Holding material ?

[Support (Admin)]

THREAD FROM ARCHIVE
================================================== =========
From: DavidB Date: 23 Jan 1999

My partner, Gene Jaeger, and I attended the last Shopbot Camp and we were very impressed with the people and the machines. We've been keeping tabs on the progress of Shopbot for a couple of years and when the new rack and pinion improved the accuracy we were sold. We take delivery on our twin Z axis"96" the middle of February and are busy researching and climbing the learning curve. I'm learning the beta software on a Mac doing softwindows. Glitches abound, but most likely due to the emulation. Anyone have any "If I'd only known...." suggestions for newbies?

We make musical instruments, and are interested in vacuum tables, drilling set ups, dust collection, sound isolation, etc. All input welcome. Thanks.
New "botters" on the block


From: Jim Turner Date: 23 Jan 1999

David, A couple of suggestions for you.

Vacuum clamping - don't underestimate the porosity of wood, especially thin parts. Make your vacuum hold down box out of plastic or some other non-porous material, or use wood and lay on several coats of finish.

Drilling - to square the drill motor to the table, wrap a piece of wire, (I use copper because it's soft) around the bit and let it stick out about 8-10 inches from the bit, parallel to the table. Bend the end down so it nearly touches the table. Rotate the bit by hand. Then end of the wire should stay the same distance away from the table if the bit is square to the table. If not, adjust accordingly. Also be sure your z-axis is traveling perpendicular to the table by using a framing square pointing up from the table. move the z-axis up and down. The drill should remain the same distance from the blade of the square as it travels.

[cmrtom@worldnet.att.net]

I saw a "BOTTER" use a hot melt glue gun to hold material in place while he was cutting. It had good holding capacity, left no marks at all. He sprayed denatured alcohol on it after he had finished and it released perfectly. He had MDF board on his table but recommended melanime coated MDF. Also, the coated board is sealed with the melamine and make great vacuum chambers.

[sheldon@dingwallguitars.com]

I'm in the final stages of machine setup and am looking forward to converting and running some files.

I plan to use removable fixtures with index pins to locate the fixture and more pins to locate the parts (plus vacuum cells and toggle clamps etc).

How do you go about aligning everything up so that
A: the part files are in the right place with reference to actual 0,0. 2D parts are in AutoCAD now and will either be converted straight to Shopbot or run through Vector (if I ever get the hang of it). 3D parts I'm still working on but will likely use Vector or Rhino.

B: the parts are aligned perfectly with the part file so that everything is in exactly the right place. I was hoping to make use of laser cut steel in a lot of the fixtures for the mass and rigidity, but that means you can't use the shopbot to rout alignment marks or vacuum cells.

Maybe the router could peck the index hole positions - I don't know.

[jorgy.tucson@worldnet.att.net]

Sheldon,
This may help. Design your fixture to allow a small flange on the part, then trim this flange/flashing. Or make alingment marks similiar to multi-page CAD drawings. I find this easier than doing "perfect" positioning. Sometimes I leave a 1" or 2" border for clamping or screwing to the spoiler board. Often not even presizing material. Once your up and running you'll find that there are a number of different ways to locate and run a part file anywhere on the table.
John

[sutter@iinet.com]

Sheldon,

I would also recommend the installation of the proximity switch kit. Then when you run the sb_home.sbp file it will return to the same place very closely every time and from this it will make all subsequent placements more accurate. For my PRT 96 I homed the machine and then engraved a v groove matrix in the table only .040 deep, I created this matrix with 1" squares.

The matrix makes it easy to line up parts anywhere on the table with excellent accuracy and true alignment in both X & Y.

The proximity kit uses an electronic sensor that is highly repeatable and accurate.

[annetts@mb.sympatico.ca]

Hello

Our High School is waiting for our shopbot to arrive shortly. Does anyone know of any sites related to making a vacuum table using a shopvac or air compressor.

Thanks in advance

Mike

[Donna]

Mike, Bill Young is working on a table top hold down that will work with a shop vac. Check out his site at:
http://www.seasidesmallcraft.com/smallvac.htm Also on his web site at
http://www.seasidesmallcraft.com click on the ShopBot toward the bottom of the page he has a link to the full size vacuum that he uses with his table and shop vac.