[dtronvig]

So, I'm putting together an enclosure for my Taig mill, and I'm getting around to the front double doors. It occurs to me that I'll be wiping off a mixture of coolant and fine metal chips, and it seems like the door would scratch up pretty quickly. Is this actually an issue with, say, acrylic or polycarbonate?

If this is a potential problem, I was thinking I could use a sacrificial protective film over the door material and replace it when it gets scuffed up. There's self-adhesive clear protective film that seems to come either in letter-size sheets for protecting artwork, or in humongous rolls for protecting windows. The most likely material I've seen is this 600-foot roll. That's a lot of film, but it only costs about what I'm likely to pay for the base 1/4 inch door material, and I'd have about 100 changes of film.

Does this make any sense? What would you suggest for door material, and for protective film, if any?

Thanks,
Drew

[Skuzzy]

Keep in mind, I am new to this, so I may just be full of it.

I just plan on replacing the panels periodically. So I designed my interior clear panels to be mounted using bolts through flat aluminum strips and rubber gaskets.

The lower 6 inches of the panels are HDPE, as I figure that is where most of the metal/coolant/lube will end up. The upper parts are simple acrylic panels.

Just a thought.

How did you solve the drain pan problem? I am struggling with that. I figure to use perforated HHPE which is raised up from the drain pan to catch most of the metal shavings. Those will not be mounted, so they can be easily removed to clean. It should also keep the shavings from clogging up the drain pipe.

But for the life of me, I cannot quite get the drain pan design licked.

[dtronvig]

Hi Skuzzy,

I'm just getting into this myself, so I can't say I know the best solution. For the tub, if that's a good term, I'm doing a variation on this. I can't figure out what sort of drain he's using, but I'm putting mine together with a regular kitchen sink drain, more or less like this. I got rid of the little structure at the bottom of the drain that supports the basket, so the outlet won't clog with the small stuff. That stuff is caught in a paint straining bag in the 5-gallon bucket coolant reservoir.

I can't really picture how big a pile of chips I'll have, but if it all fits in the basket, I can just pull that out and empty it. I would use something with a lager basket if I could find something. You could probably use a shower drain or garden drain and fabricate a basket out of some kind of screen material or hardware cloth.

Have fun with this,
Drew

[Geof]

In a practical sense you may find it is not worth worrying about the plastic getting scratched, you can still see through it okay.

I think you might find those adhesive films impossible to get off once they have been on for a while.

And just in case someone suggest getting the Lexan, Tuffak, Polycarbonate, (all the same thing) with the scratch resistant coating, MarGard it is called or something like that be careful. I discovered that the coating makes it much more likely to shatter when it receives an impact. Regular polycarbonate can often take a good hammer blow with nothing except a small dint; I once had some MarGard stuff shatter just like glass.

[Ken_Shea]

Since Lexan is widely used in aircraft windows / canopies, safety goggles and even bullet proof windows, it seems highly doubtful that it would be subject to shattering like tempered glass when struck etc. It would surely be my first choice for material of your need.

One for, One against

[Geof]

Since Lexan is widely used in aircraft windows / canopies, safety goggles and even bullet proof windows, it seems highly doubtful that it would be subject to shattering like tempered glass when struck etc. It would surely be my first choice for material of your need.

One for, One against

Correct; so I will give you another chance to read the distinction I made:

And just in case someone suggest getting the Lexan, Tuffak, Polycarbonate, (all the same thing) with the scratch resistant coating, MarGard it is called or something like that be careful. I discovered that the coating makes it much more likely to shatter when it receives an impact. Regular polycarbonate can often take a good hammer blow with nothing except a small dint; I once had some MarGard stuff shatter just like glass.

[Ken_Shea]

Well it does read clearer with my "2ND" chance, but still dubious about wide spread shattering experience that would be caused by the scratch resistant coating as that coating is also widely used on mil-spec safety glasses.

[Geof]

Well it does read clearer with my "2ND" chance, but still dubious about wide spread shattering experience that would be caused by the scratch resistant coating as that coating is also widely used on mil-spec safety glasses.

Where did I say it was widespread?

I simply pointed out that I have had experience with the coated polycarbonate shattering under treatment that did not shatter normal polycarbonate.

[dtronvig]

Well, when you treat materials to make them harder they generally become more brittle, more inclined to break under tension than to stretch. If the whole thickness of the material is hard/brittle it'll all break in a hurry, like glass, or steel that's hardened all the way through. If you're really careful to harden just the outside and to leave the inside somewhat malleable, like in a good sword, for example, the hardened surface will nick, but the whole thing won't shatter.

So I can buy that a hardened version of polycarbonate would be brittle, able to take high stress up to a point, but then shattering, because it can't bend.

Thanks for all the suggestions,
Drew

[Ken_Shea]

Where did I say it was widespread?

