Dev#008 Mirror holder from Ebay. What should I do with it???


chinese manufacturing?

Well here we are for another little update of the development blog. 20161022_110735As you might recall from other articles on the site, the main purpose of the project is to create a good laser cutter with off the shelf part which are easy to obtain. So… I bought a couple of different types of mirror holder.

Today the K40-type mirror holder arrived and … well I don’t know what to say.

Compared to my pro laser head on the 80W machine, this device is tiny and it looks like it should do the job. The thumbscrews on it are just regular M3 metric screw thread , so not with a very fine pitch.

20161022_110741But there are a couple of things which bother me.

First of all, this holder should be bolted onto the gantry with 2 M3 screws. I found that the 2 m3 holes are NOT centered on the block of aluminum. My logic (which is not Chinese) would advise me to create these holes in a consistent centered place if you want to mount this kind of holder correctly. Of course, there are always tricks to mount this, because you can use a cut out slot in the gantry to you have the needed play to mount this, but I do wonder if these are the places where these holes are always put, or would this just be a “hey, look, today I’m going to drill them here and tomorrow I’ll drill in another position”. Anyway, these are things to think about. I would not like to be dependent on a design that is not consistent.

wait, there is more

20161022_110735When you look to the front side (mirror side) then you can see that there is another little problem with the thing. The front part is supported by 3 M3 thumbscrews to change orientation and held in place with 2 springs. A very simple but good way to do it. But… have a good look at the bottom side of the main base piece and the bottom side of the mirror part. 20161022_110907They are not parallel to each other. It is also not possible to just get them parallel by hand because the moveable piece rests onto the 3 M3 screws in little milled or drilled pits. You can do whatever you want, but they will snap back into position.

Maybe it is not all that bad

At this moment, I am a little bit confused. I wonder if other people, who for example have a Chinese K40 cutter, have the same problem or maybe not…

I also might be a little paranoia, because I’m pretty sure I can machine a mirror holder of a lot better quality on my own cnc milling machine, but… this project promises to use only off the shelf source able parts. So no can do that 😉

What do you think? I never asked for my followers opinion, but this is maybe a good start to do this. Do you gave an opinion on this ? Would you accept such a part from an Ebay order? Do you have a K40 and is yours also like that ? Do you have other ideas for laser heads to try ? All comments are very welcome. Both on Facebook or below here in the comments section.

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  1. I don’t buy Chinese (except through a big vendor like Walmart or Dell, where I have no choice). I’m worried that, if I get a bad part and complain, some poor slave girl on a factory floor will catch hell. Given the condition those are in (dirty, stained, and out-of-spec), I’d just eat the cost and learn the lesson.

  2. i have a k40.
    how often do you realign your laser? does it really matter that the adjustment screws are 1-2 degrees off, as long as you hit your target, so to speak.
    the biggest problem i have with that mirror holder is that the collar holding the mirror on, is so thick that there is very little “opening” where the laser actually can hit the mirror when it is at 45 degrees

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