Starting my build

[almondsurf]

Re: Starting my build

Those pictures are a great help. I have never heard of the elephant's foot analogy, but it makes sence. I like the idea of putting morter around edges of the pcrete, or I may wait to put some refractory cast material as a border. I may just slap it onto the side without a form as the pcrete is rough enough that it should hold / stick well to morter or cast material.

So... I have a dumb question... I have a compound miter saw with which I am planning to use to cut the firebrick like this. What type of blade do I buy to cut the brick?
Or, do I just use a hand grinder, which I have, but again, not sure which blade to use. (I assume the miter saw would be easier to make accurate cuts with.)

[DavidApp]

Re: Starting my build

Hello Almondsurf

You will need a Diamond Brick/Tile saw blade. The best way is to cut the brick wet because cutting makes a lot of dust.
The dust is very abrasive and will not do your compound miter saw much good. If you cut the bricks dry you need a dust mask and eye protection.

Look for a Harbor Freight 10" wet saw. You may find one used on e bay or Craigslist.

People have cut bricks with an angle grinder and diamond blade but that is hard work.

David

[SableSprings]

Re: Starting my build

I have a compound miter saw with which I am planning to use to cut the firebrick like this. What type of blade do I buy to cut the brick?
Or, do I just use a hand grinder, which I have, but again, not sure which blade to use. (I assume the miter saw would be easier to make accurate cuts with.)

I see DavidApp and I were both answering at the same time.

I agree that the miter saw will work better for your hearth cuts. You'll need to pick up a diamond saw blade for it to make the job relatively painless. Be aware that cutting dry will produce a large cloud of pretty fine brick dust. A wet saw is preferred (as David noted above), but use what you have. Make sure you wear a good dust mask, eye protection, and be very conscious of which way the wind is blowing...not going to make the family happy if you fill the house with brick dust . I don't know the diameter of your miter saw, I borrowed a 10" wet saw (and bought a new blade) so I could cut a brick with one pass. Prices will vary, but you should be able to find a reasonably good 10" blade for between $30-$50 if you shop around. You aren't going to be making a lot of cuts for the hearth, so you don't have to go top of the line.

The dust can be quite abrasive to the miter saw motor and parts (again, as David noted above), so be prepared to blow out the motor often or set up a good fan to keep the bulk of dust heading away from you as you cut. Some folks have reported that by wetting the bricks prior to cutting, the dust is reduced.

A grinder will also do the job, again get a diamond blade and use a mask. If you use a grinder, you'll want to set up something to hold the brick in place since you'll need both hands for the tool. Because you have relatively few cuts to make and since a grinder and its diamond blade are less expensive (more expendable), you might go this route simply to lower costs and save wear & tear on your miter saw (As David noted, it is a little more work to use a grinder...but if you're only cutting your hearth bricks...)

[almondsurf]

Re: Starting my build

Thank you guys, I now know not to us the miter saw. Sounds like it would have been a mess, leaving me scratching my head midway through the job wondering how to do it differently.

I have now looked at tile saws at HF as well as other stores. I don't think I'll be buying one new. Those 10" saws are not cheep... and when else would I use the thing? I already tiled my walk-in shower, but did that with a borrowed, smaller tile saw. The rental shop near me has a brick saw with a diamond blade for $63 per day. Since I am only cutting the hearth bricks, I am confident I could cut those within one day... so I may just rent one?

One thought... When I tiled my shower, I put a granite slab (5'x1.5') on the top of the seat bench. We used a circular saw with a diamiond blade to cut the granite, running a little stream of water infront of the blade. No damage to the saw (that I know of), and cut fine. Wonder if this would work for the brick since it is much softer than granite?

of note... I still have my tarp over the pcrete base... It seems to be drying well without issues.

[Greenman]

Re: Starting my build

You might consider purchasing a second hand wet saw and selling it when you are done with it. You should get close to your purchase price back and the job would be much easier. You would get to do it in your own time too.

I bought a good 14" bricksaw for $450 to do mine and ended up keeping it and building two more ovens for family and a friend. Being a hoarder of such things I now justify keeping it with the notion that it now owes me nothing even if I could sell it for $500 quite easily.

[rodeair]

Re: Starting my build

Steve,Greenman ...It took me 3 to 4 months to make my 42 incher. You made yours and 2 others?? I'm not worthy...I'm not worthy ........

[Greenman]

Re: Starting my build

Rodeair - those 3 ovens were built over 18 months. I finished mine completely but the other two I built as far as the completed dome and flue gallery. The 3 to 4 months you took is probably a lot less than the average for most of the builds here.

