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Drilling holes to reduce frame weight: best pattern
We are reducing the weight by drilling into our 1"X4" hollow, rectangular Al tubing (1/8" thick-walled). Two questions:
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Re: Drilling holes to reduce frame weight: best pattern
Can you please provide a photo of the actual component you are trying to cut weight from? Without that we cannot really tell what safe pocketing looks like.
However, in most cases, myself and others would recommend attempting to replace the current structure with thinner walled material, if possible. . |
Re: Drilling holes to reduce frame weight: best pattern
2. Depends on the loading, eh?
I'd start with big holes, because they actually reduce weight. But they don't reduce it by much. If you drill a dozen 3" diameter holes in 1/8" thick material, you'll get rid of a pound of aluminum. You'll need 26 2" diameter holes to get that same pound. The smaller the holes, the worse it gets. I'd be seriously looking at other things to change, and drill holes in the frame as a last resort. But that's because I'm naturally lazy. |
Re: Drilling holes to reduce frame weight: best pattern
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Re: Drilling holes to reduce frame weight: best pattern
Aluminum nuts for 1/4-20 exist and have been used by us. Saves a surprising amount of weight if you have a lot of fasteners.
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Re: Drilling holes to reduce frame weight: best pattern
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2> before we can truly answer this we need to know the amount of force expected on the part and the direction of the expected force. |
Re: Drilling holes to reduce frame weight: best pattern
best bit to use is a step drill
best to use a pilot hole Staggered center pattern is easy. Allows up to 70 percent open McMaster 8841A34 |
Re: Drilling holes to reduce frame weight: best pattern
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I've had good luck making 1 to 1-1/2 inch dia holes with a conduit punch--they look nicer than any drill and they go quickly. You mentioned diamond, so maybe you're intending on NC machining Also, all of the people worried about strength, I can't think of many areas where you need the amount of strength a 1 x 4 x 1/8" aluminum rectangular section will provide. But I don't know your loading. Another way to shave weight from such a section would be to thin it using a table-saw with an aluminum blade. This would have the least effect on stress, less than any holes. Another note: if the tube sees mostly bending, remove holes or thin evenly. across the faces. If the tube sees lots of torsion (twisting), remove more toward the corners and leave the centerline of each face intact. Highest stress in torsion is down the center axis of the face. |
Re: Drilling holes to reduce frame weight: best pattern
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Re: Drilling holes to reduce frame weight: best pattern
I second the hole saw recommendation. Notice I started by suggesting 3" holes....
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Re: Drilling holes to reduce frame weight: best pattern
One of the easier ways to drop weight is to switch from CIMs to Mini-CIMs. You can drop 0.6 lbs. a motor. The two have very similar torque at 40 amps, the Mini-CIM just doesn't have as high of a stall torque.
Might be easier than drilling that many holes in your frame. |
Re: Drilling holes to reduce frame weight: best pattern
You're going about this all wrong. To reduce weight don't drill holes, shorten the code. The less lines of code, the lighter the robot. 1s weigh more than 0s. :rolleyes:
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Re: Drilling holes to reduce frame weight: best pattern
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It's similar to Hollerith cards and paper tape that way -- adding code removes material. ;) |
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Maybe I can use this as an excuse to get my hands on the robot from the mechanical team. |
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