Whitfield Quest WP4 auger

[stellep]

Inspired by Bugs' thread I pulled the lower bearing plate on the auger. And here it is.

The auger seems to have scored the plate at some point, but I could not make it contact the plate by hand. It is veeeery close to the plate though. The auger has 1/8 inch play vertically and just a little bit side to side.

I guess I'll replace the Nylatron bearing anyway for piece of mind The auger motor seems fine for a 20 year old part.

Anyone know what the pin sticking out from the auger shaft is for?

 

[Stovensen]

Anyone know what the pin sticking out from the auger shaft is for?

That is a "stirrer pin" to ensure good distribution of the pellets, when they drop over the edge down into the burn pot.
The stirrer pin operates in the small pellet-reservoir between the end of the upper auger-blade and the edge of the drop chute.

In 2008 I also had my auger shaft pulled to replace the Nylatron bearing, just like you have it these days. I noticed that there was only one stirrer pin, but 180 degrees away on the other side of the shaft there was an empty hole, so one stirrer pin was missing!!

The auger shaft on your regular Quest and my Quest Plus looked like this originally. Note: Two stirrer pins:

It is your luck that you now have had your auger pulled for inspection and can be certain that the missing stirrer pin has not dropped down in the auger, causing potential severe damage to the auger mechanism by blocking the rotation. This must have been the case for the previous owner of my stove, since there are deep marks on the involved auger parts from a severe auger jam!

The stirrer pin is made of a "tube rivet" pressed into a predrilled hole of a smaller diameter. The rivet is sliced in the side and therefore it has a springy action in the radial direction. When they are pressed into a smaller diameter hole, the springy action is holding them in place, hopefully!
I don't know if "tube rivet" is the correct term in US-English, but I had an old Citroën car, where the door hinges were joined together by a longer version of these. They are made of hardened steel, so eventually they would grind a clearance in the hinge, thus making the doors "hang"

I made a mod to my auger shaft to avoid these unsafe "stirrer pins". A simple mod, actually: I removed the lonely stirrer pin, and drilled through the hole, all the way to the hole on the other side. Then I cut thread all the way through the hole, and screwed a threaded stud in here. With two tight nuts ( one on each side of the studs ), the "threaded stirrer stud" is now held safely in place.
It is of course vey important that the stirrer stud has the same length ( diameter ) as the original pins.

And BTW, the early Whitfield auger shafts had stirrer paddles instead of pins ( see pic below ) Why did Whitfield change the design from stirrer paddles to pins? I have made my thoughts about this, but will keep them from this posting to avoid derailing the thread.

 

[stellep]

Thank you for the information Stovensen. I was sure that you would know it.
I found out that spring pin is the correct description in US-English.
Both the inside of the pin and the lonely hole were filled with pellet dust.

I am curious that the abandoned pin would not follow the path of the pellets and end up in the burn pot.

For now, I think I will replace the pin and wick a drop of super glue in the hole. In the warm season, I might attempt the excellent mod that you made.

Thanks for that suggestion and for all the help you give here.

 

[stellep]

I wonder if on the later models, Whitifield used just the single pin to cut costs.

 

[Stovensen]

I found out that spring pin is the correct description in US-English.

Ah, spring pin. that makes a lot more sense. Thanks for the info.

I wonder if on the later models, Whitifield used just the single pin to cut costs.

It certainly saves both production time and material replacing four welded-on paddles with two spring pins.
On my Quest Plus, however, the drop chute is rectangular shaped. Wouldn't the paddle auger simply be paddling too many pellets away from the center, thus giving an asymmetric feed to the burn pot?
The oval shaped drop chute ( on your stove and others ) would compensate automatically for this off center paddling.

 

[stellep]

I was thinking more of the two pin version. Maybe it was a design decision to use only one pin and cut costs.

Food for thought.

They went from four paddles to two pins. Then maybe to one pin? Did Whitfield decide only one pin is as good as two?
Both of our stoves have only one pin and neither of us has found the missing pin. Neither of us has 0 pins.
What would happen with 0 pins?
My stove runs fine with the single pin. If not for Bugs' thread, I would not know one was missing.
Not sure how or if a spring pin could fall out of the auger.

