Mamabear Flue pipe issues

[Todd_C]

I have a Mama bear with a 6" rear Flue.
Here is my problem. The 6" stove pipe fits really lose & sloppy. It doesnt matter if I insert the crimped side or the female side. Still sloppy lose. The rolled flange on the pipe near the crimp kinda fits snug but is pretty lose. Any suggestions would be appreciated.

 

[coaly]

Are you sure you have 6 inch stove connector pipe?? It will be black and made of at least 24 gauge.

Does the stove outlet pipe measure 6 inch outside + - 1/16 inch ??

The crimped end is normally a very tight fit inside the stove collar. You usually have to crimp it down smaller with a hand crimper to get it in.

The female end normally fits over the outside of the flue collar with a good fit.

 

[Todd_C]

ID is approx 6 1/8 OD is 6 9/16. I even looked at using a 7" to 6" reducer but it's off as well. I can see the inside being bigger due to age corrosion wear etc. But by this much makes no sense.

 

[coaly]

That is normal for later stoves. Most measure between 6 and 6 1/8 ID, 1/4 inch wall measuring 6 1/2 to 6 5/8 OD. I'd try a different manufacturer of pipe ?? My crimped end is just right in the 6 inch ID stoves and outside of pipe with no crimp is just right in the stoves that measure 6 1/8 ID. (attach with 3 screws at stove and at each joint) I have the cheap type (Canadian made) here I am test fitting with seam you put together. It came from Lowe's or Home Depot and works in the newer stoves I have here to try. I keep a new length in each stove with top vent just for display.
The welded seamless pipe by Dura-Vent (Dura Black stocked at Home Depot) is not crimped. The female end is expanded and may be just the size you need. I'd try a length of Dura Black for fit first. It's the best to put the damper in that stays perfectly round with no seam too.

The Kitchen Queen we use in our kitchen has a steel ring made from flat stock welded to the stove top for the 7 inch vent pipe, and is made very loose. So I cut the crimped end off leaving the larger bulge for the stop, and forced the bulge down into the stove collar. It's a really tight fit but works well. Haven't had to do that with a Fisher, yet. I try to get the fit as good as possible without using furnace cement, but you can always fill loose pipe joints with it.

https://www.hearth.com/talk/threads/sealing-stove-pipe-joints.115747/#post-1548392

 

[Todd_C]

I was thinking of trying a different brand. maybe a higher gauge. Are they measuring the ID or OD? If it works it looks like I have to return the pipe I have. Or will the differing brands work together. O'h well. Live and learn.
If I end up using Stove cement how big of a gap can it safely fill? I'm guessing on this , but I would think as long as the mechanical fastening is strong then it shouldn't be a problem. Or would expansion cause problems? I like the idea of welded seam pipe. But I do not like the idea of the cost. Being a cheap skate has it's drawbacks.

 

[coaly]

6 inch inside.
Mix and match as you need to. Crimpers are a necessity cutting and putting it together. You can adjust the shrinkage at the crimp by how much you squeeze it down. Put a 2 X 4 on edge inside the pipe against the side and hit with a hammer to flatten back out again if you go too far. It's workable stuff.

1/8 inch gap is stated on the black Rutland in a tube. But we've all stretched that. I've tucked round door gasket material in between poor fitting cast iron parts on antiques - and covered my tracks with cement........ Us Fisher users are spoiled with a precision built stove not needing to glue it back together every few years. I use more gasket cement than anything, so I use whatever I have. Rutland "black stove & gasket cement" does not come apart easily. It adheres so well, it needs to be removed with a wire wheel. Tough stuff.

 

[Todd_C]

Ya know what. I was thinking about the gasket material with gasket cement as well. I was worried it wouldn't hold up. I have this paranoia streak that keeps my bearings on track. Have you ever used meecos red devil?
Any experience with this brand?

 

[Todd_C]

The rutland cement requires heat to cure. Can I use a map gas torch to cure it in advance. I want the fitting tight and strong to keep the rest of the pipe fittings from getting off kilter.

 

[coaly]

3 screws at each joint doesn't allow it to move, then caulk the joint. Fire it lightly just to warm it good a couple times for cure. You can tuck gasket material in the joint to be air tight enough if you have something thin enough. Poke it in with a screwdriver. I only covered it in stove joints to look nice and cover the gasket material, not for sealing air. It will leak air in, not smoke out.
Another reason to avoid a leak there, is in case you get enough smoke in the pipe, it's at the highest temperature right there, and an oxygen source right there can allow the smoke to ignite burning way hot in the pipe as secondary combustion. The pipe will glow right above the air inlet and you know you have rolling flames inside from the smoke right there.
A baffle plate inside burns a lot of the smoke off, diverts flames from going out the exhaust, and lowers temperatures at the exhaust outlet, reducing that possibility drastically.

 

[coaly]

I had a can of Red Devil furnace cement years ago (maybe 1980) that I used on a badly cracked and deteriorated firebox liner in a Buckwalter cookstove. 100 years ago it was common to lay it on thick and make an entire liner the thickness of brick with it. (refractory cement) It's only sides to contain the coal, and not touched with tools or wood and worked well. Looks like cement but doesn't degrade from the heat. The black Rutland goes on smooth and cast parts can be bolted together - wipe the excess off, the joint is black, and doesn't leak.

 

[Todd_C]

I plan on fabricating a baffle plate. I was looking at the baffle plates others have designed. I'm partial to the one in the honey bear. The bent center gives me the impression that it would create more turbulence for the smoke and flames. I'm thinking it would be even more efficient this way. would my assumption be right?