reflection mirror from a old Hardrive disc

Discussions on optics for laser cutter/engravers

Re: reflection mirror from a old Hardrive disc

Postby a542002 » Fri Jan 20, 2012 9:55 pm

Hi lasersafe1
no probleme I could send you one if you send me your addresse to my email but they are just 20mm diameter.
greetings
walt



lasersafe1 wrote:I have a power meter for CO2. If you want to send me a sample, for the cost of a stamp I can give you a definitive answer on the value of any loss as compared to a gold coated mirror (up to 35W).
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Re: reflection mirror from a old Hardrive disc

Postby a542002 » Sun Jan 22, 2012 10:11 pm

Hi all
I have made a few picture from my setup to cut the reflection mirrors from old Harddreive disc
and also a test with acrylic engraving
there is not realy a visible difference with the disc mirrors
greetings
walt
Attachments
lightpier2.JPG
thats a test enrgaving in acrylic with the head mirror replaced with the disc mirror
lenscuttinglens2.JPG
thats how clean the lense comes out the edges need to be de burred
lenscuttinglens.JPG
this are two lenses cutted each at a time
lenscutting3.JPG
thats the disc covered with tape
lenscutting2.JPG
thats the whole parts, I used the parts from a 4 inch pvc pipe plug from Homedepot
lenscutting1.JPG
thats the whole thing I put it in My drillpree vize
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Re: reflection mirror from a old Hardrive disc

Postby twehr » Mon Jan 23, 2012 2:20 am

Walt,

Just wanted to say thanks for this idea. I just completed a long and photo-filled blog on the whole process. It worked great for me. I gave you all the credit for the idea, as it was truly a great one.

If anyone want to see the process in detail, along with some cutting tests, check it out here.
tim
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"The answer is usually easy and obvious once you know what it is." tw

DIYLaser Blog
SemiHomemadeTools.com
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Re: reflection mirror from a old Hardrive disc

Postby lasersafe1 » Mon Jan 23, 2012 3:15 am

Now you can sell them on ebay!
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Re: reflection mirror from a old Hardrive disc

Postby iGull » Mon Jan 23, 2012 9:17 am

Nice write-up Tim and good work Walt!

I'm wondering about the rough edges, and the timber layers, about 40 years ago I had to cut a lot of holes in sheet glass (we wanted the glass discs) and we used a short length of 15 mm copper tube chucked in the drillpress. The glass was clamped down and a 'well' made with plasticene - play putty - the well filled with paraffin - kerosene- and very fine carborundum powder - can't remember the grit size. The results were perfect, the drill press handle had a length of string and a weight on it for constant pressure and the whole thing left running while we drank tea :D

Not a quick method by any means, but the results are good.

I'm sure there must be a more modern version now - maybe the same setup as yours except no teeth, just carborundum - a bit of cutting fluid in there would help too.
Maybe a cnc waterjet even if you know a friend who has one (as if :D )

Thanks again for all the info.

Cheers

Neil
EMOs are a sign of weakness ...
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Re: reflection mirror from a old Hardrive disc

Postby callcbm » Mon Jan 23, 2012 12:31 pm

This is a link to a diamond core drill that should make nice round disk a little pricey. A stain glass person has a diamond spindle grinder that you can use also.
http://www.mcmaster.com/?orderview=new# ... ts/=fxh13o
Thanks Randy
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Re: reflection mirror from a old Hardrive disc

Postby twehr » Mon Jan 23, 2012 1:30 pm

If I were going to do this again - and I might, just for fun - I would no doubt try some alternative methods of holding the disk. After I did my work, Walt showed some pictures of another hold down that looks pretty good. Fortunately, the central area of the mirror is the only part we really care about - the edges being unimportant. Once installed, you can't see any of the edge area roughness anyway.

It was a fun exercise - and a profitable one. Interesting this is that when I went to put the extra 8 mirrors away for safe keeping, I noticed I had to new gold-plated mirrors I had forgotten about. But I think I will just leave them there - I am pretty happy with the HD mirrors and think they will hold up to cleaning better.
tim
--
"The answer is usually easy and obvious once you know what it is." tw

DIYLaser Blog
SemiHomemadeTools.com
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Re: reflection mirror from a old Hardrive disc

Postby twehr » Mon Jan 23, 2012 1:35 pm

lasersafe1 wrote:Now you can sell them on ebay!


Let's see - $20/disk (make them attractive to buyers) - 9/18 mirrors per HD - 1.5 hr work - that's about $120-$240 per hour. Nah! USING the mirrors in my laser is worth a lot more than that! :P
tim
--
"The answer is usually easy and obvious once you know what it is." tw

DIYLaser Blog
SemiHomemadeTools.com
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Re: reflection mirror from a old Hardrive disc

Postby edmond22 » Mon Jan 23, 2012 6:15 pm

Good idea Walt and an awesome write up by Tim.

Im going to scrounge a old hard drive from our IT guy at work and make some spare mirrors for my Buildlog 1.0 laser.

They are free and thats a good thing because a single mirror here in SA costs about the equivalent to $80.

Thanks again guys for sharing this :)
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Re: reflection mirror from a old Hardrive disc

Postby canadianavenger » Mon Jan 23, 2012 9:10 pm

Nice write-up. I'd suggest using some thin double-sided tape [carpet tape] to adhere the masking tape covered disc to the wood, this will help prevent it from slipping/spinning and being scratched as the drill cuts through.
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