Scroll Cutting Rafter Tails
Cutting a scroll detail on the end of big, heavy rafters requires some tooling ingenuity. February 25, 2009
Question
I landed a job cutting a scrolled pattern on all the rafter tails for a tudor styled house soon to be framed. Unfortunately, the contractor wants to receive the work from me in the form of 10 foot long pieces scroll cut on both ends so that he has some latitude in cutting these pieces to final length before cutting the birdsmouth’s and "sistering" them to the rough fir framing.
I am sure it will be impossible to use any of my band saws to scroll the end of a 10 footer so with my tools the jig saw seems the only alternative. This is a pain because the stocks (western red cedar/tight knot) actual measurements are 2 5/8" x 5 5/8". I can foresee that the blade will wander out of square to the face even in a soft wood like cedar at this thickness.
So, the question is, does anyone have a better tool to cut curves in thick material that is too long and heavy for the band saw? I tried to get information on a tool called a Portaband and it seems as though that machine is made for cutting steel to length and doesn't have any sort of table/base to hold it at strictly 90 degrees to a surface while scroll cutting.
Forum Responses
(Architectural Woodworking Forum)
From contributor J:
We just cut some curves and notches in a 3 1/4" thick bar top with a Festool jig saw. The cut stayed square within .5mm. I think the long Festool blades fit the Bosch jig saw but not sure if they cut as good. Mafell makes a portable band saw for that type cut also but very pricy.
From the original questioner:
I am doing this as a side adventure in woodworking so losing $4,000.00 wouldn't work out. My Bosh jig saw has a blade called the "Progressor" that is long enough so it’s just a matter of how much it will deflect. Anyone have any experience with one of those hand held oscillating spindle sanders?
From contributor D:
I did this the poor man's way on my home shop by gang clamping all the rafters together, nailing on a fence, and running my circular saw at an angle - or actually several angles, several passes. This made for a real quick cut and gave me some time to fiddle with beltsander, r/o sander, chisel and even a few hand planes. The result was near perfect.
From contributor K:
About three years ago I did a timberframe pergola in white oak and needed to do the same thing. I rented a timberframing bandsaw. The process was very fast and slick. I do not remember what I paid but definitely reasonable.
From contributor E:
Not sure if this would work for your need, but if I understand your dilemma. Try this – on a good flat concrete surface, rig a set of tall horses to support the lumber/timber and make a sturdy base with swivel dolly wheels and mount your band saw to this base.
Rather than move the wood through the saw, roll the band saw through the wood allowing the wheels to roll on the concrete floor with ease. If the timber is secured at the right elevation and is level/perpendicular to the blade you should have no problem with the blade wandering. The larger the wheels the smoother the rolling action.
From contributor H:
I would imagine this is not an option (or one you thought of and can't use). What's the shortest length the guy will accept? I mean, could you cut him 6 footers? If he's planning on using both ends for tails, seems his target range length must be in the neighborhood of 5 feet?
From contributor S:
Rough cut most of the stock away with a jigsaw. Make a template and use a pattern bit in a 3 1/2 hp router.
From the original questioner:
As usual, this forum is a wealth of great information! The guy who dimensioned the cedar for my job uses the "rolling 14" bandsaw technique" himself. He stages the material on horses that rest on a thick flat steel plate on the floor. He has a second steel plate that the band saw rolls and registers on. Both plates are of course shimmed to be on the same flat plane.
The real secret to his set up is the casters under his bandsaw. They are a 2" diameter ball and cup type and can roll any direction with no drag unlike standard casters with wheels and axels.
The correct name of that type of caster is "Steel Ball Transfers" or "Ball Transfers". Typically used in table tops as a conveyor device.
From contributor R:
How about a HoverPad instead of casters? I would imagine it would do a much better job of not transferring any small irregularities in the floor.
From contributor V:
I saw a friend years ago do this on a bandsaw and an articulating boom that he built to hold (in a sling) the other end of the rafter so the tail that he was not working on could move in all directions (180 degrees and in and out on the same plane as the band saw table). Pretty cool and I think not that expensive to build. I actually bought one of these on auction (not for this purpose) for $100.00.
From the original questioner:
The Hover Pad is an interesting idea and would even fit the tooling budget for this project. I do have doubts about how well it would work for the application. I have no doubt that it would raise the saw and allow it to be pushed around.
What I am unsure of is if it would be as rock solid as gravity holding a heavy machine on ball transfers rolling on a flat plate (a sheet of 3/4" core pine in my case) pushing solidly down onto the concrete slab.
I fear that the cushion of air could be defeated by the pressures of manipulating the saw through the cuts and that it would rock slightly in and out of square in the two planes that need to stay at 90 degrees.
From contributor B:
We did use the rolling benchtop bandsaw on a level concrete floor with much success. The unit was light enough that even cheap plastic casters on the rolling base worked fine. I like the roughsawn look over the template router approach. Our total investment was less than $100.00 (used).
