[Scalesoar]

Hi folks,

This may or may not be the best place to post these questions but I'll try here first as it seems like this forum has the right skill sets.

The problem: I own a Universal Laser V-460 machine. It is a 24" x 18" Laser cutter that uses a Corel printer driver to move the X and Y axis. I need a larger laser cutter but I simply cannot afford to buy a larger one. I am considering expanding the size of the X-axis to double its current size - to 48". I have discussed the option of a custom firmware with ULS but they are unwilling to assist. The firmware that I currently have has a 24" X-axis limitation. The X and Y axis are driven by toothed belts from stepper motors, shafts and toothed drive wheels.

Since the driver/firmware has the limitation of 24" max, here's what I have envisioned for this modification. I am looking for guidance to tell me if I am on the right track or not.

1). I will expand the base table (where you put the material to be cut)from 24 to 48" using the existing manually operated Z-axis adjustment motors and screws (no issues here).
2). I will move the Y-axis rails out to where they need to be to cater for a new 48" X-axis carriage (again, no technical issues here).
3). I will create a new X-axis carriage from extrusion paying careful attention to keep the weight of the new 48" carrage as close to the 24" carriage as possible (attempt to eliminate additional loading on the Y-axis motor by keeping the carriage mass unchanged)
4). Update the X-axis belt drive system to create a 1:2 speed increase in the X-axis shuttle that traverses the new X-axis carriage.

In addition, all input files (vector and raster files) from the PC (Corel) will be reduced in the X-axis direction by 50%. My hope is that the net result of the twice as long carriage, the doubling of the X-axis shuttle speed and the 50% reduction in X-axis of the input file results in a 1:1 representation of what I need cut albeit at slightly less accuracy.

There are a couple of areas I am unsure of, one of which I really can't even change and would just have to wait and see if it works (number 2 below).

1). Is my logic about combining a doubling of the X-axis shuttle speed and reducing my input file X-axis to 50% correct? Will I get a result that is true to scale?

2). The X-axis shuttle is fixed in mass albeit very low mass. It is a small aluminum box with some optics inside that runs on grooved wheels on rails. It will be very difficult to adjust the mass of this shuttle yet I need to move it twice as fast with a 1:2 speed increase in pulley selection and a new belt. I'm guessing the shuttle weighs no more than about 10oz or so (but that's a guess only). As a guage, there are obviously two motors on the unit - the Y-axis motor is a Lin Engineering 4209L High Torque stepper with 62in.oz torque rating. It controls the movement of the X-axis carriage which also holds the X-axis shuttle and X-axis shuttle motor, belt and pulleys.

The X-axis motor is a LIN Engineering 4209M High torque motor that is rated at 51in oz. It's only job is to move the x-axis shuttle which is probably ten times lighter than the X-axis carriage assembly (contains the carriage, shuttle and its motor and is driven by a motor only 11 in oz stronger). It seems to me that the torque needed to move the shuttle twice as fast is there but I am unsure of the physics of it all. Anyone have any input in this area?

Thanks in advance

Tony

[Scalesoar]

Does nobody have any comments for this? Is there a better forum that I should post this in?

Tony

[KTP]

There are a lot of things to consider. Remember that the laser beam is not a perfect parallel beam, but rather it diverges. If you double the distance it has to travel, it may overspill your final mirrors/lens.

A working Universal engraver has a high resale value unmodified. Something to think about...

[TLHarrell]

1. I'm not sure you can achieve 2x the speed on the flying head. You can do some machining of both the mirror holder and the brackets to lighten the load, maybe even 50%. The toothed belts may be a factor, as they may not mesh well at the higher speed. Also, extending the gantry rail would require stiffening of some sort, either by using a larger extrusion or a doubler plate. This increases mass of the gantry itself, not the head... but would be something to consider.

2. A 48"x18" laser would be a very strange size. Since the software limitation is on the X axis (gantry), wouldn't it be preferable to extend the Y axis rails? Theoretically then your machine would be a more realistic 24"x48".

3. As mentioned, the divergence of the beam will become an issue. The larger the beam path, the more this becomes a factor. There are beam straighteners which will lose you some power, but will produce less divergence (at a slightly larger beam diameter). You'd have to find the divergence specs for your tube, and the specs for a beam straightener and see if the numbers work out for the diameter of your optics. If not, you'll have to replace your mirrors and lens and the mounts for them.

4. Beam alignment becomes much more touchy to get right. Even the tiniest misalignment becomes drastically multiplied.

5. What are your plans as far as rebuilding the case to fit this modification?

6. What are the drive electronics in that system? I'm not familiar with it, but would assume that there is both a motor control board and the system controller plugged together. If the software/firmware package doesn't work for you, it might be worth looking into converting to a LO DSP, Retina Engrave or some other controller card and software stack.

7. If you are not doing engraving, and doing cutting only, you could very simply convert the works over to use LinuxCNC or something along those lines.

[Lee DeRaud]

This is a four-year-old thread. Since we haven't heard back from the original poster, I'll assume he gave up the whole thing as a really bad idea.
At least, as the owner of a ULS laser, I sincerely hope so.