+- MetalworkingFun Forum (http://www.metalworkingfun.com)
+-- Forum: Machining (http://www.metalworkingfun.com/forum-5.html)
+--- Forum: Welding & Casting (http://www.metalworkingfun.com/forum-9.html)
+--- Thread: Oil furnace build (/thread-2678.html)
RE: Oil furnace build - dallen - 06-04-2015
your welcome, the hole in my furnace is almost 6 inches now what with wear and tear on it. lot of times I stick a big hunk of scrap over it that I need to make smaller and let it melt into the crucible. hottest place in the furnace is the exhaust if the burner is working like it should.
RE: Oil furnace build - Pete O - 06-04-2015
Got the refractory poured, took quite a while and I had very little left over, just enough to do some minor patching up if required.
Sure is funny stuff to work with, I've done a lot of work with concrete and mortar over the years, although not recently- I earned my living laying bricks for several years a few decades ago. This stuff is very coarse-grained, difficult to get a good finish around the ports as it is either pouring out so you have to hold it back, or gone off too much to trowel it.
Mixed it up in a barrow- I have a tractor-mounted cement mixer but you tend to end up with a fair bit of waste that way and with this stuff being so expensive that was not an option. Actually did the last stage of the mixing by kneading it with gloved hands- something that would have got me laughed out of any bricklaying job back when.
[attachment=10953]
Had a helper to hold the various tubes in place while I rammed the refractory around them, was not an easy task
[attachment=10954]
I ended up running back and forth to the bandsaw cutting pieces of plywood to hold the stuff back from coming out the holes; this arrangement worked well for the tap hole so we could move on to the other ports
[attachment=10955]
Got the inlet and preheater hole formers in place
[attachment=10956]
then worked my way to the top, drop a layer in then tamp it down.
[attachment=10957]
I made the exhaust hole in the lid a fair bit bigger, found some pvc pipe about 4 1/4" o.d
[attachment=10958]
made a few plinths.
[attachment=10959]
and a choke ring for the exhaust. This will probably be good for placing a full crucible on I think. 6" pvc pipe outside, 3" soup tin inside
[attachment=10960]
Glad to get this job done, I plan to leave it sit for a month before disturbing it. Time to start getting the new mill sorted, then we're off on a bit of an outback trip so this can wait til I get back.
RE: Oil furnace build - vtsteam - 06-08-2015
Furnace looks very good!
RE: Oil furnace build - DaveH - 06-08-2015
Very good
DaveH
RE: Oil furnace build - EdK - 06-08-2015
+1. Very nice.Ed
RE: Oil furnace build - Pete O - 07-03-2015
We cut our holiday short. When it rains in outback Australia, this is what happens
[attachment=11199]
And then this happens
[attachment=11200]
and you find you have driven a thousand miles for nothing. Couldn't get to where we had planned so we ended up coming home 4 days earlier than planned.
Which may seem somewhat off-topic, but it meant that today, instead of canoeing on Coongie Lake, I made some progress on the furnace.
I did a big shopping trip, 2 different foundry suppliers to get these supplies for the furnace
[attachment=11201]
An offcut from a roll of ceramic fibre insulation, some foundry cement, 6kg bag of vermiculite and an A8 crucible (already had the A6, thought I'd get a bigger one while I was in the right place).
While I was shopping I also picked up a length of 7/8" 4140 heat-treated shaft for the power feed drive on the mill and some phosphor bronze for the bushes that the shaft runs in. Every time I have to buy bronze the price shocks me.
I got the insulation stuffed into the outer cavity of the furnace
[attachment=11202]
and packed down to leave about a 3/4" space for the capping
[attachment=11203]
I capped the insulation with a mixture of fire cement and vermiculite, which the guy at the foundry suppliers recommended I try for the floor of the furnace. Will be interesting to see how it stands up to the job, easy enough to re-do if it doesn't last. Unfortunately I haven't found a suitable chunk of steel plate for the base yet so I can't put the clay floor in. Hoping to get a chance to make some progress on the air / fuel system tomorrow. Was nice to get a chance to make some progress on this, I'm waiting on a friend to get components for my phase converter so I can get the mill running, might actually get the furnace finished while the other distractions are stalled.
RE: Oil furnace build - Pete O - 07-06-2015
A little more progress, put the bottom plate on with the lid lifting pedal arrangement; really starting to raid the scrap bin now.
[attachment=11246]
[attachment=11247]
I found an error in the setup of the tap hole, I think the rod that I had in place to form the tap hole when pouring the refractory must have shifted at the inner end, the clay bottom is supposed to come up to the bottom of the tap hole but that is 80mm (3 1/4") up from the base plate and only about an inch below the air intake port, so not much of a well in the furnace. Also I wouldn't like to be trying to break out a 3" thick clay base which is supposed to be able to be done from time to time to clear spills and build-up. I compromised and made the base about 2" thick, might mean that I can't melt directly in the bottom of the furnace but I'm not sure that is a big issue anyway.
I also got the air & fuel inlet system finished, the heat shield is a bit of an eyesore being straight from the scrap bin but if this works okay I might see if I can find the time to tidy it up.
Got some 3/8 (o.d.) steel pipe used for truck air brakes for the oil feed line, brazed into the air pipe so it finishes flush with the end of the pipe in the middle of the reduced end. I haven't welded the taper yet, folded and bent it down to experiment with air and oil flow.
[attachment=11248]
[attachment=11249]
I did a bit of a trial run with the air and oil feed to see if the oil would spray out with the air flow, very happy with the result- I held an old piece of carpet in front of the airflow and had a bucket under the end of the pipe, half expecting the oil to just dribble out into the bucket. None dripped into the bucket, the piece of carpet got spray painted with nice black sump oil.
[attachment=11250]
[attachment=11251]
Putting this aside for a little while now to let the base set, but really all I need to do is connect up a container of oil and it is ready to get hot. Need to make some crucible handling tools before I can melt anything, then I guess it will be time to set up some sand moulding equipment. Might look around for some safety gear too.
I'm tossing up whether to give it a coat of high-temp paint like the stuff that is sold for exhaust headers, I'd like to give it some corrosion protection but I don't know whether the paint would just disappear the first time it gets to melting temperature. Any input on that one would be welcome.
RE: Oil furnace build - Mayhem - 07-06-2015
Looking good Pete.
RE: Oil furnace build - dallen - 07-06-2015
the only place the paint will disappear from is where it gets hotter then the paint can handle which will be the joint between the lid and body and the exhaust.
The entry for the burner should be ok to not burn the paint off if you pack it around the burner tube with some ceramic fiber to stop the burner from sucking in air.
RE: Oil furnace build - dallen - 07-06-2015
paint it you will loose some but not much.
And if you don't already know the solid refractory is going to crack, its designed to crack, one reason manufactures recommend that the minimum pour/cast thickness be 1.5 inches. The cracks are there to relieve stress in the refractory as it heats up and cools. So when you look in it an see little tiny cracks don't worry its not going to fall apart, and you don't have to try to patch them like some do.