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cross poles

2K views 8 replies 9 participants last post by  MEBCWD 
#1 ·
Hi, my work has come up with a strange job. I'm trying to see if anyone can come up with a caving program to suite. If you imagine a pole (lets say 1800mm long) stuck in the ground but not at 90 deg to land but at say 80 deg and another pole cris-cross the other way at 80 deg through the fist pole, As in like an X . trying to get a program that would be able to carve the 2nd pole to join the first (be in 2 peices) Now the next problem is that the bottom of the poles are 1 size say 180mm and they tapper up to the top to say 120mm. Can anyone help? email; r.mcabinets@bigpond.com
 
#2 ·
welcome to the forum Harry James...

do you want to make a blind half lap joint at the intersection of the two poles...
be easier just to lay it out and hand cut them...
how many do you want to make???
you can pictures of this if you have a drawing or prototype already made form the computer you are posting from......

FWIW.. posting email addies on this forum is frowned upon...
 
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#4 ·
Due to the lack of uniformity of your material unless you use log scanning eyes like a sawmill that feed that info into the computer along with the milling parameters then it may not work satisfactory. I agree with Stick that you may be better to scribe the logs and do it by hand like the log house builders do it.
 
#6 ·
My approach would be to either lay them at the ~80 degrees on the CNC table and then cut the half lap normal to the Y-axis, or lay them normal to the X-axis and mill the half lap on the angle of your choice. This would work if the taper was the same for each upright at the point you were milling.

As said above, sometimes CNC isn't the best choice. This seems like a time that a simple jig and hand held router are the best.

Steve.
 
#8 ·
Based on your numbers, the taper on the pole is a little less than 1° per side. So you're talking about "notching" the ends of the two shorter pieces to match the body of the one piece rod to make the cross - similar to the way that a piece of pipe is notched to weld a "T" joint, except that the notch is tapered and on an angle?

How about the idea of making both full length and then "drilling" through the one piece with a (really special) tapered drill? The tricky part would be fixturing it for drilling - maybe set it in a cradle to hold it at the correct angle relative to the table and drill vertically, unless you have a way to tilt the axis of the drill spindle. Without knowing the capabilities of your NC machine.

Another option would be to generate a flat pattern for the surface - two cones intersecting at an angle, that should be fun - wrap the parts with the pattern, rough out the notch and finish by hand to get a good fit. It may be possible to make a sanding drum with the required size and taper and use that to finish up the ends to the required size. Assuming that the poles are made of wood by the way.
 
#9 ·
Should be doable if the parts will fit the bed of your CNC and you use the proper tooling.

You left out one critical measurement. You need to let us know how far above the ground you want them to cross.
 
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