Comco Mb 1000 Nozzle Question

[Cluros]

I just bought a used Comco mb 1000 micro abraider. It came with a rectangular nozzle. Can anyone tell me what size round nozzle I should get for fossil prep? Is there any advantage to the longer nozzle?

[jpc]

what size powder do you plan to use? When I got my air abrasive, I bought two nozz;es, one for finer powder and smaller fossils and one for bigger fossils and bigger powder.

[Cluros]

I plan on using dolomite, bicarbonate and aluminum oxide. I believe it is 40 micron.

[jpc]

You are in She;burn, VT. Can I assume you will be prepping VT tributes I will try to go see what sizes mine are and get back to you. PM me to remind me.

[Malcolmt]

I have a Comco unit. The size nozzle I use most often is the round high precision .030 followed by the .018. I use dolomite in the 40 micron range. I do all prepping under a scope. I do have the .010, .015,.018, .025, .030, .040, .060. nozzles in both high and low precision versions. All my nozzles are the round type. I have a few long nozzle .040 and I really never use them . The shorter lengths are more precise with less over spray.

The .010 and .015 are really only usable when you have extremely small particle size. I screen what will pass through a 320 mesh to use with these.With these small nozzles I use them for fine detail work and use a very low pressure 2 to 3 PSI.

I use what will pass through a 200 mesh screen for the .018 and what will pass through a 120 mesh screen for the rest.

I throw away anything that will not go through a 120 mesh screen.

I have a full set of geological sieves that allows me to reuse abrasive (30,40,50,60, 80, 100,120,170, 200,320)

A good selection of sieves in my opinion would be (30, 60, 100, 120,200, 320)

Some people do not agree with this opinion but I would never use aluminum oxide for prepping. It is too hard and unforgiving. Aluminum oxide will also wear out your nozzles, lines and equipment faster. There is very little that you cannot prep with an airscibe followed by dolomite abrasion with control of powder flow and PSI.

Edited November 24, 2014 by Malcolmt

[jpc]

Malcomt has a great set-up here. Lots of choices... right tool for the right job. And I agree with him on Al Oxide. I have prepared thousands of fossils and only once was I forced to use Aluminum Oxide. It is too harsh.

[Cluros]

Hi Malcomt. Thank you for your response. It was very informative. I will pick up some nozzles based on your recommendation. I too plan on working under a binocular microscope.

[funfordds]

I would definitely recommend a larger nozzle, in my experience the smaller the nozzle the greater chance it will clog periodically. Also smaller nozzles can create gouges in the matrix much quicker.