You did not need to say it Geof, it was inferred, at least to me, when you said "be careful" and "I discovered that the coating makes it much more likely to shatter", I am not doubting your experience at all or even saying you are wrong, only that I am just very suspect that it was the coating that was the cause of your experience. Doubtful it can be proved by either of us that it was / was not the cause. so I guess it is, after all, what "we" believe that makes it true to each of us.


So Drew, get the Lexan or similar w/or wo the coating, either way you still will have some tough durable and long lasting material to look through.

[dtronvig]

Also, it occurs to me that you'll probably scuff up the plastic less if you sluice the fine chips off, rather than grinding them against the plastic by wiping them off.

Thanks again,
Drew

[BrendaEM]

I wonder if certain food wraps might work.

[dtronvig]

Interesting possibility. If they're clear enough, and you can get them to lay flat, it might work. I'll check back in if I find something that works.

[BrendaEM]

There's a company that makes visors for motorcycle helmets. The sell you a stack of sheets that you peel off during the race. I wonder what material that is.

Alternatively, you could create a frame supporting a piece of black fiberglass window screen, which would deflect the chips before they hit the plastic sheet. Coolant might fill the spaces in the screen though, impairing visibility.

A trip to a junkyard might yield a piece of flat tempered safely glass from a bus or hatchback, which could be added to the inside of the enclosure.

[Al_The_Man]

A trip to a junkyard might yield a piece of flat tempered safely glass from a bus or hatchback, which could be added to the inside of the enclosure.

Thats what I have used in the past, and in some cases a specialty glass place will cut it or supply it, I got the idea when I retrofitted an older leblond lathe that had it, it is extremely hard and does not scratch.
They can also supply the rubber moulding to mount it in, you need a nice radius on the corners.
The toughest glass I ever found though was hardened glass windows used in locomotive cabs, came across some in a locomotive scrap yard once.
Al.

[dtronvig]

There's a company that makes visors for motorcycle helmets. The sell you a stack of sheets that you peel off during the race. I wonder what material that is.

I have a woodworking faceguard-air-filter that takes replaceable self-adhesive overlays. That's what got me thinkin' in the first place. The overlays I have are probably PVC, but they might be acetate or Mylar, which is to say they're some sort of clear glossy plastic sheet.

- Drew

[dtronvig]

Thats what I have used in the past, and in some cases a specialty glass place will cut it or supply it, I got the idea when I retrofitted an older leblond lathe that had it, it is extremely hard and does not scratch.
They can also supply the rubber moulding to mount it in, you need a nice radius on the corners.
The toughest glass I ever found though was hardened glass windows used in locomotive cabs, came across some in a locomotive scrap yard once.
Al.

Just to avoid any confusion, we're probably talking about laminated safety glass, the glass-plastic-glass sandwich typically used in windshields. Tempered glass breaks more easily, but into thousands of relatively harmless small pieces. That's generally used in side windows, and I don't think it can be cut without shattering.

The tempered glass would help on the mill side of a plastic door. On it's own it wouldn't help much if something heavy shot out of the mill (I hope that never happens). The laminated glass would work great. A bus or train windshield would actually be flat, and could be cut down.

Thanks for all the suggestions,
Drew

[xiphmont]

So, I'm putting together an enclosure for my Taig mill, and I'm getting around to the front double doors. It occurs to me that I'll be wiping off a mixture of coolant and fine metal chips, and it seems like the door would scratch up pretty quickly. Is this actually an issue with, say, acrylic or polycarbonate?

I use both alot. Polycarb is used because it's dense and shatterproof (from shock; it can shatter from crazing), but it's very soft and scratches if a moth farts in the same room.

Acrylic is harder than polycarb but still easy to scratch; for example, I made aquariums out of acrylic and the care instructions included 'clean only with cotton cloth; paper towels will scratch and cloud the surface'.

There are coated versions of both that increase scratch resistance, but honestly, they only slightly increase the durability in my experience. Also, so you know, both acrylic and polycarbonate absorb water (just not very much) and if they get wet for a few hours, they will bow and warp considerably. Aquariums that use the stuff are designed to either not use flat surfaces or overly thick panels for that reason. And scratches, cracks or chips (like in the edge from cutting) will craze from moisture and eventually crack/crumble the panel. You have to anneal the sheets after cutting to mitigate this problem.

Honestly, if you care about longevity, there's no substitute for glass.

[twocik]

Do you have any pictures of the enclosure to post?

[under-dog]

Correct; so I will give you another chance to read the distinction I made:

And just in case someone suggest getting the Lexan, Tuffak, Polycarbonate, (all the same thing) with the scratch resistant coating, MarGard it is called or something like that be careful. I discovered that the coating makes it much more likely to shatter when it receives an impact. Regular polycarbonate can often take a good hammer blow with nothing except a small dint; I once had some MarGard stuff shatter just like glass.

Polycarbonate on its own scratches very easily.