Trying lost wax casting

[ghart3]

Did couple wax patterns. Sure wish would of done core for big end. Ruined first one. Took long time for wax to freeze in big end and had opened rubber mold too soon. Second one came out ok, think need higher wax temperature.

 

[T70MkIII]

Thanks, shred - I'll give it a go once I have my shop set up, and see what I can come up with.

Looking nice, ghart3 - plenty of trial and error required, but you're getting there. Looking forward to seeing it in the metal. Can you drill the wax out of the big end and replace it with a carburised steel plug? That may work as a core that can be driven out of the finished casting and re-used.

 

[ghart3]

The wax can be drilled out and no core would be needed. With investment casting no relief is needed, metal will go only where the wax was melted out.

What should of done was drill out the metal model and insert pin in the hole. After vulcanizing the pin slips out of the metal model and goes back in the rubber mold. After injecting the wax and removing, the pin can be pushed out of the wax pattern, leaving the hole in the wax. gary

 

[T70MkIII]

Okay, I see now. When you mentioned 'core' 4 posts up I went off on a tangent, having only done casting from wooden patterns before.

 

[ghart3]

Made some wax patterns. Rubber mold is dusted with baby powder so hot wax don’t stick to the rubber

Rubber mold lightly clamped to hold halves together without distorting them.

Using home made pressurized wax pot to inject wax into mold.

Left mold clamped for 5 minutes to make sure wax solidified before opening.

11 waxes ready for treeing and investing.

Gary

 

[BillH]

Your going to upload plans for that wax melting pot right?

 

[xlchainsaw]

this is a great thread and im following it closely!

 

[cfellows]

Gary, you sure do make it look easy! And the results are amazing.

Chuck

 

[ghart3]

Bill, for making a wax injector you might one to see if you can find a small book called "Handbook of Lost Wax or Investment Casting" by James E. Sopcak. Has lots of "How to Make" articles in there. Made manual pot like in book and it works good. Only reason made air pot was, well, cause like making tools. Will try do some info on mine. Never done one of the PDF things but will give it a go.


Chuck, mostly what makes it looks easy is cause don't take pictures of the goofs and messes that I make. Actually it is not hard but is kind of involved.

Gary

 

[rickharris]

http://users.frii.com/dnorris/onlineclasses.html this is a jewellery site but has some usable information on lost wax steam casting and silver soldering as well.

 

[Kludge]

http://users.frii.com/dnorris/onlineclasses.html this is a jewellery site but has some usable information on lost wax steam casting and silver soldering as well.

Coolness! Thanks, Rick. Another site to wander through.

Best regards,

Kludge

 

[ghart3]

Good link, Rick. That is a good way too get started and keeping it simple.
Lots of good info.

My problem is getting free catalogs from the big boys like:
http://www.gesswein.com/catalog/home.cfm?CFID=2195339&CFTOKEN=74423899
https://www.riogrande.com/home/
http://www.grobetusa.com/
Looking thru the catalog and seeing the expensive equipment, I think Gee, got some stuff (mostly junk) that is on hand. I can make that for all most nothing. Trouble is it can be long road when should of just got in and done something with what could do with what’s on hand as shown on link Rick posted.

 

[ghart3]

Manual wax pot. Old hot plate with pot on top, simple hand pump, temperature gauge. Outer shell is old coffee can.

Waxes turned out about 1/16” to long between bearing centers. Shortened the waxes by taking saw cut out of middle of rod using band saw.

Wax pieces are held in alignment in V-block and welded using hot pen. Kept pen on in picture only to show it is hot. This is way to hot for the wax.

Picture showing rod on bottom before cutting and one on top is welded back together. Welded rod still needs little work in welded area to even up. Working the wax with hot pen is very easy and have much control. Very easy with the hot pen to add just part of a drop of wax if wanted.

 

[Alphawolf45]

Thats inspirational. I bought some stuff for a try at lost wax casting but havent had the right project come up yet.Id like to see more of this type project.

 

[ghart3]

Made some lost wax equipment ten years ago after seeing a demonstration and been wanting to do it ever since. Was lucky to have gone to a 3 day class a year ago. Should of done something right after class but didn't. Would of been far easier to just machine 4 rods but figured this was as good as any place to start and if I posted as going along maybe will give me incentive to finish this first project.

Having trouble figuring out how to sprue up the con rod waxes. Thought bigger flask would work better. Made new 4 and half diameter investment vacuum flask.

Sprued up 8 waxes all at same level and think will fit in the 3 and half inch diameter flask

8 waxes in 3 and half inch diameter investment flask. Might be too crowded. Suppose to have 1/8” between waxes, 3/8” from sides and half “ on bottom. Picture is showing bottom up.

 

[ghart3]

Little more work on sprues before attaching to base. Wish hadn't done such a sloppy job. Got fears hunks of investment will be left after burnout that can be washed into casting when pouring

Base taped on and holes taped over with cheap electrician tape to keep investment from leaking out while pouring.

Found some good information at Ransom-Randolph site on investment.
They told about using rubber disk for mixing investment. Made one and was quite impressed at how well it worked and didn't seem to pull any air into mix. Also site has nice calculator for figuring out how much mix and proportions needed.

http://www.ransom-randolph.com/English_measure_calculator_worksheet_jewelry.xls

Mixing with drill press turning about 760 rpm.

Vacuum after mixing about 4 minutes to remove air in mix.

Second vacuuming after pouring in flask.

Vacuum pump set up. Two vacuum chambers one made from used kitchen canner and the other one from capped aluminum pipe.

Ready for burnout.
Had bought investment at rock shop. Was a mistake as the investment is old. The gloss over time was about 4 minutes over what is called for. Next time will buy from jeweler supply place that sells more.

Burn out oven. Vacuum cleaner can, soft fire bricks with slots cut for wire and heating element from an electric furnace.

 

[ghart3]

Investment burnout over night and did pour this morning

Crucible is charged with some bronze with hunk of graphite on top. Not sure if graphite does any good. Thinking it might burn up oxygen in crucible.

This is only third time use for this propane furnace. Made a lifting device so crucible is raised up after metal has melted. Them made a special pouring shank that slides open allowing shank to slip over top of crucible. Lower shank and slide shank close and it has latch to hold in closed position. This works good and am pleased with this system.

Test run before pour, checking for trouble makers.

Bronze melting

Just after pouring.

Dunking investment with casting in water just after solidifying

Lightly bead blasted to clean up some. Was surprise no shrinkage between rod bearing centers. Good thing had shortened waxes before pouring. Maybe there is usable rods in there. Thinking maybe might redo and cast in aluminum to have lighter rods.

End of story...............gary

 

[Bernd]

Gary,

A very informative post of investment casting. :bow: :bow: :bow: :bow:

One question, were do you get your ingots from?

Again a very nice thread on casting.

Bernd

 

[ghart3]

Bernd, I'm a scrounger and been saving scrap for years. This was all from the same kind of parts, cast electrical contacts. It looked like color of bronze and lucked out as melted good and got not dross.

If buying ingots, have read silicon bronze is good choice. Also have heard brass boat props are good for casting. Sorry, not much help.
Gary

 

[Bernd]

That's fine Gary. I don't plan on doing any casting soon. Was just curious as to were you got yours. So it's scrap instead of ingots form a supplier.

Bernd