Page 8 of 11 FirstFirst ... 678910 ... LastLast
Results 71 to 80 of 110

Thread: Kelly's Furnace Build Log

  1. #71
    Quote Originally Posted by Robert View Post
    Somehow I have missed this build from the start! I think the internet is broken! This may be overkill but it is certainly the most amazing furnace every created.
    No doubt more than was needed but exactly what was wanted. I enjoy building as much as casting and try to learn new things on every project that can be applied to the next. Future builds will have more castings

    Has it been fired much yet?Robert
    The smaller A20 capable Electric has about a dozen melts of 2-5 lbs of aluminum each, just scrap into ingot. The refractory pieces in my last post are for the larger A60 capable furnace body which can be installed in place of the smaller one. It has not been fired. I have an LP and an NG burner yet to make for that one. After I complete the larger furnace, I have a couple small casting projects planned but at some point I also need to build flasks, a muller, and molding bench and at some point. -All things in time. Thanks for your post.

    Best,
    Kelly
    Last edited by kcoffield; 12-27-2016 at 09:10 PM.

  2. #72
    Senior Member r4z0r7o3's Avatar
    Join Date
    Jul 2015
    Location
    Raleigh, North Carolina
    Posts
    1,196
    Quote Originally Posted by kcoffield View Post
    • There is a very fine line between too dry and way too wet when it comes to adding water to castable. Only add water under duress and even then just a few squirts at a time.
    • Mixing a portion of the refractory very wet and add remaining refractory in successive steps is very helpful to achieve full and even mixing.
    • For larger batches I think I’ll buy or make a drill powered mixing paddle like used for PoP.
    • Vibration is pretty much a must for dry mixtures.
    • Never give up, never give in.
    It's really odd stuff to work with isn't it? I'm surprised you had so much trouble with the ratios. What I took from my data-sheet was spot-on. Perhaps something to do with the age of your (unmixed) refractory, and/or it's storage conditions (humidity)? Anyway, I'm glad you found success, and appreciate your sharing lessons learned.

    As for the drill-powered mixing, for any type of mixer (swirly or paddle), they're just not made for this density of material. The main problem I found is with the jacobs drill-chuck: They're designed for thrust and very little sidewards loading, e.g. if you push them sideways too hard, they loosen and spin. What you really need for this application is a collet, or at least some type of positive grip on the sides of the mixer shaft. In any case, it helps to spin them slowly rather than fast, but then you eat up your pot-time. What I settled on was to do the initial thrashing at a high-speed, plunging the mixer down in different spots. Then I would turn the bucket on it's side and finish mixing by hand (it's good exercise) with a pointed trowel. I also found that mixing small batches and vibe'ing them in (maybe 1-2 inches thick) produced far fewer bugholes that doing it all in one go.

    For the furnace body, I'm curious about the color differences, did you use two different kinds of refractory or is that just how it dried out?

    Garsh that thing has to be HEAVY!
    "Things that are complex are not useful, things that are useful are simple."
    - Mikhail Kalashnikov

  3. #73
    Quote Originally Posted by r4z[SIZE=3
    0r7o3;197165]It'sr eally odd stuff to work with isn't it? I'm surprised you had so much trouble with the ratios. What I took from my data-sheet was spot-on. Perhaps something to do with the age of your (unmixed) refractory, and/or it's storage conditions(humidity)? Anyway, I'm glad you found success, and appreciate your sharing lessons learned.


    Definitely not age or storage. The insulating castable (Harbison Walker Greenlite 45LPlus) was just fine but was recommended at 23% by weight water and was very easily mixed. The dense castable (Harbison Walker Ultra Express 70 AL) recommended 6.8% water. Mizzou for example would be 8.6% which is not quite but probably pretty close to where I ended up. These are all vibratory placement recommendations. Hand placement is modestly more water for all. I could not get that dense castable to mix at that 6.8% ratio in any batch size. After the Plinth fail, I weighed smaller test batches on a triple beam scale and still no-go. For power mixing this dense castable you’d need something with a lot of shear. I could have mixed the insulating castable with anything.


