laser cutter/engraver rebuild build log

[Robin Hewitt]

Why do you think you want 1.5m/s?

If you wanted speed why are you planning to reduce the motor rpm 3:1?

[gavztheouch]

Why do you think you want 1.5m/s?

If you wanted speed why are you planning to reduce the motor rpm 3:1?

Robin I do not necessarily need 1.5m/s. A decent laser like a trotec will run higher at 3m/s. Speed is important when rastering an image with the laser, not so important when cutting.

The manufacture of the slides suggest a max speed of 1.5m/s so I was just looking to see what rpm I would need to hit the max. In reality I think the laser head is too heavy to run at 1.5/ms so I would be backing off the speed until it looks about right.

The 3:1 reducer is part of the kit so I prefer to leave it in, I think the reduction also helps with the sudden changes in direction the xy is subject too.

[EddyCurrent]

Is it possible to keep everything static and just move a mirror accurately to reflect the beam around the tool path ? the strength of the beam would need to be continuously adjusted to compensate for distance changes I think ?

[Robin Hewitt]

Presumably you would only go for engraving speed on the lightest axis, call it X? Making it fast will make it heavy so you will need a different motor and much lower target speed for the Y. In my day if you wanted enormous speed and acceleration then you used a pancake motor, is that what the Trotec uses?

[gavztheouch]

I think the Trotec uses a small dc motor and everything mechanical is kept very light.

May just go with the closed loop stepper motors for now and then maybe upgrade to a servo motor (on just the x axis) in the future if need be. Going to buy the stepper sets from Aliexpress and hope for a similer good experience. I don't think they will come till after christmas, so I can get to work on the frame in the meantime.

Im thinking box section construction, which I will level with epoxy to mount all the components on a flat plane. I could use shims but id like to give the epoxy method a try.

[Boyan Silyavski]

Interesting. About the Mjunit. Looks Well thought. Could you tell us some more info please?

-What is the sliding element? I can not figure that from the photos.
- v or u bearings ? balls like Hiwin?
-size/type timing belt?
-What the price for the setup you bought? Looking at aliexpress but all say same price, may be the price of an element
-Does it seem precise, i mean move smoothly and without play?

[gavztheouch]

Hi Silyavski,

I paid £600 for the 900 by 600mm laser kit, import tax brought the total up to £750. You contact the seller and he/she will send you a quote.

The sliding element is 4 U bearings. The extrusion is Alu alloy but the tracks that the U bearings slide on is not, I guess stainless steel or chrome plated steel? I will take some pictures to show you.

Im not sure about the timing belt will need to measure.

It seems quite precise and smooth with no play. Time will tell how it really performs.

After buying this kit I recently spotted a second company selling smiler items. http://www.ccmmade.com/ I think the mjunit laser stuff looks better, but this other company has videos on their website and facebook page you can check out. Their prices are also cheaper.

[Boyan Silyavski]

Thanks.

At the second link they seem they have also slightly bigger 60x60mm.

i figured why the 3:1 ratio, they build it for time lapse photography, where a resolution is needed.