Sandblasting Lime Stone

A friend of mine approached me about a project to do some engraving into stone for a outdoor class room at a local grade school.  I had seen the technique at a stone carving conference in Lawrence Kansas.  After some research I was ready to tackle the project.  The stones were cut at a local quarry and delivered to me for the engraving/sandblasting.  I started by cutting templates on a COPAM vinyl cutter using a 60 deg blade and a sandblast resistant that is sticky backed.  I discovered right away that the stone needed to be free of any stone dust in order for the resist to adhere.  Once the resist was placed I was ready for sandblasting.

The blaster had to be filled several times and the job required about 4 bags of media.  The media used is Coal Slag.  Its a byproduct of the coal fired electric plants.  The greatest advantage to the coal slag over silica sand is that the coal slag has only .01 % silica as compared to sand being 100%.  Using a media with a low silica content  reduces the possibility of developing silicosis being developed in the lungs.  However using a respirator is still a must. 

                                              

 

I started out using Black Diamond but the grit was to course and kept getting clogged in the sandblasting valve.  I then found a similar product called Black Magic.  It was finer and didn’t get clogged in the spray nozzle.  Once the blaster was working properly the stone carving was rather easy.  The stone used in this project was called Silver-dale limestone.

        

Once the blasting was completed the letters were painted to create a stronger contrast. 

Hand rail bending Jig

I have been working outdoor handrail that needed a rolled top cap.  This is particularly difficult because of the shape of the steel.  My friend Jack and I built a hydraulic bending jig to get the job done.   We started with a small A-frame press from harbor freight and went to modifying it to do the job.   The hardest part was keeping the bar from twisting.  I used 1/2″ plate for the majority of the fixture.   The trick to making the bend is to keep bar flat as you bend the bar.

            

check out my web site

I finally got my web up and running.  Feel free to check it out and tell me what you think.  It’s at www.atwoodstudio.com

Some Final Shots of the machine

Thursday was a critique for the machine and I guess it went ok. Everything that was a problem was address as I already new what most of those things were. I was surprised not to see all of my team mates during the discussion.

This is those present during the crit. giving it the hard look over.

these images of the machine were created by Bill Jones. I think they are beautiful drawings of the machine for an ee. The schematic for the machines electronics were drawn up by Tim Force.Schematic Allso I am posting the code used to make the machine function. The code is nervous machine.txt

One asspect that I have neglected to discuss has been the logo chip. The center board has the logo chip and the ultrasonic sensors are tied direrctly onto this board. The motors all tied into the two boards on the left and right of the logo chip.

Student Show

Student Show, Steckline Gallery, Newman University, Wichita, Kansas

Transposition

Transposition, Debi Kaufman, Ulrich Museum, Wichita State University, Wichita, Kansas

Figure in Space

Figure in Space, Steckline Gallery, Newman University, Wichita, Kansas

Jacob Prater

Jacob Prater, RSC Gallery, Wichita State University, Wichita, Kansas

Installing the guts

Tim had me build some heat sinks for the fets we were going to use to turn the motors on and off. I started with an aluminum angle and with the use of a table saw equipped with a negative 2 degree rake on the blade, I was able to make quick work of the aluminum.

Building the main body

The plasma cutter is set up and ready for cutting on a 4' X 4' plasma table. The machine is a CNC Plasmacam with a Hypertherm 1100 plasma cutter, that is capable of cutting plate up to 1-1/4" thick.  The plate I used is only 16ga. that I purchased at Central Plains Steel here in Wichita.  I noticed that on the Central Plains Steels web site, my picture is still on the site as an employee.  I havent worked there in six years I find it kind of funny.

Cutting the plate with the DXF file downloaded into the cutters computer

the main parts are cut and ready for assembly

The plate used is 16ga A36 cold rolled steel, this makes it rather easy to fold and weld the edges.

the connections for the tubes are 1/4" pipe couples with the end turned on the lathe so that fits through the plate and makes the joint easy to weld. The third image is from the inside of the body. Notice that the inside is clean and shinny because the plate had been left outside and only one side got wet and rusted, however I think it is to my advantage for this work. With the couple turned down on the end you can see how the pipe protrudes through and creates a lip to weld on. I chose this method so that the pipe would be perpendicular to the plate and would require less clean-up or grinding.

this next image is the body all welded up and just about ready for some paint. I notice in this picture that not all the parts on the bottom are welding into place, but I think you get the idea on how its all but together.

The paint job I chose is reminiscent of some safety and lifting equipment that was used at steel warehouse I worked at, some years back.