Bought a K40, my experience so far

Hi all,

New owner here, just chiming in with my experience with the thought that some of you might point out additional things I should do to my machine. This is definitely a machine for someone who is not afraid of taking a wrench to things.

I bought one of the omtech units with the foolish thought that perhaps the higher price would equal higher quality. After going through some of what I detail below I sort of wish I had purchased a cheaper unit since some of what I perceived to be value added will end up in the waste bin lol. . To be fair, it did work basically out of the box after removing the totally useless original bed and setting material to the proper focus height. I got some fairly nice engravings out of it before I tore it down to improve.

Major issues-

1- The advertising is totally messed up on these machines. Mine has a 630mm “38 watt” tube in it. Really probably 30 watts. I mentioned this to the seller and they brushed it off, but then offered a partial refund so go figure. There is a port next to the end of the tube I presume I could install a longer tube in it in the future if I want.

2- The gantry was bent. Not from mishandling/shipping, but just the way it was made. It is basically four pieces of stamped sheet channel stock tack welded together, so its no surprise that its not totally level. I managed to straighten it out by twisting the frame of the gantry until the rails are completely parallel side to side and front to back. When I install it back into the sheet metal housing ill shim it so it is not twisted when the bolts are tightened. I was not able to perfectly align the beam no matter what I tried so I expected the gantry to be off. In the end it was around 2-3mm off from one side to another. I’m amazed it worked at all.

Things I have done or are doing.

1- Went over the grounding an added a star washer to the main ground point, removed the paint etc. Verified grounding with my DMM. Did this before I turned it on the first time.
2- Removed the original near useless bed.
3- Removed the original exhaust fan and duct (WTH are they thinking with the duct design). Ill have to cut out some sheet metal to get better flow between the rear of the case and the work area.
4- I removed and straitened the gantry.
5- I am building an adjustable Z bed with honeycomb, lots of cool designs out there for this. I see this as a must have.
6- Adding interlocks to the three access doors.
7- Install an air assist head with adjustable beam focus.
8- Install a smoke assist system of some sort.
9- Maybe work up something better than the bucket and frozen water bottles for cooling. I saw someone used one of those countertop ice makers to cool the water, I may give that a go.

I think the above is the bare minimum (for me) to have something useful. I plan to use the original control board for now, since k40 whisperer seems to mostly function fine. I do get weird glitches some times when asking the machine to outline the design, or when trying to use the arrows to move the head around.

Anyway, I welcome any input. I have done TONS of reading about these, and will continue to do so. Great forum you all have here, I have learned a ton from you all.

  • If your unit does not have an ammeter I would add one.
  • Include a water flow sensor and alarm in the interlock circuit if it did not come with one.
  • Make sure to use distilled water.
  • I took out the exhaust port and screwed a 4" floor duct to the outside back. I did not find it necessary to add ductwork from the back to the work area.

This may help your journey:


Excellent, thank you. Ill have a look at that website also.

I did install the ammeter, forgot to mention that. Also using distilled water.

Do you recommend a particular flow sensor/switch? I dove into looking at those yesterday and did not come up with anything I liked. Right now I have the temp sensor in the coolant tank but no way to monitor flow.

Did your unit have the boxed in area where the original fan sits, and then a small rectangular cutout that allows flow from the work area? Ill have to post up a pic its difficult to describe. Seems that would be fairly restrictive to airflow, so I had planned to make the opening into the work area larger, but if this is un necessary I wouldn’t mind forgoing it.


A picture of the duct would help. I cut out most of the took out the restrictor if that is what you mean.

This one worked the best: it goes in and out of avail on amazon but you can also get them from light objects:

Here is the install:


Here is what I have going on. The duct is similar in to yours and can be unbolted from the rear of the work area. I am thinking of enlarging that opening so there is better over all ventilation into the work area.

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Welcome @Nathan1!

We’re glad you found us and able to help. Your experience is valuable so keep us updated.


I would suggest a door lock:

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I use this type of flow sensor:

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