Hello. I'm curious if any of you have ideas on how to mount a 20" OD steel pipe, 14" length, on my 9" X 42" table to drill small longitudinal 10-32 clearance holes 2" on center from each other? Pedestal mounted rollers? TIA
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Ideas How to Mount Pipe on Knee Mill
- Thread starter D. Kent
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- Nov 24, 2014
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I'm not following your description of the work.
When you say "longitudinal" do you mean the drilled holes will be parallel to the central axis of the tube (drilled into the wall from the tube end face, a bolt circle)?
If so, I don't understand the 2" OC dimension.
How many holes? How deep?
If you intend to drill hole through the tube wall (hole axis perpendicular to the tube axis) they will be radial holes (not longitudinal).
A sketch would probably help a lot.
When you say "longitudinal" do you mean the drilled holes will be parallel to the central axis of the tube (drilled into the wall from the tube end face, a bolt circle)?
If so, I don't understand the 2" OC dimension.
How many holes? How deep?
If you intend to drill hole through the tube wall (hole axis perpendicular to the tube axis) they will be radial holes (not longitudinal).
A sketch would probably help a lot.
Yeah, my apologies for not being more clear. Usually "longitudinal" in my world of pipe terms is long length, like the long seam in large diameter pipe. So by definition, yes the holes are radial in direction thru the .375 wall thickness, longitudinal in pattern, ~2 inches apart. Say 6 holes to keep the concept easy to understand and indexed every 40 degrees for a total of 9 places (repeated pattern), total of 54 holes.
Just looking for a simple means to secure the pipe to the table, but also have a decent means of indexing. The size and shape make it awkward to fixture. The accuracy on indexing can be slightly off.
Just looking for a simple means to secure the pipe to the table, but also have a decent means of indexing. The size and shape make it awkward to fixture. The accuracy on indexing can be slightly off.
20" O.D. circumference = 62.83". 62.83/54 = 1.164". You could use a tape measure to mark off 1 5/32 increments around the circumference. Or you could do the math (360 deg / 54 = 6.666666 deg. Use a right triangle to calculate 1/2 of the cord distance, ( sine (6.666666 /2 ) = opposite / 10 (hypotenuse). Opposite = .581448289. Opposite X 2 for chord length of 1.163 (rounded). Set a dividers to 1.163" and scribe 54 places about the circumference. Make sense? Set tube on rollers / improvised Vee Block with end stop and clamp. Drill holes.
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- Nov 24, 2014
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I think I understand the hole pattern now.
Exactly how to fixture the part depends on the required accuracy for the finished hole pattern.
Assuming the tolerances are loose enough, clamp two pieces of 1/2" (or thicker) flat bar stock down to the table. Make the long axis of the bar stock precisely parallel to the X axis and space the bars such that they are both tangent to the workpiece, front and back, when it rests in the center T-slot. Add an end stop bearing somewhere on one end of the workpiece. All that will provide a fairly repeatable nest for the workpiece. Make a central hold-down bar that extends out both ends of the workpiece and secures to the central T-slot. Add 3 or 4 additional threaded holes along the length of the hold-down bar and use bolts there to bear on the ID of the workpiece.
The last issue is indexing. One way would be to make a steel plate with 9 equally spaced facets (9 x 40° = 360°) and with a 10" radius (central point to each facet point). Tack weld (or even epoxy) that plate to one end of the tube. Use an adjustable parallel to index each facet parallel to the table. If the table surface is too congested for the adjustable parallel to be used, just index by indicating each facet at the top of the workpiece.
If that method sounds too sloppy, reply with GD&T requirements.
Exactly how to fixture the part depends on the required accuracy for the finished hole pattern.
Assuming the tolerances are loose enough, clamp two pieces of 1/2" (or thicker) flat bar stock down to the table. Make the long axis of the bar stock precisely parallel to the X axis and space the bars such that they are both tangent to the workpiece, front and back, when it rests in the center T-slot. Add an end stop bearing somewhere on one end of the workpiece. All that will provide a fairly repeatable nest for the workpiece. Make a central hold-down bar that extends out both ends of the workpiece and secures to the central T-slot. Add 3 or 4 additional threaded holes along the length of the hold-down bar and use bolts there to bear on the ID of the workpiece.
The last issue is indexing. One way would be to make a steel plate with 9 equally spaced facets (9 x 40° = 360°) and with a 10" radius (central point to each facet point). Tack weld (or even epoxy) that plate to one end of the tube. Use an adjustable parallel to index each facet parallel to the table. If the table surface is too congested for the adjustable parallel to be used, just index by indicating each facet at the top of the workpiece.
If that method sounds too sloppy, reply with GD&T requirements.
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Can you tack weld it to a steel plate bolted to a rotary table. Depends on your max distance to the table and cutting tool. If you don't have room tack weld a piece of plate with holes drilled in a bolt circle of the number holes you want and that will give you an indexing method. Then do as mentioned above with an end stop and something that will engage in the holes you drilled. Depends on how accurate your holes need to be. Will be hard to center the plate and weld it also.
Martin
Martin
Could add 3+ pins to the plate to register on the pipe’s ID for centering.
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- Oct 13, 2014
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I would make a "V block" by using a piece of 6"-8" wide channel, slightly less length than the pipe, bolted to the table, open end facing up, then mill the top edges of the channel at 45º. Secure the pipe at the ends with hold-down clamp/step blocks. It could also be done with 2 pieces of angle as well. Index, manually to scribed lines. My BP clone has a maximum spindle to table of 22" so it would be close but doable.
The channel concept reads the most clear and straight forward approach. Thank you. Yeah, I may have to use a tape along the OD to scribe and index manually. Tolerance can be up to +/- 1/32, give or take. I thought of methods to use my 10" rotary, but the size of work is formidable.