Keeping Blowdowns In Line

[ChuckHackett-844]

From time to time the blowdowns on my Northern would stick and the blowdown would rotate on its thread in the boiler instead of rotating valve plate.

It's hard to get these things 1) tight, and 2) in the correct orientation for proper relationship with the linkage.

This year I found the solution ... a locking arm ...

I machined mine from 1/8" thick aluminum because it was at hand. Brass or Stainless would be good also since they don't rust. I considered 3D-printed ABS plastic but I was afraid that it would soften in the heat from the firebox sides.

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I affixed the arm with a bolt that was in a convenient location. There is a spacer between it and the firebox side to hold it parallel to the firebox.

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You can see the lock gripping the hex on the back of the blowdown.

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Should work great ... we will see ...

[makinsmoke]

That’s pretty slick Chuck!

You are all set up. Run a few off and offer them!

[ChuckHackett-844]

Each would probably have to be custom since the mounting hole offset and hex angle are probably different.

They are made using a parametric CAD file in Fusion 360 and cut on my Haas MiniMill CNC.

Glad to share the Fusion project - if I can figure out how ...

To make them, either someone would have to send the modified Fusion project back to me (preferred) or I would have to modify the fastener offset distance, angle (in relation to the blowdown hex), and possibly hex size (mine was .5").

I used a hex angle of 0 on both of mine. The right one could have used tweaking on the angle but I didn't think it was worth the effort. They each had different offsets to the mounting bolts (about 0.200").

If they had a 3D printer they could verify dimensions before I cut it in metal on the mill to avoid re-runs.

[NP317]

Interesting need, and a logical solution for you.
I've never have the blowdown valves on my locos come loose as you described.
Different attitude/longitude, perhaps...
RussN

[cbrew]

Interesting need, and a logical solution for you.
I've never have the blowdown valves on my locos come loose as you described.
Different attitude/longitude, perhaps...
RussN

same, but i tend to be heavy handed with tightening pipe tread

[Odyknuck]

You could probably adapt a pair of air tool wrenches to work.

[Bill Shields]

Slick ideas to common problems

[ChuckHackett-844]

You could probably adapt a pair of air tool wrenches to work.

What would be the fun in that? I wouldn't be able to justify the Haas CNC to the wife!

[ChuckHackett-844]

Interesting need, and a logical solution for you.
I've never have the blowdown valves on my locos come loose as you described.
Different attitude/longitude, perhaps...
RussN

same, but i tend to be heavy handed with tightening pipe tread

Chris, .. and these have been in and out many times and each time they loosen a bit. I'm Leary of pushing them another turn - just what I need, snapped off or stripped - another project

Wrapping them with Teflon tape takes up the slack but the tape has somewhat of an anti-friction effect so you really need to use a lot of tape to get them tight again.

[cbrew]

Interesting need, and a logical solution for you.
I've never have the blowdown valves on my locos come loose as you described.
Different attitude/longitude, perhaps...
RussN

same, but i tend to be heavy handed with tightening pipe tread

Chris, .. and these have been in and out many times and each time they loosen a bit. I'm Leary of pushing them another turn - just what I need, snapped off or stripped - another project

Wrapping them with Teflon tape takes up the slack but the tape has somewhat of an anti-friction effect so you really need to use a lot of tape to get them tight again.

yeah,,, i hear ya, pretty sure loctite makes a nice pipe thread compound that may help the moving

[ChuckHackett-844]

yeah,,, i hear ya, pretty sure loctite makes a nice pipe thread compound that may help the moving

... and holds its strength at 250 F ?

[Odyknuck]

You could probably adapt a pair of air tool wrenches to work.

What would be the fun in that? I wouldn't be able to justify the Haas CNC to the wife!

Ah! Now I understand ypur method of madness!