Im looking to purchase one of these soon, the reason is to cut holes in my round tanks at certain angles one is cheaper than the other, ive never used one before, what one is best suited, this job maybe the only thing i need it for, i have a few to make, or maybe you can think of something better suited
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BrokenBiker
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A rotary table generally is just that, a table that rotates with usually 360° markings...so if your angles easily divide into 360, its fine...a dividingnhead however is a bit more complicated, but as a result can cut angles/hole positions that doesn't easilly divine into 360...
For instance, If you wanted to cut 76 holes in a circular pattern on a rotary table you would need a way to accurately index for 4.736 degrees between each hole...but on a dividing head you can do some simple maths and figure out which plate and hole pattern you need and then its a case of just turning the handle a set amount of times to get the angle you want.
Pros and cons to both
For instance, If you wanted to cut 76 holes in a circular pattern on a rotary table you would need a way to accurately index for 4.736 degrees between each hole...but on a dividing head you can do some simple maths and figure out which plate and hole pattern you need and then its a case of just turning the handle a set amount of times to get the angle you want.
Pros and cons to both
Agroshield
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The way I read the question, there will be no dividing taking place.
I think he is looking for a rotary fixture, something that will hold an item rigidly and allow it to be rotated in a controlled manner while a cutter is knawing at it.
A dividing head normally takes a chuck (possibly a faceplate) so from that point of view, workholding is challenging. A large, tilting rotary table, has a T-slotted, flat circular surface which gives more space for clamps.
Make a mock up in plywood and you will see what size of table/base is needed on your rotating thing to clamp your workpiece properly. A 12" RT needs four Weetabix.
For those small pipes coming off at an angle, a 3D-printed drill guide that slips over the main cylinder might work well. If it is to be used more than once, sleeve the guide hole with a piece of pipe. A similar/separate guide could be used to mark the clock position of the outlets. Throw some nominal dimensions on the plan view drawing and I can make a test model.
Agroshield
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For two holes, print out the drawing in your photo full size, stick to a lump of wood, mark the centre of the big cylinder and the centreline of the intersecting tubes. Cut out the big hole. Stand the wood in the milling vice and use a square to get the centrelines vertical. Drill the holes in the wood.
BrokenBiker
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I'd just opt for accurate marking out and a good centre pop for something like that
8ob
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daleyd
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You can get rotary tables with dividing head plates too, just to complicate matters!
I’ve got one, the holes plates are detachable so you can use it as a simple rotary table, or attach the plates for dividing if you need to.
Probably not as accurate as a dedicated dividing head but it’s a good enough compromise for me.
I’ve got one, the holes plates are detachable so you can use it as a simple rotary table, or attach the plates for dividing if you need to.
Probably not as accurate as a dedicated dividing head but it’s a good enough compromise for me.
its 4" tube which my 6" vice holds secure enough with a peice of wood through the centre, it also helps if i pre swage the tube before i cut the holes
Its the most popular size i do on hole is fine, its when theres 2 or more that are clocked
