36" in Seattle

[cynon767]

Re: 36" in Seattle

The # refers to the screen mesh used to grade the sand. The higher the number, the finer the grain. I tried #20, #30, and #60. The finer stuff was definitely smoother, but I don't know that 60 was really necessary.

[eprante]

Re: 36" in Seattle

A question about your home brew, specifically about the sand. You mention sand rated at #30 and #50. What is the difference( I am a newcomer to this masonry stuff). Is #50 finer than #30. I am thinking of doing the FB home brew mortar but have questions about the sand. I am planning on doing compound cuts on my bricks, so fine grained mortar is going to be easier to work with. I was originally going to use beach sand (very fine grain). Is increasing the proportion of fireclay going to give a stronger mortar joint.

Sorry if this is too many questions, but you seem to have thought the mortar thing through.

Eric

[kebwi]

Re: 36" in Seattle

Second attempt at that last image, which was ridiculously shrunken during the last upload for some reason (some png/jpg discrepancy).

[cynon767]

Re: 36" in Seattle

I guess so. I have no basis for comparison so I don't know if I should stop using it. I'm using 3:2:1:1. I don't know what the refractory or mortar-specific (stickinesss, set-time, etc.) effects are of doubling the fireclay. I don't know if it's a good idea at all.

One concern I have is that my mix effectively reduces the relative quantity of "glue", i.e., Portland and lime, overall, relative to the Pompeii 3:1:1:1. I don't know if that means I've weakened the mortar...but some mortars have a HECK of a lot of sand in them, far far more than Pompeii (or mine), so I assume I'm all right in that regard.

I did the same thing, based on what I'd read here and a few other places. Totally unscientific, but from what I know about portland cement breaking down at high temp while fireclay fires to brick-like consistency, I decided to go for it. Some people (including Frances from this place, I believe) have used a mix completely devoid of portland, and simply kept the project meticulously dry until it was fired. I was not so brave, so I merely increased to proportion of clay slightly in hopes of having a more solid fired product than otherwise. Mine is still in the construction phase, but I have total confidence in the strength of the mortar thus far. It has borne my full weight standing on the dome many times now while working on the chimney.

[kebwi]

Re: 36" in Seattle

I've been cutting the bricks for the first curved course. Not much else to say, hope the weekend goes smoothly.

[tfasz]

Re: 36" in Seattle

Yeah - it has been a lot nicer to work out of the garage the past month in Seattle. That is what I've been doing too.

Your brick cuts are looking great. Looking forward to seeing your dome start to go up.

[kebwi]

Re: 36" in Seattle

I guess so. I have no basis for comparison so I don't know if I should stop using it. I'm using 3:2:1:1. I don't know what the refractory or mortar-specific (stickinesss, set-time, etc.) effects are of doubling the fireclay. I don't know if it's a good idea at all.

One concern I have is that my mix effectively reduces the relative quantity of "glue", i.e., Portland and lime, overall, relative to the Pompeii 3:1:1:1. I don't know if that means I've weakened the mortar...but some mortars have a HECK of a lot of sand in them, far far more than Pompeii (or mine), so I assume I'm all right in that regard.

One other thing that should be noted is that I'm using #30 sand, for no better reason than that's what I found at HD and bought and started using before I knew any better. Subsequent discussion with mortar companies have suggested that #50 might be better. I have noticed that my mortar is particularly gritty, making tight mortar joints rather difficult. I don't think I would recommend it, except perhaps for fat mortar pockets where larger aggregate might actually be beneficial of course.

I've also start mixing my mortar with warm water. I don't know how to quanitify "warm" of course, but I shoot for somewhere around the temperature at which it doesn't feel warm or cold on my fingers. I'm not sure what the effects of too-cold or too-warm water would be. I've made mortar with very cold water and I'm not sure what difference there was. I started using warm water simply so my fingers wouldn't freeze, not for any cementary (ha!) reason.

Anyway, charging ahead. I started trimming corners off square bricks for the curved courses. They seem to lean into each other perfectly, so I except that to go fairly well.

Cheers!

[ThisOldGarageNJ]

Re: 36" in Seattle

hey keb,,

Looks like your homebrew mortar is working okay ??

Cheers
Mark

[kebwi]

Re: 36" in Seattle

The first three courses (vertical side-walls consisting of asymmetrical right trapezoids) are totally complete, including notched arch merges. The course of wedges that will transition to the first curved dome course is also complete. No photos, but it's easy to extrapolate in your mind from photos in earlier posts.

Also built some of the pieces of the outer arch for later transport to the site. I find that is it much easier to put multiple bricks together in the basement, then transport them to the site for construction. I did this for the side walls, one of the two inner arches, and now much of the outer arch.

Recalculated and rebuilt my brick placement tool with a hinge. I now have the option of using each version of the tool (the nonhinged version is shown in an earlier post).

Cheers!

[ThisOldGarageNJ]

Re: 36" in Seattle

looks great I love the way you did the arch....

cheers
mark

[kebwi]

Re: 36" in Seattle

Mortared the first merge between the vertical side walls (the dome in effect) and the inner arch (1st pic).

