Author Topic: what dremel bit is good for routing in concrete brick?  (Read 1077 times)

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Offline CopperCone

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what dremel bit is good for routing in concrete brick?
« on: June 02, 2018, 11:39:15 am »
I need to run some trenches in concrete dense firebrick. Not that soft type, the dense type, good for surviving thermals but not the best insulator. What are the best dremel bits for doing it?

I own:
https://www.dremel.com/en_US/products/-/show-product/accessories/9933-structured-tooth-tungsten-carbide-cutter-cylinder

I use this for wood. It says its good for ceramic tile. Does this translate to being able to cut bricks?

https://www.dremel.com/en_US/products/-/show-product/accessories/9901-tungsten-carbide-cutter

Says fired ceramics. Not sure how this translates to brick.

https://www.dremel.com/en_US/products/-/show-product/accessories/7150-diamond-wheel-points

Diamond tool, but its tiny. I can see it being useful to do the fine finishing on the rough trenching down by other tools. Seems like it would take 10 hours to make the trench I want and probably wear down after 30 minutes?

I need to basically make a bunch of curved trenches, the basic volume is basically 1cm x 1cm x 16 inches. So the volume that needs to be removed is 40cm cubed.

Can any of these little tools handle the job?

They were kind of pricey so I don't want to experiment and fuck em up.

I thought to drill small holes using a carbide hammer drill but its for a kiln, so I am worried about causing damage to the integrity of the material, I would like it to last a long time.

Maybe you can take 20% off that volume number because I can take some off using the angle grinder diamond wheel and take some more off using a dremel diamond wheel, but I still need to do real trenching eventually.
« Last Edit: June 02, 2018, 11:49:08 am by CopperCone »
 

Offline tautech

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Re: what dremel bit is good for routing in concrete brick?
« Reply #1 on: June 02, 2018, 11:56:01 am »
Masonry can be a bitch with metallic cutters unless they're designed for it.
There's a heap of diamond blades available for grinders and skill saws and these are best run wet.

You could stack two carborundum masonry blades together on a small grinder and produce a wide groove.....dirty and dusty job so wear goggles and a mask.

For the curves I'd try this one, running not too fast and wet.
https://www.dremel.com/en_US/products/-/show-product/accessories/9933-structured-tooth-tungsten-carbide-cutter-cylinder
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Offline CopperCone

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Re: what dremel bit is good for routing in concrete brick?
« Reply #2 on: June 02, 2018, 12:04:14 pm »
Yea I am gonna make the main trenches by multiple passes of a water cooled diamond slide saw but I need to make the curves.

How are grinding stones for doing masonry? I have alot of dremel grinding stones and honestly I don't really use them, I tend to debur things with other tools.

I have the aluminum Oxide ones and some green ones that I think are silicon carbide.. but they are very fine and I don't see them removing much material
« Last Edit: June 02, 2018, 12:05:54 pm by CopperCone »
 

Offline tautech

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Re: what dremel bit is good for routing in concrete brick?
« Reply #3 on: June 02, 2018, 03:44:54 pm »
IME masonry blades are a much more consumable item than metal cutting and grinding blades however they're more efficient at what they're made for. I don't know if you can get masonry grinding wheels and that's why I suggested 2 masonry cutoff wheels together. Masonry cup stones are certainly available but they'll be no good for grooving.

I think I'd research the Dremel stones you have to check if they're suitable for masonry.

And BTW those concrete fire bricks will probably be fairly hard, certainly tougher than brick and more like ceramics.

Let us know how it pans out.
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Online Ian.M

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Re: what dremel bit is good for routing in concrete brick?
« Reply #4 on: June 02, 2018, 04:08:02 pm »
A Dremel simply wont stand up to that sort of duty - the bearings aren't good enough and the spindle speed is too high.  The combo of high side loads and large volumes of fine abrasive dust will kill it.

Its a job for a pneumatic die grinder, so you can safely run it  wet under a continuous water spray to keep the work surface and bit flushed.

I'd do as much as possible with the water cooled diamond saw - cross cut for the end trenches so you only have to use the grinder to round off the corners the elements will go round.
 
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Offline CopperCone

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Re: what dremel bit is good for routing in concrete brick?
« Reply #5 on: June 03, 2018, 01:03:24 am »
I found some online pictures of bricks that were shaped with dremels.

But yea I want to do it under water and I have the stupid little over priced dremel fan accessory that actually works pretty decent to keep dust out of it.

I would consider getting the milwakee fuel die grinder some time, but it has dust susceptibility and its expensive.

I maybe maybe could consider a harbor freight die grinder for like 10$. It would only be used once lol.

Can you suggest a 1/4 inch burr that would work well for my purpose on a conventional air die grinder?
 
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Offline ignator

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Re: what dremel bit is good for routing in concrete brick?
« Reply #6 on: June 03, 2018, 07:29:44 am »
The harbor freight air die grinder will serve you for this purpose. For masonry, I've never had luck with anything but diamond cutting tools. Even the cheap blades for 7-1/4 circular saws (<$10) have survived cutting a new door way in concrete block wall 7 foot tall, with the 4 vertical cuts from both sides. And the blade had very little wear. I've not had any luck with carborundum or other blade materials that are sold for cutting concrete.
If you can use a 4" angle grinder for the shaping (using 4" diamond blade) I would recommend that path over a die grinder.
 

