Ruby Casting (verneuli flame fusion)

Discussion in 'General foundry chat' started by Zapins, Apr 21, 2021.

  1. Zapins

    Zapins Gold

    Perfect I'll see if I can order some. Thanks.

    Still haven't been able to find a good local source for 45% plumbers solder. Will have a look around.

    Also another issue I found. Any idea where to get item 126 from? Top middle of the diagram. I think it is some sort of rubber or flexible material that acts as a gas seal and also isolates the vibrations to the outer container when the inner container is tapped by the motor to shake loose powder?

    I haven't seen rubber in this shape before for sale or know what it would be called. I don't think rubber corks with the hole in the center would work well since the U shape in the picture looks like it is made to dissipate vibrations.
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  2. I think a good substitute for item 126 would be a silicone grommet, good for -75 to 800 degrees C. https://rubber-grommet.com/silicone-grommet/

    Is item 139 some kind of shaker? so that 126 needs to allow movement?. If that's the case then some nested grommets: large grommet-> steel washer-> small grommet assembly should work.

    Edit: or a big flat silicone washer say 1" in diameter with a silicone grommet in the middle would work as a flexible seal.
     
    Last edited: Jun 7, 2021
  3. Zapins

    Zapins Gold

    Hmmm. I have a couple of rubber ones but they aren't very snug fitting. Not gas tight anyway. Ill have a look for silicon ones and see what shapes are available. I think they look promising
     
  4. Depending on the gas pressure, some silicone grease over the joint may be enough to seal it.
     
  5. Zapins

    Zapins Gold

    I think gas pressure will be around 2 to 10 psi. Going to see if using a hydrogen generator will work like the ones for trucks.

    Took like 4 hours to make these steel barbs... I got sick of the tap issue and just welded in the steel ones I made. Will return the crappy tap tomorrow and the $25 brass fittings.

    This is the end piece that has the water cooling part in it. Do you think it will rust the inside if I use regular water? Maybe mineral oil would be better? Or machine coolant?

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    Edit

    I think the rubber bit is called a firewall grommet?
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    Last edited: Jun 7, 2021
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  6. Zapins

    Zapins Gold

    Changed the design a bit. I don't like the threaded pipe bit. I made gaskets to seal in the oxygen and hydrogen compartments so I can open them all again when needed for replacement and cleaning. I like this design better it all just presses together and seals with friction on the rubber.

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  7. Zapins

    Zapins Gold

    Nearly finished the burner tube. Just need to add an entry point for hydrogen and oxygen to enter. I switched the design so there are no nasty threads anymore only gaskets holding the center tube in place by friction.

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  8. Jason

    Jason Gold

    Cool looking! You sure you're going to have the cajones to light that sucker?
     
  9. Zapins

    Zapins Gold

    Yeah may be scary seems like pretty explosive stuff if it gets trapped. The hydrogen generator I'm looking at makes 10 liters a minute. Pretty good amount of hydrogen to play with.

    I'm going to see about installing a flame sensor that cuts power if it isn't lit for 15 sec or more.

    Made the entrances for hydrogen and oxygen in the sides of the burner tube. Lots of aligning to get position right and still have the inner seal in the right spot. But all welded in now. Put some needle valves on for good measure, will probably get some 90 degree elbows to make them more flush then put in a shut off valve upstream so I can emergency shut off if necessary.

    One thing I'm unsure about is if I'm generating oxygen by splitting water and having it go through into the powder chamber to carry the ruby powder to the flame won't it still have some water molecules in it and cause clumping in the super dry powder? If that becomes a problem how can I dry the oxygen as it flows to the powder chamber?

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  10. You can dry gas with either silica gel or a cold trap, some 2" flexible clear tubing packed with the blue indicating silica gel will give a visual sign of when it needs to be baked dry again as it slowly changes from blue to pink from one end to the other.
     
  11. Zapins

    Zapins Gold

    Small work done today. I tapped this retainer plate onto the inner gasket so I can put rubber seals around the capillary tubes and make seals.

