Making a flow forming tool

[skintkarter]

Hi Ed. I made mine from scraps of 4140 with a shrink fit between the chisel end and the hollow tool end. Warmed them up and tig welded the two bits together. Held up so far.

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[crystallographic]

Originally Posted by route56wingnut

My solution to a long lasting version of this is to bore a hole in a bar stock piece not all the way through so as to have the end of the chisel bit fits tight in it. Now weld this to a thin wall piece of tubing either round or square depending on the product you choose to use for your forming . I also weld a nut so to use a set screw to pinch against the insert. Streck Tools also has a similar tool that is made of a composit material that has a hole for a chisel bit in it. I drove the bit out the end and started ruining the panel I was trying to form . After doing this to multiple pieces and having Streck nicely replace at no cost I finally contacted their Tech guy and he asked what I was using for a hammer source and of course proudly stated I was using Snap Ons bad boy These are way too powerful for this process as well as most rivet guns as their piston is too heavy and not needed for flow forming. I looked in the back of the droor for an old cheap muffler gun and that was the answer

Dan, I've used many different rivet guns for flow forming over the years, and some are indeed too rowdy for some tasks. It depends on the shape you are asking for and the type of alloy you are shoving along.

Sometimes in the flow of a job I will change inserts as the metal work- hardens. Other times I will change guns for a deeper push - changing from a 4x to a 5x. One one job we used 4x for the stretching
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and a 12X for the shrinking,
nacelle lip skin 3.jpg

but like most everyone knows, shrinking takes more force than stretching does, on the same material and - 2024 is just plain stubborn when work hardened enough.

I used a panel ripper to do some flow forming - once. That was enough for me.

[ed l]

Thank you again guys I appreciate all your in put ed

[Stretch]

Ed... out of the four attempts at making a welded shank, this is my most successful to date as it hasn't broken at the weld yet. And it's had some abuse! It's a cheap hammer headed air chisel shank, to which i welded a homemade machined insert holder. The hammer was a light press-fit into the machined holder prior to welding.
Matt

[Maxakarudy]

Matt,
If you use a planishing head (£3-£8, on ebay), just weld a tube to it.

[outsider347]

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IMG_2128[1].jpgWhy mess with trying to make a useable tool when the Lisle tool is available for 16.50 + ship?

I turned the delrin to fit the tool bore

Works awesome