Gang-Saw: Buzz-cutting your head. January 2006
I’ve made a number of special heads for my model airplane engines over the years. Cutting cooling fins has never been the most fun part; tiny endmills turning as fast as an old Bridgeport will go is a pain at best. With a VFD, I could spin a little 0.062” cutter at double speed, but it is still a slow and repetitive process at best. It is also too easy to ruin a head with one tiny false move.
Faced with the prospect of making a dozen engines with some significant performance improvements, amongst them making a dozen special heads, was something short of a romantic notion.
Another means to do the head cooling fins is, of course, the use of an appropriately sized jeweler’s saw in the mill. Again, old man Murphy can wreak havoc. Often, it will ruin that head on the last cut, or with some luck, it can be ruined earlier in the process, at least making the grief come sooner. Clearly, a better and simpler way had to happen.
Using a ‘gang’ of saws of the appropriate thickness, and spaced appropriately seemed like a good way to go. Once set up properly, things should progress smoothly, quickly, more accurately, and with better results.
So, the Gang Saw was born for this little project. This mandrel can be loaded with thicker or thinner saw blades, thicker or thinner spacers, and more or fewer cutting blades giving a pretty universal tool once completed.
Just a general overview here: The mandrel itself is from AISI 1144, commonly known as
“Stressproof”. It has made some great crankshafts for me in engines turning in excess of 30,000 RPM, so I figured it would be good enough for this. Also, I happened to have it on hand. Another nice feature of the 8 foot bar of 1144 that I have is that it’s SO close to 1 inch, that the 3” saws with 1” ID must be very carefully pushed into place. There just isn’t any slop; it gives an excellent fit.
This link goes to an excellent and complete description of ‘StressProof’ steel:
For the spacers, I used 6061-T6 aluminum 1½” OD ¼” wall stock I had on hand. I trimmed the ID to leave them about two thou oversized so as to slip into place easily. The nose-cap is made such that it can accommodate another half-inch stack height, and a narrower stack at any size would be easily accommodated with an appropriate spacer.
There are a few photos below to show the general arrangement. Detailed plans and more photos will be published in Home Shop Machinist or Machinist’s Workshop sometime later in the year. For that article, some minor changes will be suggested and shown on the drawings. For a one-off for me, this is filling the bill just fine.
For a more detailed look at the saw, see http://public.fotki.com/TheAeroSmith/gang_saw_for_cuttin/
I’m very pleased with the initial results. This tool will be a very useful addition to the arsenal. Any questions, feel free to ask me: