Little power flow with paasche remote air eraser.

[Lmshoemaker]

I recently got a new air abrasive as my old one finally bit the dust. The old unit was a paasche air eraser that was pretty decent, but the up time I got from it was pretty low as I spent a good amount of my time refilling the really small canister with abrasive. I decided to get a remote Paasche AEC unit to remedy the problem I had with the old unit, but as of now I'm firmly disappointed with it. My problem is I am getting almost no abrasive cycling through the unit. I'm not getting clogs at all, and the air is moving freely from the compressor to the end of the unit, with pretty good air pressure being output. I dried my abrasive in the oven for about an hour at 250^oF to dehumidify it after I noticed the lack of powder flow, thinking moisture was the issue, but that doesn't seem to be the case. Anybody have any ideas? Right now it is taking me probably about a minute to remove a thin film of shale off of a single crenulation of a small (.25 inch) brachiopod. Occasionally my unit will spurt out a bunch of abrasive at random, and when this occurs the cutting rate is pretty good, not as good as my old unit, but certainly serviceable. Shaking the canister can artificially boost the powder flow, but only during the duration of which it is being shaken, and clearly this isn't a good way of achieving the effect I want. 

 

For those who may be curious, this is what the unit looks like:

 

 

[Kane]

I have the same unit and face the same problems. My only workaround has been to bump it a bit past the PSI mark that is recommended (50 PSI). I've done the can shake to get the medium through, but it might be a design flaw in getting the medium into the piping. Oddly enough, I found it started to work a bit better when the can was close to half full rather than more full. 

 

If you go over 50 PSI, you have to change your approach. Short strokes from a bit of a distance to avoid cutting too much. Over 60 PSI and the can inflates like an aluminum balloon. 

 

I have yet to try tilting the can to see if that will make a difference. Although I doubt it should, it might. Again, it may be an issue of sampling different medium levels in the can. I know with the model that had the medium filled at the pen area that the halfway point was the best one, as opposed to more or less.

[Fossildude19]

I was thinking maybe less media, and possibly putting the canister on it's side, or creating a wire hanger frame to hold it upside down?

Might be worth playing around with canister orientation.

[Lmshoemaker]

19 minutes ago, Kane said:

I have the same unit and face the same problems. My only workaround has been to bump it a bit past the PSI mark that is recommended (50 PSI). I've done the can shake to get the medium through, but it might be a design flaw in getting the medium into the piping. Oddly enough, I found it started to work a bit better when the can was close to half full rather than more full. 

 

If you go over 50 PSI, you have to change your approach. Short strokes from a bit of a distance to avoid cutting too much. Over 60 PSI and the can inflates like an aluminum balloon. 

 

I have yet to try tilting the can to see if that will make a difference. Although I doubt it should, it might. Again, it may be an issue of sampling different medium levels in the can. I know with the model that had the medium filled at the pen area that the halfway point was the best one, as opposed to more or less.

 

17 minutes ago, Fossildude19 said:

I was thinking maybe less media, and possibly putting the canister on it's side, or creating a wire hanger frame to hold it upside down?

Might be worth playing around with canister orientation.

 

Both good suggestions, but I've tried these and unfortunately they haven't yielded results. I have the canister on its side but that doesn't seem to help much. I have tried putting upside down, but oddly the powder flow becomes so high that it overflows and clogs the unit because it can't evacuate it quick enough. I try it at around 60 psi currently, because I can't really feel much airflow at the recommended 45. 

[Sagebrush Steve]

What abrasive are you using?  I believe Paasche claims it doesn’t work reliably with baking soda, only with aluminum oxide.  I know some people claim it does fine with baking soda, but not everyone.  I also remember reading somewhere (maybe on this forum) about someone who modified the tip to make it work better with soda.

[Sagebrush Steve]

2 minutes ago, Sagebrush Steve said:

What abrasive are you using?  I believe Paasche claims it doesn’t work reliably with baking soda, only with aluminum oxide.  I know some people claim it does fine with baking soda, but not everyone.  I also remember reading somewhere (maybe on this forum) about someone who modified the tip to make it work better with soda.

It was @DevonianDigger in this post:

 

[fossilcrazy]

I have a reasonable amount of success with this inexpensive unit. Don't bother with the propellant can or the abrasive that comes with it; neither are satisfactory for fossil preparing. 

[fossilcrazy]

All these Trilobites were prepared with the Badger unit above by me years ago.

[Sagebrush Steve]

2 minutes ago, fossilcrazy said:

I have a reasonable amount of success with this inexpensive unit. Don't bother with the propellant can or the abrasive that comes with it; neither are satisfactory for fossil preparing. 

Looks like that one is on Amazon here: https://www.amazon.com/gp/product/B000IG2VEO?ie=UTF8&tag=glasetchsecr-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=B000IG2VEO

 

Does it easily connect to a compressor?

[fossilcrazy]

Yes, the brass fitting takes 1/4" NPT. I put a quick connect male fitting, to couple and uncouple easily. 

 

[Lmshoemaker]

38 minutes ago, Sagebrush Steve said:

It was @DevonianDigger in this post:

 

 

Thanks, but alas I've also tried this, haha. This is more to make the unit more precise, but I was able to get a few dispensing needles that my mother occasionally brings home from the hospital by accident to try it. It worked well with the old unit, but since I can't get any powder flow with this unit, it doesn't make too much of a difference yet..

[Lmshoemaker]

38 minutes ago, Sagebrush Steve said:

What abrasive are you using?  I believe Paasche claims it doesn’t work reliably with baking soda, only with aluminum oxide.  I know some people claim it does fine with baking soda, but not everyone.  I also remember reading somewhere (maybe on this forum) about someone who modified the tip to make it work better with soda.

 

I am using dolomite, which is pretty similar to baking soda in texture. It is weird to me that AlO2 works for this unit, since it can't get a finer powder into suspension but seems to be able to get something coarse like the oxide.

[Sagebrush Steve]

59 minutes ago, Lmshoemaker said:

 

I am using dolomite, which is pretty similar to baking soda in texture. It is weird to me that AlO2 works for this unit, since it can't get a finer powder into suspension but seems to be able to get something coarse like the oxide.

Maybe aluminum oxide is less sensitive to moisture?

[Lmshoemaker]

3 minutes ago, Sagebrush Steve said:

Maybe aluminum oxide is less sensitive to moisture?

 

Almost certainly, but I also did dry my material before trying it on my new unit.

[DevonianDigger]

The trick with the finer powders in the AECR seems to be shaking the can regularly to get it loose. A modulator for the can would make it 100x better IMO.

[Sagebrush Steve]

2 hours ago, DevonianDigger said:

The trick with the finer powders in the AECR seems to be shaking the can regularly to get it loose. A modulator for the can would make it 100x better IMO.

Sort of like a paint shaker but less violent?  Sounds like I need to spend some time in my workshop.

[DevonianDigger]

6 hours ago, Sagebrush Steve said:

Sort of like a paint shaker but less violent?  Sounds like I need to spend some time in my workshop.

 

Something like that. Just something that vibrates the can. I think the finer powders, even dried, tend to clump in the canister so the particles are not getting airborne the way they need to.

[Kane]

4 minutes ago, DevonianDigger said:

 

Something like that. Just something that vibrates the can. I think the finer powders, even dried, tend to clump in the canister so the particles are not getting airborne the way they need to.

Set the can on top of the air compressor when it's filling.  

[Kane]

10 hours ago, Sagebrush Steve said:

Maybe aluminum oxide is less sensitive to moisture?

It may not be a moisture issue... When pouring the medium directly into the can from the oven baking sheet, the problem does manifest.  And alum oxide is a bit too aggressive a cutting agent on a lot of trilobites!

[DevonianDigger]

10 minutes ago, Kane said:

Set the can on top of the air compressor when it's filling.  

 

Not the worst idea, really.

[DevonianDigger]

2 hours ago, Kane said:

It may not be a moisture issue... When pouring the medium directly into the can from the oven baking sheet, the problem does manifest.  And alum oxide is a bit too aggressive a cutting agent on a lot of trilobites!

 

It's not moisture, it's almost like a static issue. The finer particles just cling to each other more regardless of moisture, and in that particular can, they tend to just stay clung together. The air coming into the canister is forcing the particles down into a matted situation keeping them from becoming airborne in enough quantity to be useful. By shaking the can, the particles are being sent airborne allowing the pseudo-venturi effect to collect them into the outbound airflow.

[Sagebrush Steve]

3 hours ago, Kane said:

Set the can on top of the air compressor when it's filling.  

 

21 minutes ago, DevonianDigger said:

 

It's not moisture, it's almost like a static issue. The finer particles just cling to each other more regardless of moisture, and in that particular can, they tend to just stay clung together. The air coming into the canister is forcing the particles down into a matted situation keeping them from becoming airborne in enough quantity to be useful. By shaking the can, the particles are being sent airborne allowing the pseudo-venturi effect to collect them into the outbound airflow.

Speaking as someone who has three patents myself, I think you guys are onto a patentable idea!   Of course we would expect all the royalties to go to TFF. 

[DevonianDigger]

3 minutes ago, Sagebrush Steve said:

 

Speaking as someone who has three patents myself, I think you guys are onto a patentable idea!   Of course we would expect all the royalties to go to TFF. 

 

It's basically the same setup as what's on the Crystal Mark, Comco and S. S. Whites. They have modulators built in that vibrate the media canisters at high frequency to keep the particles free and airborne. Wish I could take credit for the idea  

[Pemphix]

IMO it's an effect of all: you need the abrasive material to fit the unit - not all works with all.

Than moisture HAS an effect, it's better to use a drying unit to get out the moisture out of the airstream (different technical possibilities here - drying in the oven will not really help here).

The abrasive will clump and damaging the unit (blocking the air ways of the unit -> valves). And iron powder for example is getting rusty.

Next is the pressure: for sure, if not enough pressure arives at the end, nothing will happen. So you need to know the optimum pressure to work with.

Furthermore, abrasive needs to be clean, sieving it is absolutely necessary (iron powder for example), if not used only one time.

Shaking the unit from time to time helps indeed - is the same with my unit - and not filling it full, helps too. 

 

Drying equip:

http://www.kaeser.de/produkte/druckluftaufbereitung-und-kondensattechnik/trockner/kaeltetrockner/

  

Units:

https://www.sandmaster-technology.com/DE/industry-category/restoration--palaeontology-/13

http://www.hw10.de/alle_werkzeuge/hw150/hw150_01.html

 

 

[Sagebrush Steve]

Would love to hear @Vaniman‘s thoughts on this problem.