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By James Morikawa
My first two Belt-miters were fabricated using a drill press, both giving me good results. Thus I say, "Yes, you can use a drill-press".
The ability to vary the spindle RPM on a drill-press, did allowed me to experiment with various roller speeds. The higher RPMs, faster belt speeds produced better results, faster cut speeds, and extended abravise belt life.
One needs a drill-press that spins true at the spindle. My drill-press had a slight wobble at the spindle/drill chuck, which caused vibration problems at the higher RPMs. At spindle RPMs of 1500 and above, the vibration and noise became a bit intolerable — and really put a lot of stress on the roller-pilot-bearing that was used.
I later went on to fabricating a simpler design, which eliminated the use of the drill-press.
My present beltmiter design, which uses no drill-press, has a motor which directly turns the roller. The motor is rated at 3450 RPM.
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Picture 1: Here you see the basic parts that will turn my drill-press into a belt-miter. Most of the parts are of 6061 Aluminum stock.
All machine work were done on a veritical mill, and a lathe. I'm sure one could fabricate using wood, such as maple, if you
don't have a mill or lathe. I still have the idea of attempting a fabrication using wood for cost-cutting reasons.
Picture 2:. I don't need a lot of custom sized rollers. Rollers can be "shimmed-up" in diameter with 2" wide masking tape.
The thicker M3 Scott brand masking tape has worked the best for me.
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Picture 3: A side view of the set-up.
Picture 4: Another view of the set-up. Shown is a tube with a squared off end being mitered. To speed the process up, and save on belt
wear, a rough-cut of the miter shape can be done with aircraft sheetmetal snips, from there the joint can be mitered to a
precision fit.
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Picture 5: The tube fixture slides between it's guides. The holder and tube are hand-fed, there is no fed-screw system. Because it
floats between the guides, it can be easily lift off.
There are 14 gauge sheet metal "wear-plates" glued to the sliding contact surfaces of the base and holder. They are always
lubricated with parafin wax (rubbed on). The miter process produces a lot of loose abrasive grit, so the sheet metal, and wax
prevent wear to the basic aluminum structure. These sheet metal plates can be replace when worn to excess. The parafin
wax greatly increases the wear life of the plates.
Picture 6: Here you have the a view of the belt tensioning, and adjusting parts. That grooved plate which the belt runs between, has an
important tube alignment purpose. It's a alignment target grid broad I'll attempt to describe it's use in the next section..
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Picture 7: Here I have one end of a top-tube mitered. I need to get the tube in alignment to do the other end. I hold a short length of
dummy seat-tube in the finished miter. With eye-sight, I looked down the length of the tube, and at target the grid board.
I turn and adjust, the tube so that the dummy seat tube aligns with the appropiate grid lines, in this case it's the vertical lines.
Once aligned, I secure the tube to the fixture. There's a tube clamp that can be seen.
Picture 8: Here I'm aligning the Bottom-Bracket to Head-tube miter joint. In this case, I'm targeting and aligning using the horizontal
lines of the grid board.
It may seem an inaccurate way to align the joint ends, but it's not. Done right, it's fast, and accurate.
Well, that's all I'm going to write. I hope the pictures help better describe things.
Goodnight