J1000 Convection motor grinding down to a halt.

[robsik]

I have a Jamestown J1000 insert. The convection motor, which is a dual crossflow, has been nothing but a nightmare. The current issue it is having is it will run for hours with no issue, putting out good air flow. Then, all of a sudden, it will come grinding to a halt. After disassembly, I see the rotor is actually scored around the center. How could this occur after hours of operation? And how could the center be scored? Does it bulge out when it gets hot? When I put it back together with fan blades, it spins nice and free, and it will run fine again (for a while) so I don't think the bearings are shot. Could it be a balancing issue? Could the rotor be too large for the stator? I'm not sure what my options are other than a new fan purchase. I do have new bearings on order.

This is the motor/fan:

http://jamestownpelletstoves.com/wp-content/uploads/2013/10/07EEH-Crossflow-Fan-for-J11.jpg

Any input is greatly appreciated.

 

[Bkins]

If anything in the motor is riveted together and a rivet broke loose it could do as you are describing. I would think you'd see some evidence of it though. You don't say if you replaced the assembly but the way you worded your post it's not clear what you have or haven't done. Yes, things expand when they get hot. Might ask Jamestown about your issue and see what they have to say. Would be very rare for a rivet to come apart like that, if that's what happened. I'd be looking real closely at all parts of the motor to try to figure out what is happening. The picture you provided doesn't show the motor so to me it's of no help.

Maybe give us some more information on what you have done to your stove over the last few years. There are not that many Jamestown owners here as I just don't see the name very often. I'm sure others will try to help you with a bit more info.

 

[robsik]

If anything in the motor is riveted together and a rivet broke loose it could do as you are describing. I would think you'd see some evidence of it though. You don't say if you replaced the assembly but the way you worded your post it's not clear what you have or haven't done. Yes, things expand when they get hot. Might ask Jamestown about your issue and see what they have to say. Would be very rare for a rivet to come apart like that, if that's what happened. I'd be looking real closely at all parts of the motor to try to figure out what is happening. The picture you provided doesn't show the motor so to me it's of no help.

Maybe give us some more information on what you have done to your stove over the last few years. There are not that many Jamestown owners here as I just don't see the name very often. I'm sure others will try to help you with a bit more info.

Thanks Bkins...sorry I provided so little info. I have replaced one bearing before, and I had to coat the motor shafts with a heat shrink tubing in order for the rubber grommets on the fans not to slip. My plan is to closely check the outer diameter of the bearing that I replaced to make sure it is exactly the same size as the original. If there is any play at all, that could surely cause this, as the rotor would not be perfectly centered in the stator under gravity.. I seem to be answering my own question here just thinking about it! I don't think any part of the motor assy is rivoted, but I will check. Thanks again, and I will post pix later on.

 

[Bkins]

I'm having a hard time visualizing heat shrink tubing on a fan shaft. That sounds like a setup for problems. If this was needed because of bearing size I will suggest going to a bearing supply place, one that services big industry, and get them to order the correct size bearing for both the inner and outter surfaces.

I went to the Jamestown website. It's nicely done and to me looks like a call to them may help you out. What your describing they may be fully aware of. Doesn't mean you need to buy the fix from them but it might be a starting place.

Any Jamestown owners out there that can help?

 

[robsik]

Thanks for your time again. The heat shrink around the shafts was for the rubber fan couplings (grommets?); they melted from the heat of the shafts and started to squeak and slip at high speeds (slowing down the air flow). I had a long back and forth with Jamestown then (this was last year). They essentially did not believe me and were not interested in solving the problem, just offering a small discount off a new fan assembly. I was worried about buying a new OEM fan that could simply have the same issue, when all I needed was the proper temperature-rated grommets. I ended damaging one of the bearings through my feeble McGyver attempts to firmly secure the grommets to the shafts. i.e. I used friction tape and it eventually walked its way down one of the shafts into the motor, gunking up the bearing. The heat-shrink is working much better in holding the blades to the shaft and achieving max speed.

Unloaded, the motor runs fast and freely, so the bearings seem OK, but under the load/weight of fan blades and heat of the stove, something is causing the Rotor to contact the Stator. I am thinking now that maybe the outer diameter of the replaced bearing may be slightly too small, I can't wait to get home and re-evaluate.

I appreciate the help from you and others on this site...makes me not feel so alone in my struggles!

 

[Bkins]

I understand now what you did with the heat shrink tubing. Another possible fix might be to buy a bearing sleeve to go over your shaft. They are sold in many different diameter sizes, both inner and outter. You can get them at a industrial bearing shop, like Trans Bearings or even W.w. GRAINGERs which you can look at on line. They will sell to the general public, at least they do in NJ. you could take your fan in to the counter for help in getting the right size.

If you have any play at all in your bearings it very well could cause your motor issues. If you don't have the tools or knowledge to do a bearing replacement yourself you might try taking it to a automotive place that presses bearings on and off. A lot of Napa shops do this. You may find a aAutozone to do it also although they may be less willing to take on something like that. A motor repair shop is another possibility. You need to make sure the bearing outter race is not going to move in its mounting.

