Harman exhaust stub, impossible to drill for attaching stove adapter?

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tlc1976

Minister of Fire
Oct 7, 2012
846
Northwest Lower Michigan

you replied in that post so you must of forgot about it.

ignition explosion

and another

another

Some of these can be pretty violent depending how much gas builds up in the firebox. It's in the Harman install manual that you need screws into the exhaust stub, now if some one wants to put their family at risk by not following the manufactures install procedure that's their choice.

His reply in that thread said he never heard of it happening in a pellet burner, which is what we are talking about here.

I get the occasional poor ignite, and a poof. The worst that’s ever happened is a puff of smoke pushing past the door seal. Never anything violent enough to break glass.

In any case, if the pipe isn’t fixed from movement (like wall brackets) then I’d screw it to the stove collar.

Sharpening drills is one thing I was taught in machine shop class in college. At the old house I never had a place for a bench grinder, so I learned to sharpen them with my angle grinder. They weren’t perfect but knowing the principle of attack edge and clearance, they worked pretty well. Having no money meant I had to keep what I had sharp and regrind broken ones.
 

SidecarFlip

Minister of Fire
I’ve had the “POOF” a few times and found either under the burnpot where the igniter is had too much gunk/fines in it, the burnpot holes needed a little hone of the holes(carbon buildup) or damp pellets. I believe Sidecar as he’s VERY anal about how clean his stove is...but I’ve seen the posts here before....unique circumstance to have an ignition that big though I’d think.....extremely dirty would be my first guess
I am anal about it being clean. You have to be when roasting corn. Corn, unlike pellets makes a ton of ash and it's not the fine ash that pellets make, it's more like tiny lumps of fluffy coal. My unit gets cleaned (when I'm running hard) every 4 days and the pot soaked and cleaned and every 8 days, the pot gets cleaned, the ash pushed into the ash pan and dumped, the inside of the firebox gets vacuumed out, the exhaust path behind the back wall gets a bottle brush treatment (and vacuumed out) and the entrance to the combustion blower plenum gets vacuumed out as well. When I start the stove, I leave the door open so the draft fan is running on high and I dump any ash in the transition Tee outside. I have it down to about 10 minutes tops but I do it on a schedule and I stick to it.

One thing about a clean stove (inside the firebox), it heats much better when there is no ash accumulation on the heat exchangers inside. The more ash buildup you have the less heat transfer you get for the amount of fuel burned. Now that I have my new ($275 buck) pot, I'll be exchanging pots. One will be soaking while one is in service. Been wanting to do that for a while now. Bought a new room air fan too. Old one works fine but after 20 years, it's time to 'upgrade'. Pellet Stove Parts for less had everything in stock. Fast (free shipping) to. I like them. Put part of my stimulus check to good use. the rest gets put away in the bank.
 
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SidecarFlip

Minister of Fire
they worked pretty well. Having no money meant I had to keep what I had sharp and regrind broken ones.
Key is buy quality ones, not the Harbor Freight box store junk. Heck I can even sharpen end mills off hand. They really need jigged on a surface grinder but they work for 'government work' when I don't want to set up the surface grinder to dress them properly.

Like I said, at my age, it's hard to see the little ones anymore. Big ones, no issue. getting old isn't all it's cracked up to be. I can testify to that.
 

tlc1976

Minister of Fire
Oct 7, 2012
846
Northwest Lower Michigan
Key is buy quality ones, not the Harbor Freight box store junk. Heck I can even sharpen end mills off hand. They really need jigged on a surface grinder but they work for 'government work' when I don't want to set up the surface grinder to dress them properly.

Like I said, at my age, it's hard to see the little ones anymore. Big ones, no issue. getting old isn't all it's cracked up to be. I can testify to that.

I had a set of cheap ones that were only good for wood. Otherwise softer than what I was drilling. My normal set was good. But even a good set is only as good as the conditions you have to work with. No workbench or drill press. I got good at drilling straight down by eyeballing, with the workpiece on my porch held down with my steel toe boot.
 

