yup…me again. I have learned so much since the previous topic was retired. I thought I would start the new topic with something I learned that, at least for me, makes a difference if I were to build the same LR4 machine/ Strut-table again.
When I designed the strut table with t-track and 3/4” MDF spoil board strips to accommodate at 48” wide X 60” deep work surface, I really worked hard on making sure the entire work area could be utilized by the router. (That is when I realized I should have built the gantry about 1” wider than the calculator called for to give more room for the strut channel brackets as explained in the older post).
The issue: It was driving me nuts why I could never center the work on the material along the X while I had no problem doing so along the Y axis.
Apparently I took into consideration the Y homing pull off when setting the front edge of the spoil board so it is dead nuts zero after pull off right on the front edge.
Not so much on the X… so it took me a bit to figure out why when I set the material over 5-3/4” inches from the left edge it was closer to 5-29/32”… Doh! (my Homer Simpson moment) I never accounted for the 4mm pull off when the X homed before I set the left edge of my spoil board… so in reality, the edge of my perfect spoil board is roughly 5/32” too far to the left… so when I measure over 5-3/4” and place my workpiece, the tool would always start 4mm too far to the right”
Now I could loosen the entire spoil board and slide everything to the right 5/32” or 4mm, I could pull the far left MDF spoil strip and re dado the lip that covers the t-track making it 4mm narrower and know I do not have full use of 48” wide (no big deal) or I could account for this by setting ZERO in lower left corner of the material prior to running the job which is the easiest.
Thought this was worth posting so anyone going the strut channel table route… might be worth noting.
While thinking about my remedy for my miscalculation, I was cruising the Internet and found where some folks were using laser cross pointers to aid in the ability to accurately pinpoint position. Ideally, I would want the crosshair to be perfectly aligned with the point of a very sharp V bit. However, was just a little math. I think I can achieve the same thing.
So last night, while watching Hogan‘s heroes, I whipped out my laptop, emerged a couple files together, and came up with this lower tool mount, which has a laser cross pointer, and battery holder.
when I get back from the office today, I will try to install this and see if it actually works.
This is something I was looking into. The only thing I heard but couldn’t get a definite answer on was that it changed depending on the height of the material. This made it inaccurate. I don’t know if it true or not because the people saying it never tried it. Which happens alot.
I can see how different heights of material would make this less accurate in terms of thickness of the crosshair, but the idea is, in my head anyway, would be to determine in millimeters the exact distance between the point of the bit and the point on the material so I can enter that amount of offset both in the X and Y into Millmage. My theory is this will make it a wee bit easier but then who really knows until you try it. We will see.
Well, it is trammed as well as it can ever be for my skill level… and I would think the pointer would be similar too, if not the same as the router since it is mounted directly on the lower tool mount. Still will be fun to test the idea and see if it works or not (almost more fun than using the machine )
Supports? … are you referring the printing of the lower Kobalt tool mount with the laser holder attached? if so, Yes, I used slim tree supports. If I need to print again, I would remember to turn that function off before printing.
Well, y’all, it installed easy enough. I was able to get a good sharp crosshair so now it’s just a matter of seeing if it works and I’ll do it on different parts of the table that way we’ll see if it matters
I do hope it works because everything fits so well, the battery holder is the switch and it fits in the little pocket which I took off another part mounted for a different CNC machine, as well as the part of the clamp and then fused it into Ryan’s lower tool mount, so it’s all one piece. Hopefully it works.
I apologize (to Ryan) for not unchecking the supports before printing. It was late and i hit print on my way turning in last night. When I saw all those things dangling from my model this morning I’m like I’m not gonna print it again and I know I’m gonna get a bunch of crap.
That is a great idea to find Y on a crosshair, but for X you can only set the intersection at one point due to parallax. However, once this is set then you can solve for the distance between the laser dot and the bit at any height.
If you know your set angle you can plug in and solve for tan(0) x Z plus your parallax offset. Or you could find the angle by measuring the difference of bit-laser at two different heights.
I would think you could make a macro to solve for any height once you know the variables. That would be quite a bit of futzing, but I’m sure AI can help with that.
Thinking twice about it, easier would just be to have the known offset height intersection known and then make sure you are at that height from the work piece when you are setting the corner.
After setting Z with the touch plate have it retract to that known distance. Easy.
playing around with it last night, I think my usage will be to use the z home position vs the spoil board since I am not really concerned about the thickness of the material when lining up X0,Y0. getting the crosshair to straddle the lower left corner seems to be right where I need to be before running the simple macro. will do some real-world tests on scrap MDF and see how it does.
Today, I finally surfaced my spoil boards. I used Millmage to set up the project with a 1/2” dove tail bit 1/32” depth per pass at 150mm/s. The job took three passes for the 48” x 60” table… roughly 25 minutes per pass.
Ordered a pair of these enclosed steel drawers from the giant jungle store for bits and clamps.
In trying to figure out how to securely mount them, I decided to use the lower profile channel mounted underneath securing them on the ends and in the middle of my table top sub construction.
I had planned on then mounting three-quarter inch plywood 12 inches deep the width of the table underneath that and then screw the enclosures as though they were mounted underneath a desk as they were designed.
However, as luck would have it, the space between the two lower profile channels were right at 6” which is the spacing on the enclosure bracket mounting holes so all I needed to order from the giant river jungle store was some 1/4”-20 spring loaded channel nuts which should allow me to mount the enclosed drawers directly on those low profile channel rails.
they’ll sit back a little further than I wanted, and if that becomes an issue, I can always go back to the plywood and mount them more flush to the front.
hi great looking build and love the table, im in the process of building a LR4 just waiting on cables.
on my build which i followed the video but ive noticed that both my X axis limit switches are facing the same way, both on the front facing side. could you do me a favour and show me the position of yours
X only uses one limit switch, the one on the left when standing in front of your machine (or right when looking at the back of the core during assembly).
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