Brand new Rohde kiln lid gap and burnt ropes

[FMPotter]

Hi, newbie potter here, I'm having some issue with a brand new Rohde ecotop 60s kiln and I'm not sure if it's something normal or I had bad luck and received a bad kiln. I hope all the experienced people in this forum can help me out.

I've just bough a new Rohde ecotop kiln (my first ever kiln) and after ONLY THREE FIRINGS the rope insulation on the outside of the barrel looks burned and the steel ring holding the lid is all stained from the heat. The lid doesn't sit fully on the brick walls letting heat escape, which caused the damage I think.

As said I only fired 3 times at:

1. 1000 C
2. 1000 C
3. 1230 C

The Kiln is rated at 1320 C so all were well below the maximum. I'm attaching pictures I took after the third firing, these are all at room temperature after it's completely cooled down.

Rohde says it's all fine but I feel they're just trying to avoid responsibility. They asked me to loosen the metal band round the lid and just press the bricks down. I've done that very carefully and the bricks have come down quite a bit but there's still a very visible gap. Also doing this caused some cracks on the lid bricks.

In your experience are these things normal for such a new kiln? Or did I have bad luck receiving a bad kiln and I should try to send it back?

Thank you for your help

[Bill Kielb]

1 hour ago, FMPotter said:

In your experience are these things normal for such a new kiln? Or did I have bad luck receiving a bad kiln and I should try to send it back?

My perception, poorly manufactured and poorly fitted lid. Disappointing if they do not stand behind it in my opinion.

[neilestrick]

You will get discoloration of the rope and the metal. That's unavoidable. Kilns do not stay shiny and clean for very long. And the lid will typically gap during a firing as the bricks expand, however it should fit tight when the kiln is cold. Is the hinge adjustable at all? If the gap is in the front, then the back probably needs to be raised slightly to allow it to sit flush all the way around.

[Min]

Ask Rohde for instructions on how to adjust the lid. Lid should float somewhat so it can raise when the kiln expands and then lower back down to be level and flat with the body when cool.

[Mark C.]

That kiln look like quality construction stainless fasteners -powder coated parts,extra wall insulation.

I wish US manufactures would offer better made kilns-yes they would cost more but could be called a professional line

[FMPotter]

Thank you all for your replies. Yes, I wasn't expecting the kiln to stay beautiful forever but just 3 firings seems too low to star showing this kind of wear.

@neilestrick, @Min

Rohde sent me some instructions but mainly consisted in asking me to loosen some screws and push the lid dow, not very technical. I managed to reduce the gap a little this way (not much) but after another bisque firing more discoloration appeared so heat is still escaping quite a lot.

@Bill Kielb

I also think it's poor manufacturing. I think because we bought it beginning of this year, when the pandemic was starting Rohde might have rushed some orders and quality wasn't checked properly.

@Mark C. this is a German kiln

[neilestrick]

23 minutes ago, FMPotter said:

 

Rohde sent me some instructions but mainly consisted in asking me to loosen some screws and push the lid dow, not very technical. I managed to reduce the gap a little this way (not much) but after another bisque firing more discoloration appeared so heat is still escaping quite a lot.

That's basically how it works. If the front isn't closing tight, the back needs to come up. Might need to pull up on the back as well as push down on the front. Depending on how it's built, if the hinge itself isn't adjustable, you may need to bring up the outer jacket in back.

[LinR]

My kiln also gapes when hot.  I can't figure out how to loosen the hinge, so I have started placing bricks along the front edge of the lid making sure they are right over the top edge of the kiln wall.  That seems to work. Lin

[Min]

6 hours ago, FMPotter said:

the rope insulation on the outside of the barrel looks burned and the steel ring holding the lid is all stained from the heat

The discolouration will be from materials gassing off during the firing, the rope isn't burnt. Same thing will happen around the spy/peep holes and from under the lid as fumes escape. It's okay (and expected) for the lid to gape while firing but it should come back down to flush with the body of the kiln when cooling.

[FMPotter]

I was told about the lid lifting during firing, but these pictures were taken with the kiln cold. From all your comments it seems it's not normal to be this way with the kiln cold

I see there is some confusion with where the gap is. I wasn't very clear, my fault,  but the gap is on the right side of the kiln. The front sits well and it has a latch.

Thanks again for all your comments

[Bill Kielb]

1 hour ago, LinR said:

My kiln also gapes when hot.  I can't figure out how to loosen the hinge, so I have started placing bricks along the front edge of the lid making sure they are right over the top edge of the kiln wall.  That seems to work. Lin

I am sorry, kiln lids are designed with offset closure for the lid. This is a high quality kiln and leaks excessively after only three firings. In my opinion, just not acceptable, and adjusting this by loosening the band is even less impressive as the slab will tend to re-square itself in the band. Loosening  and adjusting the hinge (not the tension band) when this is at temperature would be more typical. I can’t help hoping  you happened to get a disinterested technician. Can you post a few pictures of the hinge pivot, hopefully adjustment is designed in and available.

[oldlady]

nothing to say about the problem but , FM, just fyi, the "rope" is made of heat resistant insulating fiber(fibre) not ordinary rope.  it should settle down after firing it a number of times to look brown all the way around.   the individual threads that are woven into the rope will not burn up.

[neilestrick]

3 hours ago, FMPotter said:

I see there is some confusion with where the gap is. I wasn't very clear, my fault,  but the gap is on the right side of the kiln. The front sits well and it has a latch.

So the problem could be the lid itself, the hinge, or the top row of bricks. I'd take a straight edge and see if the lid is flat, and if the top row of bricks is flat and even all the way around. If those are good, then either the hinge needs to be adjusted or something was mounted out of whack.

[FMPotter]

So I've placed a metal bar across the top of the  open kiln (I.e. on top of the wall bricks) and used a level. It has an inclination of ~0.8deg (the floor is level) taking into account the diameter of the kiln it means that side is a good few millimeters lower which would explain the gap. I don't think it was the lid. As I said I managed to reduce the gap slightly by pushing the lids down. I started a firing and I can see the red hot inside of the kiln through the gap. Is this normal? I'm attaching a picture

Oh, and the lose piece now finally fell off. I'm now 99% convinced I've got a bad egg here and will take it to the manufacturer

[Bill Kielb]

41 minutes ago, FMPotter said:

Oh, and the lose piece now finally fell off. I'm now 99% convinced I've got a bad egg here and will take it to the manufacturer

I would.
Whether something is level is not as relevant as if it is square to the hinge installation. Looking at your pictures, I was not impressed with the giant mortar joint in the lid anyway so no surprise it has fallen out. The out of level thing could be an issue, but kilns can be slightly out of level and all the hardware is square to itself and self supporting.  My thought would be a bit of a lemon in fabrication and assembly. Who knows, maybe it was damaged a bit in shipping. These are traditionally good quality kilns and solid built so the vendor response seems a bit inadequate as well. I still would like to see a picture of the hinge design. It really should be set up to accommodate some of this in my opinion. There are a number of  simple  ways manufactures guard against this very thing with their hinges.

[liambesaw]

Normal to see red laser coming out of the kiln during firing, the lid bricks expand against the stainless steel band and as a result they bend into a slightly concave form, lifting up at the edges.  

[newuser]

 

 

 

 

[liambesaw]

Like I said above, this is normal from what I can tell.  My kiln even has braided refractory rope as a gasket and when it heats up the lid still bows to show a gap.  It hasn't been a problem.

[neilestrick]

Lids lift as the kiln gets hotter. It's normal as long as they sit flat when the kiln is cool. If there is a gap at the front but tight at the hinge when the kiln is cool, then the hinge needs to be raised up slightly. If the gap is at the hinge side when cool but tight at the front, then the hinge needs to be lowered.

[FMPotter]

I raised this issue with the distributor and they talked to Rohde but Rohde kept insisting it was because the kiln was lifted by the hinge (it wasn't) so in their view it's not their fault. Your post @newuser confirms my suspicion that quality seems to have suffered in Rohde this year. I fired my kiln a few times and seems to work OK. I gave up trying to replace the kiln because it would have cost me a great deal of time and money. Also I figure if their production quality was suffering from pandemic issues this year, any other kiln from them would have similar problems and your post confirms it. Yours has a bigger gap than mine, especially when cold so I don't know... but I think as long as it doesn't lift excessively the other people here with more experience is right and should work just fine.

[neilestrick]

Bricks expand as they heat up. The center of the lid, on the inside, is the hottest point, and it gets cooler as you move out to the edge. So the inside center expands the most, the outside expands far less, and you end up with a dish/contact lens shape, with the center being the lowest point. As the center drops, the edges raise. At the hinge it can't raise much at all because the hinge is holding it, so it tends to raise at the front edge instead. You could put a latch there to keep it from raising too much, but chances are the kiln has plenty of power to deal with the gap, and not letting it raise anywhere can put extra stress on the lid slab.

The original lid on my large rectangular kiln would drop a full inch in the center due to expansion.

[Bill Kielb]

@newuser
I thought all the Rhodes had a single center latch at the front. Their new models do I believe just to help out in this situation. Some of the old Paragons had two latches about sixty degrees offset from center to compensate for the spring lift system they had and this issue as they heated up. If there is a latch then generally the rear hinge also needs to pivot up sufficiently at top temperature. This is usually a slot rather than a hole in the rear hinge. You might double check your alignment cold and hot to see if it’s binding a bit.

Just looked, if you have the model below the lid lock is adjustable.