Cutting telescope mirror blanks out of a thick glass tabletop

[@danbysoul2630]

I love your videos and listen to you. Really practical and informative. Hope to see more on what you are doing. Thumbs up!

[@farpointstation]

I love how varied your hobbies are

[@mthurtell]

I've been waiting to a follow up to this one with baited breath! Please don't leave us hanging mike!

[@ReinaldoGonzalezreix2x]

Yaaaaaaaay a video about telescope mirrors! Thanks mike!

[@gppl77]

Love your mirror making vids. Very useful, detailed and without any water (except for cutting). Thanks for sharing !:)

[@noriszilverbergen5227]

One more thing: I think... if you fill up your jerry can with water, hangingit from above (even out & away from your work top), then bring the water by right diameter pipe to your saw blade, will be much easier than fill the little tank repeatedly; Let alone you also can change the feeding of the water to debit which you think it might be suitable.. ... just my thoughts.. might be useful. Keep the hood works. I like your clips very much...

[@seditt5146]

I find a thin layer of Wax helps when I am cutting glass to prevent cracking and chipping because my tile saw is garbage and chips everything so I needed a work around and its fairly effective for me

[@Bigalinjapan]

Too bad you didn't make that whole table one big lens :D

[@Timtron432]

Fantastic video!!!

[@risby2]

Thanks

[@vizionthing]

Have you considered getting a job like this done using water jet cutting service, just a quick search listed around twenty locations in Florida, would probably also negate the need for edge grinding, just a thought, always nice when you upload mirror video's, you are an inspiration.

[@omegageek64]

Yes. I have actually had some blanks water jet cut in the past. It is a great process. Unfortunately it is more difficult than you'd think to find firms willing to do it. They are generally pretty busy with big jobs and aren't necessarily willing to take on a small one-off job. I did find one company to do it for me once, but it was expensive, and a fairly long drive to deliver the glass and pick up the blanks. After that I decided to find an alternative way to cut out the blanks myself. Even figuring in the cost of my new saw, I probably couldn't have had them water jet cut for much less. Edge grinding after slumping is still generally needed anyway.

[@travismiller5548]

Just wondering if the water jetting was noticeably tapered on material that thick. I like your cutting solution- much easier and budget friendly than even Applied Science's budget water jet build. I'm shocked you got it done in one blade with no dressing stone- or so it appeared. Maybe partially submerge the next one in a kiddie pool?

[@omegageek64]

@@travismiller5548 There was no noticeable taper on the 3/4 inch glass I had cut. Can't say about thicker glass.

[@fatitankeris6327]

Table brcoming such high art...

[@TGUlricksen]

Can I still cut like this if the table is tempered? Is there a way to know if the table is tempered before destroying it? Thank you.

[@omegageek64]

You can't cut tempered glass. The whole thing will shatter. If the glass has nicks, chips or deep scratches, it likely isn't tempered. Damage tells me the glass isn't tempered, and is also a negotiating point on price.

[@gppl77]

Could you make a videos on how you polish a slumped blank? There are lots of them polishing flat ones, but slumped will be rolling. What kind of fixture do you use? I want to make a big mirror, like 30" (yes , it''s ambitious, to say the least) , for myself, but I lack any experience in it. So plan is to start from 10" made from offcuts and gradually go up in size. At the moment I'm accumulating common (and uncommon) knowledge.

[@knight2255]

Did you end up making a slumped mirror?

[@MrMaker-se1qr]

Which liquid use on cutting disk while cutting?

[@omegageek64]

Just water to cool the blade and wash the swarf away.

[@Arcainmech2]

I have a method of using a trepan to cut my glass. Do you offer a slump service?

[@billkaroly]

Would it be possible to cast a mirror out of ceramics? I saw a web page for a type of ceramic for just that purpose. Make a CNC cut hex form to glue to the back.

[@vaibhavghodekar2768]

I really loved watching this video, would you be please like to guide me, is 40 inch parabolic primary mirror possible to make at home ...what would it take to make it

[@PRon-lj8zh]

yess brother its posible but not at home you need a factory where mirror are mader go to them and ask to make you an mirror 40 inch with binosilicon

[@kenhunter9522]

Use a power supply to run the Makita saw. 19V HP Laptop supplies at Goodwill for $10 or so will work a treat.

[@omegageek64]

Thanks for the tip!

[@gordtulloch]

Any thoughts on saving the scraps to melt into another 10"?

[@ravbin86]

i was thinking the same thing. melt the extras into a circle shape and you have an extra mirror blank.

[@samsmith9764]

he tried something like that on a light weight blank that he slumped- i forget the video tho. What happened was some bubbles migrated out of the material and others didn't. Because hes not melting then pouring and the glass is so viscous, bubbles from many parts are a serious problem. Hence the 10" blanks

[@inspector1794]

Very informative, thanks for sharing and educating. I was wondering if it is necessary to cut completely through with the Makita saw. Would it work to cut to half depth then break along cut line, like scoring and breaking.

[@omegageek64]

I don't want to try snapping it at all. Too much chance of the break running wild. The way I am doing it works great. No waste due to wild breaks. Never had it so good with glass this thick. I think the only reason I would cut only partway through is if the glass is thicker than the saw can cut in one pass. Then I would likely flip it over and finish the cut from the other side. I've seen people cut glass up to a couple inches thick doing it that way.

[@levy0810]

I use the same portative glass saw... I hate it...

[@countcristo2481]

Just curious, but aren't tabletops normally tempered? How do you prevent them from shattering? I understand, that in the past, the edges were the potential weak points.

