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Safety glass vs tiny carbide chunks

Generic Default

Aluminum
Joined
Jan 23, 2016
Location
Wilmington / Long Beach
I was slotting a small block of acetal with a 1/4 extra long carbide end mill. Part slid in the vise a little, then grabbed the end mill and kicked the part out of the vise. Not a big deal to lose 5 dollars of plastic and a 12 dollar end mill, but those tiny chunks of carbide from the 1/4 end mill were apparently enough to fracture the safety glass on the inside of BOTH door windows. The outside is fine, I think it's polycarbonate so there is no risk of shattering.

Still, I want to replace the windows so I can see again.


glass outside.jpg
glass inside.jpg

The machine is a Doosan DNM 5700, my problem is that I can't figure out how to get the old window out and a new one in. It seems they are bonded together along the perimeter but there is a 1mm or so air gap between the sheets. Does anyone have experience with windows like these? I already took off the steel retaining cover, I thought the glass would be easy to pull off but it looks glued around the edge. Older machines I have used before either had no enclosure or had a more simple polycarb sheet in a frame design, none of this super fragile, hard to replace stuff.
 
Probably similar to this video even though its a haas lathe. I've never really looked before, but how many mills come with interior glass?
YouTube
 
That will likely be an assembly.
I'd imagine the sheet metal cover comes off on the interior, then the adhesive that seals the assembly to the door needs to be cut.

Not going to be a cheap fix.

Dude, the door handles still have packing wrap on them.....
 
I’d figure out a way to mount something cheap on the inside after you replace the glass, like a disposable layer,


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It looks a lot like an automotive glass installation. If you can sneak a piece of music/spring wire around the edge of the glass, working one's way around the perimeter will release the glass, that is, if it hasn't finished shattering all over the floor first. Then there's some adhesive cleanup to do.

Consider replacing it with laminated glass. (Flat windshield glass.) Any automotive glass shop should have it in stock and be able to cut it with the aid of a template. IIRC, the proper adhesive/sealant is urethane based. Or maybe there's a mobile glass guy near you that'll come out and do it, then you don't have to. There's something appealing about that....:)
 
I have always just made my own with Lexan, never any issues. It is also readily available, easy to work with and not that expensive.
 
First things first...have you contacted the manufacturer or your distributor to see what replacements cost? It might be worth just getting the real thing and not re-engineering it. If they're a couple hundred each I'd just order them and be done with it.
 
I haven't contacted the dealer for a replacement because I realized that if breaking a 1/4 inch end mill can shatter both panes, it is probably not worth it to have any type of glass in the machine because it could happen again just as easily. That, and other threads have been saying these window replacements often cost over 1000 dollars each.

I think I'll go with the polycarb sheet approach. Better to lose clarity over time due to abrasion than to ruin the entire thing from a small tool breaking.
 
my HAAS machines are all just 3/16" polycarb. It works, but they do get beat up real fast. I swap my windows every 3-6mo or else I end up flying blind.
 
I replaced our busted window with a compatible double pane that we bought locally. Haas wanted $275 for the pane, local company was able to cut more than 100 off that price. The shape was easy to cut though, since it was rectangular with 90deg corners, so ymmv
 
... if breaking a 1/4 inch end mill can shatter both panes, it is probably not worth it to have any type of glass in the machine because it could happen again just as easily. ...

I think I'll go with the polycarb sheet approach. Better to lose clarity over time due to abrasion than to ruin the entire thing from a small tool breaking.

True of tempered glass, but not of laminated. Think windshield. Your carbide end mill chunks would just make a chip in laminated glass, if at all. Its clarity remains much better over time than polycarbonate.
 
Generic Default,
I saw this thread. I agree that you may have some other options but thought I would chime in just in case you wanted to give us a call for pricing. While I cannot give you an exact price because I do not have control over dealer pricing. I do know it will be well under 1000$. The part number, if you choose to look into it will be #220209-00219-KIT.

Regards,
Paul
 
... breaking a 1/4 inch end mill can shatter both panes...

If your description of events was accurate, then I'd say you got very unlucky. It's extremely rare for small carbide endmills to shatter with enough energy to break windows, unless they explode at 50k rpm or something. Are you certain it was only the endmill that hit them?

The only thing that I've ever broken glass windows with in machines is insert drill slugs in lathes, that would have massively more kinetic energy than a 1/4" endmill.

It seems overly pessimistic to me to assume that this will happen again, or at least with any kind of frequency, which makes switching to polycarbonate a knee-jerk reaction to a non-problem.

As I recall you bought this machine to cut aluminium mainly, and if you are doing that with any kind of efficiency you will throwing a lot of chips at the windows. Expect polycarbonate to have a very short lifespan before you can't see through it.

Contact OEM and get an actual quote rather than making assumptions based on hearsay. If it turns out that they are hideously expensive (which is possible), then get a quote from a local glass company to supply laminate panes.
 
Just to be different: how about automotive glass for the inside layer and polycarbonate for the outside. That should get you less fogging and good impact resistance. Indeed as with everything else the difference between theory and practice can be much larger than theory predicts.
 
I blew up a 5/16" cobalt drill on a DNM500 (?) and it shattered one of the windows, just like that. If I remember right the replacement was around $600. Boss wasn't happy about it... wanted to buy a sheet of plastic from McMaster. :nutter:

We have a local glass shop that I talked to about my old VMC, they can cut safety glass to size, just about any shape, and it was CHEAP (in my opinion).
 
Contact OEM and get an actual quote rather than making assumptions based on hearsay. If it turns out that they are hideously expensive (which is possible), then get a quote from a local glass company to supply laminate panes.

Emails and phone calls are free, and knowing is half the battle :p
 








 
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