Offline nctnico

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Re: what dremel bit is good for routing in concrete brick?
« Reply #7 on: June 03, 2018, 07:48:42 am »
How about making (pouring) the concrete blocks yourself in the right shape? A wooden mold will be easier to make.
Even with diamond tools working on dense concrete just sucks.
« Last Edit: June 03, 2018, 07:50:36 am by nctnico »
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Offline CopperCone

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Re: what dremel bit is good for routing in concrete brick?
« Reply #8 on: June 03, 2018, 10:00:37 am »
do you have a formula for making good fire brick for a kiln? Need to survive 1450C

i watched manufacturing videos and it looks like its a complicated process that requires firing.

I need to make 8 C shaped grooves that are basically semicircles with 1 inch diameter
« Last Edit: June 03, 2018, 10:02:12 am by CopperCone »
 

Offline KL27x

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Re: what dremel bit is good for routing in concrete brick?
« Reply #9 on: June 05, 2018, 04:46:30 pm »
Diamond burrs work, and there's no reason you can't run them wet. I put water in the divot when making holes in glass and stone. But the size of what you're doing probably wants a bigger tool unless you have a few days you want to kill with mind-numbing monotony. Dunno how dense is your brick, but it takes me circa 5 minutes just to make a small hole in a glass bottle.

If the curves are too tight for an angle grinder, a die grinder is definitely faster. But even there, I don't think you can use carbide cutters by hand on something really hard like that. Rigidly mounted, you might have some luck, but I'd try a carbide bur vs cutter/endmill to get anywhere other than ruining a bit.

I would try roughing out some of the brick with a hammer drill and masonry bits. Or maybe even a small cold chisel and hammer.  1cm wide/deep groove is pretty big.
« Last Edit: June 05, 2018, 04:57:59 pm by KL27x »
 

Offline CopperCone

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Re: what dremel bit is good for routing in concrete brick?
« Reply #10 on: June 06, 2018, 12:31:17 pm »
mm I noticed you can do some kind of crude stone "milling" using a hammer drill carefully, I was able to kind of clean old concrete off a brick face when I was mounting a gate on my steps. The fire bricks are fragile though, just dropping it makes it shatter, unlike the other construction bricks, which can take it no problem.

I do want the geometry fairly precise though, so I don't stress the wire with hot/cold spots, otherwise I would just make the curved portion of the trench much wider with a diamond grinder wheel.

I really don't want to use soft brick since I see it basically decays and youtube is filled with furnace repair videos etc, i hate dealing with ceramic shit really, unless its natural stone big and inprecise, where I can hit it with a chisel and bang on it hard.
« Last Edit: June 06, 2018, 12:36:35 pm by CopperCone »
 

Offline Bud

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Re: what dremel bit is good for routing in concrete brick?
« Reply #11 on: June 07, 2018, 01:52:49 am »
Dremel rotary tool does not have torque, all those itty bitty attachments and blades are close to useless for any considerable intensity work.
 

Offline CopperCone

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Re: what dremel bit is good for routing in concrete brick?
« Reply #12 on: June 07, 2018, 09:30:37 am »
I gave it a try with both the end mill and the carbide sponge attachments. I suspect to do the full work, of the volume stated, it will take approximately 1.5-2 hours of tool time, maybe less.

The material actually moves pretty good, easier to work with then aluminum actually, but it removes slower, it does not seem to get the dremel into the so called chatter mode when its pressed too hard.  If I press too hard in aluminum it embeds and recoils off and starts bouncing around so you need to be real careful with force.

« Last Edit: June 07, 2018, 12:12:47 pm by CopperCone »
 

Offline CopperCone

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Re: what dremel bit is good for routing in concrete brick?
« Reply #13 on: June 09, 2018, 02:17:35 pm »
If you are looking to do this on the cheap,
The rotary hammer can be used to do some slight boring.

I found acceptable control using a bosch brand carbide masonry drill with a relatively weak 1.1 Joule impact force M12 Fuel can do some surface removal, but in the material of the brittle brick, the hole is kind of nasty, its not nice like drilling out a buncha holes in metal to ease grinding.

The bigger ones that run on 18V batteries are like 5 J, while the top of the line dewalt construction ones are about 14 joules, and a serious jackhammer begins at like 25J

I also found some diamond hole saws that can possibly be used to assist this, but they are EXPENSIVE, I don't want to wear them down. I was not particularly impressed with the life span of these from youtube videos, I don't remember what I bought em for. You can do the metal working technique here,which is to drill a bunch of holes on the profile of the curve using this thing.. i Just wonder when tis gonna wear out.. and then you have the interior left, so you need to beat that out.

I really wonder if you can get similar performance from some kind of home made concoction. That video makes me think not so easily. I am not impressed with the stuff people make on forums etc.




I would like to coat the interior walls with this stuff after to make it even more robust
https://www.amazon.com/ITC-100HT-Ceramic-Reflection-Refractory-Protection/dp/B01LWI8V0G
« Last Edit: June 09, 2018, 02:20:09 pm by CopperCone »
 


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