Time for bed. I'll check back tomorrow.

 

[robsik]

Here's a photo of the scoring, but it is a bit worse now.

I didn't think I needed any special tools, because the bearing slides off and on quite easily, sits in a plastic shell and then into the mounting.

I just don't understand why it runs with no issues for a while (seemingly forever if no fans blades attached), then suddenly grinds down...perhaps the replacement bearing can't tolerate the heat? This motor gets very hot, but they probably all do.

I will try the new bearings when they come, but I have no confidence now in the scored-up rotor and most likely will just order the new fan for around $250...ouch...

Thanks again.

 

[SidecarFlip]

Thats dirt (crud) between the laminations (field) and the armature and psobably a sloppy bearing too. you only have a couple thousands running cleatance in the first place.. Clean it, replace the bearings and move on.

 

[Bkins]

Bearings are supposed to be a pressed fit on both inner and outter surfaces. If either surfaces, or both are not tight your wasting your time and money putting in new bearings without fixing the looseness issue.

It looks very much like the motor shaft is very worn on the right side in your picture. That would be a good place to use a sleeve to go over the shaft. In reality your better off just replacing the assembly as it appears you have other damage and the combined problems would be easier fixed by replacing the fan assembly. In order to put a sleeve on and new bearings you need to have a very good idea what's needed, where to go to get the parts, and the proper tools to get the sleeve and bearings on correctly. You also said you have some outter housing damage/looseness which would be difficult to fix.

It appears that there is enough wear on the motor shaft to cause the slowdown you have described especially once things get hot and do their expansion thing.

 

[SidecarFlip]

I'm trying to be nice. It's basically rime to renew the whole thing.

 

[robsik]

Bearings are supposed to be a pressed fit on both inner and outter surfaces. If either surfaces, or both are not tight your wasting your time and money putting in new bearings without fixing the looseness issue.

It looks very much like the motor shaft is very worn on the right side in your picture. That would be a good place to use a sleeve to go over the shaft. In reality your better off just replacing the assembly as it appears you have other damage and the combined problems would be easier fixed by replacing the fan assembly. In order to put a sleeve on and new bearings you need to have a very good idea what's needed, where to go to get the parts, and the proper tools to get the sleeve and bearings on correctly. You also said you have some outter housing damage/looseness which would be difficult to fix.

It appears that there is enough wear on the motor shaft to cause the slowdown you have described especially once things get hot and do their expansion thing.

hmmm...there's a plastic sleeve that the outer race of each bearing sits in that slides into the each end of the housing...you can see the black sleeve on the bearing on the right side of the photo. I don't think pressing is even possible in that case. the inner is metal-to-metal obviously, but seems to be slip fit.

But, in any case, is it safe to say the only way to get that kind of scoring around the center of the rotor is faulty bearings? I did thoroughly clean the rotor and the stator inside for re-assembly.

Any suggestions for where to get good temp resistant bearings? These are the ones that are coming:

http://www.amazon.com/gp/product/B002BBGDM0/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

 

[robsik]

I'm trying to be nice. It's basically rime to renew the whole thing.

thanks...just trying to avoid that after only two years use...

 

[Bkins]

Sorry I couldn't tell from the picture that there was a sleeve on the bearing. It just looks dark to me.

You asked if anything else could cause the scoring other then a bearing. The only other way that I can think of is if something foreign got caught in there. Does the other part of the motor show the same type scoring? I would think that the bearings would really have to be really bad to cause something like your showing.

Are the plastic pieces that the bearings mount in replaceable? Doesn't seem like a good way to mount a metal bearing. Does Jamestown offer a metal inser for that part?

I'll try to look around today as I have seen a metal slide in piece for the outter bearing surface. I don't remember what they are called or it you have any way to put something like that in there.

 

[robsik]

The inside of the motor (stator) must be harder material, looks ok. The intermittent nature of the issue is what drives me crazy...it's been running at full speed for 24 hours now... :-|

The plastic pieces are completely replaceable, and they actually have small cracks in them. I would definitely be interested in replacing them with something metal.

Jamestown can only offer to sell the whole fan, I think they get it now from Bay Motors (the original OEM no longer around), but Bay told me to call Jamestown.

(broken link removed to http://www.baymotorproducts.com/cross-flow-blowers)

I look forward to putting in the new bearings, the existing ones show signs that they are 'leaking' their internal lubrication though they are supposed to be sealed. But I ain't touching it if it continues to work !

Thanks

 

[robsik]

Sorry I couldn't tell from the picture that there was a sleeve on the bearing. It just looks dark to me.

You asked if anything else could cause the scoring other then a bearing. The only other way that I can think of is if something foreign got caught in there. Does the other part of the motor show the same type scoring? I would think that the bearings would really have to be really bad to cause something like your showing.

Are the plastic pieces that the bearings mount in replaceable? Doesn't seem like a good way to mount a metal bearing. Does Jamestown offer a metal inser for that part?

I'll try to look around today as I have seen a metal slide in piece for the outter bearing surface. I don't remember what they are called or it you have any way to put something like that in there.

