I needed another metalworking project for this Spring. For the past several years, I have tapped several maple trees in my yard and made maple syrup. After a few years of boiling the sap in pots on a turkey fryer burner, I decided I needed something a little bit bigger. And I decided that something wood-fired would be the most appropriate, and the most fun to build.
After looking online for ideas it seemed like the easiest plan would be t convert an old 55 gallon drum to a wood-burning evaporator. With a used olive-oil drum bought on Craigslist, a couple of cheap steam table pans, a barrel stove kit, some black iron pipe for a frame, an oxy-acetylene cutting torch, grinder, and some tools, I slapped one together in a day.
In maple-syrup speak, the big pan you use to evaporate the water from sap to turn it into syrup is called, simply enough, an evaporator. But the burner is called an “arch.” (Don’t believe me? Look here for an example.) Presumably named after the shape that early wood-fired evaporators took, if you search the Internet for “maple syrup arch” you’ll come up with a host of plans and descriptions. So, technically, I made a wood-fired arch out of an olive oil barrel to hold a steam table pan evaporator. No matter the terms though – here’s what it looks like when done:
The design has a few notable features:
- The black iron pipe frame and barrel can be separated to make movement and storage easier.
- Two pans allow the sap to be warmed in the upper pan before being moved to the lower pan.
- The chimney is completely removable.
Materials & Tools
This project used these materials:
- Used steel drum. This one contained olive oil and I bought it for $10 on Craigslist.
- 1/2″ ID black iron pipe. I used about 20 feet of it. Cost about $50 at Lowe’s.
- A barrel stove kit for the door and chimney collar. ($40 – $60. Got mine on Amazon.com).
- One full-size and one half-size steam-table pans. I bought mine new for about $30 with shipping from an online restaurant supply company. But you might find cheaper at a local auction or on EBay.
Total cost: about $130.
Most of this project was accomplished with the basic metal-working tools I already owned. The pipe base was cut on a basic chopsaw, fitted with an angle grinder, and MIG welded together. The barrel was cut with my oxy-acetylene torch (using a fine #000 tip). A lot of grinding was done with a 4 1/2″ angle grinder.
First, build the base. A very simple welded frame that was done using only a MIG welder and a few magnetic welding squares.
Next the barrel was fitted to the frame.
After some bracing was added t the frame, I started to cut the holes for the evaporator pan with a torch.
I fitted the pans and then went to work on the door and chimney collar following the barrel stove kit’s directions.
Finally I fired it up the next day.
Overall the whole thing was fin to build and worked well enough. One thing that proved tougher than I expected was getting the fire close enough to the bottom of the pans t really get a good boil going. I ultimately ended up adding a couple of half concrete blocks to the barrel to elevate the fire. But the whole system did work faster then the old turkey fryer.
If you are at all handy with metal I encourage you to try and make one of these.
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