Technical Dimple Dies and their Purpose

I am a do-it-yourself type of guy and still like to learn new processes at my old age. I am building a center U-channel X-Member for a 34 chassis. I have the channels done and before drilling the holes I watched several Youtube videos about the various methods to use. I have an H-press with enough capacity to do the job but I am concerned about distortion from punching 6 - 8 holes in the channel. Here is the question – Will the vertical surface over the 6' span bow as the holes are punched? I like the look and I believe it increases the strength of the structure. Any assistance is appreciated.


Here is what I copied for my center X-member…10 ga CRS.


Here is what I want to duplicate using a 3" dimple die without distorting the flat vertical surface or putting a bow in the channel.

 

I can't help you with the specifics of punching (or store-bought dimple dies) but I did these with a holesaw, a piece of heavy wall tubing( tabs welded to the sides for clamps) and a cobbled together 'die' that will work on different diameters.....
No visible distortion of the flat..

 

The belled holes make the component lighter and stronger as per aircraft design, that's what I heard.

A bit more information, http://www.jalopyjournal.com/forum/...rom-aircraft-to-race-car-construction.746432/

 

Watch the piece being belled move as you apply pressure in the press, you will see and feel the dies move down until they bottom out and stop, the part will "warp" at first then straighten when the bell is completed.
Try some on some same thickness scrap material first to get the feel for it.

 

Geez Lynn,
You and I must lead parallel lives. I think I'm lagging a little behind. I am in the planning stages of a new build and want to dimple (bellmouth?) some holes in the frame rails. I thought I had it pretty well figured out, but am bothered by the thought of distorting the rails when dimpling them. I'll be watching!
Bruce

 

Hi. Wow, those sure look much better than just cut out holes and they will definately be adding strength back into the metal with the lips around the holes. Jimmie

 

Up top it says 6' (foot) but I'll guess you mean 6 inches.
It probably will distort a small amount but it will be easily straightened back out.

 

6' length.

 

Will the vertical surface bow over the 6' length. Stated another way. The vertical is 6 inches, actually 5-7/8 ish

with the legs in the channel it's going to remain as straight as it was over the 6 foot length.
The as installed vertical will have some gentile contour as it dips and climbs through the dimples.

 

I am out of town for the holidays and just now catching up. Thanks for all the helpful hints on keeping the distortion to a minimum. I am having a tool maker do the dimple dies and I will try on a scrap piece to test my skills. I looked at some CE units while on my vacation and they were distorted (bowed just a tad) and would not be noticeable under the car.
BarryA - those holes look great with your homemade die.

Bruce - I found a NOS Culver City Champ to go with this build. I will PM you.

31Vicky - I thought there would be some distortion in the vertical surface.


I think the dimpled holes add some hot rod flavor to the chassis plus strength.

 

My thought is that gentile contouring with the holes will look far better than something that's supposed to be flat but didn't quite make it.

 

Little off topic but that frame is looking very sharp! Nice craftsmanship!