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CP or Dnsons ARO


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Hi everyone :),

 

Recently I’ve been looking into getting an air scribe and have looked at three, the cp9160, cp9361 and the dnsons ARO. Which would you recommend. The cp9160 is considerably cheaper than the other two scribes. Also, which scribe will be best for working on ammonites? And what would be the smallest possible compressor that could work with one of these? Thanks.

 

 

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F320A8EB-D5CF-41D5-A453-D57E9CA09F1D.jpeg

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I would think the longer stylus would be a bit more helpful to get into tighter spots on the ammo whorls. 

 

The CP 9361 (the middle one pictured above) is more the workhorse of tools, comparable to PaleoTools' ME9100. It will move a lot of tougher matrix, but not the best for very fine work (although it can be done in a pinch, but not recommended without some experience). 

 

The minimum you should be running the CP 9361 is about 90 PSI. It actually favours around 100-110, from what I've heard from others, but I'm able to dial down my ME-9100 to 70. 

 

In terms of air compressor, the bigger the volume you can afford, the better. Anything less than a 20 gallon tank is going to be turning on quite often, reducing its longevity. 

 

I'll quote our prep pro Kris  (@Ptychodus04) on this point: "If you are going to run a small air scribe, a compressor running at 90psi and around 3cfm with a 20L tank is the smallest you can use with any success. You will still have to stop every 5 minutes or so to let the compressor catch up (not a good scenario)."

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8 minutes ago, Kane said:

I would think the longer stylus would be a bit more helpful to get into tighter spots on the ammo whorls. 

 

The CP 9361 (the middle one pictured above) is more the workhorse of tools, comparable to PaleoTools' ME9100. It will move a lot of tougher matrix, but not the best for very fine work (although it can be done in a pinch, but not recommended without some experience). 

 

The minimum you should be running the CP 9361 is about 90 PSI. It actually favours around 100-110, from what I've heard from others, but I'm able to dial down my ME-9100 to 70. 

 

In terms of air compressor, the bigger the volume you can afford, the better. Anything less than a 20 gallon tank is going to be turning on quite often, reducing its longevity. 

 

I'll quote our prep pro Kris  (@Ptychodus04) on this point: "If you are going to run a small air scribe, a compressor running at 90psi and around 3cfm with a 20L tank is the smallest you can use with any success. You will still have to stop every 5 minutes or so to let the compressor catch up (not a good scenario)."

Thanks, the description of the dnsons says that it can run from 55 to 90 PSI. This is better than the other two am I right? :)

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I've heard some good things about Dnsons, but I don't have any firsthand experience with that one to confirm that. I wouldn't base your decision on the PSI, though. The two CPs you have on option there would also be for different tasks / matrix hardness. If it were me I'd go with the CP as that is a brand I know about and trust. 

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If you are looking at scrimping on costs you are not yet at the point you need to be to really get into this. In the end you get what you pay for. 

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12 hours ago, Kane said:

I've heard some good things about Dnsons, but I don't have any firsthand experience with that one to confirm that. I wouldn't base your decision on the PSI, though. The two CPs you have on option there would also be for different tasks / matrix hardness. If it were me I'd go with the CP as that is a brand I know about and trust. 

Thanks again. Would you recommend the cp9361 or the cp9160 for Charmouth/Lyme Regis ammonite nodules?

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I'll have to defer to our UK folks as I haven't had the opportunity to prep those ammonites. I think @DanJeavs does work on these, and it doesn't get more professional in terms of ammonite prep in general than our (non-UK) @Ludwigia who has maybe done his fair share of commission work that might have included ammos from that area.

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Ptychodus04

The longer stylus is better. You will need it to get into the umbilicus effectively. 
 

Of the 3, I only have experience with the CP9361. It worked well for bulk removal but that’s all. You can’t get details worked out with the stock stylus. I worked it hard for a few years and it suffered a catastrophic piston failure. I opened it up and the front end was full of shrapnel!

