If I wait long enough (which I will) - all the little bits will not only be designed but tested too! Looks good Doug!
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lol, yeah
im looking for a quick attach NEJE 40640 laser mount next…
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Finally got around to measuring my LR3 for square, and across a 4’x8’ area I’m off by 6mm. I’m out now, but when I get back I will work to calculate how to offset to counteract this.
Also, I’m experiencing some deflection at the center area of the beam, and it’s pretty noticeable. I think I will switch to 1/4" struts out of plywood, and switch from 8 braces to 10, and switch from 3/4 (ID) EMT back to my 1" stainless steel tubes, which were on my LR2, and would need cut down to fit. Thoughts anyone?
The above 2 are what I used in my build and I don’t see much deflection. I used them because I already had them from the LR2 build and some spare plywood lying around. But that may not be the only solution. Will let others chime in.
I can’t imagine any deflection you have is anywhere even close to LR2 levels. This should be far far more rigid in comparison as designed. You should be trying to bend your strut plates on end, as in not gunna happen. The slow down we get with this one is twist, not really deflection.
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This worked with 1/2" emt at LR2 levels with super thin Strut plates. We went to 1/4" hardboard and 3/4" emt and everything was better.
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If I used the wrong term please pardon me. The issue seems to be related to the beam twisting in the middle, allowing the router to change angle. I called it deflection for lack of a better word but it does seem to be based upon the beam twisting.
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Would love to have purchased 1/4” thick hardboard, but the only thing sold in our area was 1/8” thick hardboard. So the current bit of twisting I am seeing is happening with 1/8” thick hardboard.
At this time my plan is to redo my beam, partly because I want to extend it from 1425 mm to 1435 mm, and partly to try to eliminate this little bit of twisting that I am seeing. Since the 3/4” EMT has already been cut down to the 1425 mm length, in order to extend it I would either have to buy more EMT, or cut these stainless steel tubes down that were used for my LR2.
Is there a simple test cut one can try? Or what do I need to do observe/measure it? I can try it on my build and comment on the twisting part.
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I noticed the twisting while attempting to cut 1/8” hardboard at a depth of cut deep enough to cut through the whole thing in one pass. When I reduced my depth of cut to about only half of the thickness or 1/16”, the twisting reduced substantially but was still slightly noticeable. The twisting happens when the LowRider is pushing in the Y axis direction against a load as it’s trying to cut.
Got it. What should be the position on the X-axis - center of the beam or the corners?
You mean without the strut plates on? It is absolutely going to twist more without them. Still the twist is the limiting factor here, it should be better than a LR2 with SS tubes as you have it built. 1/8" hardboard with strut plates on should be no issue whatsoever. We were doing full depth test cuts in 1/2" MDF at crazy speeds.
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That was cutting 1/8" hardboard full depth, 1800 mm/min with 1/2" EMT and only the temporary struts. (Also a super long bit so lots of twisting force on the gantry.) I cut all three struts side by side that way with very little distortion. (Full disclosure, because my spoilboard wasn’t level, I had to cut that last strut again, about 1mm lower.)
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Yes with 1/8” strut plates on I’m getting a little bit of twist.
1/8th inch should be a breeze. Are all the strut plate screws snugged up? There has to be something missing here.
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I know you enjoy modifying things, but the base design here should not require more braces. Your strut plates should be fine, as well as the 3/4".
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Pretty sure they are snugged up. Maybe will see if I can catch it on video.
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I was a little concerned because by me stretching the strut from 1400 to 1425 I think I’m a little past the suggested limit you set per between struts. Also because it stretched my screw holes by a tenth of a mm or something.
If any twist should happen it would be most noticeable in the center of the beam. Closer you get to X-min or X-max, the closer to the screws attaching beam to side plates.
Just for clarity sake is 1/4” hardboard the standard spec and 1/8” hardboard is tolerable but less than ideal? If so that may be my issue.