# Sight glass for fuel tanks etc



## pat_pending (Jan 17, 2022)

Hi, after playing around and wasting a load of time cutting my own glass disks to make sight glass on the Webster and other builds, I went searching for somewhere I could buy them pre-cut. Took me a while and thought I'd share with anyone thats interested. In the end the right search term was "flash light glass lens" and I ended up finding some on Ali Express at a reasonable price. Since postage was over a month, i bought a lifetime supply .




			Buy Products Online from China Wholesalers at Aliexpress.com
		


Cheers, 
Patrick


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## Oldiron (Jan 18, 2022)

Very nice. How did you fasten them and seal them? Bob


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## pat_pending (Jan 18, 2022)

Oldiron said:


> Very nice. How did you fasten them and seal them? Bob


Hi Bob. I used Cyanoacrylate glue. No problems with petrol/gasoline, Coleman fuel, Nitro glow fuel or Ether/Paraffin model CI engine fuel. The only annoyance is the white residue that can form on the inside of the glass as it dries.... not a biggie.


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## Ken I (Jan 19, 2022)

Hi Pat, Just for future reference - here's how I managed to cut glass disks for a Mendocino motor.

I needed to make a couple of 30mm diameter glass disks for the end stops. All attempts with a diamond coated hole saw resulted in disks that could be done better by a Neolithic flint knapper (Photo - bottom right).





I eventually succeeded (Photo - Top right) by first glueing scrap pieces of glass with cyanoacrylate to either side of the target piece.

The rubber ring was also glued down as a cofferdam to hold water / coolant (you can use modeling clay).

First attempt failed along with the adhesive - you need to let it cure for about an hour.

Second attempt – very much better - but my drill press chuck does not run very true - transferred to the minimill where I finally succeeded.

You do not have to apply a lot of force - being particularly prudent at the breakthroughs. Make sure the glass is spotless in order that the superglue layer is very thin (dust specs will increase the thickness).

The diamond bit went through about 10mm of glass (3+4+3) in under a minute at about 500 rpm.

After removing the three layered glass sandwich from the bit, I heated it (slowly) with a propane torch until the glue decomposed - cleaned the disk up and voila.

I suggest the sacrificial glass be thinner than the target glass – I noticed a tendency for the sacrificial pieces to crack during heating – probably due to differential stresses and the splintered edges – so if the sacrificial pieces are thicker then the target disk might crack.

When glueing – make sure the pieces of glass are cleaned spotless – any dust will hold the glass apart making the superglue layer thicker which detracts from performance – also allow the glue to cure for about an hour before drilling – if the glue fails during drilling so does the method – guess how I found that out. By the same token don’t glue large pieces of glass together – unevenness translates into areas of thicker glue, which will lead to failure of the method.

Regards, Ken


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## minh-thanh (Jan 19, 2022)

Hi !
More :  
 1 / with hand drill : draw a circle according to the diameter of the drill bit, then incline  drill  about 30 - 45 degrees and drill along that circle with water. when there is a groove about 1mm deep put the drill 90 degrees and drill.
2 / Use Glass cutter Roller pen cutter : seems more complicated


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## Engine maker (Jan 19, 2022)

If you need Glass for fuel tanks I always use this site. Been using it since 2009. They have Flat Mineral Glass watch crystals in many sizes. This is just one page. You may want to bookmark this page as it's quite a large site and easy to get lost. They have thicknesses from 1mm to 3mm and diameters go up by .003"



			3.0 mm Thick Mineral Glass Crystals
		


Jim G


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## pat_pending (Jan 19, 2022)

Engine maker said:


> If you need Glass for fuel tanks I always use this site. Been using it since 2009. They have Flat Mineral Glass watch crystals in many sizes. This is just one page. You may want to bookmark this page as it's quite a large site and easy to get lost. They have thicknesses from 1mm to 3mm and diameters go up by .003"
> 
> 
> 
> ...


cool! have bookmarked though not sure what the postage from US to UK might be... will have a look.


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## pat_pending (Jan 19, 2022)

great thread. Excellent to see other people's approaches. While we're on the subject of not 'cheating' and making your own. The one shown on the tank above was cut as below with a circular glass cutter. Took about an hour and great result. Without a lot of practice i got a near perfect glass lens just needed to diamond file/emery off the edges a bit. I opted to buy some pre-cut now as the glass disk cutting 'badge' was already achieved. 










Thanks, 
Patrick


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## awake (Jan 19, 2022)

I have read about (but never tried) cutting glass with a bit of copper pipe, running in a diamond grit slurry. Has anybody here tried that?


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## ds engines (Jan 20, 2022)

Hi I found a cheap solution by using the lens from an old led bulb which is 45mm diam and slightly curved. I have made two fuel tanks with these and stick the glass in with a thin bead of JB weld .


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## L98fiero (Jan 20, 2022)

awake said:


> I have read about (but never tried) cutting glass with a bit of copper pipe, running in a diamond grit slurry. Has anybody here tried that?


It works but is a lot slower and you do need to use a sacrificial piece of glass under the part you are cutting, typically it's adhered with rosin, at least in the amateur astronomy crowd. The abrasive is generally just loose 60 grit SiC.


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## stanstocker (Jan 20, 2022)

pat_pending said:


> cool! have bookmarked though not sure what the postage from US to UK might be... will have a look.


Greetings,
In the UK Cousins is a well regarded watch and clock parts vendor.





