. My work table is a section of maple bowling lane; it looks like a giant butcher's block, but made with 1" maple strips on edge and over 2" thick. The top is ~ 3' x 5', and it's so heavy it's difficult to pick up one end without help. I'd be surprised if one could build a simple plywood work surface stiff enough to allow good C-frame work.

Charlie

That's where the DRDT-2 really comes in handy.

[rv7charlie]

Sure, if you're building on a cubic money budget. And if you search the archives, there are numerous posts by people having the same issues with the DRDT-2.

Not saying you shouldn't buy one, if that floats your boat, but it won't get you better results than properly using a C-frame.

[rvbuilder2002]

Originally Posted by rv7charlie

Sure, if you're building on a cubic money budget. And if you search the archives, there are numerous posts by people having the same issues with the DRDT-2.

Not saying you shouldn't buy one, if that floats your boat, but it won't get you better results than properly using a C-frame.

I agree.

Every dimpling tool requires some level of skill and understanding for good results.

I have seen no indication that the DRDT-2 assures good results. I have seen it produce just as much bad results as any other method.

[wirejock]

Kyle.
If possible, position the c-frame over the leg area of the bench for solid supoort. I have two EAA benches. I place the benches beside each other and position the c-frame so the business end is over the leg end of the benches. Everything gets clamped so nothing can move from all the beating. Check position of everything often. I use a 2lb HF Dead blow but I know several builders use 2lb steel. HF has a lifetime warranty. I'm on my 4th. Gives you an idea how hard the hammer is driven. Best of luck.

[LittleDave]

Hmm, interesting. All this rubber mallet stuff seems like too much work. I use a 4# steel hammer held just below the head and about a 6-8" swing. More like lifting and let drop than having to swing. One hit does it......... just me I guess.

[rv7charlie]

Originally Posted by LittleDave

Hmm, interesting. All this rubber mallet stuff seems like too much work. I use a 4# steel hammer held just below the head and about a 6-8" swing. More like lifting and let drop than having to swing. One hit does it......... just me I guess.

Show your work. ;-)

Seriously, I avoided using a steel hammer partly for safety (hate wearing goggles), but mainly because I didn't know what effect it would have on the C-frame's ram. Didn't want it to end up looking like an abused cold chisel. Besides, it's not like I couldn't use the exercise.

Charlie

[Flyin'Bryan]

I started with a plastic dead blow hammer from HF, but did not like the results/effort I had to put in to it. So I switched to a standard sized ball peen hammer and I've been happy with that ever since. yes my ram has mushroomed just a very tiny bit, but that is mostly from the occasional "miss" of the hammer on the center of the ram with a slight glancing blow on the edges of the ram being the result.

After using it that way for a long time now, the ram is still in very good shape and will last me at least as long as it will take to finish the fuselage.

+1 on concrete or stiffening up the "strike area" as much as possible
+ 1 using the Cleaveland dimpling table with adjustable legs to really get the dimple height just right.
+1 on supports all around the ram/set of the C-Frame
+1 that many times the wrong height of the dimple die compared to its support surroundings can leave some very odd shapes in the skin surrounding the dimple.

Would also recommend to the OP to try different hammers and also try using different amounts of force with each blow. with my hammer sometimes only 1 hit will suffice, and almost always never more than 2.

Practice with scrap - with different techniques and different tools, until you find the one you like.

[LittleDave]

Here's some pics of the rivets on an aileron (if I get this posting thing to work)




guess it didn't post....

https://www.flickr.com/photos/155351.../shares/Y7GY1o