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Danny7

Well Known Member
I've been using a 3-4 pound hard rubber hammer to do dimples in my c frame tool. It is really easy with the thin rudder skins. I've been trying to do the horiz. stab. skins and i am not getting very good depth on the dimples. I am also trying to spread the skin enough to get into the middle section, this might be reducing the amount of force i can apply.

Do I need a dead blow hammer to make this work right? what kinds of hammers have you guys used?

And i've noticed that just for inspection i've put some 426 rivets in the dimple, the holes seem pretty sloppy after the skin gets dimpled. I am only deburring one turn or less on the hand spinnerfrom avery. The rudder skin i did several months ago (I worked on the emp some part of the summer than got interrupted by other stuff) I didn't check the rivets in the skin, but the finished part looks good and everything is tight. I'm talking about the rudder stiffeners to the rudder skin rivets.

thanks
 
Danny,

I used a hamer with a hard yellow plastic piece on one end (rubber on the other). This worked great and I just wacked it one really hard blow for each hole. Don't do the "tap, tap, tap" thing.

The other trick was to make "tables" to go on either side of the C-frame so the aluminum is level with the face of the diimple die.

See the Dimpling Tables section on my web site for details.
 
Thin sheet the rubber worked "OK" I found that my brass hammer worked much better and formed cleaner dimples. I was worried that is may have been too much force so I did several holes in some scrap and looked at them under magnification and they didn't have any signs of distress like cracks etc. I found the heavier, metallic head required little muscle other than a gentle strike to the rod. I'm sure someone will chime in and tell me my -10 will disintegrate for using this hammer :D
 
N941WR said:
Danny,

I used a hamer with a hard yellow plastic piece on one end (rubber on the other). This worked great and I just wacked it one really hard blow for each hole. Don't do the "tap, tap, tap" thing.

The other trick was to make "tables" to go on either side of the C-frame so the aluminum is level with the face of the diimple die.

See the Dimpling Tables section on my web site for details.
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I have the c frame on a very sturdy wood bench made with 4x4's for legs andtable supports, 2x4s for bracing at the bottom of the table, with a 3/4 flat plywood top with 3/4 particle board on top of that for sacrificial use when drilling. the c frame is surrounded by foam mats (the big squares you can stand on) to bring the alu. sheet up to the height of the dies.

I seem to get the dimples good if i don't have to open up the alu to access, I might see if i can get a friend to hold the alu sheet open then i can whack it freehanded.
 
I use a dead blow hammer and a good firm whack.
No bouncing of the hammer.
Make sure the dimple die is slightly above the dimpling table for good
contact.
 
Danny, I have a spare dead blow like the one I use for dimpling (might even be a bit heavier) if you're interested. Also, if you're having trouble holding the skin open and flat while you swing the mallet, try reversing the dies in the C-frame, moving it close to the edge of the table, and turning the skin upside down. This way, the skin doesn't need to be held "open" to get a good swing with the mallet since it is hanging underneath the C-frame and table top:)
 
Building an RV was my first experience doing this kind of work. I never could get decent dimples with a dead blow hammer. My HS just looked like **** because of under-dimpling so I got some instruction from an expert who suggested using a brass hammer. (2LB hammer at H-F $10) Cheap, works good, lasts a long time. Second time around the HS turned out great!

BTW I was a little concerned about Van's warning not to over-dimple and I have beat the heck out of some scraps and haven't been able to accomplish this. I think you'd really have to whack at it for a while to cause a problem.
 
I use whatever hammer happens to be close. Dead blow doesn't work as well as a standard ball peen.
 
I second the use of a ball peen. My harbor freight dead blow just did not have enough to dimple the thicker skins. Using the ball peen, it appears at least to me that I get a nicer looking dimple.
 
16 oz steel hammer

I third that. I use a plain old 16 oz. hammer. Just one good solid whack. You feel the die bottom out and you get a perfectly formed dimple, every time. No cracks, and not much tendency for the hammer to bounce either. Works great.
 
roee said:
I third that. I use a plain old 16 oz. hammer. Just one good solid whack. You feel the die bottom out and you get a perfectly formed dimple, every time. No cracks, and not much tendency for the hammer to bounce either. Works great.
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Yep...ball pien. Works great for me!

And I'm always reminded of that SNL routine..."The other day I was hittin' myself on the nose with one of them ball pien hammers..." "Oooooh, I hate it when that happens..."
 
AVERY has a mallet just for this purpose. Years ago, they sold me a wooden mallet that worked just fine. But now I see that they have a new kind. The wood mallet would give a firm hit without all of the metal to metal ring..............
 
Dead Blow Ball Pein

Found a Dead Blow Ball Pein hammer years ago. One firm whack and the hammer never bounces back. Dimples are always perfect.;) A lot louder than a standard plastic face Dead Blow.
 
Rubber!

Dead blow hammer requires more force to get the same level of dimple--ask me how I know. Started with Rubber then tried a Dead Blow, then noticed that rivets did not sit flush--went back to rubber hammer.
 
don't forget the usefullness of feet

I use a dead blow hammer. never tried anything else.

Also, I would sit on my work bench and use my feet (no shoes) to hold the skins down, one hand to hold the skins open, and the other to hammer and move the skin around. Works great but may seem silly to passerbys.
 
thanks guys, i found that i had to turn the skins (and dies) upside down and that was the biggest help.

dimples are now 100% good.
 
I also had the mallet from Avery. White plastic of some sort, maybe delrin? It was just the right weight and easy to yield just the right wack.

Roberta
 
Avery's hammer

robertahegy said:
I also had the mallet from Avery. White plastic of some sort, maybe delrin? It was just the right weight and easy to yield just the right wack.

Roberta
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I second the vote for Avery's plastic (yeah, I think it's Delrin, too) hammer. You have to swat it a bit harder than a dead blow but's it's quite a bit quieter. I used a brass hammer in the beginning but you tend to get a few brass shavings on your work after a while. On the folded control surface skins I just let the folded section hang off the edge of the bench towards me, had the female die on the bottom, used my left hand to draw the male die and rod down into the hole (so's I didn't make any new holes!) and gave it a good whack. In the tight areas like near the bends where you have to use pulled rivets I used the Avery deburring tool to lightly cut the dimples a bit deeper. The dimple dies put a very slight radius in the dimple, and by making a quick pass with the deburring tool, it allowed the pulled rivets (which I believe may be a slightly different c'sink angle) to sit much more flush.
Whack away!
 
I used different weight hammers for different thickness skins. I did the "tap,tap" method and used sound as much as anything to decide if I had a good dimple. To keep from mushrooming the top of the driver, I made a brass "cap" for the driver rod. I took a 1" brass rod, cut about 1 1/4" length of it and drilled a hole in it so it fits over the driver. Five minutes work on a lathe. No need to use a brass hammer that way and the driver would last forever. This cap would probably last 3-4 airplanes.

Bob Kelly
 
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