Harman Mark II Shaker Repair

 
Don H
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Post by Don H » Mon. Aug. 29, 2016 10:10 am

First post.
I have a Harman Mark II coal stove that needs some repair to the shaker assembly. I did a search and found a post on a similar repair here Shaker Arm "Linkage" Q for Mark III Owners so I decided to join.

My Mark II has about 15 winters of service and the shaker linkage has become extremely worn and loose. The shaker bar pin that passes through the stove wall was worn well over 1/8". Also the hole through the welded piece on the side side of the stove that the pin passes through was worn, being out of round and also about 1/8". These two issues combined made the shaker so loose that the shaker bar pin could slip out of the grate link. So basically the assembly is worn out and needs to be repaired.
Harman.JPG
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(hole after grinding)

Step 1: Remove everything from inside the stove including the grates and bricks (which also need replacing). Then I cut the pin passing through stove to remove the linkage. I ended up with an extremely out of round and over sized hole in the side of the stove. the pin is 3/4" (0.750") but the hole was 0.843" at it's greatest point and 0.772" at its least point. This hole would need to be brought back into round.

Step 2: Bring the hole back into round. Drilling a hole was not an option so I used a drill with a 3/4" X 1- 1/2" grinding bit. Using micrometers I ground and checked until I had as round and even a hole as possible. The dimensions ended up being 0.845 to 0.851 so within six thousands of an inch of being round. I felt this was good enough.

Step 3: Remove the 3/4" cut/worn pin from the shaker bar and handle plate. This was done on a lathe, boring out the two pieces and leaving a clean 3/4" hole where the new pin will go.

Next step is to make a new pin. This will be 0.750 on each end and 0.845 in the center to fit the new stove hole size. I'll use a 7/8" x 8" bolt which I have on hand for this.

If there's interest I'll continue posting as I finish up the repair.


 
titleist1
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Post by titleist1 » Mon. Aug. 29, 2016 2:21 pm

Welcome Don H! Great first post since you had pics included! And of course we are interested in the rest of the story on the repair, you never have to ask about that.

Looking great so far....I am pretty sure if you were using micrometers you are way ahead of the production process for the shaker linkage. :D

 
Don H
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Post by Don H » Wed. Aug. 31, 2016 5:47 pm

So we finished making the replacement shaker shaft. My Dad, who is a retired machinist did the work and it turned out great.
We reused the shaker bar and handle mounting block. Both had to be bored out to remove the remaining pieces from the old shaft. Once this was done we moved on to making the new shaft.
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Parts.JPG
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Welded.JPG
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Handle block.JPG
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The new shaft was made to fit the oversized hole in the side of the stove. That hole was increased to 0.850 to get it back into round. Both ends were turned to fit the shaker handle and the shaker bar, the center was cut to 0.846 x 3/4" long to accommodate the 1/2" block welded to the side of the stove and the 1/4" stove body. The new shaft was made and pressed into the shaker bar, then welded.
Shaker shaft.JPG
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Welded.JPG
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The shaft was then installed in the stove and the Handle Block was installed. The block has two set screws that engage dimples in the shaft. Hopefully this will prevent slipping. If not I can drill the shaft and install a roll ping. This will allow disassembly if needed in the future.
Handle block.JPG
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Handle block installed.JPG
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The next step is to install the rest of the stoves components, including new fire brick.

 
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JBS
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Post by JBS » Fri. Jan. 05, 2018 2:19 pm

Don,
Wow, this is my issue as well. I spoke to a dealer previously and he didn't seem to understand where the worn parts could be! My Harman Magnafire insert is about 30 years old and we still love it. I need to do a similar repair this spring, so I'll be reading & re-reading your post. How is your repair holding up? Thanks for an awesome post!
(Sure wish you were close)
Jim

 
Don H
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Post by Don H » Fri. Jan. 05, 2018 2:36 pm

JBS, your welcome!
I had the same reaction from the local Harman dealer here. They just couldn't understand how this could wear. They even said they'd never had anyone ask about a worn shaker pin.

One thing I did do when I reassembled is to use a touch of Never-Seez on the pin. I think annual lubing of this pin would help prevent wear.