Perhaps I think too much about these things, but I find it interesting.
Thank you for your indulgence.

 

[Stovensen]

What would happen with 0 pins?

Well, when I had the auger pulled almost 10 years ago, I did scratch my head over several questions concerning the design of the auger: Why does the auger blade stop a couple of inches before the edge of the chute, and why do the spring pins have to stir the "pellet-reservoir"piling up here? My conclusion was that it was to ensure an even distribution of the pellets on both these points: An even amount of pellets timewise and an even release locationwise down the chute. The latter is particularly critical on a rectangular shaped drop chute.
With no spring pin wouldn't there be the risk of a long pause in pellet feed, while the pile was forming? ( fire might go almost out ). Then suddenly, the pile would release an "avalanche" of pellets that might take out the rest of the embers in the pot. Just my thoughts on this.
I have no detailed knowledge about the auger design of other top feeding pellet stoves, but it could interesting to hear from more experienced forum members on this topic.

 

[stellep]

That sounds reasonable to me.
Actually, my stove sometimes suffers from a mild form of what you describe.
Perhaps when I replace the second pin, I will have a smoother pellet feed.
I'll let you know!

 

[stellep]

I just thought, maybe the pins break up some of the longer out-of-spec pellets too.

 

[Stovensen]

Actually, my stove sometimes suffers from a mild form of what you describe.
Perhaps when I replace the second pin, I will have a smoother pellet feed.
I'll let you know!

Looking forward to hear about your results on this.
Pellet feed on my Quest Plus is absolutely flawless, just as long as I remember to vacuum out the accumulated sawdust, when the hopper needs a refill. I keep a handheld accu-vac next to the stove just for this purpose.
Some pellet batches are worse than others, though.

 

[stellep]

Interesting. I never vacuum the hopper except for the annual maintenance. The stove seems to eat the fines up.
I do have the same experience as you with pellet feed. Some will put the fire out. But others maintain the fire correctly at a lower much feed setting. It seems to vary with the size of the pellets(if some are long) or how fast the particular wood source burns.
I hope the parts arrive by the weekend, but I am using the stove so no emergency.

I also plan to measure the wear on the old bearing vs new. I expect it to be quite worn but I've been wrong before
I'll let you know all results.

 

[stellep]

I was right for once.
The old bearing measured against the new one showed no wear at all. I have maintained this stove for at least 10 years and never replaced the bearing.
The damage to the plate happened in a previous lifetime.

I thought I'd replace it anyway.

Rut Roe. The bearing is just a touch too small for the auger. So I used the old one. The way these things wear, I'll probably never need the new one. I'll massage it and keep it or return it if I can.

While I had the auger out, I replaced the missing spring pin (or tension pin or roller pin depending where you get them). I could not get the right length, so I bought a longer one and massaged it with Stovensen's favorite (rotary) tool.

The pellet feed is now much smoother, I didn't realize how erratic it was with the single pin. Also, the better burn seems to keep the glass cleaner.

The specs in case it helps someone, someday, somewhere, somehow.

The new bearing is 1/8" above the plate on the auger side, 3/4" opening.
The correct pin is 1/4x3/4". 1/2" outside the auger shaft.

Rock on.

 

[Stovensen]

The old bearing measured against the new one showed no wear at all. I have maintained this stove for at least 10 years and never replaced the bearing

Impressive! That nylon material appears to have some wonderful longterm self-lubing properties compared to Oilite sintered bronze. 10 years of use clearly proves that.

Rut Roe. The bearing is just a touch too small for the auger. So I used the old one. The way these things wear, I'll probably never need the new one. I'll massage it and keep it or return it if I can.

My brain can only work in the metric system. After so many decades with millimeters, micrometers etc. it's hard for me to get an idea of how much 0.7440 - 0.7400 = 0.040 inch is.
But hey, here we have our wonderful "New Age"vernier calipers All I have to do is to dial the inch value and then press the inch/mm button and voila, the mm value is there: 0.040" = 1.03 mm.
1.03 mm is a lot in this place, I would certainly return the bearing and have my money back. Must be for a different stove brand. It cannot be for a Whitfield stove.

