Forced Air LPG Burner Mk2

[RayG]

Hi All,

Here is the new burner for the furnace, it's a forced air lpg burner, which will replace the normally aspirated burner.

Construction is way over complicated, by the addition of brass mounting blocks, that I thought would make for a more robust mounting for the quick shut off lpg valve.

The main tube is 32mm diameter titanium which has a higher melting point, so maybe it will last a bit longer. There is no flare on the burner end, as it is flared with the ceramic mounting block inside the furnace. Although I still need to make a temporary flare so that we can do some free air tuning.

http://www.backsaw.net/pics/Misc/DSCN0398.JPG

http://www.backsaw.net/pics/Misc/DSCN0399.JPG

http://www.backsaw.net/pics/Misc/DSCN0401.JPG

The air blower I was planning to use doesn't develop enough pressure, so a vacuum cleaner running on a variac will have to do for the interim testing, a spa air blower is on order, so I hope that works out better.

Regards
Ray

[Stustoys]

Nice Ray,
Just how many of us have titanium laying around in the shed?
The free air testing should be good for some interesting pictures.
Got your first pour planned yet?

Stuart

[RayG]

Hi Stuart,

I got the titanium from ebay, a guy in Latvia of all places... rupucis371 | eBay (http://shop.ebay.com.au/rupucis371/m.html?_trksid=p4340.l2562)

The little bit of sheet titanium for the flare was weird stuff, brilliant white sparks from the grinder, and very springy, must be some sort of high tensile alloy
whereas the tubing was a lot like machining aluminium.

Still fiddling with the tuning, this is running way lean, and the temporary flare is a bit dodgy, held on with high temperature multi-grips. :)

http://www.backsaw.net/pics/Misc/DSCN0410.JPG

So far it looking the goods, and we will try a cast iron pour tomorrow.

Regards
Ray

[4-6-4]

What metals are you melting I used a Gas air torch with a Sadie Vac to supply the choof. This was used over a number of years in a furnace lined with Caowool. I have been assured that a normally aspirated torch should work quite happily 4-6-4

[Stustoys]

Ray,
Looks great, maybe when you fit it to you furnace it will richen up a little?
Good luck with the pour, take lots of pictures.

Stuart

[RayG]

Hi 4-6-4,

I've been using a normally aspirated burner for bronze and brass, this is a new burner for doing cast iron, it's a vacuum cleaner blower, the vacuum cleaner is running off a variac.

Just curious, are you by any chance doing a talk on pattern making in July?

Regards
Ray

[RayG]

Ray,
Looks great, maybe when you fit it to you furnace it will richen up a little?
Good luck with the pore, take lots of pictures.

Stuart

Hi Stuart,

Just finished a small test run, melted about 1kg (of broken up brake drums) but by the time the slag was skimmed, we didn't have enough for the pattern.. the test pattern is a base plate for a digital height gage. Pictures later.

Regards
Ray

[RayG]

Hi Stuart,

Here is the first cast iron part.

http://www.backsaw.net/pics/Misc/DSCN0411.JPG

http://www.backsaw.net/pics/Misc/DSCN0412.JPG

Tomorrow we'll see if it's machinable, there is some porous sections on the side, and the pattern is not right, but with a bit of tweaking, should get closer to the mark.

In case you are wondering it's going to be a base for a height gage. It will be bored out for a bit of 1" shafting, which will take a nice rigid adjustable mounting for the digital dial gage.

Surface ground top and bottom of course! :)

Regards
Ray

[eskimo]

Ray
what sort of pressure and airflow do you think you might need
I have some where in the shed a couple of small backward curve fan motor assy.

[Stustoys]

Ray,
When you said tomorrow it didnt cross my mind that you meant 12:30am!!!!!!! lol
Looks great from here. How long did it take to get up to temp?
What sort of sand are you using?

Stuart

[RayG]

Hi Eskimo, Stuart,

It was all looking good, so we got enthused and had another go. That was 2 Kg, and heated for 20 minutes.

