Removed fume extract shroud on Monport 40W (K40 clone). How do I configure to use additional space?

Hi all. I just received my Monport 40W which to my understanding is a K40 clone that comes with a GRBL 1.1 board to make it compatible with LB. The machine works great. I’ve removed the fume extract shroud which takes up space in the work area. I can see that the laser can actually move quite a bit higher from the workspace defined in the controller. I would like to gain that space and am unsure how to go about doing that.

I’ve done a bit of research and have found that $130 and $131 define the max travel. Mine is set for 300mm and 200mm. I also note that the machine homes in the upper left corner and then proceeds to go to a starting point (origin?) that is an inch or so in the X of where it physically can travel in addition to the inches of space it skips in the Y to clear the fume extractor I removed.

Is it possible to reconfigure the controller via GRBL commands to use all space? Would the origin also be able to be set to start at or near the home position?

Please excuse my ignorance on this. I did do a bit of searching and did not find an answer. I’m sure I’m not the first person to want to do this. Any help is most appreciated.

I’d like to make sure I have all facts straight. Can you confirm my understanding and answer questions?

  1. Machine native area is 300x200 mm WxH
  2. Machine homes upper-left
  3. Machine origin is upper-left (you are at 0,0 after homing)
  4. It sounds like the extra available space from removing the shroud is above the current homing point. Please confirm.
  5. If the above is true, would you need to home higher up than the current homing position? If not, please explain.

Unless Monport has done something very odd with the firmware this should be possible.

I think what you’re asking is that you don’t want the machine to pull-off as much from home after the homing cycle is completed?

If you can provide photos that may also simplify things.

Thanks for taking the time to respond. Apologies for not making things clear from the OP. I did upgrade from an Ortur LM2 laser but I do have limited experience in regards to terminology.

I’ll explain what I see happening when I connect to the machine using LB. Machine moves towards the upper left corner and hits limit switches. It then moves down about 1.75" in both X and Y position. I think this is the machine origin that LB uses.

I can physically move the laser head on the gantry and can bring it to about .75" from the rail on the X axis without pressing the limit switch. And I can move it about .75" up from that origin on the Y axis.

While I realize that gaining this small amount may not seem like too big of a win for most, I am of the thinking that if it’s possible to gain the space then why not. It ends up being a fair amount more for a machine with an already limited bed.

I can also provide my GRBL $$ output if it helps. Thanks again.

Please do so.

Can you also please run the following in Console and please return output:

G0 X300Y200

Note that the first command will home so look out for it. The last command should move the laser to the bottom right. Can you confirm the location and also confirm how much clearance you in terms of mm of additional potential travel both down and to the right.

Grbl 1.1f ['$' for help]

I will run those commands later today and report back. Again, thank you for the support.

This indicates that the laser head should be pulling off by 25 mm (less than an inch) from the homing switches. This is quite a divergence from your stated pull-off of 1.75". Can you recheck and confirm whether or nor it’s actually pulling off by 1.75" or if you may have overestimated. Want to make sure reality is lining up to the settings before proposing anything.

Also, can you confirm the type of homing switch is in the machine? Are they mechanical or possibly a proximity based sensor?

Grbl 1.1f ['$' for help]
G0 X300Y200

The G90 command did not appear to do anything. The G0 command did send the head to the absolute bottom right corner of the workspace.

In reference to the 25mm, yes, it does appear that that is a better number from where it homes to the origin. I was mistakenly measuring from the Y axis rail to the origin rather than where the actual home position was. My apologies. The limit switches are two mechanical switches.

Okay. Here are my takeaways based on the output:

  1. The laser is setting post pull-off location as 0,0. This will make it hopefully simple to adjust.
  2. If current pull-off is 25mm I’m going to assume you can get away with much less given these are mechanical switches
  3. If 300,200 is truly the extreme of the bed sounds like we won’t be able to recover any additional space there.

Here’s what I suggest:

  1. Change pull-off to 1mm. That should leave an additional 24mm you can recover - $27=1
  2. Extend X and Y by 24mm - $130=324 and $131=224

You may find that the pull-off of 1mm is insufficient to clear the switch. If that’s the case then make the necessary adjustments to those settings to even out the difference.

First take a backup or your settings so that you can go back to them if you need. Then either use Machine Settings to make the adjustments or run these commands in Console:

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In case someone wants to do this in the future, I was able to use these settings on my Monport 40W:


I found that the X axis was crashing into the right rail when using any value greater than 313. I’m assuming I need to set my LB work area to match these news values right and then I’m all done?

Cannot thank you enough for your quick help on this and your mindfulness to keep me from damaging my machine.

Yes. Sorry. Neglected to mention that.

I’m surprised you’re hitting the rail with a higher $130 value though. That makes me believe the pull-off wasn’t happening in the way I understood since you should minimally be able to recover the full pull-off distance I would think but not sure.

Anyhow, glad you got something that works for you and increased your work area by almost 17%.

In regards to hitting the rail, I was seeing that before but didn’t have enough knowledge on how to control the head to determine that’s what was happening. It was making a noise that didn’t sound right but it was not obnoxious. Using what you showed me with the GRBL commands I was able to determine the max value that prevents it from banging on that side. There’s no limit switches on the right side of the machine at all.

Thanks for recognizing this. I did realize that this machine is limited in capacity when I purchased it and had hoped to increase the usable area by removing that fume extract shroud and with your help was able to accomplish just that!

Just a quick comment… As I understand it, what you have done is to remove the “box” that surrounds the laser movement mechanisms, meaning that fume extraction will be very minimal.

I hope that you plan for some additional ventilation, since even doing simple engraving will result in lots of smoke being generated. Not only is that smoke (even for wood, not to mention acrylic) not good for your health, it will quickly be adsorbed onto every surface in the room, and it will stink badly. Removing that smell from a room is not easy, nor is it inexpensive. You can’t just hide it with air freshener.

In other words, you really need good ventilation in the laser work area. Is the additional work area worth the cost of the extra ventilation you will need?

Dave, thank you for your kindness and concern. It is certainly appreciated. Here’s a picture of what I removed:

In addition to the stock fan, I also added another fan inline that moves 200 cubic feet per minute. The shroud I removed has been discussed on forums/YT videos that I’ve watched and my understanding is that it restricted airflow so removing it is actually beneficial for air flow and, in addition, beneficial for work area.

Well, it looks good, and appears you have a good appreciation of airflow and fume extraction needs.

Happy Lasing!!!

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