 This article details how to build an indexing jig to allow building
canister accumulators. I had struggled with this problem, I tried
patterns, dividers, drilling in the lathe, etc., all to no avail. So
if you have a lathe or a friend with a lathe, here are some drawings
& notes for your reference/use.
The jig's operation:
The item to be drilled is placed in a holder on the center of the upper
index plate and the first hole is drilled. The correct number of teeth
are counted (12 teeth for 5 holes, 15 teeth for 4 holes, etc.), and the
index plate is rotated & the pin reset. The next hole is
drilled....
Reasons for choosing a 60 tooth 10" diameter saw blade:
1. 60 has a greater number of factors available than a 48 tooth
blade, which means you can drill 2, 4, 5, 6, 10 & 12 holes
immediately after completing the project. With a simple modification
of rotating the material holder 45 degrees, you can drill 8 holes;
drill 4 holes, rotate the holder 45 degrees & drill 4 more.
2. The larger the diameter the greater the accuracy, so the 10" diameter blade was chosen in lieu of a 7-1/4" one.
3. The cnc cut saw blades are accurate, much more so than anything that I could create with the tools that I have available.
4. The cost - if you have an old blade in the scrap heap & some
material available, you can make the index for nothing. I didn't have
one available, but was able to buy an import off of ebay for $12.00
plus $5.00 shipping.
There are a total of 6 components:
1. A bottom plate to keep the saw blade tips off of the drill press table.
2. The saw blade.
3. The indexing plate and it's pin assembly.
4. The shaft to align all the parts.
5. A hand wheel to tighten it all in place on the table.
6. The material holder (not shown in this picture, it's detailed below)
(Click here or on the image for a larger view)
Building the jig:
 1.
Turn the shaft first. By keeping the tolerances close, you will build
a very accurate jig, I kept the critical clearances within 0.001". Click here or on the image for a pdf file which details the dimensions I used for the saw blade/materials I had on hand.
2. Turn the aluminum plates. To do this, I mounted some 1/8" thick
aluminum plate on a wooden block with 3 wood screws, mounted the wood
in a 4 jaw chuck & cut the outside diameter down to 9-1/8"
diameter, and the inside diameter to 0.786" for the bottom plate
(0.001" clearance) and 1.251" for the indexing plate. Be cautious
& don't do anything unsafe!!!!!
3. Turn a hand wheel to tighten the assembly in the table, I
knurled some 3" diameter stock that I had lying around. If you use a
bolt, you would need to make a backing bar or plate to fit the bottom
of your table.
 4. Turn an index pin & fabricate an assembly to hold the pin in place. Click here
or on the image for a pdf file which details the dimensions I used. To
align the pin with the saw blade, I used some double stick tape between
the pin assembly & the aluminum indexing plate & then
drilled/threaded the holes to hold it in place. I also fashioned a
knob to pull the pin up, by knurling some 1/2" diameter aluminum stock
& drill/tapping it for #6 threads.
Building the material holder
 I
struggled with the idea of making permanent holders that were sized for
individual projects, or for making a left/right hand shaft & making
a self centering holder. I decided to keep it simple & created
another plate with a 1/16" center hole to align the material with the
holder; plus double stick tape to hold the material in place. Click here
or on the image for a pdf file which details the dimensions I used.
Round material will have a 1/16" hold drilled in it's center, and a pin
will be used to align it with the 1/16" hole in the holder. Flat
material can be simply taped in place.
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