I am wondering if anyone has tried this pressure trace unit for load development. I am thinking about getting it to use and was wondering if anyone has used it or owns it.

Thanks in advance.

Craig

Here is a link to the company:

RSI, Inc.

I have used Pressure Trace for a few years now. It is a wonderful tool to aid you in load development. It is quite a bit less expensive than the Oehler M43 and every bit as accurate. There have been a few updates to the program (always free) that runs it allowing you to see where the optimum point of exit is predicted to be, thus allowing you to tune your load. It also comes with a no hassle warrenty. If it breaks, they will fix it or replace it for free. The catch is, if you opened it or altered it and buggered it up, it's your problem. Case in point, I had an issue with the cable that connected to my rifle. I returned the unit and was given a completely new set up including an extra gauge at no cost to me. I have been very happy with it

N

There`s been a lot of argument here on what people think of them, I`m sure it`ll start soon. That said I`ve one and concider it a excellent tool. Remember though, it doesn`t give "absolute" pressures but is close. I test a couple of factory rds to establish a bench mark and go from there. I personally believe its more accurate at telling me where my pressures run then other established methods.

Now for the flames...................

I've been using Pressure Trace for about 9 months now.

I find that the indicated pressures are more believe-able in some firearms than others. For example, my PT pressures in a 30-06 seem spot on, but my PT pressures in a 357 have always seemed very low, compared to published data.

Initially, I experienced numerous problems with adhesive failure, but think I have that licked now. I can supply specific adhesive recommendations if anyone is interested.

I've also had a few problems with electrical connections. Owing to the wiring thrashing around as the rifle recoils, the miniature connectors do take a beating, so that will probably be an ongoing struggle.

The software is buggy. Several times I've had to exit out and restart the program, and several times I've had to reinstall the software.

The display on my cheapo used laptop tends to wash out in bright light at the range, so I wait until I get home to study the pressure data -- no big deal. A $20 inverter plugged into the truck's cigarette lighter powers the laptop during lengthy range sessions.

Despite the problems, I've learned as much about reloading in the 9 months that I have used Pressure Trace as in the previous 25 odd years without it. Now I would feel naked and blind if I reloaded without Pressure Trace and a chronograph.

If you decide to get it, understand that it is not idiot proof, that it is challenging to mount the gages correctly, that there will be occasional failures, sometimes due to operator error, and other times due to component failure, and that the indicated pressures may or may not reflect absolute pressures.

quote:

The display on my cheapo used laptop tends to wash out in bright light at the range, so I wait until I get home to study the pressure data -- no big deal. A $20 inverter plugged into the truck's cigarette lighter powers the laptop during lengthy range sessions

I have had good luck with one of these on my laptop, highly recommend it.

http://www.pcshade.com/

Originally posted by popenmann:

quote:

Initially, I experienced numerous problems with adhesive failure, but think I have that licked now. I can supply specific adhesive recommendations if anyone is interested.

What kind of issues with the glue and what are your recommendations

Thanks,

CRaig

There are many adhesives that will stick reliably to metal and a very few that will stick to plastic, but not many will stick to both. Often the adhesive will work OK at first but then will fail over a period of time, maybe after several months and hundreds of shots. When the glue fails, it usually causes the traces to be unusually high (every gage failure that I have experienced caused high traces. Ditto for bad electrical connections).

The gage substrate is made of a polyimide, which is not unlike teflon. Very few glues will stick to polyimide reliably. Plus, the adhesive needs to be flexible, so it won't crack as the barrel and gage expand and contract. It also has to resist peeling, and it also has to hang in there when the barrel gets too hot to touch. It's a tall order.

At one time RSI was recommending Loctite 401 superglue, and it works most of the time, but I did have one failure with it. RSI has since switched to another superglue but they wouldn't tell me which one.

My favorite adhesive to date is is Devcon "flex" superglue, product number 30340. It's not perfect because it doesn't grip metal all that great, but so far there haven't been any failures on 4 different installations (knock on wood).

Denton Bramwell often uses JB weld. I tried it once, and it worked OK that one time, but I wouldn't use it again. It sticks very well to metal but not so well to plastic.

Other bad glues: any quick-set epoxy (too brittle), Loctite 4210 or 4211 (great on metal but don't stick to polyimide).

I located an epoxy that is actually recommended for gluing polyimide to metal, but I haven't purchased it yet due to the price. It is Bondit B45TH, part number 7513A1 from McMaster-Carr. The price is about $45, plus it may requires a $20 applicator, sold seperately.

I purchased a 3M scotch-weld 2216 epoxy but haven't had a chance to test it yet. It is a two part epoxy that is very flexible and rated for both metals and plastics (but not polyimides). It wasn't cheap either, about $25, but I am hoping it will be adequate. Sounds better than JB weld, anyway.

Someone on another forum posted on gluing teflon to metal with a Loctite superglue that came with a "priming" pen. The primer is applied to the teflon prior to gluing and it softens up the surface so that the glue sticks better. However, I haven't seen such a product and don't know the part number.

