Distance Tube to Mirror and Mirror to Mirror

[Udo Juerss]

Hello,

assuming a wavelength of 10.6µs: might there be any difference placing the tube at a certain distance to the first mirror?
Meaning at a certain distance the beam can hit the mirror with zero power, at another distance it can hit with max power (+-).

Don´t call the question useless - at least it can serve as a silly one!

Cheers

Udo

[Dave Vigness]

You're going to have to have better eyeballs and fingers than I have to make that fine adjustment... LOL

[Gene Uselman]

Theoretically there might be slight loss but I doubt it can be measured with our equipment- some lasers are 4x8 foot and it does not seem to be a problem.

[Dave Vigness]

Gene,

A bit off subject, but have you seen many posts from guys with large machines having beam alignment problems? I caught a recent post both here and on another forum of a guy with a 1300 wide DIY machine having X axis alignment problems. I've been considering a large DIY build, but this has me concerned. I had already thought about larger and or double rail bearings on both axis' for stability, but now I'm wondering if I'm going to making my own money and time pit.

[Gene Uselman]

My machine is 1300x900 and I haven't had to realign it in years. If constructed well and with good parts, it will not be a problem.

[Dave Vigness]

Factory machine, or DIY build?

[Tim Mellor]

Hello,

assuming a wavelength of 10.6µs: might there be any difference placing the tube at a certain distance to the first mirror?
Meaning at a certain distance the beam can hit the mirror with zero power, at another distance it can hit with max power (+-).

Don´t call the question useless - at least it can serve as a silly one!

Cheers

Udo

Given the beam has width and Mirror one is at 45 degrees best you define which particular part of the beam you want to hit which part of the mirror

Gene,

A bit off subject, but have you seen many posts from guys with large machines having beam alignment problems? I caught a recent post both here and on another forum of a guy with a 1300 wide DIY machine having X axis alignment problems. I've been considering a large DIY build, but this has me concerned. I had already thought about larger and or double rail bearings on both axis' for stability, but now I'm wondering if I'm going to making my own money and time pit.

The best advice is get the weight on the head down and KISS. To that end Russ's new Lens mount saves needing to DIY and takes a heap of weight off which makes the Kinematics much less an issue on the gantry. With mine I am starting with Open build wheels for the 'slow axis' but have already factored in swapping them ot Linear baerings/rails later in needed. That is one of the benefits of using V Slot re engineering takes an Allen Key.

[Gene Uselman]

This was built by a company experienced with building CNCs, so they used good parts but were a bit loose on the wiring and control fronts. I would love to build a machine knowing what I know now, but, as my dad used to say, too soon old [and too late smart.]

[Dave Vigness]

Yeah, for as much as I've modified mine, that idea of a DIY build is still alive and kicking. Sometimes it even puts its boots on.

Just out of curiosity, how big is your gantry? My 80W has a 20mm x 40mm 2mm box beam. I know Russ' has a wider gantry because his sliding mount is too big for mine. Found that out after I built one. Thankfully from some scrap MDF and not purchased from Cloudray.

My biggest peeve is having to cut strips to feed in the front instead of just feeding a sheet. I know it's a step up from the cutting squares before I got the custom lens tubes from Russ, but it still kinda irks me when I know I could have used the piece in between if I didn't have to cut it to feed the machine. Especially when I have a tube extension sticking out far enough that I could have had a wider machine...

[Tim Mellor]

You can always have a bigger 'toy'

My gut feel is 40x20 V Slot or to a lesser degree plain extrusion should be fine for a 900mm Gantry but over that I suspect you are risking sag and harmonic issues. Easy fix would be to bump it to 60x20 providing you can bump the Laser path up to compensate. It was one of the attractions to the FF build is that it gives me 1200+ front feed/cut and with some wiggling with Robs design I have 1000mm (only circa 930 cut width) wide endless pass through from the sides for roll use with two drop down doors. The skin fits a W2 Reci inside with a touch to spare without an extension box.

I did think about going to 1200x1200 but it would be really pushing space with the extra depth and use case for me.