# Prototype help needed for a hyperbaric pin



## silverforgestudio (Mar 6, 2021)

So the background do you know where Im coming from...

Being a paramedic in my "real" job, I have a general knowledge of medicine... I also do not work 911- I started there many years ago... but evolved into an interfacility transport guy (Im the dude who picks up from the ICU or Cath Lab at small hospitals and takes you to the big hospitals). So I am exposed to a large number of hospitals and other specialty care medicine centers.

I have been engaged by a friend in a local facility to come up with a solution for a problem their hyperbaric chamber has- replacing a plastic pin for IV lines that goes through the chamber wall.

I have the idea- I have a wooden proof of concept, I have the specs and even the materials.... BUT- I lack the machining equipment to make this happen.

It is a tight tolerance , involves O-ring seals, and a wierd 6% (not 6 deg) taper... 

Anyone have a few minutes to chat and get a chuckle out of the naieve chutzpah of the dreamer?

Thanks for reading and I hope all are enjoying the weekend!


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## eugene13 (Mar 6, 2021)

I wish I could help you but I'm too far away, I'd like to try a hyperbaric treatment once, just for fun,


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## 7milesup (Mar 6, 2021)

Can't believe no one else has chimed in.  
I would love to help but I know there are other guys on here that have serious skillz compared to my butcher abilities.  

I do know a thing or two about o-rings though because I have seen a thing or two.


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## jcp (Mar 6, 2021)

Parker probably has a design and engineering book available for o-rings. We had on at the shop I worked at.


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## 7milesup (Mar 6, 2021)

Yep, they sure do.  Available for download.

5700 is the number of the catalog.


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## Brento (Mar 6, 2021)

I messaged him but i wasnt sure how big the part was going to be. I only have a watchmakers lathe at my disposal right now so i cant do much.


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## Brento (Mar 6, 2021)

Figured message first instead of commenting on here.


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## Alexander McGilton (Mar 6, 2021)

Vacuum and low pressure chambers are something I make and work on fairly often at work. Send me a message to let me know how I can help.


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## silverforgestudio (Mar 6, 2021)

Folks- I thank you for the responses- I have a better idea of the actual part now and the scope of this endeavor. I actually posted the request then went to a meeting with the 3 folks Im trying to help with this.

Here's a picture so you can get a visual:








Its got to be pressure sealed to 48psi (roughly 3.1 standard atmospheres)... this chamber rarely goes above 29-32 psi so 48 is "Max Failure point"




eugene13 said:


> I wish I could help you but I'm too far away, I'd like to try a hyperbaric treatment once, just for fun,


Its pretty cool- actually. I couldnt afford it myself- but I was able to accompany a patient in a large chamber for a 1.5 ATA  dive- hyper oxygenated and felt really good for about 48 hours- many of the NFL teams use them for recovery training. There are "private" clinics in a lot of areas that offer it as a rejuvenation therapy.

And heck- Montana isnt far- the mail reaches there! HA!




7milesup said:


> Can't believe no one else has chimed in.
> I would love to help but I know there are other guys on here that have serious skillz compared to my butcher abilities.
> 
> I do know a thing or two about o-rings though because I have seen a thing or two.


7miles- Butcher abilities are still better than my capacity to do nothing my friend!  I appreciate any input- Are you commercial or private for the picture?



jcp said:


> Parker probably has a design and engineering book available for o-rings. We had on at the shop I worked at.


JCP- thanks my friend! The O ring book you mention I am going to have to look into- Thank you for that resource!



Alexander McGilton said:


> Vacuum and low pressure chambers are something I make and work on fairly often at work. Send me a message to let me know how I can help.


Thanks Alexander- I will be reaching out for sure! It will be tomorrow as I am in between dad duties and tuck-ins and laundry tonight!

Folks- thanks for the resources offered and I am looking forward to moving on this- I will reach out tomorrow! Be safe and as always- at peace.


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## Flyinfool (Mar 6, 2021)

I do not have permission to view your pic.


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## silverforgestudio (Mar 6, 2021)

Sorry for that- try again!