SidecarFlip

Minister of Fire
Been there and did that before myself. Most times I'm drilling precision holes with a vertical mill anyway. problem is, when drilling on your porch you have to be careful not to drill into the porch itself... :)
 
Jan 29, 2021
145
VA, east central
I think you do too. Gold colored 'Titanium Nitride' don't mean squat, all it does is promote good chip flow and cheap bits are just that, cheap. Could be a dull bit too. Bet you don't know how to sharpen a twist drill.... I do.

Go to MSC and buy yourself a set of quality American made twist drills, like Chicago Latrobe or Cleveland Twist or Triumph. They ain't cheap but good stuff is never cheap. Only cheap stuff is cheap,

Having said that, I've never screwed my venting to the exhaust stub but here is what I do...

I take a thin kerf cutoff wheel in my battery operated 4.5" angle grinder and I cut the galvanized outer jacket from the venting just past the crimped in part, exposing the stainless inner pipe. Then I coat the inside of the inner pipe and the outside of the exhaust stub with high temp (red) rtv and slip the stainless steel inner pipe over the stub and put on a Witek (worm clamp) and cinch it down. Been doing it that way for decades. No leaks whatsoever.
But Flip, the bit packaging says Titanium coated is the best! ;lol
So, you gonna tell us how to sharpen bits or just brag about knowing? :) I figure get a gizmo that sharpens them. But mine are just Dewalt or similar, so who knows how long they would even stay sharpened for harder material.
 
Jan 29, 2021
145
VA, east central
Key is buy quality ones, not the Harbor Freight box store junk. Heck I can even sharpen end mills off hand. They really need jigged on a surface grinder but they work for 'government work' when I don't want to set up the surface grinder to dress them properly.

Like I said, at my age, it's hard to see the little ones anymore. Big ones, no issue. getting old isn't all it's cracked up to be. I can testify to that.
Wait, who said getting old is great?
But tell me about it, in the past year I reached the point I need magnifiers for tiny print. I can't focus well closer than 10 -12 inches. Happened quick. I hear I'm in store for even more unpleasant discoveries.
 

SidecarFlip

Minister of Fire
But Flip, the bit packaging says Titanium coated is the best! ;lol
So, you gonna tell us how to sharpen bits or just brag about knowing? :) I figure get a gizmo that sharpens them. But mine are just Dewalt or similar, so who knows how long they would even stay sharpened for harder material.
Wish I could... offhand bit sharpening is an acquired by experience skill. You just cannot look it up on Goggle or You-Tube and go do it. Kind of like TIG welding or gas welding, takes experience to master. I suggest if you really want to sharpen your bits, go buy a consumer grade Darex Drill Doctor. I think they are less than 100 bucks and the do work well though the range is somewhat limited and they will only sharpen conventional twist drills (no parabolic or left had or spit points). With a drill doctor and a few dull bits, it's paid for itself and they do, do tungsten carbide masonry drills too.

if I'm not mistaken, I think the exhaust stub on a Harman is die cast aluminum, it's not cast iron, the wall thickness is too thin. If you want to dispense with the drill all together, go to the local hardware store and buy 3 self drilling metal screws (commonly called Teks). the ends are the drill bit and they self thread. Get the socket headed ones or the Torx headed ones, they are easier to start and your drill motor won't slip off (and cause you to cuss)....

TiN coating has nothing to do with the cutting end of ANY drill bit (look at the end, you won't see any 'gold' on it. Titanium Nitride is a coating that improves chip flow and a big selling thing for consumer drill bits that don't mean beans.

Buy yourself good quality black oxide HSS bits and use a little lubricant when drilling too.
 
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SidecarFlip

Minister of Fire
Wait, who said getting old is great?
But tell me about it, in the past year I reached the point I need magnifiers for tiny print. I can't focus well closer than 10 -12 inches. Happened quick. I hear I'm in store for even more unpleasant discoveries.
I had both my lenses replaced last spring. How's that grab ya. I now have lenses made in Austin Texas. I still have a hard time seeing tiny stuff but it is better. Just refracted at 20-23. Wore glasses all my life and kept getting worse until I developed cataracts so I had them dealt with. 5 minutes per eye, 2 day recovery and all is good. Wish the rest of it was that easy.