From the original questioner:
I just wanted to post about the final tooling for the project. I decided that rather than messing with my dedicated shop bandsaws for this one off project I would resurrect an old heavy cast iron 12" bandsaw that has been in a corner of my shop forever. Looks like it was made in the 40's or 50's being still slightly ornamental but has no highly detailed filigree and has ball bearings. I installed new tires and worked the upper guides over and added lower shop made guides.
I built a cabinet to put the throat of the saw at the height I need and added the ball transfers to the base for what I hoped would be a fluid movement.
This caster style was a failure because although the ball transfers can roll in any direction on a dime a little bit of coarse bandsaw dust is all it takes to hitch them up and cause stalling and jerky movement. The weight of the old saw and the heavy motor I added were a factor in how the ball transfers were bad for this application. I removed the ball transfers and replaced them with a good set of 4" wheel casters and the saw did a great job of cutting the scrolls.
Since my client insisted that the scroll cuts be sanded to remove the bandsaw marks I decided to buy an oscillating spindle sander and use the same basic idea of rolling the machine to do the millwork on a stationary timber. I got lucky and found the Rigid brand oscillating spindle sander at a local store for the low price of $200.00. This machine is unique because along with the normal spindle sanding drums it comes with a 4x24 belt sanding attachment that also oscillates and can be installed in less than a minute.
The oscillating belt turned out to be just the ticket to sand the elongated ogee shape I was sawing on the rafter tails. I used the belts drive wheel for the small radiused part of the curve and then shifted to the flat part of the sanders platen to sand the larger radiuses of the "S" curve portion.
Because this machine and the cabinet I built for it were much lighter than the bandsaw rig I decided to give the ball transfers another shot and I installed eight of them under the oscillating. Also, I thought they would work better since I could sweep away the coarse bandsaw dust from the footing area and would only have a bit of fine sanding dust since the sander is dust collected.
It worked ok. It still hitched up a bit on the fine dust but I learned to power through the rough spots and deliver a fair curve on the sanded scrolls. I noticed there can be a huge price difference between differing ball transfers and the expensive ones may work well for this sort of thing. I was using the cheapest ones I could find.
From contributor J:
I just finished a piece with scroll work on it and I used a Sawzall to cut the 2 1/4" western red cedar. This worked well but I sort of dented the soft cedar with the vibration from the saw. I than ran it through my planer and a little sanding. Several layers of masking tape on the saw plate might have helped.
From the original questioner:
That’s funny. Only after I racked my brains and asked here and then spent a couple of unpaid days tooling up did I remember my Sawzall. I suppose for the volume of scrolls I had to do I was better off with the bandsaw. I want to add that the ball transfers were not helpful. The guy who said bigger wheels are best for this has it right.
From contributor P:
I've done a project similar to this before, but it was for the tails on a pergola. I rough cut the shape with a jigsaw, and finish cut with a 3hp router with a straight cutting bit and bushing guide against a template. It seems easier than rolling heavy machines into the stock, more consistent too.
From contributor E:
I would have to agree with those advocating a pattern and router approach. We made some decorative porch brackets a few years ago from full finish 2" old growth pine and cut the rough shape on a bandsaw. To get everything uniform we made the plywood pattern and I bought a 3" spiral pattern bit. When they were stacked on top of each other everything lined up perfectly. I made 20 pieces for that job.
From contributor F:
Especially since the saw marks had to be sanded, I agree that the router template method would have been a faster, easier process. I would still have used this approach where a rough product desired. My shop is just small and sometimes travels with me, so I can move a router from end to end easier than I can rotate a board across a bandsaw. A good beefy jigsaw will also cut relatively square, and the template removes any errors, not to mention that each piece is completely identical.
From the original questioner:
Actually, I had occasion on this job to use a router on a single beam that was 5.5" thick and exceeded the sanders capacity. The router bit simply made a mess of the soft western cedar - tearout and a lot of fuzz that needed to be sanded.
When it comes to rafter tails that are installed 16" on center minimum the 1/32" max differences caused by machine sanding cannot be detected so perfectly identical parts are no real gain.
I would recommend the rolling tool technique highly. The beam goes through only one set up/placement for both sawing and sanding and the whole process took only three to five minutes per end and they came out very nice looking. I didn't know they made portable router bits longer than two inches!
From contributor D:
As for perfectly identical shaping from tail to tail, I'll assume this is emulating work that was heretofore done by hand. It is correct to let the tails differ a bit to show that it is indeed handwork and therefore of a higher order of craft than machine made. I have often worked to make something look machine made, when the larger picture required only my variable handwork.
From contributor F:
I definitely respect the handmade concept. As for the longer than 2" router bit, they do make them, I never read anything about portable so I should maybe be more selective with my input, but I have used them in this manner with great results. Bottom line, I'm sure they came out great. It’s really interesting how many of us can have so many different approaches to any project.
