Block Stand Question - Pompeii 42"

[gastagg]

Ok, I'm jealous...I never got any scientific analysis at Smith Sharpe! Thanks for posting that! However, they were very helpful for the many times I went in there. Looks like I went with Scenario 2/11 with 160 degrees. Your worksite and patio look great. Keep the pics coming!

I used a 3:1:1:1 (sand: lime: portland: fire clay) homebrew. Some say a 5:1:1:1 mix for mortar is better. Homebrew is less expensive. Throw it in a bucket with a lid and roll it around your yard a bit to mix. I don't know anything about the refractory mortar.

[RandyJ]

You are welcome. I would recommend that you not use the refactory mortar. If you do not keep your joints to under 1\8" and I do mean under. It will crack. The home brew is used on the vast majority of the oven builds on this site. Make sure to use the finest sand you can find. The stuff I had was like sugar. It was quick Crete commercial ultra fine sand. It was like the stuff they use to put in ash trays at the mall.

Randy

[Yeager]

Thanks everyone. I'll go with the homebrew. Any suggestions on where to buy the hydrated lime(I think that's what i need?) in Minneapolis area? (I live in Burnsville\

Yeager

[RandyJ]

Hi Yeager I got mine from menards along with the Portland cement. The sand I got from home depot and fire clay from Smith-Sharpe. You picked the right option.

Randy

[gastagg]

Menards has a great product for sand. It is $5/bag and is used for mortar mixes. Super consistent, almost white, great to work with. They'll have the lime and portland too. I just looked at my recipe on the previous post and I listed lime twice. It's 3 sand, 1 lime, 1 portland, and 1 fire clay. Get from Smith Sharpe or Continental Clay a block away from Smith Sharpe if they don't have it.

[Yeager]

Made some progress yesterday - hopefully more today!

[UtahBeehiver]

Nice taper joint cuts. It may be an optical illusion but check and see if the centerline of the rod on your IT is at the centerline of you brick face. If offset, this introduces a angle error that is cumulative as you move up in courses along the dome. Now would be a good time to confirm and correct if necessary. Leave the cardboard spacer in on the floor, it will keep errant mortar from falling in the gap that could cause expansion gap problems later on.

[the Beagle]

if you're building in the twin city area and familiar with Smith Sharpe buy calcium aluminate cement from them instead of portland. Your hi-heat mortar wll be more heat resistant. Portland breaks down at temps above 450F. Calcium aluminate cement is good at much higher temps and is used in castable refractories.Smith Sharpe has the stuff in 47# bags for about $20-25

[RandyJ]

From what I have heard that stuff flashes over very fast and makes it much harder to work with. My advice is to use the standard mix. It is much easier to use and if you are not a pro Masson that is good.

Randy

[gastagg]

Joints look great Yeager!

[david s]

From what I have heard that stuff flashes over very fast and makes it much harder to work with. My advice is to use the standard mix. It is much easier to use and if you are not a pro Masson that is good.

Randy

I agree. For the temperature range we use the home-brew is adequate and proved to be more workable as well as cheaper, we are building ovens not kilns. You could make out an argument for using calcium aluminate for the top third of the dome, which does receive higher temps, but I don't think it's necessary. You will also get a shock when you hear the price of calcium aluminate cement.

[Yeager]

I've been able to do the joints without making a jig. The newer 10" HF Saw allows for compound cuts. I use my dewalt miter saw and cut the angle on a 2x4 (I get better angle precision on that) and then transfer that angle to the HF saw blade. I'll work on a picture or video.

thanks!

Yeager

[Yeager]

Made some good progress over the past couple weekends! Starting to get the hang of the cuts! It's taking me about 2 - 2.5 hours per level including cuts. I think my Diamond Blade needs to be replaced soon - not cutting as smooth/quick as it used to.

[RandyJ]

Hey Yeager it is looking great. Yes you will probably need to replace the blade a time or 2. It depends on what blade you are useing. If yo are useing the continues rim blades you might go through 3. I used the rigid brand segmented blades and went through 2. When you think about it it is suprising how long they last.

What type of oven entry arch are you doing? I am a little confused looking at the pictures.

Randy

[UtahBeehiver]

Yeager,

Very nice brick joint work. Here is a pic from, I think MrChipster, on how you use your IT to do a tapered arch like the one I think you are going to do.

Also, as you do your courses, the last thing to do is set a brick or two on the next course at the back of the dome and let it cure overnight. It will give you an anchor to set the bricks especially as you move up in the higher courses.