Mortared the keystone into the outer-inner arch, thus completing the inner arch (2nd pic)...although I have discovered upon removing the arch-form that there is vastly insufficient mortar between the two layers as viewed from inside the arch despite good appearances to the contrary along the outside edge. The crevices as viewed from the underside of the arch are distressingly deep. I intend to smear and push fresh mortar into the interior gap a.s.a.p.

Finished cutting the bricks for the outer arch and the second course wall-arch merge (3rd pic). I liked the look of the taper that I put on the inside of the inner arch (for functional reasons) so much that I put a similar taper on the outside of the outer arch bricks for purely aesthetic reasons. I think it will look very nice if the now completed inner arch is any indication (as vaguely suggested by the 2nd pic).

Also made the necessary calculations to alter my brick-placement tool to include a hinge between the floor strut and the lower arm of the radial strut. I hope to make the associated pieces tomorrow.

With any luck, if I get the bricks for the first curved course cut this week, I hope to begin mortaring the curved courses by next weekend...although I might build the outer arch first since the bricks are ready to go anyway.

[kebwi]

Re: 36" in Seattle

Here is my brick placement tool, or as FB calls it, the indispensable tool, designed and manufactured to approximately 1/16" precision...give or take . It is a little more complicated than some other designs I've seen. My design enables full control over the brick orientation on a per-course basis by providing adjustment of the following parameters:

• the distance from the center (of the floor) to the point of intersection between the brick radial axis and the floor
• the length along the radial axis from the floor to the brick.

These two adjustable parameters make it possible to construct a dome of any conceivable curvature while still maintaining perfect edge alignment between the upper edge of one course and the lower edge of the next course up the dome.

Notice that the representation of the floor strut in the diagram (shown magenta) is floating in the air above the oven floor. This accounts for the 3/4" plywood protecting the floor.

In addition, notice that my design does not currently include a hinge between the floor strut and the radial strut. Rather, the floor strut represents a stop against which the foot of the radial strut braces. This is an arbitrary design decision of course...and perhaps not the better of the two options since it will require me to keep the two pieces in alignment. I opted for this design in my first pass due to concern that a small hinge might not withstand the repeated stressful application to a full oven's worth of heavy bricks. However, if after beginning the dome portion of my build I decide that adjusting the two struts independently is too much of a hassle, I can always redesign with a hinge in mind...although it will require recalculating all parameters of the tool (floor-strut length for every course, radial arm length for every course, pin-hole positions along the floor strut, and pin-hole positions along the radial strut arms).

Cheers!

[kebwi]

Re: 36" in Seattle

Almost finished the outer-inner arch (minus the keystone which was too tight: mortar gaps were too large, placement didn't perfectly conform to the protractor...I had to shave the keystone, which I haven't placed yet).

Note that the inner-inner arch, which lies just behind the outer-inner arch (visible in the photos attached) did not form a mortar bond between the feet and the bricks that line the entryway, although the bricks comprising the arch itself seem to have bonded to one another. Consequently, that arch could easily rock or tilt up on its feet with the slightest push. Hopefully the construction of the second layer will solidify things significantly.

This two-layer arch forms the inner arch, i.e., that arch behind the vent against which the dome merges. The outer arch will continue from where the inner arch leaves off to the front of the oven, indicated by the floor bricks. It will obviously have a vent opening as opposed to being closed off like the inner arch.

Added most of the wedges that will transition from the vertical side-walls to the first curved dome course. Also made my trickiest cuts yet, transitions from the wall to the arch. They are not merely straight notch cuts. Rather, one side of the notch is actually tilted w.r.t. the axes of the brick, so as to slope up the side of the arch. Overkill? Yeah, I think so.

Also finished building my dome-brick placement tool ("indispensable tool" as FB colloquially calls it), described in the next post.

[kebwi]

Re: 36" in Seattle

Just cutting bricks, waiting for the weekend. I can't do much mortaring during the week. The brick shot shows, in the background, some long-ways tapered bricks that will comprise the outer arch. They were trimmed to 3.5" wide first, so as to fit under the saw. On the end, next to the long tapered outer arch bricks, is the last brick of the inner-inner arch (my inner arch will have two layers). I couldn't mortar it with the rest of the arch because it was too tight. Had to give it a shave first. The numerous wedges in the foreground will form a transition from the vertical sidewall to the first dome course.

The second shot shows my inner arch (on the left) being kept warm under the tarps with a halogen. It has been dipping into the low forties, possibly the high thirties, at night. Although it is highly unlikely, I don't want to risk a freeze on fresh mortar.

Cheers!

[KINGRIUS]

Re: 36" in Seattle

Thought- I have had a few of those visible crack scenarios and it appears to me that the bond with the neighboring brick is not completely broken but just partially broken. I have one of those cracks in my entry arch but the brick doesn't budge. I think as long as long as the mortar is still moist and it is bumped it will still seal, even if you see a crack. Just my input.

By the way your cuts look very nice. So far so good!

Darius