 

I run a 2.5hp, 4.7cfm compressor with a 21 gallon (79.5L) tank. This cycles every 10-15 minutes and recovers in about 2 minutes. This will run everything I use at full capacity except for my Super Jack. I have to run it at 1/2 power due to air consumption. I wouldn’t recommend a smaller compressor (even though I proposed a “minimum size” as @Kane quoted above). Minimum capacity just wears out your equipment.

 

I agree with @Malcolmt, if you have to scrimp on cost, save your money a bit longer and buy something that will work well.

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Bob Saunders

Regarding the Dnsons check on available replacement parts and pin/needles. If non available and a throw away item I would buy a better one. Not sure if needles are available in a different brand name that will  interchange.  

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I'm not at all familiar with any of these tools, so I'm afraid I can't be of much help here.

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* Possibly a blast box

* Something for dust collection

* Magnification and light

* Safety equipment (ear-cancelling headphones, high-rated dust mask)

* Oil for the occasional few drops in the scribe

 

And most importantly:

* Patience

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23 hours ago, Ptychodus04 said:

The longer stylus is better. You will need it to get into the umbilicus effectively. 
 

Of the 3, I only have experience with the CP9361. It worked well for bulk removal but that’s all. You can’t get details worked out with the stock stylus. I worked it hard for a few years and it suffered a catastrophic piston failure. I opened it up and the front end was full of shrapnel!

 

I run a 2.5hp, 4.7cfm compressor with a 21 gallon (79.5L) tank. This cycles every 10-15 minutes and recovers in about 2 minutes. This will run everything I use at full capacity except for my Super Jack. I have to run it at 1/2 power due to air consumption. I wouldn’t recommend a smaller compressor (even though I proposed a “minimum size” as @Kane quoted above). Minimum capacity just wears out your equipment.

 

I agree with @Malcolmt, if you have to scrimp on cost, save your money a bit longer and buy something that will work well.

Would a 50 litre compressor work well? Sorry for all the questions everyone. For example this one: also, oil or oil free? :)

4E88AC2E-EE53-457D-9F86-268A880F3EF1.jpeg

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Must be oil free if you ever are looking at getting into air abrasion. If it is only ever going to be scribe then either is good. Must be capable of approximately 5 CFM at 110 PSI. Most lower cost scribes run best at 90 to 110 PSI. Some of the more expensive scribes work in the 50 PSI range and the most expensive can run down around 20 PSI. I believe if you are only going to own 1 scribe then the best first purchase is an Original American ARO (not the Chinese clone as they do not last).

 

I currently own and use

      Original ARO 8513

      Modified Original ARO 8513 with longer stylus

       Pferd MST-31 (my most used scribe, very expensive, Stylus are expensive and do not last long)

       Paleotools MicroJack 2 (Very fine detail but must use with air blower as does not blow away dust that it creates, very expensive)

       Chicago CP-9361

        Chicago CP-9361

       British Sealy  (good for bulk matrix removal and not very expensive)

        Ingersoll Rand EP50 (my normal bulk tool but lots of vibration transferred to fingers)

 

On my list to buy one of these days are HW10, HW322

 

 

 

 

 

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3 minutes ago, Malcolmt said:

Must be oil free if you ever are looking at getting into air abrasion. If it is only ever going to be scribe then either is good. Must be capable of approximately 5 CFM at 110 PSI. Most lower cost scribes run best at 90 to 110 PSI. Some of the more expensive scribes work in the 50 PSI range and the most expensive can run down around 20 PSI. I believe if you are only going to own 1 scribe then the best first purchase is an Original American ARO (not the Chinese clone as they do not last).

 

I currently own and use

      Original ARO 8513

      Modified Original ARO 8513 with longer stylus

       Pferd MST-31 (my most used scribe, very expensive, Stylus are expensive and do not last long)

       Paleotools MicroJack 2 (Very fine detail but must use with air blower as does not blow away dust that it creates, very expensive)

       Chicago CP-9361

        Chicago CP-9361

       British Sealy  (good for bulk matrix removal and not very expensive)

        Ingersoll Rand EP50 (my normal bulk tool but lots of vibration transferred to fingers)

 

On my list to buy one of these days are HW10, HW322

 

 

 

 

 

Thanks, I’ve never been able to find an original ARO before. Could you please point me to somewhere where I could find one? Thanks. Also, the compressor above is listed at 9.6 cfm. Is that fine?

