Hello Joe, We have a small sandblaster that seems to have been made from an airbrush. It was used by our paleontologist to gently clean away unwanted material from fossils. It runs at 20-30 psi from a compressed nitrogen tank and uses SiC grit that is probably 400 or 320. The grit sits in the small cup that normally holds paint. It is very controlable and I have used it to clean feedthroughs and other ceramic parts that couldn't be baked. I don't know how much it cost but I would bet it was less than a few feedthroughs, let alone an entire source flange! good luck, Charles >Hi Tim, > > Thanks for the info! We are still trying to figure out how this >coating got there. We did have to "make" new seats to hold the leads >of small heater bulbs. The new metal was supposed to be stainless >steel but maybe it is our problem. The bad thing is that we did not >notice if the coating happened suddenly or slowly over time. > > Our Physics shop has a sand blaster but not a "bead" blaster. I'm >guessing this would be too rough. It is a large device that you put >your material in rather than a handheld sprayer. I'm not sure how we >would protect the parts of the source we did not want blasted. What >does your bead blaster look like? Any ideas on how much they would >cost? The bead blasting seems to be the best idea so far. > >Joe > >> Hi Joe... >> >> We have seen a similar buildup at the base of our ion source on our >> Delta Plus XL, though it was due to a different reason. One of the >> leads of our filaments had broken, and we used a little clamp to >> clamp the broken wire back together. The screws in this little clamp >> were coated with zinc, which is apparently a bad metal to have under >> vacuum as it degases. The result was a coating similar to yours. >> >> We solved the problem by using a bead blaster we have in our lab that >> we use to clean filaments for thermal mass specs. It did a very nice >> job of cleaning off the grime without damaging the metal or ceramics. >> >> Do you know of anyone with a bead blaster? I would suggest larger >> round beads (~ 100 micron diameter) at low pressures so as not to be >> aggressive. >> >> Hope this helps... >> >> Tim Prokopiuk >> >> On 27-Mar-06, at 3:40 PM, Joe Lambert wrote: >> >> Hi All, >> >> We have a Delta Plus IRMS that is about 5 years old and recently >> have >> started having problems with arcing in the source, which is shutting >> off the >> high voltage on the machine. We belive the problem has to do with a >> build-up on the ceramic leads at the base of the source (see attached >> picture). This build-up may be graphite. A glass-fiber brush seems to >> remove the material but the brush is too bulky to reach some of the >> surfaces >> in tight places. Has anyone seen this happen to their source before >> or does >> anyone have any ideas on how to clean this? Acetone and alcohol did not >> remove anything. The ceramic pieces are not removable and if broken >> would >> be bad news. Our last resort is a 5% nitric acid solution, which we are >> trying to stay away from if possible. If the attached image does not go >> through, the picture of the dirty ceramics can also be viewed at: >> >> http://www.bama.ua.edu/~lambe012/DirtySource.jpg >> >> The strange thing is that the rest of the source is almost as clean >> as if it >> were brand new. >> >> Thanks, >> >> Joe Lambert >> >> >> W. Joe Lambert >> Research Scientist >> Alabama Stable Isotope Laboratory >> University of Alabama >> Geological Sciences >> 202 Bevill Building >> 7th Avenue >> P.O. Box 870338 >> Tuscaloosa, AL 35487-0338 >> Phone: (205) 348-4404 >> Fax: (205) 348-0818 >> email: [log in to unmask] >> Visit our web-site: http:www.geo.ua.edu/asil >> >> >> ------------------------------------------------- >> Tim Prokopiuk >> B. Sc. Geology/Technician >> Saskatchewan Isotope Laboratory >> Room 241 >> Department of Geological Sciences >> University of Saskatchewan >> 114 Science Place >> Saskatoon, Saskatchewan, Canada > > S7N 5E2 >> Phone: (306) 966-5712 >> Fax: (306) 966-8593 >> Email: [log in to unmask] >> >> > > >W. Joe Lambert >Research Scientist >Alabama Stable Isotope Laboratory >University of Alabama >Geological Sciences >202 Bevill Building >7th Avenue >P.O. Box 870338 >Tuscaloosa, AL 35487-0338 >Phone: (205) 348-4404 >Fax: (205) 348-0818 >email: [log in to unmask] >Visit our web-site: http:www.geo.ua.edu/asil -- Charles Knaack GeoAnalytical Laboratory Geology Department Washington State Univ. Pullman, WA 99164-2812 (509)335-6742, FAX (509)335-7816 [log in to unmask], [log in to unmask]