I expect that makes you quite worthy indeed!

[rodeair]

Re: Starting my build

Well, I'll tell you what .... after making my igloo, the last thing I would consider is making another one or two even over an 18 month period. You are truly a Fornobravo Il Pizzaiolo. If you ever get over here to waters that don't want to eat, bite, kill you...I would be honored to show you around. Cheers from the great Gulf Coast of Florida.

[rodeair]

Re: Starting my build

Almondsurf .. A circular saw with a masonry blade works well cutting the brick. If you want the beveled edges and etc., I would recommend the wet saw. If you end up just cutting the bricks in half, you could get away with the circular saw. If that's the way you go, soak the bricks in water for awhile to cut down on the huge amount of dust kicked up. Make sure to use a respirator or at least a dust mask either way. Good luck, it's a lot of fun either way.
Leigh

[Greenman]

Re: Starting my build

Rodeair - Thank you. If I venture your way I will be honoured to catch up with you.

[almondsurf]

Re: Starting my build

Almondsurf .. A circular saw with a masonry blade works well cutting the brick. If you want the beveled edges and etc., I would recommend the wet saw. If you end up just cutting the bricks in half, you could get away with the circular saw. If that's the way you go, soak the bricks in water for awhile to cut down on the huge amount of dust kicked up. Make sure to use a respirator or at least a dust mask either way. Good luck, it's a lot of fun either way.
Leigh

Thank you for the info Rodeair. I just purchased a 7" diamond blade at HD for $15. Thought that was a pretty good price. I will be using a circular saw as you mentioned. I will wet the brick as well as spray A LITTLE water on the blade as I cut. I will probably clamp the brick down to something and have my wife hold the sprayer. This way I should get a decent cut (maybe not the small ones) for each brick. I'll give it a go and report back if it becomes a success or failure.

[NCMan]

Re: Starting my build

I would highly recommend a respirator for the both of you and skip the dust masks. If all you are going to do is cut them in half, you can simply score each one, turn it over and whack it w/a hammer. The rough edge goes to the exterior of the oven. No need to completely cut each one all the way through. It'll save time, a lot of dust and wear and tear on your cutting blade. Just my 2?.

[mrchipster]

Re: Starting my build

I did some cutting of granite this way and zip tied a 3 ft piece of 1/4 inc vinyl tubing to my saw. The other end was connected to a garden hose via some plastic adapters and a couple of hose clamps. It worked quite well and the water stream was always in the right place.

[almondsurf]

Re: Starting my build

I have been patiently waiting for this perlite to cure / fully dry. I figured I'd post a picture of the insulation layer without the form. It seems solid. I may put up a half inch or so layer of mortar around the outside of this insulation layer. Not sure if that is even necessary???

I am going to go purchase all the ingredients for my casting recipe over the next 2 weeks. As previously posted... here is my recipe:
1 part cement
6 parts sharp sand
2 parts hydrated lime
1 part fire clay
4% 1" Stainless Steel Needles
1% polypropylene fibers

This week I will be buying my fire brick for my oven floor. I plan to cut them soon and will post what damage I can get done this week.

Should I use coarse sand or fine sand under my fire brick to level them out? I have bags of fine sand available in my garage, but would have to buy more sharp sand if that would be better. Thoughts?

[SableSprings]

Re: Starting my build

I have been patiently waiting for this perlite to cure / fully dry. I figured I'd post a picture of the insulation layer without the form. It seems solid. I may put up a half inch or so layer of mortar around the outside of this insulation layer. Not sure if that is even necessary???

Should I use coarse sand or fine sand under my fire brick to level them out? I have bags of fine sand available in my garage, but would have to buy more sharp sand if that would be better. Thoughts?

The insulation slab looks great! Remember that the only reason for a mortar outer ring is to protect the perlcrete from impact/abrasion on the edges of that insulation slab. So, as long as you are just casting on top (no dancing or mountain climbing practice) you'll probably be fine without the extra mortar ring.

Builder's sand (sharp) is nice because it holds its shape better when you wet it, but the fine sand you have will work. Just remember to put down a 1/2"-1" layer, wet it, close level, then use a grout tool to put in some ridges on top. That way as you set the bricks you can tap them down to make the hearth level & firm. If you don't trowel in grooves you don't give the sand any room to move when you tap them down...same as when you lay tiles on quickset.

Sorry I don't have any comments for you on your casting materials list, but I'm sure those with experience will chime in.