    For the furnace body, I'm curious about the color differences, did you use two different kinds of refractory or is that just how it dried out?


    Yes, the flanges are the insulating castable and the hot face dense castable.

    Garsh that thing has to be HEAVY!

    Total weight of the main body is 77lbs. 12lbs each flange and 53lbs for cylindrical hot face which is only 5/8" wall. I was thinking it’s pretty light considering size and what it is. The base is about half that.

    It’s a bit windy but if you get a chance, have a read of the update to my build thread on these parts that I posted at the bottom of post 6 on page 1.

    Best,
    Kelly
    Last edited by kcoffield; 12-27-2016 at 05:06 PM.

  4. #74
    Senior Member
    Join Date
    Jan 2012
    Location
    Buffalo, NY
    Posts
    2,507
    I worked with mizzou for the first time last week one batch at 30# and one at 36#. The dry bags were 55#. Both the manufacturer and the brickie that gave me the stuff were pretty clear about working with full bags. Evidently its prone to separation in the bag through settlement so I dumped a whole bag and mixed it good before i measured out my batches. I used the recommended ratio of water (5 pints per 55lb) and it was alittle disconcerting at first, but as i mixed it more and more , it got better. Instructions also say to mix for at least 5 minutes. It think it has to slake a bit to act right. I used a trowel in a 10 gallon washtub. I poured and rammed by hand. It aint pretty but it went ok. Even so, a couple of extra squirts probably wouldnt have hurt.
    Your furnace looks great!

    Pete

  5. #75
    Quote Originally Posted by Petee716 View Post
    I worked with mizzou for the first time....I used the recommended ratio of water (5 pints per 55lb) and it was alittle disconcerting at first, but as i mixed it more and more , it got better.
    Being the first time I worked with either of the two materials I don’t really have anything to compare to. The insulating castable was a breeze probably because it’s half the density and nearly 4x the water. Under vibe it flowed like thick syrup.

    The dense castable was a totally different experience. I mixed a portion of the batch wet with all the water and then kept adding dry castable because I found this to be a better approach in previous batches. There were times that it got so dry I couldn’t believe it would come back but after heavy kneading and churning it became something that could flow again but never at the recommended 6.8% by weight. At that ratio I could never get it to more than something the that would barely hang together when squeezed in your fist.

    Even at only 5/8” wall, the furnace hot face took a whole 55lb bag so no worries about settling within the bag for that one. I broke my own guidance and did it one batch which I had to divide a couple times to manage it. I was worn out after mixing it and took a lot longer to get it placed than I should have but it worked out OK. I just used my hands with heavy rubber gloves in a 5 gallon bucket. I must have used some muscles I hadn’t used in a while because the next morning was actually sore from the work out. The 70AL also had a noticeable amount of one inch long chopped ceramic fiber strand. It flowed well under vibe but not as easily as the insulating castable. You can actually over-vibrate the insulating making the filler rise and binder settle.


    I poured and rammed by hand. It aint pretty but it went ok. Even so, a couple of extra squirts probably wouldnt have hurt.Pete
    I cant even imagine trying to place the 70AL without vibration. It doesn't seem to move when you compress or ram it but vibrate it and it flows and densifies. The grog is fine, I'd say mostly 1/8" pebbles with a few 1/4".

    I may have to try a different dense castable for comparison sake but some times the devil ya-know is better than the one you don't.

    Your furnace looks great!
    Thanks Pete, slowly but surely....getting there.

    Best,
    Kelly
    Last edited by kcoffield; 01-02-2017 at 11:32 PM.

  6. #76
    More fun with castable refractory. -The Lid.

    I updated the build thread on page 1, at the end of post # 6 under the heading Furnace Build Update 1-2-2017 but I’m at picture limit there so here’s the unabridged post with better pictures.

    Having gained some confidence with the previous castable refractory parts, for the furnace lid I decided to make a much more challenging shape. Now without a doubt, a simple disc with a hole in the center would have worked fine but I wanted to explore the art of the possible for future use……and well, just for the heck of it. The lost foam plug I used for the furnace base basin and Tuyere tunnel were so easy to form and worked so well I decided to use lost foam more extensively as the mold material for the lid. So I made some wooden structure and hoops for the cylindrical features and went crazy with the lost foam aided shapes. - I sure do like my over-arm router. Best machine I ever made and sure makes this type of pattern work go fast.