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## 7milesup (Mar 6, 2021)

The O-ring handbook is available for download ---> here <---
Eriks also has a good resource....  ---> Available here <---

PS.  Flew private jets for https://www.netjets.com


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## brino (Mar 7, 2021)

One other good resource is Machinery's Handbook.
They have specs and equations to work out the grooves you need for o-rings.

I used it for some aluminum fittings I made to replace the broken/lost ones on a friends UV water filtration system.
I pressure tested that with shop air and it seemed to work.

-brino


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## silverforgestudio (Mar 9, 2021)

Thank you folks for the assist so fat to this point- without more data I dont want to get into "analysis paralysis" by being afraid of moving forward- Ill post the updates to the project as I move forward- Stay tuned for more shenanigans! 

Next update should be within the week- Thanks for helping folks!


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## brino (Mar 9, 2021)

I hate to be "that guy", but there is one facet of this I did NOT see mentioned above.......
I usually approach projects just from the the technical aspect of "How would I do it", however with anything medical-related a first better question is "Should I do it?"

What if the seal leaks?
What is the IV tube(s) are restricted? 

Special precautions may be required to protect life and cover yourself from legal action.
I would expect a medical devices manufacturers to have engineers with big, expensive training and big, expensive insurance for this task.
Also, there must be hundreds of specifications that must be met, both designed to and then tested to.

If this is just a "proof of concept" or "mechanical prototype" perhaps there is no real risk......but if any of it could ever be used to actually treat people then it should be re-designed by the professionals.

-brino


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## silverforgestudio (Mar 9, 2021)

Brino- right you are on all accounts- one reason the Parker catalogue was a better choice than Machinery Handbook was it has the ISO and other industry solutions that do not need to be re-hashed or vetted. 

Ill reach out off the forum to give more info- Not trying to hide anything for those reading/following along- but the due diligence portion of any project (What Brino is referring to) is something I cannot divulge as it is project specific and you need to be able to do your own. 

Not being terse- but my solution may not work for your problem- you have to figure that out to insure the project is viable.


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## silverforgestudio (Apr 20, 2021)

Allright folks- its 11pm on a Tuesday night and Im going to be reaching out to each of you individually- I owe the group a bit of an explanation...

So Almost a month... In that time, a cease and desist, a gag/halt request, several long conversations and 2 meetings with team members and we are back on track!

So the summation of the story is I have received a clearance to do R&D on the project with testing in the event we can make it work. 

My personal apologies for dragging this out- but I didnt have a choice as I was asked to stop work until it could be figured out even IF it could happen.


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## matthewsx (Apr 21, 2021)

My daughter is a bio-medical engineer, there's serious money and very serious barriers to entry for that field.

John


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## brino (Apr 21, 2021)

silverforgestudio said:


> So the summation of the story is I have received a clearance to do R&D on the project with testing in the event we can make it work.



Excellent, thanks for the update.

-brino


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## 7milesup (Apr 21, 2021)

No worries *@Silverforgestudio*. Projects seem to take way longer than expected; that seems to be the norm. As an example, I was given the task of determining why some of our product was being damaged in shipping and a course of correction. I figured "meh, 3 weeks and I'll have it done". I am now going into the _*4th month*_ and I am getting closer!


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## silverforgestudio (Apr 21, 2021)

matthewsx said:


> My daughter is a bio-medical engineer, there's serious money and very serious barriers to entry for that field.
> 
> John


Agreed... And the waters get even muddier when you have 3 facilities and 2 companies in the "entity mix"




7milesup said:


> No worries *@Silverforgestudio*. Projects seem to take way longer than expected; that seems to be the norm. As an example, I was given the task of determining why some of our product was being damaged in shipping and a course of correction. I figured "meh, 3 weeks and I'll have it done". I am now going into the _*4th month*_ and I am getting closer!


Well... That is comforting to know from my perspective- sorry you're jammed up as well, but glad I've got some company too!

I feel like this is why stuff doesn't get done... It's just attrition and being able to outlast the arguments...