						Watch Glasses
					

Cousins UK for Watch Glasses




					www.cousinsuk.com
				



Cheers,
Stan


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## pat_pending (Jan 20, 2022)

stanstocker said:


> Greetings,
> In the UK Cousins is a well regarded watch and clock parts vendor.
> 
> 
> ...


Thanks Stan. Good to know. P


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## bluejets (Jan 21, 2022)

These may be of interest to some as fuel container, perhaps even if cut down.
Several different types are around.

Stirling Engine Hot Air Accessories Glass Tube Education Toy


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## canfly (Jan 22, 2022)

Slightly off topic, but has anyone posted use of common household sink downers for tank main bodies? Nice thinwall brass 1.5" dia., various lengths, cheap and available. Nowadays unfortunately many of these are chrome plated.


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## pat_pending (Jan 22, 2022)

canfly said:


> Slightly off topic, but has anyone posted use of common household sink downers for tank main bodies? Nice thinwall brass 1.5" dia., various lengths, cheap and available. Nowadays unfortunately many of these are chrome plated.


Worth a try! Wondering how to strip off the chrome plating though. Perhaps Lye?


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## pat_pending (Jan 22, 2022)

Even more off-topic....I had good success using replacement glass meant for a Vape device thingy to make a fuel tank for an aero. Worked a treat but was a tiny bit too small for the 1.8cc Boll Aero as it was only enough for a 2 minute run.


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## Bentwings (Jan 22, 2022)

pat_pending said:


> great thread. Excellent to see other people's approaches. While we're on the subject of not 'cheating' and making your own. The one shown on the tank above was cut as below with a circular glass cutter. Took about an hour and great result. Without a lot of practice i got a near perfect glass lens just needed to diamond file/emery off the edges a bit. I opted to buy some pre-cut now as the glass disk cutting 'badge' was already achieved.
> 
> View attachment 133265
> 
> ...


That’s really cool I sa veo n how to cut the sight glsss tubs . Ow butvwarwaterjet ? 
this spell  check is really dumb .
Byron


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## bluejets (Jan 22, 2022)

What's a "sink downer" ??? Guessing some American plumbing fitting as opposed to some truckie drug.


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## propclock (Jan 23, 2022)

Yes I recently used a boat, aka naval sink drain as a gas tank. Worked great. No plating as it was Naval /  ship related.


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## RM-MN (Jan 23, 2022)

bluejets said:


> What's a "sink downer" ??? Guessing some American plumbing fitting as opposed to some truckie drug.


The common term for "sink downer" here is sink tailpiece.


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## TonySteamHobby (Jan 23, 2022)

Old movie projectors have a round piece of glass in front of the light bulb. They are made for the high temperature.


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## jamesmattioli (Jan 23, 2022)

Io ho usato questo sistema, il tubo di vetro sul tornio con gomma nelle griffe 
Poi col drimmel e lama al diamante con acqua,  il tornio gira piano e il drimmel velocemente,  sono riuscito a fare un cilindro di vetro con foro di scarico


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## minh-thanh (Jan 23, 2022)

jamesmattioli !
 Do you have a video of the engine of the last picture ?


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## olympic (Jan 23, 2022)

Old gas engine oilers make good fuel tanks.


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## Oldiron (Jan 23, 2022)

Now that is a neat idea. How long will it run on that oiler full? Bob


olympic said:


> Old gas engine oilers make good fuel tanks.


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## methuselah1 (Jan 24, 2022)

Lab glassware comes in all shapes and sizes, and doesn't cost much. All my sight glasses and oil reservoirs are made from cut down *pyrex* test tubes. they come in many sizes. My set up is as per the photo- dremel drill in the toolpost; the lathe rotates at a low reverse speed, with the bed covered. I use a diamond disc to cut, and then heat the finished piece to melt the sharp edges with a blowtorch.

As an interesting aside, chemists refer to the heating process as annealing!

-Andrew UK


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## jamesmattioli (Jan 24, 2022)

minh-thanh said:


> jamesmattioli !
> Hai un video del motore dell'ultima foto?
> [/CITAZIONE]
> Si eccolo
> ...


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## minh-thanh (Jan 24, 2022)

*jamesmattioli !*
Nice engine and great to see it running!
  I've always liked engines like that. , I will make a similar engine.
  Thanks for sharing !


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## werowance (Jan 24, 2022)

canfly said:


> Slightly off topic, but has anyone posted use of common household sink downers for tank main bodies? Nice thinwall brass 1.5" dia., various lengths, cheap and available. Nowadays unfortunately many of these are chrome plated.



Hi Canfly,  yep i used the down pipe for my tank in the upshur engine.  it was chrome coated brass.  cost me about 7.00 US  if i remember right.  probably could have gotten 2 tanks out of it.  it worked great.  just used some emory cloth to sand the chrome coat off of the brass and everything soldered up just fine


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## awake (Jan 24, 2022)

propclock said:


> Yes I recently used a boat, aka naval sink drain as a gas tank. Worked great. No plating as it was Naval /  ship related.



I've heard people refer to boats as a naval sink drain for money ...


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## Badhippie (Jan 25, 2022)

Boat stands for ( break out another thousand )
Thanks 
  Tom


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## doc1955 (Jan 25, 2022)

I sandwich a few pieces of Polycarbonate between a couple pieces of plywood and pinch in lathe with tail stock and turn them to dia that I need.


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## ddmckee54 (Feb 4, 2022)

Sink downers - Google sink down tube

Everything gets a nick name over here.


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