Back to our vernier calipers. I have a question to you. As you can see the top button on my caliper has a different text. On yours is says mm/inch/F. What does the F after the slash mean?

 

[stellep]

It's for Fraction of inches. Makes it easy to measure things like the auger pin and directly find the spec on the package. Initially I did not realize that it had this feature. Then, I was happy to find it.

Question for you. Does your display turn on when you move the slider. I stumbled upon this feature too. Almost thought that it was defective. I have to make sure that the slider is locked, otherwise it can turn on by accident. It does seem to shut down automatically after a while.

I am still amazed how much difference it made to replace the missing pin on the auger. I'm fairly certain that it was always missing.

 

[Stovensen]

It's for Fraction of inches.

I see. The use of fractions of inches is of course more common in the US, so this is included as a feature on your caliper. Some things are still measured in inches here, though. Waterpipes for instance.
And I have had several Mercury outboard engines through the years. To repair these I had to buy a socket wrench set and some spanners.
The real nightmare starts, when you need to cut thread on such an engine and you only have metric thread cutting taps and dies. Had to buy a set of taps and dies for UNF thread. Or was it Whitworth thread? Don't remember the difference.
On the other side on my caliper there is a tap and drill chart for both metric and imperial thread. Does yours also have this chart?

Question for you. Does your display turn on when you move the slider. I stumbled upon this feature too. Almost thought that it was defective. I have to make sure that the slider is locked, otherwise it can turn on by accident. It does seem to shut down automatically after a while.

Yes, it also turns on when moving the slider, and the locking screw could be have been better, more precise. A larger diameter of the screw would have helped this.

I am still amazed how much difference it made to replace the missing pin on the auger

Glad to hear. Stay warm and safe.

 

[stellep]

On the other side on my caliper there is a tap and drill chart for both metric and imperial thread. Does yours also have this chart?

Mine has a chart for metric and Whitworth(UK). Similar measurements here are called US Standard. I don't know the difference if any.

Speaking of measurements. I think the measurements of the auger vs bearing I showed above are 0.0040 different. That is 1/128 inch or 0.10 mm.
I had to think about this a bit.
I could tightly get the bushing started on the auger. It would bind. So I moved on.

To further confuse you, it's 19F degrees here today.

Thanks.

 

[Stovensen]

Mine has a chart for metric and Whitworth(UK). Similar measurements here are called US Standard. I don't know the difference if any.

Neither do I. On my Mercury outboard engines the thread was all UNF. There is also UNC. The F and C should indicate Fine vs. Coarse thread.

Speaking of measurements. I think the measurements of the auger vs bearing I showed above are 0.0040 different. That is 1/128 inch or 0.10 mm.
I had to think about this a bit.

My mistake, sorry. Thanks for correcting me. Shouldn't have relied on my head, but instead used a calculator. 0.10 mm is a lot more acceptable. The binding could be fixed in several ways. Sanding material away would be a pity on a brand new bearing, but how about mounting the bearing on the auger shaft and then heat both in a oven at a very low temperature, say 120 ( 50 ). Don't go any higher. This would be a very mild "heat shaping action" of the binding bearing. Just an idea that might work and certainly not harm the material at only 120.

 

[Ssyko]

Rut Roe. The bearing is just a touch too small for the auger. So I used the old one.

You could heat the bearing and freeze the shaft may slide on that way.

 

[stellep]

Too late. All fixed.

 

[stellep]

how about mounting the bearing on the auger shaft and then heat both in a oven at a very low temperature

I can't mount the bearing on the auger shaft. Too tight. It would damage or destroy the bearing.

 

[stellep]

how about mounting the bearing on the auger shaft and then heat both in a oven at a very low temperature,

I can't mount it. Too tight. I would damage or destroy the bearing.

 

[Stovensen]

I can't mount it. Too tight. I would damage or destroy the bearing.

Ok, I thought that it was only binding too much, but still possible to mount on the shaft. The nylon material is not very flexible then, since 0.1mm undersize can cause this.
Somehow it must be slightly out of specs then. A little sanding could do the trick.