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## lesrhorer (Aug 6, 2021)

silverforgestudio said:


> It is a tight tolerance , involves O-ring seals, and a wierd 6% (not 6 deg) taper...


So it's curved?


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## 7milesup (Aug 6, 2021)

lesrhorer said:


> So it's curved?


Taper is different than curved.


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## lesrhorer (Aug 6, 2021)

7milesup said:


> Taper is different than curved.


I realize that., but "%" is not a measure of a conical surface.  Indeed, it's not in and of itself really a measure of any sort of surface.  If, however, the diameter of an object changes uniformly by some factor - like 6% - over some unit length, then its surface is curved along its longitudinal axis.  This compared to a cone, for example, whose diameter changes by a fixed measure over some unit length.  The longitudinal cross section is a simple triangle.

Oh, and just by the way, conical tapers are only 1 type of taper.  Any object whose perpendicular cross section diminishes in circumference as one moves in one direction along the longitudinal axis is tapered.  The collapsing circumference needn't even be uniform, just continually decreasing.  Sheet metal screws, for example, are tapered:


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## 7milesup (Aug 6, 2021)

^^^ Interesting^^^.  Thanks for the enlightenment.  
The "%" is an odd way to look at a taper, if that is what is going on there.


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## jmkasunich (Aug 6, 2021)

lesrhorer said:


> I realize that., but "%" is not a measure of a conical surface.  Indeed, it's not in and of itself really a measure of any sort of surface.  If, however, the diameter of an object changes uniformly by some factor - like 6% - over some unit length, then its surface is curved along its longitudinal axis.  This compared to a cone, for example, whose diameter changes by a fixed measure over some unit length.  The longitudinal cross section is a simple triangle.
> 
> Oh, and just by the way, conical tapers are only 1 type of taper.  Any object whose perpendicular cross section diminishes in circumference as one moves in one direction along the longitudinal axis is tapered.  The collapsing circumference needn't even be uniform, just continually decreasing.  Sheet metal screws, for example, are tapered:
> View attachment 374528


Pretty sure its not "diameter changes by a percent of the diameter", but "diameter changes by a percent of the lengthwise distance".  For example, this table says that a Morse 3 taper is 0.6024 inches per foot or 0.0502 inches per inch.  "5.02%" is just another way of saying "0.0502 inches per inch".


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## brino (Aug 6, 2021)

Great discussion!

Thanks to all involved.
It goes to show how carefully one must spec the part to not be misunderstood.
I think the perspective/experience really comes into play here.

As Dr. John Zoidberg once said:


> You kids and your topologies!








-brino


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## lesrhorer (Aug 9, 2021)

jmkasunich said:


> Pretty sure its not "diameter changes by a percent of the diameter", but "diameter changes by a percent of the lengthwise distance".  For example, this table says that a Morse 3 taper is 0.6024 inches per foot or 0.0502 inches per inch.  "5.02%" is just another way of saying "0.0502 inches per inch".


That is an ordinary conical taper.  The OP said it was "weird", though, and the taper did actually look cured in the picture.  This could have simply been perspective, however.


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## lesrhorer (Aug 9, 2021)

7milesup said:


> ^^^ Interesting^^^.  Thanks for the enlightenment.
> The "%" is an odd way to look at a taper, if that is what is going on there.


If jmkasunich is correct, as well may be the case, then it is simply a different unitless measure.  If it really is a geometrically decreasing taper, however, then it is not so odd, except that the unit length must be specified.  Unlike a conical, parabolic, hyperbolic, or elliptical taper, which can be specified with only the angle of the vertex, or the eccentriciy in the case of an elliptical taper, the spec is not unitless.  Here is a picture (sort of) of a 6% per unit geometrically decreasing taper:




Unlike the linear relationship between the cross section and the axis of a conical, etc. taper, a K% / x unit taper is NOT the same as a 2K% / 2x unit taper.  A 6% / unit taper is the same as an 11.64% / 2x taper.


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## 7milesup (Aug 9, 2021)

After reading through these last few posts it is no wonder I became a pilot versus a career that required thinking.  LOL


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