Gavztheouchs Home Built 1.3 * .8m Laser

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Gavztheouchs Home Built 1.3 * .8m Laser

Postby gavztheouch » Sat Apr 07, 2012 1:22 pm

I would like to share some photos of my recent laser build, this has taken me about a month on and off to get this far. I have had success engraving with mach3 and the aliginment all over the table is good. But now its time to take it to the next level with a DSP controller from Lightobjet, hopefully this will add the convience of a commercial machine and allow me to work it hard. I am hoping to try and make back some of the money I have spent on the machine by doing jobs for customers and selling my own laser art online and locally. Look forward to some feedback from the forum.

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Re: Gavztheouchs Home Built 1.3 * .8m Laser

Postby Enraged » Sat Apr 07, 2012 6:19 pm

looks great! I like what you did with the belt arrangment.
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Re: Gavztheouchs Home Built 1.3 * .8m Laser

Postby StigOE » Sun Apr 08, 2012 6:47 am

Looks nice and clean, but not very safe with no protection against stray laser light. What will you do for fume extraction?
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Re: Gavztheouchs Home Built 1.3 * .8m Laser

Postby iGull » Mon Apr 23, 2012 5:52 pm

Nice layout Gav, I would also fit slides the next time around rather than vee wheel.

My only comment would be on the Y axis shaft diameter - it looks a bit wee - I'd be inclined to up it to about 12 to 15mm alloy tube with steel ferrules at 6.35mm - or change to 10mm steel shafting. At 6mm, I think it would whip or cause some compliance in the shaft which would lead to the dreaded backlash.
After the pain I've had over the past week, I'd be swapping out those sexy black flexible shaft couplers for solid ones as well :lol:
Is that a toy laser you've fitted :D

Nice work - I'm guessing it will end up in a box at some point?

What size/type of slides did you use BTW ?

Cheers

Neil
EMOs are a sign of weakness ...
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Re: Gavztheouchs Home Built 1.3 * .8m Laser

Postby gavztheouch » Mon Apr 23, 2012 8:10 pm

Hi Neil thanks for your comments,

Yes I actually ordered some new solid couplings on Sat, the flexible ones on this laser had to be the worst quality couplings I have ever used. The rubber that holds the two pieces together was noticeably too small and not in interference causing the couplings too move in relation to each other quite considerably under very little load.

The 10mm plus shaft is also in the pipe line as well as an upgrade to servos instead of steppers, I have some nice Panasonic drives that I have from another project that should work quite nicely.

The slides are Hiwin, HG15's I think. I bought them from a Scottish company that did quite a good deal on them http://www.mes4thk.co.uk/ The 1.4m rail with carriage was £90. They are the main dealer for THK in Scotland/UK but the do deal in Hiwin if you ask.
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Re: Gavztheouchs Home Built 1.3 * .8m Laser

Postby gavztheouch » Thu Apr 26, 2012 1:31 pm

I have installed the shaft couplers and they have made a big difference to my backlash issues, unfortunately there is still a too much backlash left for the laser to be useful. With the motors locked you can rock the gantry about 1mm, the compliance is in the shaft just as Neil thought. The next job is going to be a switch around to 10mm steel shafting. It's times like this I wish I had a lathe with all these mods I now need to make to my couplers.

Here is an equation I found online, the numbers are from their example but if I change some of them ie.. double the diameter or reduce the length of the shaft it shows you what sort of gains you can expect.

The angular deflection of the shaft can be calculated as

θ = L T / Ip G

= L T / (π D4/32) G

= (1 m) (1000 Nm) / (π ((0.05 m)4 - (0.03 m)4)/32) (79 GPa)

= 0.023 radians

= 1.4 Degrees
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Re: Gavztheouchs Home Built 1.3 * .8m Laser

Postby gavztheouch » Sun May 13, 2012 7:50 pm

Backlash woes continue...

I have replaced the shafts with 10mm stainless steel upgrades and I have turned down the ends to 6mm so I only have couplers joining to the motor.

I have tried running with super tight belts and with very loose belts and everything in between and its seems to make very little if any difference.

I am totally clueless as to what is causing this, 30mm high letters with curves are visibly distorted yet I can only trace 0.15mm of backlash max. Is 0.15mm enough to casue problems.

Any ideas as to what to try next would appreciated.

Cheers

Gav
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