I'm sure your 'discoveries' won't equal mine or at least I hope they don't. Lets just say I'm a survivor and leave it at that. it's a continuous battle staying on this side of the dirt. having fun though and everyday I'm blessed with opening my eyes is another great day.
 
Jan 29, 2021
145
VA, east central
Wish I could... offhand bit sharpening is an acquired by experience skill. You just cannot look it up on Goggle or You-Tube and go do it. Kind of like TIG welding or gas welding, takes experience to master. I suggest if you really want to sharpen your bits, go buy a consumer grade Darex Drill Doctor. I think they are less than 100 bucks and the do work well though the range is somewhat limited and they will only sharpen conventional twist drills (no parabolic or left had or spit points). With a drill doctor and a few dull bits, it's paid for itself and they do, do tungsten carbide masonry drills too.

if I'm not mistaken, I think the exhaust stub on a Harman is die cast aluminum, it's not cast iron, the wall thickness is too thin. If you want to dispense with the drill all together, go to the local hardware store and buy 3 self drilling metal screws (commonly called Teks). the ends are the drill bit and they self thread. Get the socket headed ones or the Torx headed ones, they are easier to start and your drill motor won't slip off (and cause you to cuss)....

TiN coating has nothing to do with the cutting end of ANY drill bit (look at the end, you won't see any 'gold' on it. Titanium Nitride is a coating that improves chip flow and a big selling thing for consumer drill bits that don't mean beans.

Buy yourself good quality black oxide HSS bits and use a little lubricant when drilling too.
So it can't be cast aluminum, I know for a fact that these bits would have eaten right through it if it were aluminum. As it were, they barely marked it.
I probably would buy a sharpener if I drilled enough. For now it's generally a few times a year. And yeah, I figured TiN was pretty much there to make consumer ooh and ahh over their shiny drill bits. No way a thin coating actually stays near the cutting edge that is experiencing extreme pressures.
I may revisit drilling the stub again when I take the piping off over the summer to install a chimney liner. Depends on what things look like when I take the silicone tape and adapter off.
 
Jan 29, 2021
145
VA, east central
I had both my lenses replaced last spring. How's that grab ya. I now have lenses made in Austin Texas. I still have a hard time seeing tiny stuff but it is better. Just refracted at 20-23. Wore glasses all my life and kept getting worse until I developed cataracts so I had them dealt with. 5 minutes per eye, 2 day recovery and all is good. Wish the rest of it was that easy.

I'm sure your 'discoveries' won't equal mine or at least I hope they don't. Lets just say I'm a survivor and leave it at that. it's a continuous battle staying on this side of the dirt. having fun though and everyday I'm blessed with opening my eyes is another great day.
Sucks... lol
My dad had his lenses done a few years ago, I think he's 77.
But yeah, I figure I need to take advantage of the time I have at this age and appreciate what I have while I have it. The last ten years went by pretty quickly and they weren't all that great. But here's to a better next ten years!
 

rich2500

Minister of Fire
Nov 19, 2005
1,385
Berks County PA.
His reply in that thread said he never heard of it happening in a pellet burner, which is what we are talking about here.

I get the occasional poor ignite, and a poof. The worst that’s ever happened is a puff of smoke pushing past the door seal. Never anything violent enough to break glass.

In any case, if the pipe isn’t fixed from movement (like wall brackets) then I’d screw it to the stove collar.

Sharpening drills is one thing I was taught in machine shop class in college. At the old house I never had a place for a bench grinder, so I learned to sharpen them with my angle grinder. They weren’t perfect but knowing the principle of attack edge and clearance, they worked pretty well. Having no money meant I had to keep what I had sharp and regrind broken ones.

Correct and his post in this post is that he never heard of it happening so indeed he did in a pellet stove but like I said he probably forgot about it,what ever who really cares. Like I said I don't care what some one chooses to do but if the manufacturer tells me I need to do something a certain way then that's the way I'm doing it. I'm not risking a possible Ins. claim denial or putting my family at risk for not following the manufacturers installation procedure. Remember folks your playing with fire here and all it takes is one stupid thing to happen and you may regret not following those manufactures procedures. SAFETY FIRST
 
Last edited:

tbear853

Feeling the Heat
I take it that these explosions only occur with ignitors ... not our old manual lit match types.