    I'm looking into options for acme threads. I need to slow rotation down to about 0.16 rpm. Should be doable with a 50 rpm motor and a 1:120 worm gear and a rheostat for fine tuning.

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  12. Zapins

    Zapins Gold

    Its got next to no load on it its the rod 36, 35, 32 in the picture that will rotate without load that goes at 10 rpm, but the motor below that that climbs up and down an acme rod has a bit of load on it. Not much but it needs to run for 4 hours at a time without overheating. A lot of the cheap motors burn out quickly with constant use. I'll have a look at the one you linked.
     
  13. Zapins

    Zapins Gold

    Made the bearing housing that holds the rod that grows the ruby. I used a 10 mm 3d printer ground and hardened rod and a linear bearing inside the housing. The little cavity under the lid is for some felt that will fit snuggly around the shaft and keep powder and other debris out of the bearing and motor compartment.

    I need to order acme threads and a gear motor with gear wheel to start the next part of the build but they are kind of pricey and I am hesitating to pay for expensive gears and precision acme rods.

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  14. dtsh

    dtsh Silver

    What size of acme threaded rod are you looking for and what are your gear specs?
     
  15. Zapins

    Zapins Gold

    From what I can tell 1 inch per 1 hr is the goal retraction rate.

    I figure if I have a 16 tpi acme rod then each rotation is 1/16th of inch, so if I rotate it 16 times an hour I get 1 inch of retraction. Thats 16 revolutions/60 mins or 0.266 rpm is the rotation rate I'd need to get 1 inch per hour.

    I could then buy a 50 rpm gear motor and a 1:170 worm gear off ebay. This would be 50 rpm/170 = 0.29 rpm which is pretty close to my goal rate for 1 inch per minute retraction rate. I could use a speed controller to fine tune.

    Or if I went with a 10 tpi acme rod that would bring me to the same 0.29 rpm output but id need only 0.16 rpm to get an inch per hour. So I'd have a lot more wiggle room to play with speed rates.

    Not sure which would be better to go with. The 10 tpi or 16 tpi. Any thoughts?

    Mcmaster and carr have some nice options on their site for acme rods.
     
  16. rocco

    rocco Silver

    What diameter are you looking for? Metric T8 lead screw with a 2mm pitch is commonly used in 3D printers, it's inexpensive and readily available.
     
  17. Zapins

    Zapins Gold

    Hmm. I'll have a look at those. My reqs aren't super specific in terms of size. I'm just eyeballing what I need and making it fit together with custom connector pieces so those might work. How accurate are they? Not going to get stuck I am guessing.
     
  18. No idea of which pitch is more suitable, but using a cheap ball screw would reduce the friction and power needed to drive the assembly. Also a stepper motor and suitable driver board will have the torque and effectively infinite range of speed to do the job. You'd need a controller board to generate suitable pulses to feed into a driver board like the combo listed below. You'd eliminate the gearbox and have full motor torque regardless of speed with a minimum movement of the screw pitch divided by 400 steps per revolution that the stepper motor has, so for a 16 TPI it would have a minimum movement of 16/400=0.040 inches or 40 thou. A 2mm pitch Rocco mentions above, divided by 400 would get you 0.005mm increments.

    https://www.ebay.com.au/itm/313352268460?hash=item48f5402aac:g:lrUAAOSwU6pf4Biy

    https://www.ebay.com.au/itm/304018527780?hash=item46c8ea9624:g:EN0AAOSwQ9lcKcaA

    https://www.ebay.com.au/itm/172143803596?hash=item281491fccc:g:gH4AAOSwFIVe3Zpa

    Edit made a mistake with my maths: a 16 TPI screw would give 1/(16 x 400) = 0.0002 inches or 2/10 of a thou minimum movement.
     
    Last edited: Jun 18, 2021
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  19. Zapins

    Zapins Gold

    I'd love a stepper motor but I'm a bit scared off by the electronics part of things. Whats involved in setting up a controller for it?
     

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