Hi Bkins, just curious, were you ever able to find the items you referred to above ('metal slide in piece'). The plastic ones in my motor have all but disintegrated, and I'd like to get new ones. The motor is working, but there is a rattling sound that is very loud.

Thanks.

 

[Bkins]

I actually forgot about looking. I just spent a few minutes looking in. A older GRAINGER catalog but didn't immediately find what I was looking for. These plastic pieces your. Talking about, how much room are they designed to take up?

I will spend some time this evening looking again.

 

[robsik]

Sorry, thought I uploaded these two pix already. One shows the black plastic piece off of the bearing, the other with the bearing inside the plastic piece. The metal part shown is one end of the motor housing, into which the plastic piece and bearing slip in. The shaft (not shown) then slip fits through. I neglected to take a picture with the bearing in the housing, but I think you can see that its a snug fit.

Thanks for your time.

 

[Bkins]

Your pictures helped and it is what I thought. I've still not found the metal band that could go around the outside of the bearing. I'm did see cups like you have shown in your picture. Maybe just getting a higher grade plastic cup would work also. I saw them in a Graingers catalog. I'll look more closely today at the cup. The flat surface of the cup would need to be very close on size, or thickness. I'll find out what they call them and let you know. Anybody can buy from GRAINGER not like years ago when you had to have a account there.

 

[robsik]

Awesome, I've been trying to find out what they are called. VXB (bearing supplier) said they were bearing seals, and to check with applied.com. I didn't think they were seals, maybe sleeves, IDK.

It is whatever the 'rubber cushion' is in this product:

http://www.heatingandcoolingwarehouse.com/5_8_Sealed_Sleeve_Bearing_p/38244301.htm

I have an email out to them as well to see if they have just a 'cushion' for a 3/4 in Outer Diameter.

I am sure this is what is causing the rattle, as the bearings have too much freedom in the housing now. If I could tighten them up, it would be nice and centered and free of play.

Thanks again.

 

[SidecarFlip]

So, from what I'm seeing, the skate bearing locates in the plastic retainer and that aligns the bearing in the housing, correct? I'm also presuming the the skate bearing overcame the resistance between the plastic retainer and it's outer diameter (bearing itself) and started rotating in the plastic retainer, causing it to become oval in shape which, in turn, allows the armature to become mis-aligned on the laminations...and grinds to a halt (because of the physical interference and mis alignment....)

Does that sum it up?

A simple fix, so long as you have the meabs to turn a new retainer (and it don't need to be made of plast. It's plastic because it's easiest to make (least expensive to produce) that way and nothing more). It can be made from anything so long as it's dimensionally correct and able to support the beating and keep it in alignment.

Nice granite btw. My wife has the same pattern countertops and thats the preferred material for precision surface plates in my industry.

 

[SidecarFlip]

The 'sleeve bearings' pictured are not ideal replacements. The OEM bearing is a sealed ball, not a sleeve. Sleeve bearings won't last very long, thats not the normal application.

 

[robsik]

The 'sleeve bearings' pictured are not ideal replacements. The OEM bearing is a sealed ball, not a sleeve. Sleeve bearings won't last very long, thats not the normal application.

Wow, need a dictionary to speak on your level ! Quite impressive! LOL. I believe your assessment is correct. But I don't have the means for a fabricating a new retainer. I'm new to this stuff but learning. It's not grinding to a halt anymore, but just runs a little loud.

This is the bearing I ended up installing:

http://www.vxb.com/page/bearings/PROD/Kit18429

Thanks, the granite came with the house! Lucky for us.

 

[SidecarFlip]

I have to ask, how does the bearing fit into the pot metal boss / retainer? Is it a tight fit or did you have to use the old plastic retainer to hold it in place? Reason why I ask is you can size a bearing with it's outer diameter to match (+0.001-0.002 thousands) to achieve a mild press fit in the housing with the inside diameter correct in relationship tp the armature shaft by taking the housing and the armature to a bearing distributor like Applied (Dettoit Ball) or Motion Industries and letting them size it for you, which they will do for free.... I have commercial acounts with both btw.

The it's a simple matter of press fitting the new bearing in the housing which you can do with an appropriate sized drift or socket or metal round and careful use of a hammer..

However, the plastic retainer is most likely there for a reason, that reason being manufacturing tolerances in relationship to armature alignment in the laminations. The plastic retainer allows variations in manufacturing while still providing a useable end product.

For me, bacause I have the machines to make the parts, that would be a simple 5 minute fix. Without the machines, you have to rely on a third party to provide the proper parts and advice.

 

[robsik]

It sounds like the latter - the retainer provides slop for variations in process. But they have since failed I guess due to the heat of the motor (shafts get too hot to even touch).

 

[SidecarFlip]

Most thermoformed and/or injection moulded plastics become soft around 450 degrees (f). I would suspect the retainer is commom injection moulded stuff. I do a sheet plastic HDPE part here in the shop and I have to be careful how hot the mold heat is, or the part becomes too soft and deforms.(and stinks...lol).

If molding temperature is correct, the volitale armoatic hydrocarbons in the plastic don't liberate, in other words, if the molding temperature is correct, it son't smell at all.