[@countcristo2481]

BTW, Not an expert, but I would suggest that a much better mask is in order. In fact, I would suggest total helmeted isolation with air supply from a totally different part of your area. Maybe overkill, but I look at it this way, why risk anything at all. OR ask yourself, how much is your life worth. I can only see one answer ...PRICELESS.

[@omegageek64]

Can't cut tempered glass. It will shatter into a million pieces. Most large tabletops are too big for the tempering process. I only use non-tempered glass. It's easy to know the glass isn't tempered if it has chips or deep scratches in it. Those can also be helpful in negotiating a lower price.

[@countcristo2481]

@@omegageek64 Thank you, I kind of knew the answer, but thought i'd ask. I suppose a 3/4 inch think glass is pretty tough all by its lonesome. While you are still up, What are your thoughts on vacuum forming some Mylar over a a the convex form to get a primary mirror?

[@countcristo2481]

@@omegageek64 While you are still up, What are your thoughts on vacuum forming some Mylar over a a the convex form to get a primary mirror? Curiosity again, hope you don't mind. Reply

[@MH-jt3lx]

When you make the thin blanks why not instead of the grid being removed how about getting rid of the waffle chunks?

[@nobob268]

Did you anneal the glass? I thought tempered glass explodes on cutting.

[@omegageek64]

This glass wasn't tempered.

[@stjoevideo]

Is this tempered glass you are cutting?

[@omegageek64]

No. Tempered glass would shatter.

[@stjoevideo]

@@omegageek64 That's what I thought... so how do you find ones that are not tempered?

[@omegageek64]

@@stjoevideo Look for tabletops with chips or scratches. They won't be tempered. The chips also make for good negotiating points to get the price down. There are other ways to test for tempered glass, but they aren't as easy.

[@patterdalezipsuzilil]

Most tables are safty shattering glass

[@robrich8294]

Yeah I just talked with someone yesterday who made a 40” telescope and I think I found the possible lens. They broke theirs transporting it. Yeah it would be so hard to polish that behemoth!! Well there is always new and dynamic ways of improvising . Ok you’re selling 16” lenses? What are you getting for them? I want to make a 16” telescope. Are you on Facebook or Instagram? Someone in this world has an ingenious method to grind and polish a huge lens. I want a 40” lens would look insane!!

[@csours]

Could you cut out cores at corners on the rough cut?

[@robertopereira9202]

Quanto custa um espelho .

[@griffith500tvr]

I would have slumped the whole mirror and make a large telescope

[@noriszilverbergen5227]

Would you kindly please indicate the exact model & type of your saw & also saw machine please?! I'll be very thankful 🙏😌.

[@vizionthing]

Makita CC02R1

[@bryzabone]

Gotta ask… 🤷🏼‍♂️ why not make a 40-inch mirror out of the tabletop? That would be EPIC. Shallow, but epic…

[@omegageek64]

It's tempting. I've actually considered building a kiln big enough to slump a tabletop. Big job though. Maybe someday.

[@LovenessLife]

I got a half inch round 48-in diameter glass table top. I need to cut a center hole off 14 in circle in the middle. Is that easy to do do you have instruction?

[@omegageek64]

That would be just about impossible for me to do with my tools and knowledge. You should contact a professional glass cutter.

[@gppl77]

It all boils down to whether you want to risk breaking it or not. If you do - there are multiple DIY ways to do it: drill a set of holes in circle or use a saw like this makita to cut out hexagon and grind it afterwards to a circle (in both cases). If you don't - ask a professional. if they break it they'll be responsible for it and should cover the damage.

[@edgarjones1730]

The best way is to take it to a flat glass shop that will waterjet or cnc. You could probably get a 14" diamond circular bit but I've never seen one and it'll be hard as heck to handle. If you're in Texas, DM me and I'll help you out. I do glass fab for a living.

[@johnnycash4034]

So that thickness is okay for a mirror? Thought it should be thicker?

[@omegageek64]

Thin mirrors work just fine. They just need to be well supported by mirror cells with 18 or more support points. Slumping the mirrors into shape also makes them stiffer, just like a curved piece of sheet metal is stiffer than a flat sheet.

[@johnnycash4034]

@@omegageek64 okay that makes sense thanks.

[@edwins2595]

I am now living in Tampa. If you are close to me would it be possible for me to pay you a quick visit since I am interested in making a mirror for a telescope.

[@omegageek64]

Hi Edwin, I am out of state for an extended period. Maybe when I get back.

[@senorjp21]

I thought most glass tabletops are tempered glass. But, I don't think it's possible to cut tempered glass. I like your gold content but I prefer your optics content. Cheers

[@omegageek64]

A lot of tabletops are tempered. I always check before I buy them. A real easy way to tell is if there are chips or deep scratches on it. That's a sure sign that it's not tempered, or else it would have shattered. It's also a good price negotiating point if they have damage. I just don't mention that I intend to cut it up anyway. Another way to tell is to look through the glass at the blue sky while wearing polarized sunglasses. you should see stress lines in the glass if it is tempered.

[@carlsartor1423]

One would think the tops would be tempered, but my son was helping someone move a large glass table top and bumpped something and the top broke cutting his arm down to the nerves. He got something like 27 stitches, and still has some numbness now and then.

[@timhurd6855]

I live in Texas by the way.

[@timhurd6855]

I would like to have the triangle pieces to Knapp arrow heads out of. I would pay for them so msg me if you want to work out a deal.

[@omegageek64]

Hi Tim. I kept most of the pieces to melt down. I can get more blanks out of the glass by melting the cutoffs in a mold. I'm out of town for a week or so. I'll check and see if there are any pieces I don't want when I get back.

[@timhurd6855]

Thank you. It’s hard to find glass pieces.

[@alexnet8943]

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