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Dimpling Question

dwollen89

Well Known Member
I'm dimpling my HS skins using a Cleaveland C-Frame and dies. I'm getting a lot of distortion between the holes, particularly on the line of holes in the middle of the skins. At first, I thought maybe the holes were under dimpled, so I gave them one more hit, but it didn't help. I'm sure the dimples aren't under done, so I'm wondering if the distortions are normal or maybe I'm over dimpling.

Thoughts?

I'm really enjoying building, but there is a steep learning curve...
 
Are you using a steel hammer? If not you need to, a couple of firm hits and the sound will tell you when the dimple is formed.

Russell
 
Yes I am. I’m hearing the sound change, very distinct. Wondering if I'm actually hitting it too hard. I’m not over head smashing it, but definitely giving 2 decent whacks with a 16 oz hammer.
 
Not sure then, can you post a pic?
Cleaveland dies and a C frame is a good combination although I did use one without the spring to hold the ram pin up, meaning the die would sit on the work before the hitting.

Russell
 
Dimples

Very odd. A photo would help.
I used a C-frame and Cleveland dies as well. Destroyed four HF 2lb dead blow hammers. Lifetime warranty pays.
I also remove the spring. Less chance of a extra hole mistake.
Check you have a mated pair of standard dimple dies.
 
I think I figured it out. At the risk of feeling embarrassed, I’ll post my thoughts if it’ll help someone in the future forum search. I think I was just hitting it too hard. I watched the Cleveland video again and reset my table and dimpled. I did the other side of the HS and just went about 1/2 to 3/4 force of what I was doing and they came out perfect. The only other thing could have been that my male die wasn’t proud enough of the table as the distortions are convex on the finished surface. Maybe a combo of the two. Fortunately, it’s on the bottom side of the HS, so nobody will ever see it. A wise tech adviser told me recently about 20 times that I’m building a tractor, not a watch. I’m constantly telling myself that to keep from going crazy, lol. Onward I go…
 
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Make sure your C-Frame is not in the middle of a table. You want to have the impact load transferred from the hammer, through the dimples and parts, all the way to the floor. If the C-frame does not have a table leg under it, the table will flex and you will get inconsistent results.
 
Thanks. I did move it closer to the corner of my table, so that might’ve helped too. Such a learning process…
 
Dimplingyep

I think I figured it out. At the risk of feeling embarrassed, I’ll post my thoughts if it’ll help someone in the future forum search. I think I was just hitting it too hard. I watched the Cleveland video again and reset my table and dimpled. I did the other side of the HS and just went about 1/2 to 3/4 force of what I was doing and they came out perfect. The only other thing could have been that my male die wasn’t proud enough of the table as the distortions are convex on the finished surface. Maybe a combo of the two. Fortunately, it’s on the bottom side of the HS, so nobody will ever see it. A wise tech adviser told me recently about 20 times that I’m building a tractor, not a watch. I’m constantly telling myself that to keep from going crazy, lol. Onward I go…

Yep. I ruined a top skin that way. Male die was just a little low. Don't worry about hitting it too hard. It's very difficult to hit too hard and easy to under dimple.
 
Good to see you got it sorted and identified the issue early, don’t worry my HS shows learning curve evidence too for those that know what they are looking at.

Most of mine were done on a concrete floor to avoid any bench bounce.

Russell
 
I used the plastic headed hammer I got from Avery. Hold down the dimple dies, and give it two easy whacks. You don't need a lot of force. The aluminum is very malleable, so over hitting it will distort the skin.
 
I'm also getting a little bit of distortion on the outside of my skins. It's almost like the entire c-frame is moving ever so slightly downward with each blow. I can't quite figure it out since I have a very solid timber directly under it extending to the concrete floor. I'm thinking about making a steel post to see if I can remove all flex in the system.

The good news is the slight distortion mostly goes away after riveting since the rivet set smooths it out a bit. I think after paint there will be no noticeable distortion.

I feel like you also get a slight amount of stretching of the skin along a line of dimples. I've had long j-channels and spars end up with a very slight curve to them after dimpling.
 