    As before, it was poured in several steps, dense castable first and then insulating castable on top, all using full mold body vibration to flow and settle the castable refractory material. The actual casting was done in three pours. First was the dense castable hot face layer which was cast about ” thickness everywhere.

    The dense castable was poured in two steps. First the lower portion was cast and allowed to set up well enough so a temporary mold could be used to cast the upper vent hot face cylinder.



    After a couple of hours that had set up well enough that I could remove the temporary vent mold, install the six cavity segments and cast the insulating castable at 5/8-3/4” average thickness.



    Here is the De-Molding and why they call it LOST FOAM!. The particle board hoop support structures are all split so they remove easily without stressing the still green part.

    I just put a burr on my die grinder and hollowed out foam plugs enough that they could collapse on themselves and pulled the remainder out by the tape skin. The burr made short work of foam and it went quickly albeit a bit messy. I had put a band of filament tape (which is much stronger) under the packing tape around each segment and after hollowing, I grabbed the filament tape with pliers and pulled the remainder of each plug out.




    So the lid has ribbed structure on top and bottom with the bottom (interior furnace side) ribs able to channel air flow with the crucible raised on the plinth or flow conventionally through the vent hole with the crucible placed deeper in the furnace. I don’t know if will work any better but probably won’t be any worse than a flat lid with ahole. I had a whole day available in the shop and it was mostly just me experimenting and jacking around to see how far I could take the various molding methods working with castable.

    Here’s how it came out. It’s a pretty crazy shape. The hollow segments on top and around the periphery save about 13lbs of weight/refractory and will get stuffed with ceramic wool. The lid will then get a sheet metal cap and ring around the circumference for lifting mechanism attachment points.





    Here it is on the furnace body.



    This and the remainder of the refractory castings will get a very slow cure.

    Best,
    Kelly
    Last edited by kcoffield; 01-03-2017 at 01:03 PM.

  7. #77
    Kelly,
    Wow, fantastic work. The lid turned out great. I especially like your over arm router, and how you used it on this project. If you have time to start a separate thread, I would love to see that router in a bit more detail, and maybe a bit of explanation on how you designed and built it. Keep up the great work.
    ...Dave...

  8. #78
    Have a look here Dave.

    http://www.alloyavenue.com/vb/showth...776#post130776

    I did a lot of cabinet making and some pattern work in the distant past. The pattern shop had an over arm Onsrud pin router and so did the cabinet shop. I also wanted a shaper for panel making but didn't have enough room in my shop for everything. You can center the router on the arm over the throat plate in the table and use different size guide collars for pattern routing and/or over-arm or inverted pin routing. With a base board and a pin to spin stock on it sets up very quickly, does round shapes well, and can plunge to cut segments.

    It does warrant a high degree of respect with the open cutting bit and you must always be aware of where your hands are in relation to the bit. I have guards for it but rarely use them. You can see them swung out of the way in the picture. Plunging over arm routers are more versatile than inverted pin routers but also more dangerous and that's why many manufacturers quit making them.

    Best,
    Kelly
    Last edited by kcoffield; 01-03-2017 at 01:00 PM.

  9. #79
    Thanks Kelly,
    I just read through the thread. This is definitely a piece of equipment that would help with pattern making. Great thread....
    ...Dave...

  10. #80
    Quote Originally Posted by Robert View Post
    Somehow I have missed this build from the start! I think the internet is broken!
    This may be overkill but it is certainly the most amazing furnace every created. Has it been fired much yet?
    Robert
    Your not alone Robert, somehow I missed it too.

    Kcoffield, this is an incredible build, very impressed. I've been needing to build a shank/trolly for bigger crucible that I'll use in my bigger furnace I'm building. Right now I use the A16 and when topped off with aluminum it about at the limit I can lift and pour by myself. You've given me inspiration to go build one now, just have to finish my new shop first.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •