Ademco dry mounting press - thermostat

[Trond]

Hello,

I've just got an Ademco 1113 dry mounting press. It's overall in good condition, and it heats up fine, apart from that it doesn't get hot enough. Even when the thermostat knob is turned all the way, it doesn't get any hotter than about 60 C.

Is there any way to adjust the thermostat, or does it need to be replaced?

Thanks,
Trond

 

[Ian Grant]

Most likely an element has burnt out, although they aren't made any longer there are heat pads that do the same thing and are safer & easy to fit.

Ian

 

[Trond]

I don't think it's an element, because the thermostat turns the heating elements off before the press gets hot enough, even though I have turned the knob all they way.

Trond

 

[Mike Wilde]

To get the heat over a large area, it is not uncommon to find that there may be more than one heating element.

Multiple heat elements are wired in parallel They may be arranged in different areas of the heated surface, or be routed physically in parallel as well.

Since I presume your unit is for 220/240V service, you may even find that there are element strings in parallel and series. Some devices are made with the circuits all in parallel for 110/120V service areas, and then have part of the circuitry re-arranged to allow the higher potential vorage to be accomodated, while producing the required amount of heat for 220/240V service areas.

So some sniffing under the hood with an ohm meter after the parallel connections have been undone is lilkely required. No power need be on for this testing.

 

[Trond]

I have good reason to believe that it is the thermostat which is to blame. The unit seems to get uniformly warm, but not hot enough for dry mounting. The thermostat is set to max, but it still turns off the heating elements when reaching about 60 C. So my question remains, is the thermostat adjustable and/ or easy to replace?

Trond

 

[Ian Grant]

Thermostats do weaken and become unreliable over time. My Ademco doesn't have one just two settings full or half power, the elements run in series at half power and parallel at Full power.

Ian

 

[Ulrich Drolshagen]

Right now I am in the process of repairing an Ademco 2226. Though it is somewhat larger than yours, I think the interior may be similar. There are two heating elements in parallel meandering about the pressing plate. In my press unfortunately one of the two has been gone and has taken the thermostat with it. Or the other way round, I don't know.
The original thermostat is of a kind built for an oven. To restrict the max. temperature there is simply a screw under the knob which prevents the knob from getting turned further. You can simply pull off the knob and you will see. I have replaced it already. The thermostat has three contacts, as there are two temperature controlled switches:
An opener, which opens the circuit when the temperature is reached and a closer, which closes the circuit, when the temperature is reached. The first is used for heating the second is used for the lamp which shows that the rght temperature is reached.
Right now the press heats with only one heating element to about 80°C and above but it takes about six hours with the cover removed. So I am going to replace the heating elements with new ones.
I found these elements. I called them up this morning and sent them sketches of the required pads. They will make me an offer soon. I hope it will be economically feasible for me. I will let you know, when I get an answer

Ulrich

PS: One word of caution: There is isolating material in there which might be fiberglass but which might be asbest as well. I don't know. It may pay to take proper precautions in getting rid of it and replacing it with material which is known not to be asbest. You will have to get rid of it anyway as the cover is not that close that convection won't blow loose fibers out.

 

[Trond]

I played around with the press yesterday, and found that it heats up to about 90°C with the knob turned all the way. The thermometer on the front is a bit slow to catch up I guess. With the screw under the knob removed, it heats up even further, so I suppose I'm OK.

I haven't used a dry mounting press for years, how hot does it have to be for dry mounting?

Trond

 

[Mike Wilde]

I'm an imperial press mounter; mine was made by Seal Manufacturing before they started selling them as 'Seal' and has an imperal calibrated thermostat. I usually mount RC type 2 dry mount at 180F, and FB and older shellac adhesives at 225F, or even hotter.

I usually get good adhesion with these temps of 30 blinks of my blinking light on the top of the press.

 

[Ulrich Drolshagen]

[...]
I found these elements. I called them up this morning and sent them sketches of the required pads. They will make me an offer soon. I hope it will be economically feasible for me. I will let you know, when I get an answer
[...]

All right, I am a little late but here I am. The offer I got turned out to be prohibitive expensive so I put the whole project on hold until after summer holidays. Last week I found a German supplier http://www.niggeloh-gmbh.de They are now making them for me for 650€, less than one third of the price I was offered by the Austrian supplier. It's still expensive but considering the size of the press, to me it seems worth the effort.

Ulrich