too small holes in fire grate?

[pyroguy_3]

After the orriginal grate that came on my rivet forge rusted out, I made one out of 1/4 or a little bigger steel plate. I drilled about 9 holes, about or smaller than the diameter of a pencil probably, in the plate and bolted it over the hole. However, my fire tends to burn very quickly and I am constantly adding fresh coal. Even with the airflow gate on my blower almost all the way closed it still burns quickly. Are my holes maybe too small, and this is causing the air to flow too fast through the grate? I was thinking maybe the pressure in the pipe is too great. Should I drill the holes out?

[jayco]

sounds like too much air.electric blowers are hard to control.Iuse hand crank. good luck!

[jayco]

the holes you describe sound about right

[Ed Thomas]

I have no trouble controlling air with either an electric or manual blower. Usually the problem is that people improperly size the blower or do not make a good gate. With a proper air gate, you can vary a good electric blower from a whisper to a blast just as easily as with a hand crank, and usually with more consistent results.

You don't want holes any smaller than the ones you drilled, or they will clog too easily. The only purpose of a grate is to suspend the fire above the tuyere, not to block air flow. I have had better results cutting 3 long grooves in the plate rather than drilling holes, but they both work fine as long as you clear the clinker out from blocking the air every now and then.

When you close your air gate, does it in fact block all or most of the air? If it leaks by, it doesn't take much to keep a fire going and if it leaks a lot, you'll consume your coal at a noticeable rate.

Rivet forges are different than most shop forges in that they usually don't have a separate fire pot. So you have to mound the fire ABOVE the grate more to compensate. You might be consuming coal at a reasonable rate, but not feeding it in from the edges to a middle mound at a reasonable rate and amount.

What size and type is your blower? What kind of gate are you using? What kind of coal? How are you building your fire? When you say you burn it quickly... do you have a different experience with a different forge to compare it with? All these questions and more...

Your problem is usually easier to correct than not enough air, by the way. I'd say we're just going to be tuning what you already do to fix it.

[ThomasPowers]

Another trick is to put a foot pedal switch on the blower so it only runs when you are stepping on it---no need to run while the steel is out of the fire!

Thomas

[pyroguy_3]

Well, I am led to believe it is the orriginal blower that came with the rivet forge. It is a champion, as to what size I don't know as I am not in a current position to look. It has an electric motor that connects into 110v via outlet. The motor is connected to the blower by two flywheels. I tried putting a dimmer switch inline with the power and motor, but at too low V. I was creating shorts in the motor. I might look into putting some sort of foot pedal, however I have a dirt floor and dirt and electrical components don't like eachother... I may eventually rig up an electric blower when I get sick of this finicky thing. The main question is, can the grate holes be too small? I don't have problems with clogging with these size holes, but I think the air speed is too fast.

[skunkriv]

When I run my flat bottom rivet forge out doing shows I run the coal a good 6-7 inches deep. 4 inches would be about minimum. On this kind of forge it isn't long before a lot of what is right at the bottom is stuff that won't burn anymore. If your fire is deep enough my next guess would be your air gate is leaking by.

Next time you make a grate make one with slots as mentioned above. When things start getting cruddy in there you have to find all 9 holes with a poker or pick (without seeing them). With a slotted grate you just pull your pick the length of the three slots and you're good to go. Slots are a lot easier to find.