Anyone know how to engrave on a BRICK ?

[Brady Watson]

And many are done in molds.

Yup...You'd be hard pressed to tell the difference between a 'cold cast' concrete brick and a real one with the right dye and aggregate mix. An interchangeable plate with the inscription of your choice at the bottom of the mold can easily be changed.

After machining various stone/aggregate products early on and dealing with grit getting everywhere on my expensive robotic tool - I vowed not to do that again...No matter how good your 'dust' collection is, you just can't keep grit from getting into the gear racks and machine ways. It just isn't worth it - for me anyway. It's one of those, "We can...but should we? Is it really worth the mess and risk?". Something to consider...

-B

[Davo]

Brings up a good question

Best way to make a mold on a Shopbot?

And with what?

[mtylerfl]

Brings up a good question

Best way to make a mold on a Shopbot?

And with what?

I did a presentation on mould making and casting at the 2013 Vectric User Group. It was an example scenario of creating multiple hotel wall plaques using casting instead of carving a bunch (carved the one plaque using the ShopBot, made a mould, then did the castings).

I first carved the plaque in 15 lb green foam (I think it was Duna brand?...not sure). Then made a container (called a flask) to make a silicon mould (a negative of the plaque), then made castings with plaster, Durham's Rock Hard Putty, and a quick setting plastic from Smooth-On (the silicon and spray release was from Smooth-On also).

The plaster casting was too fragile for my liking...the Durham casting had tons of air bubbles (which could be fine for a brick!)...the plastic casting was my favorite - strong, fast to set and easy to apply finish.

I just saved the PPT presentation to a PDF to get the file size down for the forum to accept the upload. Not much in the word descriptions on the slides, I'm afraid...I covered most of the details "live" during my presentation. But, I thought it might give you an idea how easy this is to do.

[Davo]

I wonder if it's more cost effective and time saving to cast things instead of remachine - loses the quality of being made from wood but neat to make it in other forms

[mtylerfl]

I wonder if it's more cost effective and time saving to cast things instead of remachine - loses the quality of being made from wood but neat to make it in other forms

It would depend upon the item. One would need to add up all the time/material costs for a particular project to see which method makes the most sense all-around.

[donclifton]

The best way is to cut a sand blast mask and sand blast it.
Don Clifton

[Davo]

i wonder if glass etching cream would be strong enough vs sand blasting - less clean up

[Brady Watson]

Brings up a good question

Best way to make a mold on a Shopbot?

And with what?

In this case using concrete etc, the easist way would be to make a clamp together melamine box. Machine your text in reverse and screw it/stick it down to the bottom. Pour in concrete, remove sides to demold. This eliminates the draft issue. There are plenty of mold box examples using melamine on the web. The only thing that you need the CNC for is engraving the text (prismatic letters etc) on your interchangeable plate if there are different names etc. When done put it on the shelf for the next time.

The best way is to cut a sand blast mask and sand blast it.
Don Clifton

There ya go...Easiest solution if you have access to a blaster setup.

I still would not recommend machining bricks on your good CNC machine...

-B

[mtylerfl]

I'm with Brady! Funny, I had to fight off the urge to just go out, make a mold with my surname and cast a brick today!

[RossMosh]

As mentioned above, laser or sandblast is the most common way. Sandblasting is more expensive than lasering. If you buy the right brick, as the laser hits the brick it turns a near black color which allows you to skip the color fill application. It's also easier to personalize as you don't have to make a new mask for each brick.