 
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Uglysquirrel
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Post by Uglysquirrel » Fri. Jan. 05, 2018 2:56 pm

The wear on the pin and body is also a path for inlet air to enter.

 
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JBS
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Post by JBS » Mon. Jan. 08, 2018 9:40 am

Don,
What are your thoughts about drilling the stove, handle, shaker out to 7/8" (.875") and cut a pin 1-3/4" long pressed & welded into the shaker and pressed into the handle & pinned on the outside of the stove? It looks like there would be enough meat on everything to allow for this. That would help eliminate the machinist work.
Thanks,
Jim


 
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Post by Storm » Mon. Jan. 08, 2018 5:58 pm

Storm here, I too have a Harman and to combat the squeaky noise when to shake down the ashes I put some high temperature grease on that shaft. It does stay for a while before it evaporates. Also I think it helps with the wear issue, but as always things eventually wear out. Good job of your repair.

 
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JBS
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Post by JBS » Mon. Jan. 08, 2018 9:40 pm

Agreed, I should have been doing that for the last 30 years! Once I get this shaker handle straightened out - I'll be doing just that.

Jim

 
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Hambden Bob
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Post by Hambden Bob » Mon. Jan. 08, 2018 10:06 pm

Welcome and Nice,Mister !

 
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Post by Seagrave1963 » Tue. Jan. 09, 2018 9:11 am

Storm wrote:
Mon. Jan. 08, 2018 5:58 pm
Storm here, I too have a Harman and to combat the squeaky noise when to shake down the ashes I put some high temperature grease on that shaft. It does stay for a while before it evaporates. Also I think it helps with the wear issue, but as always things eventually wear out. Good job of your repair.
Thanks for the tip - the TLC2000 will be getting some hi-temp grease soon!

 
Don H
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Post by Don H » Tue. Mar. 27, 2018 7:53 am

JBS wrote:
Mon. Jan. 08, 2018 9:40 am
Don,
What are your thoughts about drilling the stove, handle, shaker out to 7/8" (.875") and cut a pin 1-3/4" long pressed & welded into the shaker and pressed into the handle & pinned on the outside of the stove? It looks like there would be enough meat on everything to allow for this. That would help eliminate the machinist work.
Thanks,
Jim

Jim, I think that reducing the side wall on the Linkage Bar (inside piece) would make it weak. There's not a lot of meat there.

Also I did get your message about making a part for you.
Yea, I could probably do that. You would need to cut the shaft and send me both pieces. Also I would need the diameter of the hole you drill in the stove. What do you think a fair price would be? We're looking at 3 hours of lathe work to bore out the old shaft from both parts, make an oversized shaft, drill and tap two set screws and then weld one end in place.

As a follow up on my repair we ran the stove for a few days while the power was out a few weeks ago. Other than that we haven't used the stove since it's out back up to the geothermal heating system. I think the real fix is to remove the 1/2" welded block on the side of the stove and replace it with a 1" thick block to create a greater bearing surface.

 
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Post by franco b » Tue. Mar. 27, 2018 10:01 pm

Graphite is the preferred lubricant for high heat, slow moving parts. Most ant-seize compounds are graphite based.

 
Don H
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Post by Don H » Wed. Mar. 28, 2018 7:29 am

Never-Sees is rated for up to 2,200 degrees. That's is what I use for all my stove's working parts.

 
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JBS
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Post by JBS » Fri. Nov. 02, 2018 4:14 pm

I needed to repair to the shaker assembly on my 30-year-old Harman Magnafire insert as well. I followed Don's repair guidelines but I needed to drill the stove opening to 1" and had a machinist create the shaft @ 1.005" using a new shaker bar weldment after removing the shaft. I believe this year I will have an improved ability to shake the grates, probably almost as good a new!

Don, thanks for your offer & suggestions! I liked the idea of the 1" block, that would give the stove shaker bar an awesome amount of support, but I opted to drill out to 1" and keep the shaft ends @ 3/4", similar to what you did.

Thanks to all!
Harman worn shaker (2).JPG
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Attachments

Finished shaker.JPG
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New shaker bar_shaft.JPG
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