pot belly butterfly valve

[kraits]

anyone got any ideas on the assembly of a butterfly valve in a pot belly stove?
ive put a few together and they are either open or closed, nothing inbetween.
ive tried springs but i find they lose their tention and become soft from the heat also tried cutting a thread and tightening a nut onto the shaft of the butterfly to put weight on it, but it comes lose eventualy. any ideas would be appreciated.

[erickendall]

In my opinion, the best way to make this type of assembly is with a quadrant plate and bell crank. The attached pictures show the details of a pot belly stove I made about 22 years ago. It's looking a bit worst for wear now, but it gets used every winter, and the wife normally has it going 24 / 7 this time of year. The fittings are all 316 stainless steel.

[Driftabout]

Along the same line as Erickendall, the shaft will need to be attached to a notched or pinned arc or quadrant to give incremental steps. The previous post is a much better engineered than I was thinking. Basically my thought was to use a long small diameter rod at right angles to the shaft which would be flexible enough to spring from notch to notch or hole to hole as you moved it up and down. Would remove the need for linkages? But then I haven’t actually made such a device so it's speculative.

[kraits]

ive given thought to your idea in the past but if you take a look at the attached pics you will see my problem. i made this the other week for a friend and the style you suggest just wouldnt go, the butterfly was nice and tight to start with but that was lost with the first firing.

[erickendall]

Why not go with this:

[Driftabout]

As per erickendall's drawing except that it's just a push - pull rod. Notches in the rod engage with a simple bracket at front of the heater (could be simple bracket with a hole for the rod to slide through). Wish I could draw. However such a arrangement could be placed over the top or to the side of the heater body.

[Stustoys]

Driftabout,
This the sort of thing you mean?
(Wouldnt work exactly as drawn!)

erickendall,
How hot did the s/s handle get?

Stuart

[kraits]

can't do it with the lever/handle on the lid, every heater/stove i make has a removable lid with a grill beneath itand is left flat intentionally so you can put the kettle on it while your doing the impotant stuff in the shed, besides i don't think its all that attractive having something that resembles roosters tail on the lid. im thinking more along the lines of an internaly counter balanced butterfly that will sit on any position from 0 degrees to a right angle without flopping open or shut. any suggestions?

[Stustoys]

Can you bring the butterfly up the flue a little?
You could fit erickendalls idea directly to the butterfly or have the quadrant hang down from the butterfly shaft and have a moveable weight. Hook the weight into the hole that gives you the opening you want.

Stuart

[Driftabout]

[QUOTE=Stustoys;1338174]Driftabout,
This the sort of thing you mean?
(Wouldnt work exactly as drawn!)

Yep, now if the butterfly shaft is extended out so the push pull rod just clears the side with the lever action pointing down. Or as suggeted move the butterfly up and have it directly on the near the flue.

Might even be able to organise the rod and lever internally, not sure how to proved a sound and smoke tight gland. I've tried to think of a butterfly valve in a industrial context that does what kraits is after, but I draw a blank. Not much help really, sorry.

[erickendall]

erickendall,
How hot did the s/s handle get?

Stuart
Yes it does get hot. Not that hot that it's hard to adjust though

[Stustoys]

Yes it does get hot. Not that hot that it's hard to adjust though
Do you think its the s/s making the differance or would MS be about the same temp?
Stuart

[Skew ChiDAMN!!]

How about makin a simple plate with a series of holes drilled vertically, fitted to the side of the chimney.

Much like a ladder.

Just put a hook on the end of the bell-crank (and a wooden handle would be a good idea! :U) which can be placed in the appropriate "rung."

You'd need to counterweight the flap so it naturally fell towards the open (or shut) position by gravity when the hook was moved to a lower rung, though.

[erickendall]

Do you think its the s/s making the differance or would MS be about the same temp?
Stuart

If it was just conduction heat I would say that SS would be superior, but radiant heat is also involved. MS is not really a good choice for this type of application.

[kraits]

ive taken your ideas in and come up with something a little less obvious, ive tried to attach a drawing of it, take a look and let me know if you can see any problems with it, thanks

[erickendall]

Heat and springs aren't really a good combination.

[Stustoys]

Hi kraits,
Works for me, though I think I would have the index plate on the same side as the handle. Just wondering if the sliding shaft in the butterfly would soot up? I may of course be worried about nothing.
Also (if we are being picky on a drawing that may only be a representation of what you are thinking) you have 180 degrees of adjustment you only need 90 right? I'd also match the handle to the butterfly rather than being 90degrees out.

How many adjustment points to you think you would like?

Stuart

[Driftabout]

Looks like you have a way of moving forward. It's more elaborate than I would do it, but then my skills are well short of what you can achieve (from the wonderful pictures you posted ealier).

Having said that it might be worth remembering that the more that can go wrong, then the more likely that something will.

Good luck with it and I'd love to see the final result

Tony

[BobL]

Here is an alternative for you. Similar to yours but it uses Stustoys ide and it gets the spring further away from the flue.

http://www.woodworkforums.com/attachment.php?attachmentid=174248&stc=1&d=1309048644

[kraits]

Stuart, right about the 180 degrees, good pic up, had you not noticed i probably would have gone ahead and gone the extra 90 degrees, which wouldn't have created any problems other than wasting time drilling a few extra holes and i could always of said it was intentional and come up with a reason for it:U
as for the indexing plate been on the handle side or not i dont think is all that relevant but could be taken into consideration, purely to see what looks better.whats
important is the slide mechanism inside the elbow. ive forund that when working with these kinda things leave plenty of slack for rust and crap to build up in but,in this case too slack will almost defeat the whole purpose of going to these lenghts.im leaning towards stainless for the sleeve and rod, the valve plate can be mild steel.

[kraits]

Here is an alternative for you. Similar to yours but it uses Stustoys ide and it gets the spring further away from the flue.

http://www.woodworkforums.com/attachment.php?attachmentid=174248&stc=1&d=1309048644
now your thinking, thats alot easier then my idea and i think it would look pretty good too if its done right, thanks bob, i think i will give it a go first and if for any reason it has problems i will let you know.
cheers
greg

[azzrock]

hi how about where the buttifly goes thru the flue weld a small bit of pipe with a thread
on the outer side. rap some heat freadly packing around the buttifly Vv shaft and hold it tight with a glad nut screwed into the gland thread. this will put pressure
on the Vv shaft and hold it from unwanted turning. ill try to draw it

[Bryan]

So much complexity! :? Mine (it's home-made but not by me) has the shaft sitting in a slot, then the flue is slotted such that the weight of it sits on the shaft, rather than bottoming in the socket. It doesn't move on its own! :)

[kraits]

thanks bryan, but im not 100% with you, any chance you could sketch up a drawing or attach a pic of it? ive got the next 5 days off work so after ive finished cleaning the shed im going to make a few spares up for future projets, so any ideas would be appreciated.
cheers

[eskimo]

So much complexity! :? Mine (it's home-made but not by me) has the shaft sitting in a slot, then the flue is slotted such that the weight of it sits on the shaft, rather than bottoming in the socket. It doesn't move on its own! :)

I'd thought you'd make something like a motorised valve so it can be hooked up electrically and do it all automatically:U

[kraits]

I'd thought you'd make something like a motorised valve so it can be hooked up electrically and do it all automatically:U
too easy, why don't i just build a steam engine into the pot belly and power the valve on steam.:rolleyes:

[kraits]

thanks for all the ideas, in particular to BOBL, i went with his suggested design and although its a little rough it works well, during the week i will refine it and fit the final lever to a pot belly thats due to picked up next weekend.
thanks again.