I'm also getting a little bit of distortion on the outside of my skins. It's almost like the entire c-frame is moving ever so slightly downward with each blow. I can't quite figure it out since I have a very solid timber directly under it extending to the concrete floor. I'm thinking about making a steel post to see if I can remove all flex in the system.

The good news is the slight distortion mostly goes away after riveting since the rivet set smooths it out a bit. I think after paint there will be no noticeable distortion.

I feel like you also get a slight amount of stretching of the skin along a line of dimples. I've had long j-channels and spars end up with a very slight curve to them after dimpling.

I’m hoping it’ll smooth out some with riveting. I’ve contemplated replacing the skin, but I do believe perfectionism is the enemy of progress. I want to finish this thing. She may not be the prettiest one on the line, but at least she’ll be on the line, lol.
 
I just use a 2 lb. steel hammer, not a soft one. I've removed the spring in the C-frame, and put the male die on the bottom. When it's engaged, I let the female die down and give the thing a good hefty solid whack.

Works super.

Dave
 
I just use a 2 lb. steel hammer, not a soft one. I've removed the spring in the C-frame, and put the male die on the bottom. When it's engaged, I let the female die down and give the thing a good hefty solid whack.

Works super.

Dave

I echo Dave's technique. I used a ball peen hammer. Worked great as long as you keep the skin nice and on the same plane as die face.
 
A wise tech adviser told me recently about 20 times that I’m building a tractor, not a watch.

I sometimes think my build looks like it has been done by a Medieval blacksmith. No disparagement intended toward Medieval blacksmiths.
 
I sometimes think my build looks like it has been done by a Medieval blacksmith. No disparagement intended toward Medieval blacksmiths.

How did you get past it? I’m a perfectionist and I’m having to deal with almost everything less than perfect. Every little bit of dumb I do annoys me like using a 3/32 male die into my 1/8 small female die on the hs centre rib on one hole. Thought that does not look right. Got the right die….re did it and it has a depression ring just below the dimple but the flange is ok. I know it will be fine but irks me. Then on the centre nose rib I used the correct die but got some witness marks on the radius of the flange. If I replaced everything I screw up I may as well get a new kit on the way. None of it structural as I hammer vans but they say looks great keep going but aesthetically not pleasing to me. Keep telling myself I’ll get used to it
 
quest for perfection

How did you get past it? I’m a perfectionist and I’m having to deal with almost everything less than perfect. Every little bit of dumb I do annoys me like using a 3/32 male die into my 1/8 small female die on the hs centre rib on one hole. Thought that does not look right. Got the right die….re did it and it has a depression ring just below the dimple but the flange is ok. I know it will be fine but irks me. Then on the centre nose rib I used the correct die but got some witness marks on the radius of the flange. If I replaced everything I screw up I may as well get a new kit on the way. None of it structural as I hammer vans but they say looks great keep going but aesthetically not pleasing to me. Keep telling myself I’ll get used to it

There're thousands of opportunities to appease the gods by making little human mistakes!
The "building a tractor" mentality doesn't really work for me because some parts of the build must be absolutely precise. The trick is to know what matters and that is difficult the first time round. At least the design is over-engineered so it should be safe even with blemishes.
 
Tractor

There're thousands of opportunities to appease the gods by making little human mistakes!
The "building a tractor" mentality doesn't really work for me because some parts of the build must be absolutely precise. The trick is to know what matters and that is difficult the first time round. At least the design is over-engineered so it should be safe even with blemishes.

Doesn't work for me either. I try to be as precise as possible.
 
How did you get past it? I’m a perfectionist and I’m having to deal with almost everything less than perfect. Every little bit of dumb I do annoys me

Welcome to the club. I keep reminding myself that I'd rather be annoyed by my lack of perfection than be completely blind to mistakes though. Building a plane has been a great exercise in learning to filter my thoughts and reactions. Let's face it, most imperfections are things that will never actually be seen. Their only "problem" is my awareness of their existence. The more I build, the easier it is for me to look at something and say "it's ugly TO ME, but it's safe," and move on without losing sleep over it. I'll be a different person when I'm done.:)
 
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