After experiencing milling picture frames from 250 moldings in 11 different species of wood, we have some tips for what is usually a pretty time consuming process. Each wood has it’s own characteristics that make milling a time consuming process. Customers often ask why it takes so long to get their frame? It’s a fair question, and I hope this blog helps customers gain some insight into what it takes to bring you your custom frames.
We couldn’t possibly have 2,750 moldings milled on hand at all times, (and milled stock is also much more likely to warp). In order to keep offering the variety of options we provide for our customers, we mill your frame to your specifications as it is ordered. This is a very labor intensive process. We have a constant flow of wood delivered to us on a weekly basis. We go through this wood very quickly and therefore, create a lot of sawdust. The bags of sawdust, which stand 5 feet high, are stored in a container in our parking lot and when the container is full we call our friend Craig and he hauls it to Vermont to be used as bedding for cows. This takes us to the first step in the process of ASF creating custom frames to our customer’s specifications.
Selecting the Stock
The hardwoods, as we receive it from our suppliers, are raw stock without a straight edge. The first thing we have to do is run the board through a straight line saw. This machine is like a table saw on steroids. It has a built-in feeder on top and a steel belt driven bed which the boards run on. There’s a laser mounted to the top which allows the operator to sight the laser line down the length of the board finding the line of cut which will give us the maximum use of that board.
Once the operator is satisfied with the line he releases the stock into the automatic feeder which then grabs the board and takes it through the saw, resulting in a perfectly straight edge. Without a straight edge to run against the fence you can’t make a consistent molding. When the stock has a straight edge we can set our fence at the proper dimension and run the stock through, creating our blanks, which are approximately ¼ “ larger than the molding we are about to make.
Setting the Knives
First, we need to set the knives in the head. There are two knives per head. If the knives need sharpening we take the set heads to the grinding machine and by using a template of that knife, we can kiss the knives to give them a sharp edge, ensuring a good cut. The grinder is the same machine that creates the knives. The template is a piece of plastic that has the shape of the profile cut into it and, by following the shape of the template, the grinding wheel cuts the steel creating the profile. It’s a lot like having a key made. The key you want to duplicate is the template. The operator follows the line of the key to cut the duplicate shape into the blank.
The next step is to measure the maximum depth of the set knives and use that measurement to calibrate the proper setting of the heads in the machine. This process needs to be done on each head. The molder has 5 heads but the last head rarely changes. Sometimes we need to change just one head and other times 4 heads need changing, depending on the molding we’re running. Each change can take from 15 to 30 minutes and that doesn’t include setting and sharpening the knives. Moldings that we run frequently each have their own head and are kept ready on the shelf.
Preparing for the Run
Each head has to be set in the machine to run in unison with the others. This example will describe the process for a simple flat top molding. The first head joints the board ensuring its flatness as it enters the molder. The second head is called the inside vertical head. In my example this knife is going to create the rabbet. The third head is the outside vertical which will create the back of the frame. Sometimes the back is simply flat, other times it has a shape. Sometimes the shape of the back flows into the face, so the placement is critical. The fourth head is called the top head.
In this example, this head, which is the largest and has the most Horse Power, creates the face of the molding. It has the most horse power because it is removing the most material. There are various feeders that push the molding through and the beauty of our SCMI molder is that when we set the heads at the proper height, the feeders adjust themselves to the knives. The feeders have two roles, one is to push the stock through the machine and the second is to hold the stock down firmly so it doesn’t vibrate, thus creating a poor cut. We keep a journal of the calibrations for each of our moldings, but often we need to make adjustments.
After we have the machine set we’re ready to run a test piece (or as many as we may need), to ensure that the molding measures to the exact specifications. If everything is properly set we can begin the run. This involves feeding the stock in and receiving the finished product out the other end. When we do short runs, one person can easily perform this task, but on longer runs two people are required. Once the molding is milled, it is tagged and put into the proper bin, ready to begin the next step to becoming a finished product. But that’s another blog!
A video of a frame being milled: