Possible - New idea for brick cutting table

[UtahBeehiver]

The design of the HF saw changed a few years back but that said, post #21 of this thread show a jig for the new style HF saw that allows you to do a compound cut, ie taper and bevel in one pass. I attached a pic showing taper (angle) and bevel. For the dome ovens you will need both in one cut (compound cut). It is possible to get these cuts with two passes, doing an angle cut then doing a bevel cut but it is twice the cuts. There is also a link to DeeJayoh spreadsheet that assist builders with the angles needed for each course. The preset degrees on the saw are not much use since the angles you are dealing with are for the most part less the 10 degrees and changes with each course.
http://www.fornobravo.com/community/...ulator?t=18131

[SteveB48]

I'm trying to get my head around all these angles. Don't you also need to taper the height of the brick from the inside to the outside? Where does the "tip" inward come from?

thanks,
Steve

[RandyJ]

It all depends on how tight yoy want the joints to be. If I was going to do mine again I would just angle the sides to get rid of the inverted triangles. That is how I did the top half of my build. It is a massive pain to get the angels right from inside to out. And as for the hight that would make it exponentially more difficult and time consuming. Instead of 100 hrs to build the dome probably more like 1000. Just keep it simple and use the home brew mortar and you will be just fine. If you use heat stop you are supposed to keep all joints to 1/8" or it will crack as it dries. Most of us use the home brew and it works great and is not that expensive. Just make sure to find some ultra fine sand. Quick Crete sells some stuff that is like sugar and I loved it. I recommend that you use that too. The recipe is 3,1,1,1. Sand , hyd lime, fire clay, portland cement. Mix to peanut butter consistency. Good luck

Randy

[RandyJ]

Sorry I did not see Utah's post. So I would just do the bevels and not the angels. I just used shims to set the angle I was looking for.

Randy

[ivancito]

It all depends on how tight yoy want the joints to be. If I was going to do mine again I would just angle the sides to get rid of the inverted triangles. That is how I did the top half of my build. It is a massive pain to get the angels right from inside to out. And as for the hight that would make it exponentially more difficult and time consuming. Instead of 100 hrs to build the dome probably more like 1000. Just keep it simple and use the home brew mortar and you will be just fine. If you use heat stop you are supposed to keep all joints to 1/8" or it will crack as it dries. Most of us use the home brew and it works great and is not that expensive. Just make sure to find some ultra fine sand. Quick Crete sells some stuff that is like sugar and I loved it. I recommend that you use that too. The recipe is 3,1,1,1. Sand , hyd lime, fire clay, portland cement. Mix to peanut butter consistency. Good luck

Randy

Randy I also want to just bevel the sides of my dome bricks but I keep getting the inverted "v" when butting the bricks together. Is beveling and compound angles going to be the only way to get parallel joints inside my oven? I don't care about the larger gap in the back of the dome as I can use homebrew to fill it in, only looking for nice joints inside the dome, please anyone fill free to chime in.
Ivan

[RandyJ]

I did not angle any of my bricks past the first or second ring. I was having to much trouble getting everything to fit in a way I was happy with. You could have some small triangles if you are off a little bit on your cuts. You are just trying to keep the inside of the dome mostly brick. I would be fibbing if I said that all my joints are tight. They are plenty good enough but I am sure you could do better. But do you need to. It doesn't need to be water tight without mortar. That is unless you want to spend a lot of time on your build then by all means go for it, but it will not make a difference in the end.

Randy

[ivancito]

I think i may have come up with a very efficient and effective brick cutting table.

This came about by studying the chart of brick cutting angles developed by JCG31 and the work done in the "Its time to go vertical" thread.

jcg31 has a great idea for cutting 2 or more dome bricks from a single brick with minimal cuts. I just took this idea one step further.

In his presentation he describe the use of c clamps and stops to hold the bricks while cutting and as this is very efficient from the standpoint of investing time in building a jig The clamps must be repositioned carefully each time a new chain is created.

Here is my table design and I will have a follow up to this describing the cuts to the bricks.

The table is simply two 2 by sixes that are attached to each other with hinges. A single larger hinge would be satisfactory.

The 1st 2 x 6 is just a base and a way to clamp or attach the cutting jig to the sliding saw table. The 2nd 2 x 6 both supports and provides a cutting angle for the brick. As you can see from photo number 1 and referencing JCG31's chart on bevel and angle calculations all of the bricks are cut at 5? up to chain 11.

This static angle would be true of most dome sizes even though in smaller domes the angle might be larger and in larger domes the angle smaller.

His calculations were based on a 42 inch oven.

When creating this jig the top board is cut long enough to support the brick on the left and the right, a groove is cut to allow the saw to cut entirely through the brick without hitting the jig, and a thin board is attached to the top at the 5? angle being used for most of the cuts.

After attaching the board at 5? angle it is cut through so the saw can pass. By attaching a single stick screwing it down and then cutting it later this guarantees that both sides of the jig are the same angle.

The bevel can be adjusted for every chain easily because the hinge between the 2 boards allows the angle to be propped up with shims or thin pieces of brick. I also put a long screw in the far left end of the upper board and screwed into the lower board to hold the angle constant and shims in place while cutting all the bricks in a particular chain.

Please view the annotated photos or feel free to ask questions regarding the jig.

Chip

I Like it! My build has a full length soldier course, can I still use this jig and JCG31 spreadsheet? My 2nd course would almost be the 3rd course on the spread sheet because my dome starts after the 9" soldier.
thanks
Ivan

[autumncs]

Re: Possible - New idea for brick cutting table

The cutting of the bricks then becomes very simple.

1) Set the desired bevel angle on the jig by shimming the upper board to the desired angle. This gets rid of the inverted V's.

2) Set the brick on the left side of the jig so as to remove enough of the right side of the brick to get a full cut on the brick. Make cut #1.

3) Turn the brick over 180 degrees, leaving the freshly cut side on the right.

4) Move the brick to the right to position for cut #2 and make cut #2.

5) turn brick over 180 degrees one more time, leaving newly cut side on the right again.

6) Move brick to the right to position for cut #3. and make the final cut.

You now have two identical dome bricks with 3 cuts.

Note: when cutting bricks into 3's it is advisable to cut both ends off of the brick before making the final brick section otherwise the brick section will be small and hard to hold.

Chip

OK I built my jig today and I did a test cut. I now realize why you need it support the "off cut" side.

SO this is a b of what not to do. I miss read the instructions above to read, "3) Turn the brick over 180 degrees, leaving the freshly cut side on the right.", I read to be turn brick so bottom left becomes top right and cut then I rotated to brick front to back (which is what I think is meant to be done for the normal cuts) and cut the third cut.

Now is there a way to cut the sides then the center cut from the left side.I know I'll have issues with the great angles because of the motor.

[Rocko Bonaparte]

Re: Possible - New idea for brick cutting table

here's my version. Knew i would be building a second oven so designed a permanent solution.

I couldn't figure out what was going on in this thread until I got to the photos in this post. I can't make a jig as pretty and robust as that, but I'm going to see if I can manage something similar with HDPE.

[Rocko Bonaparte]

I don't know if anybody's still checking in on this stuff, but I wanted to verify one major thing: are any of you giving the top of the brick a sloped haircut to help the next course? I somehow I had that in my head that was part of all of this, but apparently not. I guess that's part of what you're using the indispensable tool for. I was assuming this jug could also do that if you clamped down the angled & beveled brick segments and ran it through at a very sharp angle.

I'm pondering how much time I'll fret and fetter over getting the right amount of butter under each course to keep the dome turning vertically versus just starting with bricks that are ready to party. I knew I would have similar analysis paralysis with the concrete blocks, which is why I used 3/8" stainless steel slingshot ammo under the first few courses to make sure I used enough mortar and used it consistently. That being said, I went ham on the last course without any help.

Edit: I guess this is what y'all were talking about with "taper" earlier. I guess I'll have to experiment. I should see if I can even get the angle and bevel cuts first!

[UtahBeehiver]

You are correct on assuming the IT sets the correct slope of the brick (IF the IT was correctly configured). The IT sets the inner face of the brick to be perpendicular to the center point on the dome at the floor surface. Hence no need to "shave the top of the brick for the next course".

Jigs are great to do a simultaneous bevel/taper cut. I made one and had very small "full" vertical joints. Would I do it again, probably not, you can achieve the same tight inner joint by only cutting the front sides of the bricks vs the whole sides of the brick. I believe JR did this. I spent a lot of time to make perfect joints, but it is not necessary since mortar is your friend. But it is up to you.

[Canada 150]

As I get ready to build my jig - a quick point of clarification. All of the pictures in the thread seem to show the table being hinged so the left side (under the motor arm and housing) raises. Post #22 seems to suggest that these are all backwards and should be flipped around so the right side raises (which would seem to give more clearance for a bevel angle) - Am I reading that right?

I'm considering using 3/8" polycarbonate to make the jig as it is relatively thin to fit under the blade and waterproof vs wood - make sense?

Finally, if the jig is only 6" wide x 12" long - does that work (the size of the stock I have)? I think that would support most of the material without issues.

Thanks for your help C150

[patjer1]

I'm trying to get al my joints in line which is working at the moment, but what if your brick gets to small to handle? Do you guys use a bigger brick for the following ring?
Thx.

[patjer1]

Just tried to cut Some bricks for my next course, a bit bigger then the previous course. But the tilt angle on the sides is changing from brick to brick, anyone had this problem too?
Greetings!

[Robysan]

I cut all my bricks the same up till about the 10th course, or last 3. then I reduced my cust by 1 inch from front to back. I did not do any bevel on the sides. My cuts were based on the brick calculator.
soldiered my first course then angle only. 3 1/4 front to 4 inch back, then on about the 8th course switched to 2.5 to 3. I have template I made from cardboard. I got in a practice of using cardboard to check fit and angle to I had fewer mistakes.