As to adapter to stove, I have just clamped the inner SS liner to 3" stub, no sealant or screws.

Drill bit sounds dull too.
 
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SidecarFlip

Minister of Fire
No ignition source with no cal rod ignitor. me, I wouldn't have it any other way.
 

SidecarFlip

Minister of Fire
I can buy a lot of bits for 100 bucks....

Dan
You can buy a boatload of cheap Chinese bits for 100 bucks but when they are dull, you get to landfill them so what's the point? Dull is dull. Dull is worthless. With a Drill Doctor you can even sharpen the cheap Chinese bits and then they will work maybe another time and get dull again.
 

tlc1976

Minister of Fire
Oct 7, 2012
846
Northwest Lower Michigan
I don’t like to throw away things that have useful life in them. To me, throwing away dull drill bits is like junking a car because it needs a tuneup.

I was given a drill doctor. It’s ok but I find it works better to just do it by hand. Maybe that’s why he gave it away.

I had a set of Chinese bits a long time ago and I swear they were powdered metal. If I can’t even get through one hole without it going dull then it’s pretty worthless. The bits I have now are no $100 set, but they bite through steel.

With a good drill doctor, you can save a lot of money in the long run. Not to mention the inconvenience of having to run to the store when you’re in the middle of a project. I hate that the most. Learn to sharpen them yourself and you can save the cost of a drill doctor too. Sharpening bits isn’t like being gifted, it’s a procedure that anyone can learn, and there should be more information out there now than ever before.

I still just use my angle grinder. I did it for 17 years at the old house. Old habits die hard.
 

SidecarFlip

Minister of Fire
It's a two hand operation to apply the proper negative rake and split the web properly. Like TIG welding sort of. I like to relieve the heel on any drill over 1/8". Doing that makes for a lot less pressure to drill and reduces the heat that causes the cutting edge to fail. A bit of lubricant on ferrous metals does good too.
 

Pete Zahria

Minister of Fire
Jan 6, 2014
1,192
New Hampster
mcmanusfuels.com
You can buy a boatload of cheap Chinese bits for 100 bucks but when they are dull, you get to landfill them so what's the point?
Pretty sure I never suggested buying Chinese bits..
The "average" person, does not use a drill perhaps in two blue moons.
I have built a half dozen race cars, and a few custom motorcycles,
I understand good/bad drill bits.
The "average person", can buy a lot of high quality bits on a as needed basis,
for $100... Does not need to worry about a Drill Doctor.
That was really my point...

I do agree with you, and was one of the first to suggest
that buying cheap drills is a waste.. unless it is for a butter project,
and was probly the original poster's problem...

Dan
 

SidecarFlip

Minister of Fire
Even the guy on 'Project Farm' recommends the Drill Doctor.
 
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SidecarFlip

Minister of Fire
That sounds destructive....

I have the tool room Darex but I rarely use it. Bought it at a machinery auction, no way could I justify a new one. The high end ones retail for about 5 grand. They do end mills too, least flat ended ones. I'm addicted to machinery auctions but I hardly ever buy used machinery because most time, a company going out of business don't take care of their machines and I don't buy trouble. One time I did buy what I thought was a nice Series 1 Bridgeport at a machinery auction and ended up replacing all the bearings in the head. That is a job. There are 4 sets of ABEC Class ZZ precision bearings in the head and all have to be preloaded to spec by shimming. Never again. I buy tooling as in carbide inserts and tool holders and good precision measurement tools, preferably Starrett or Mitutoyo, lots of end mills and lots of reamers and 'drills' too. No Chinese stuff. Industrial shops don't use import cutting tools. European yes, Asian, no.
 

mtnbiker727

Burning Hunk
Mar 11, 2019
130
PA
Back to the original question.... I put one self tapping screw through the appliance adapter into the outlet of the stove. Then I put high temp silicone on the screw head.

I don't think you want to make a hole in there, because it'll be harder to seal it than if just the tip of the screw punctures the metal....
 

Washed-Up

Minister of Fire
Nov 5, 2011
669
Kananaskis,Alberta, Canada
It’s just a pilot hole for the screw, but if you used a self tapper, same result achieved
 
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