In hindsight, I think we had the burner wound up too high and melted some of the furnace lining ( Cerachem 1425, which melts at around 1700C ) ... That's way too hot.

Eskimo,

Thanks, but hang on to them for now, I've got a small spa blower on the way, which should be higher pressure. 10 m/s in a 32mm diameter

Regards
Ray

Edit: Forgot to answer your question about sand, that was petrobond.

[4-6-4]

Yes Ray that's me giving the talk. One minor suggestion is that your pouring hole should be bigger. You could also get some compressed Kaowool about 1/16 thick bend it into a circle and place it in the pouring hole. This allows the metal in the pouring hole to remain liquid longer than the casting this allows the casting to draw on the molten metal and you are more likely to get a sound casting. A small riser opposite the pouring treated with a lining of Kaowool will also improve chances of success. A ring of steel around the pouring hole with sand and Kaowool liner gives extra height and pressure to the melt. Before you split the mould in half to remove the pattern use a piece of wire 1/16 dia to push down until it hits the pattern. This allows the gas to escape and gives a better result.I have seen moulds in Iron look like the old gas stoves when the gas from the sand ignites with a solid whoomp. You are a brave man to play with Iron the dross on top of a melt is usually sprikkled with a powder Which I do not know the name of and this bonds the dross together and it can be scraped off before pouring. A covering of dry sand on the floor surrounding the furnace might be a good move as well. I had a couple of explosions when using scrap Aluminum very interesting. 4-6-4

[RayG]

Here is the dial gage base after surfacing top and bottom and milling the sides. Still have to bore the hole for the vertical support. It machines nicely just like normal cast iron. There is some "blotchiness" that you can see on the milled surfaces, but not on the ground surfaces. I'm guessing that this is probably due to not using the proper innoculants in the melt. We had charcoal and soda ash mixed in with the broken up brake drums, to keep the oxygen out, but I think I need to get some proper FeSiMg innoculant (I'm thinking this one might be worth a try Foseco Australia - Nodulant (http://www.foseco.com.au/processes/furnace-deck/nodulant.html) ) to add the magnesium needed to form the spheriodal graphite nodules. Also as 4-6-4 mentioned we don't have the gating, risers,sprues and runners quite right.. (There's a lot to be learned in this casting business!)

http://www.backsaw.net/pics/Misc/DSCN0419.JPG
This is the bottom of the casting.

http://www.backsaw.net/pics/Misc/DSCN0420.JPG
The top of the casting

The little bit of porous area left on the top surface will mostly be removed when we bore the hole for the vertical support.

Hi 4-6-4, I thought it might be you, when Peter McBride mentioned to me that there was a talk on pattern making at the HTPAA meeting in July, that should be interesting, I plan on coming down to Melbourne for that, it's one of the most critical steps in casting, to get the pattern right. I think I've done all the wrong ways so far! :), so I'm looking forward to it.

Now I need to get some of that green paint that Bob seems to have an endless supply of.. either that or wrinkle black..

More when it's finished.

Regards
Ray

[Stustoys]

Looking good so far.
How did you make the pattern for that? Is it three part?

Stuart

[RayG]

Looking good so far.
How did you make the pattern for that? Is it three part?

Stuart

Hi Stuart,

No, the pattern had just sloped sides, that's just how it turned out after milling off the porous crap on the sides of the casting :) ... Josh used the solid carbide endmills from ctc, and they work a treat on cast. I'll paint the sides with wrinkle black.

The edges are square, so it can be used for alignment as well.

Regards
Ray

[Stustoys]

No, the pattern had just sloped sides, that's just how it turned out after milling off the porous crap on the sides of the casting
Well that makes far more sense. I was scratching my head as I couldn't see the undercuts(?) in the first set of pictures.