In addition to the glue problems, occasionally the miniature electrical connectors will have marginal contacts. It might ohm out OK, but still, there is enough resitance to cause flakey traces. A new connector fixed the problem. A couple of times the solder joints have failed. Like the connectors, they ohmed out OK, but apparently the solder bond was marginal and it would cause flakey traces (it was one of my solder jobs, not RSI). Resoldering the connection solved the problem.

The cable connecting the PT module to the strain gage has PVC insulation that is stiff as a board when the weather is cool. The stiff cable aggravates the problem with the connections. I wish RSI would switch to a silicone insulation or something similar that would be more flexible.

I've been using one for about a year with only minor problems. If you don't use the velcro strap to hold the wire in place, it will make some funny readings. Other than that I am sure it is the most accurate pressure estimating device available to the average reloader. I haven't had any issues with glues or software on mine. I do however have problems with bright sunlight making it hard to see traces on my laptop.

Ok, my next question is where is the best place to pick one up from.... directly from the company? or is there a cheaper source?

Thanks,

Craig

Unless you can find a used one, they are only available from RSI.

Has there been any improvement in the system in the last 8 or 9 months?
Thanks
bglenn

I have a unit for sale.. it's the serial version, with the software (balltistics lab) and one bare gauge...

very impressed with the system.. just want to move on to new projects

new, it's 370bucks...

from me, 275, and shipping (should be 10-12buck conus)

do NOT use the "plastic super glue" product.. if you have used superglue on some plastics, you'll see it melts them.. this is a surface finsh designed to prevent the melt... yeah.. still sucks


the RSI is easy to use.. my biggest complaint is the cables aren't long enough for use on big bores

jeffe

quote:

Originally posted by bglenn:
Has there been any improvement in the system in the last 8 or 9 months?
Thanks
bglenn

I'm not aware of any software upgrades. If they would get the bugs out of the software, and make the cable more flexible, there wouldn't be much to complain about. The box itself seems to work very well.

I haven`t had much trouble with the soft ware by I too would like to see the cables changed. They need to be longer for one thing. I fill my bench with rifles, rests, ammo, spotter, crono, PT unit, laptop, there`s no place for me. A cable long enough to reach the next bench or the ground beside me would be a huge help.

A longer cable is not desireable electrically speaking so it is unlikely that RSI will offer one. You can always make your own, or make an extension for the existing cable, but I wouldn't recommend it.

Yes, the bench does get crowded when you add a laptop and your range notebook. Part of the problem that I have with the cable is that it is forever getting tangled up with all the clutter on the bench.

The day will come when the connection will be wireless, and instead of a notebook, the data will go in a little flash card or palm pilot. I think of the RSI unit as the equivalent to a Model A Ford in terms of the evolution of the product.

quote:

Originally posted by Ol` Joe:
There`s been a lot of argument here on what people think of them, I`m sure it`ll start soon. ...Now for the flames...

Hey Ol' Joe, Looks like you are.... wrong again! No need to argue at all about the HSGS fiascos.

You and popenmann are doing an excellent job of describing various problems with them. Once you all describe the next two problems, most of the issues are covered.

1. How it is impossible to get accurate Chamber Dimensions with regular measuring devices.
2. And how that an HSGS can't be counted on to provide reliable data because they can't be Calibrated without "Known Pressure Level Ammo"(aka SAAMI Calibration Ammo).

That should cover most of it along with your other posts.
---

So denton "recommends" JB Weld to put on a Strain Gauge. Thanks for the grin.

HC, I knew ya`d show

I`m not about to argue the chamber measureing and SAAMI calibration ammo thing with ya, but I will say I think recording the top psi measurment from a couple various factory rounds and not excedeing it allows me to "judge" my pressure level much closer then relying on case head or pressure ring expansion. I have to measure to 0.0001" to get meaningful results from them according to the father of pressure ring measuring, Ken Waters. As you`ve already stated, one can`t measure to 0.001" accurately when looking for the chamber diameter.

Hot Core,
I am not going to exchange countless posts debating this because it has already been discussed to death.

Measuring chamber dimensions? Why is that so difficult? Cerrosafe, ball gages, or internal micrometers, take your choice. I have and use all three.

Calibration is an issue for any pressure measurement system. Even I had access to SAAMI ammo, it would still produce different pressures in different chambers. Even I duplicate exactly the pressure tested loads published by Hodgdon and others, and use those loads to validate my strain gage (or my pressure ring measurements, or any other pressure measurement method), those loads may and often do give different pressures and velocities in my guns owing to dimensional differences. Even if I went to the trouble to calibrate the strain gage (or piezio, or copper crusher) with static hydraulic pressure, like Vaughn did, I would still need a way to calibrate the hydraulic gage (which Vaughn didn't do) and I could never be certain that static pressure measurement correlates directly to dynamic pressure measurement.

So yes, calibration is an issue -- for any pressure measurement system used by anyone, including your system, and including the powder companies' piezo systems.

My approach is to install a redundant gage, to validate the gages with loadbook loads, and to never assume that the indicated pressure is absolutely correct, even though some of my installations seem to be well calibrated. My pressure data is mostly used for comparing one load to another, and the PT's excellent resolution and repeatability serve that purpose better than any other system available to me. When in doubt, I try to err on the side of safety.