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You need to look at a chart that shows for that compressor how many CFM it delivers at each PSI range. You are looking for 5CFM at 110 PSI.

 

Original AROs come up from time to time on online, that where I got mine both used in the $200 range. You can still buy o-rings , springs and stylus so as long as the bushing is not badly worn you can make any used and working one close to new.

 

This is the compressor I use . I run it 24 hours a day 365 days a year . Most weeks I do 20 or more hours of prep using compressed air. It is in the garage and a 100 foot line takes the air into my basement prep lab. I burn one out about every 24 months. I have tried other brands over the years and this one is the best at the $500 Canadian price point. This one is oiless as I have high end abrasion equipment as well. Oil in the lines will ruin that equipment. You need to bleed out the water in the tank every few days when the garage temp is above the Dew Point. Not a big issue in the Canadian winter.

dewalt.jpg

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In my opinion that model dynson in the video directly above is not well sited for fine detail . Too much vibration and not a consistent stroke length.

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5 hours ago, Malcolmt said:

You need to look at a chart that shows for that compressor how many CFM it delivers at each PSI range. You are looking for 5CFM at 110 PSI.

 

Original AROs come up from time to time on online, that where I got mine both used in the $200 range. You can still buy o-rings , springs and stylus so as long as the bushing is not badly worn you can make any used and working one close to new.

 

This is the compressor I use . I run it 24 hours a day 365 days a year . Most weeks I do 20 or more hours of prep using compressed air. It is in the garage and a 100 foot line takes the air into my basement prep lab. I burn one out about every 24 months. I have tried other brands over the years and this one is the best at the $500 Canadian price point. This one is oiless as I have high end abrasion equipment as well. Oil in the lines will ruin that equipment. You need to bleed out the water in the tank every few days when the garage temp is above the Dew Point. Not a big issue in the Canadian winter.

dewalt.jpg

Thanks again :). Do you know if the ARO 8315 would be similar to the cp9160?

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The 9160 is a very low end scribe. I always recommend that if you are cutting corners on costs then you should wait. Many a fossil has been ruined by low end equipment. The costs add up very quickly, scribe, scope, connectors, hoses, compressor, water trap , shop vac... just starting you are easily over $1000

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18 hours ago, Malcolmt said:

Must be oil free if you ever are looking at getting into air abrasion. If it is only ever going to be scribe then either is good. Must be capable of approximately 5 CFM at 110 PSI. Most lower cost scribes run best at 90 to 110 PSI. Some of the more expensive scribes work in the 50 PSI range and the most expensive can run down around 20 PSI. I believe if you are only going to own 1 scribe then the best first purchase is an Original American ARO (not the Chinese clone as they do not last).

 

I currently own and use

      Original ARO 8513

      Modified Original ARO 8513 with longer stylus

       Pferd MST-31 (my most used scribe, very expensive, Stylus are expensive and do not last long)

       Paleotools MicroJack 2 (Very fine detail but must use with air blower as does not blow away dust that it creates, very expensive)

       Chicago CP-9361

        Chicago CP-9361

       British Sealy  (good for bulk matrix removal and not very expensive)

        Ingersoll Rand EP50 (my normal bulk tool but lots of vibration transferred to fingers)

 

On my list to buy one of these days are HW10, HW322

 

 

 

 

 

Would you recommend a Sealey SA-96 :)? Sorry for all my silly questions.

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The sealey is really only for initial roughing . It is the least precise of all the scribes I own. However it is great for removing a lot of matrix away from the fossil fast

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Ptychodus04

You can buy an oil lubricated compressor and still do abrasive work. doing this requires additional equipment but it is doable. I have an oil lubricated compressor; between it and the abrasive I have 3 coalescing filters and a massive desiccant canister.

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Fossildude19
22 hours ago, Pterygotus said:

Thanks, I’ve never been able to find an original ARO before. Could you please point me to somewhere where I could find one? Thanks. Also, the compressor above is listed at 9.6 cfm. Is that fine?

LINK

 

Aro8315.JPG

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