You need to add a shaper to your shop. :)

Stuart

[RayG]

Well, here's the finished dial gauge height measurement stand. (I trust I'm not infringing on somebody's patent by making this! :rolleyes: )

The dial gage can be swivelled around to measure part thicknessess directly on the grinder chuck. This particular dial gauge has a resolution of 0.005mm.

http://www.backsaw.net/pics/Misc/DSCN0421.JPG
http://www.backsaw.net/pics/Misc/DSCN0422.JPG
http://www.backsaw.net/pics/Misc/DSCN0423.JPG
http://www.backsaw.net/pics/Misc/DSCN0424.JPG

The base is the cast iron part referred to earlier in this thread, the vertical post is a bit of scrap 1" shafting, the meter clamp is milled from 2 pieces of brass sandwiched together.

The paint is a hammertone green spray can, originally it was going to be wrinkle black.

The clamp mechanism doesn't work very well, and is fiddly to adjust, so I'm going to change to a better clamping mechanism, just a soon as I figure out how..

Regards
Ray

[Stustoys]

Ray,
Looking great.
How about a second collar below the one you have with a threaded ring that can raise and lower the bracket you have say 5mm? Get what I mean?

Oh and behave lol

Stuart

[Dave J]

Nice work Ray, looks like a factory made one.:2tsup:
Stuarts idea for a fine adjuster sounds a good idea, even a small plate on top with a threaded thumb wheel going down to the sliding block.
Another thing CTC sells cheap (around $45) is a 0.001 digital indicator. Going by there digital micrometers the quality would be good.

Dave

[Dave J]

Forgot to add, you had painted it.:D

Dave

[Stustoys]

Is there a reason for having the bracket that way up?

Stuart

[Dave J]

It looks like it would come close to bottoming out the other way and would leave less room for the job.

Dave

[RayG]

Hi Stuart,

The bracket is reversible, I guess, this dial gauge has 1" travel , so it will reach down to the chuck when you swing it around to the other side. The bottom of the bracket is flat.
Having it this way around gets the meter as low as it can.

The procedure is to zero it, with the dial gauge adjusted down touching the chuck. (or surface plate, if I can ever find one)

Hi Dave,
Thanks for that, I ordered that 0.001 dial gauge already, the travel on that CTC one is 1/2" so I'll have to wait to see how it goes when it arrives.

I think I can make a locking mechanism, similar to the quill lock on the mill, with a small lever. I like the thumbwheel adjustment idea, I'll see what can be done.



Forgot to add, you had painted it.:D

And, as far as I can tell no one painted it before either..:rolleyes:

Regards
Ray

Edit: Dave beat me to it.. but maybe if you wanted to measure something higher you could flip the bracket the other way up.

[Stustoys]

:doh:I forgot you said you would be reading over the side.
Stuart

[eskimo]

wow...great work Ray...from molten material to a piece of art:2tsup:

[RayG]

Thanks Eskimo,
Rusty brake drums to rusty tools.. :)

http://www.backsaw.net/pics/Misc/DSCN0428.JPG

There's that little locking lever on the side...

This is how I imagined using it, for checking setup's on the magnetic chuck, I'm not sure how it will go for checking grinding progress, I would have to demag put the gauge on and then magnetize to hold it in place, and then demag to get it off, and magnetize again to hold the work... all of which is going to disturb the work and ruin the accuracy.. :doh: not to mention carefully cleaning the coolant and grinding dust..

I think it's back to square one, maybe this time I'll think it through a bit better...

UPDATE: It works just fine, the residual magnetism in the work holds it in place just fine, I just turn the magnet off, don't demagnetize and just do the measurement with the magnet switched off. The work stays put nicely.. :) I must learn to stop imagining problems that don't exist. (Thanks to Josh for pointing that out!)

Still makes a nice thickness gauge, even if it's not going to work as I intended..

Edit: I wonder how it would go if I made it from stainless (which is non-magnetic)?

Regards
Ray

PS.. that bit of steel, looks like it might do the job nicely for a diamond tool holder..

[Stustoys]

lol I missed your edit Ray, I was just going to suggest a heat treated Alum base filled with lead. Needn't have worried.

Stuart