Packing a tube for bending

[tornitore45]

I need to bend a SS tube for the exhaust of my model engine
Is a tight bend
OD 0.375 ID 0.305 Neutral Radius = 0.5

I have Cerrobend but that means it has to be bent cold
If I have to bend it hot needs to be packed and I need a cup but must lug a whole bag from the store.

Sand is difficult to pack so I was thinking Table Salt, but I am not sure if there are problems using something potentially chemically active.
The salt melts at 801C so the pipe can only be dark red

Heat or Cold?

Salt OK? Or Sand?

[RSG]

Why not use steel shot? It's melting point is somewhere around 2200 F Lots of auto supply shops sell it for blasting media and fairly cheap.

[tornitore45]

Not familiar with steel shots, I like the idea. Are they small enough to unpack and fall out.

[Russ Hanscom]

Salt should probably not be on the list, SS is susceptible to stress cracking when exposed to chlorides at relatively low temperatures.

[tornitore45]

Salt should probably not be on the list, SS is susceptible to stress cracking when exposed to chlorides at relatively low temperatures.

So glad I ask.

[tornitore45]

Sourcing steel shots as blasting media is a problem since they come in large quantity.
I can source ball bearing balls east, cheaply and in all dimensions.

What would be a recommended diameter to fill a 0.305 ID tube?
I am inclined to think that the smaller the better down to a size where no longer matter. I am thinking around 1 mm.

[Bill Shields]

I use glass beads for cases like this.

I save the dust from my blasting cabinet.

No hard and fast rule here...just the finest whatever you can get and pack it in as tight as possible.

Some it the "shot" is intentionally rough shaped and has trouble packing into small places.

Of course you need to be careful to not heat it above the melting point of the glass beads..if that is what you use

[tornitore45]

I ordered 1.5mm ball bearing but I was too slow to think to add a bag of 0.5 mm for interstitial packing.
Will see if the outside looks bumpy.

[Bill Shields]

think about getting the ball bearings OUT if the OD is bumpy....

[RSG]

I can buy screen size 35 (.5mm) locally in a 50lb bag for $95.00 so I'm sure there are smaller container sizes available. 1.5mm is a bit big but should work. Let us know how it goes.

[pat1027]

Anybody ever use this stuff?

https://www.belmontmetals.com/product/b ... y%20kinks.

[Bill Shields]

that is cerro metal under a different name.