DIY Laser Build - X/Y reducers ?

[m0ng00se]

Hi Guys,

I am looking at building my own laser machine. I have looked at a lot of other builds, both diy and commercial and noticed almost everyone uses reducers on the X/Y, what looks like about 2:1.

I am just trying to figure out what is the reason for that ? To get smaller resolution ?

Thanks.

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[Dean448]

The X axis is made up of the slide, bearings, stepper and optics which can be heavy so you typically use 2:1 on the Y axis when using nema 17 Otherwise high accelerations cause loss of steps.
I dropped the 17 and switched to 23 direct, dual shafts.
You want to go single pulley on X with a 17 to keep the weight down.


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[m0ng00se]

Thank you for the reply.

So Nema23 dual on the Y and nema 17 on the X without gear reduction should be fine then ?

[cinematic2]

Thank you for the reply.
So Nema23 dual on the Y and nema 17 on the X without gear reduction should be fine then ?

No.
All depends on scale. What size of working area?
For smaller machine you may use NEMA17 both for X and Y without reduction.
But no 1.8 deg step motors. It won`t work well without reduction even with microstepping.
You should use 0.9 deg motors.
This is up to 400x600mm
If machine is bigger you can not use direct belt on motor shaft because of higher belt tension. Longer belt means higher tension.
Then you have to use NEMA 23 with reduction or servos.

[m0ng00se]

No.
All depends on scale. What size of working area?
For smaller machine you may use NEMA17 both for X and Y without reduction.
But no 1.8 deg step motors. It won`t work well without reduction even with microstepping.
You should use 0.9 deg motors.
This is up to 400x600mm
If machine is bigger you can not use direct belt on motor shaft because of higher belt tension. Longer belt means higher tension.
Then you have to use NEMA 23 with reduction or servos.

Thank you, I think I will design it with reduction then.

[Dean448]

I'm running 450 in Y using 23 and 610 in X using 17 these are steel rail slides so they have some weight. Belt tension on Y is on outer bearings. X is taking all the load but I've seen no issues. 17 steppers are cheap anyway.
On the steps folks seem to get hung up on accuracy but the nature of the inconsistent beam lowers any chance for high accuracy. At least with these Chinese tubes.
I think that would work. Not many posts about folks wanting to make vs buy so good luck.


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[m0ng00se]

Thanks, I have started the design and the 2:1 reduction on the X-axis ... just a bit worried that the one side is going to be too heavy with the stepper and all ?

[cinematic2]

Never mind.
Why not to set belt on the back side of a gantry?
Or at least going around gantry, like Epilog do? You could add one or two tensioning rolls invisible from the front.
Those cheap rollers instead of rail guide are f... sh...

[Dean448]

I've seen this system in Openbuilds used on routers and lasers. If you are looking for precision you will be as good at a cheap Chinese unit. I'm just not sure these 80:20 beams have high accuracy. I purchased used linear slides off eBay where everything is ground. I'm sure someone will disagree but it's difficult to measure. Fact is that it hard to correct for bending in your slides yet on a laser it has a large effect. Your focus point wanders at best and won't cut at worst. I would save the potential hassle and go with linear bearing slide rails
In my opinion belts aren't an issue as long as they don't have slack and track on center of the pulleys


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[m0ng00se]

I've seen this system in Openbuilds used on routers and lasers. If you are looking for precision you will be as good at a cheap Chinese unit. I'm just not sure these 80:20 beams have high accuracy. I purchased used linear slides off eBay where everything is ground. I'm sure someone will disagree but it's difficult to measure. Fact is that it hard to correct for bending in your slides yet on a laser it has a large effect. Your focus point wanders at best and won't cut at worst. I would save the potential hassle and go with linear bearing slide rails
In my opinion belts aren't an issue as long as they don't have slack and track on center of the pulleys


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Thanks .. maybe it is a good idea to go linear rails from the start. I know they are not cheap, but probably worth it in the long run.

[Dean448]

one more small point is to consider construction method. 80:20 comes with a wide array of design possibilities, but buying components off ebay does not. I'm talking about various components to connect slides to each other or the machine. Also connect motors and pulleys to the slides and the machine frame. My method of fabrication has been welded steel shapes cut from squares and bars purchased in a home center. I think the other way is to print components in plastic. In my case I found the welder to be handy for a number of projects. I guess if you have a mill you can machine from solid. The fun and challenging part is to come up with a design approach that you can build.

[m0ng00se]

one more small point is to consider construction method. 80:20 comes with a wide array of design possibilities, but buying components off ebay does not. I'm talking about various components to connect slides to each other or the machine. Also connect motors and pulleys to the slides and the machine frame. My method of fabrication has been welded steel shapes cut from squares and bars purchased in a home center. I think the other way is to print components in plastic. In my case I found the welder to be handy for a number of projects. I guess if you have a mill you can machine from solid. The fun and challenging part is to come up with a design approach that you can build.

I plan to buy all my components (or most of it) from MiSUMi, so I have downloaded the 3D cad models for each component I plan to purchase and use that in my design. Also, all the other custom stuff, like plates etc. that I design, I plan to cut/mill on my CNC. Stuff like mirror mounts, will be from Thorlabs, who also provided the 3D model on their website

thanks for the advise to far.