My attitude about handloading is more conservative and cautious now that I have Pressure Trace.

Regarding the JB weld, what I meant was, that when I went to unistall the gage that had been glued with JB weld, I was able to peel the gage off with little effort. The JB had stuck tenaciously to the barrel but the bond to the gage was pretty marginal. It worked, but I wouldn't use it again.

quote:

Originally posted by popenmann:
Hot Core,
I am not going to exchange countless posts debating this because it has already been discussed to death.

Measuring chamber dimensions? Why is that so difficult? Cerrosafe, ball gages, or internal micrometers, take your choice. I have and use all three.

Hey popenmann, Not disagreeing with you at all. In fact, I agree if a Reloader knows how to use Cerrosafe, that is an excellent way to measure the Chamber Internal Diameter. Again, not arguing at all, just wondering how many folks buying a HSGS(fiasco) have actually used it.

Also agree with the Ball Micrometers "if" a person has access to them and "if" the Micrometer will go into the Ejection Port and far enough into the Chamber to be worthwhile. I'd say it depends on the style of Ball Micrometer a person has access to, but I agree that will get them fairly close.

Not arguing at all when I ask if you think Cerrosafe and Ball Micrometers are something most of us Reloaders(especially the Beginners) have access to?

Did they point out the need for Cerrosafe or Ball Micrometers in the RSI Pressure Trace Manual?

quote:

Calibration is an issue...

By golly, we agree again.

quote:

My approach is to install a redundant gage, to validate the gages with loadbook loads, and to never assume that the indicated pressure is absolutely correct, even though some of my installations seem to be well calibrated. My pressure data is mostly used for comparing one load to another, and the PT's excellent resolution and repeatability serve that purpose better than any other system available to me. When in doubt, I try to err on the side of safety.

My attitude about handloading is more conservative and cautious now that I have Pressure Trace.

Still in agreement. I especially like the portion where you said "never assume that the indicated pressure is absolutely correct".
---

Hey Ol' Joe, As long as the Beginners know what they are actually getting into when they toss out their money, I've got nothing to argue about.

I compliment both Ol' Joe and popenmann on pointing out some of the problems with the HSGS(fiascos) that often do not get mentioned. And I intend to stick a Link to this thread in my file so I can head the next person that asks about them to it.

Excellent posts by both of you.
---

All you Beginners that believe all the trash that denton spewed forth, here is another classic - "JB Weld" put on your firearm.

For those of you who believe "denton" knows what he is talking about, get a tube of JB Weld, clean an area of your Chamer on the outside with Alcohol to remove all traces of oil and squeeze out a bit of the JB Weld right there. Length? About as long as the word "doozie" should be sufficent.

Let it set for a week, a month, or how long you would normally consider having a Strain Gauge stuck to the barrel. Then "remove" the JB Weld and think about what you have done to your rifle.

Another classic "denton doozie"!

SAAMI reference ammunition is used to qualify a barrel, not calibrate a sensor. It is used to verify a new pressure barrel produces the same pressures and velocities that existing SAAMI pressure barrels do. This verifies the cut of the chamber and the rifling in the new barrel, nothing more. SAAMI states it does not calibrate the sensor, but they suggest it might be used to adjust crusher readings which are suspect.

popenmann: Your concerns about the calibration of the hydraulic systems have me curious. I would hope the piezo bench's calibration units are themselves calibrated regularly by other means! Also, you mention dynamic pressures. It seems to me this would be more of a concern with strain gauges than with piezo crystals. I've wondered how fast strain at the outside of a barrel responds to the pressures inside the barrel (inertia -- admittedly small), and I've wondered how fast strain is transmitted through the glue and the plastic of the gauge to the wire inside. I seem to have discarded my textbook on sensors, so I must look for one again to try to find what the frequency response of strain gauges are. Perhaps you've already looked into this one. The needed response isn't that high, at about 1 kHz, but I'll google a bit and see if I can find something...

OK, so far I've found that a conformal piezo sensor has a response better than 300 kHz...

It seems the strain gauge makers are more concerned with the response of the conditioning electronics than of the gauges...

... got to get the kids to school.

Thanks to every one who has a pressure trace and gave their opinion on it. I have been woundering about some of the things talked about. Keep up the good work. It looks like a interesting system.

How easy is it to determine the relative burning speed of a powder using Pressure Trace?

I frequently hear comments like 'the new lot of powder X is slower than the previous lot - I had to add 2 gr of powder to reach the same velocity as my old load." But I'm not certain how that 'proves' the powder is slower, as a lower energy density would have the same effect.

I assume it's possible to save the 'pressure' vs. time trace, and compare it to previous traces? Since we'd be interested in a displacement on the time (horizontal) axis as compared to the vertical axis, calibration shouldn't be as much as an issue.

Have any of you used your strain gauges for this?

Thanks,
Washougal Chris

quote:

How easy is it to determine the relative burning speed of a powder using Pressure Trace?

Go to the RSI web page, they explain useing "rise time" to get an indication of the powders speed. They also show pics of the trace and data that is captured by it.
http://www.shootingsoftware.com/pressure.htm