Gempro tips sought

[stubbicatt]

Guys, I bought a Gempro 250 scale, and had it plugged in for nearly a week before using it for the first time. It requires "tare" frequently I have found.

However, it weighs to .01 grains. Prior to buying this scale I had dribbled powder to get to the .1 grain level of precision. My ammo shot as accurately or more accurately than the "nut behind the bolt."

I still weigh to the .1 grain but I trust that the level of precision of the .01 grain assures that my loads are right on.

Anybody have any tips and suggestions for getting the most out of this equipment?

Thanks.

 

[284driver]

Read my post here
http://forum.accurateshooter.com/index.php?topic=3812469.msg36218534#msg36218534

 

[jlow]

A few things.

1) What do you mean “tare” frequently? All scales need to be “tared” occasionally but in a weight session lasting a hour, I may tare it about 10-20 times. It should be stable enough to maintain zero within 0.02 to 0.04 grains at most (yea, that is when I tare…)

2) You don’t need to plug it in for a week to warm up. This is a digital scale and only needs about 30-60 min warm up.

3) Have you level the scale using the bubble level?

4) Have you calibrated the scale? To do the linear calibration, you will need to buy a 50 gram calibration weight. I calibrate it every time before I use it.

 

[BaconFat]

The only thing I needed was to add a ferrite choke to the power cord. You can get them at Radio Shack:http://www.radioshack.com/product/index.jsp?productId=2103222. You can't be sure the guys that work there know what a choke is so educate yourself first and then educate the Radio Shack guys. That's what I had to do.

 

[snakepit]

I used a GemPro 250 scale until my frustration level with it reached its maximum. I did all the normal things that have been mentioned in other post such as no air flow from fans, air conditioning or heating. No fluorescent lights or other electrical devices which could disturb it and even tried the Radio Shack ferrite choke on the power cord. Also making sure it was level but nothing seemed to keep it from drifting. With constant calibration and using the tare function I was able to get my loading done but it took a lot more time than I thought powder measuring should take. One thing that did seem to help was getting rid of that small & short plastic lid on the scale. I went to WalMart and got a plastic container that would cover the entire GemPro 250. It is about 7" round and 5" tall and clear enough to see through. I glued a small handle to it to make it easy to put over and lift off the scale. Also now I could use a good size metal powder pan instead of that very small plastic pan that comes with the scale to clear the lid. This cover did seem to settle the scale down some. After returning the scale and receiving another one which really was not any better I finally realized I was not going to be happy with the GemPro 250. On a past thread about digital scales someone posted a video about Force Restoration Scales vs Strain Gauge Scales. After seeing that video and doing some more research I realized that a Force Restoration Scale was the way to go if you wanted to use a digital scale. The GemPro is a Strain Guage Scale. I bought a FX-120i which has reduced a lot of my frustations in weighing powder and saved a lot of time. There are a lot of testimonials on this forum about the FX-120i. When it comes to Force Restoration Scales the FX-120i is one of the best deals out there.

 

[stubbicatt]

Thanks for the tips. I haven't noticed any drifting per se. It does take a while to settle out when trickling powder into it.

Do you guys attempt to load your ammo to the .00 or is some small variance up or down ok with you?

Thanks guys.

 

[AR Shooter]

Recently purchased the Gempro. For my 'throw, weigh & trickle' (my finger and thumb are my trickler) method of weighing it works great. Is so much faster and more accurate than my previous scale that I can't imagine being displeased. If it will simply be trouble-free for a few years I'll be quite happy.

 

[BaconFat]

I'm assuming when you say, "to the .00", you mean to the actual tenth of a grain. Because I can't help myself, I started out weighing to the .00. I've just recently allowed my loads to be + .02 on occasion, but never -.02. Now I'm pretty sure being off by a kernel or two doesn't make any difference, at least with a .308, but it's kind of satisfying to be right on the money every time.

 

[jlow]

A couple of things that will help you.

First, don’t wait for the scale to settle after you put in the last few kernels, that will be slow and also not accurate. What you want is to always have the scale approach the actual weight from the same direction.

Here is what I mean – Say I already have the weight close and I drop that last few kernels using a spatula (see link below), and then I gently (I CANNOT empharsize this more) put my spatula on the pan and then immediately take it off. Say you are aiming for 40.20 grains and you were close, when you put that spatula on, the noted weight on the scale will go up quite a bit say to 70 grains. When you take the spatula off, it will now settle down to the actual weight. Even if you tickle and it gives you what appears to be the right weight, you should still do the spatula trick, this is because it is very difficult for a scale to sense say a single kernel of varget (0.02 grain) and inertia can hang things up but this won’t happen with the spatula trick. I know this because I worked in research for 30 years and have been using analytical balance for many years and for that matter have more time on the GemPro 250 than anyone on this board (more than 3 years).

http://www.grainger.com/Grainger/BELART-SCIENCEWARE-SPOON-SPATULA-WEIGHING-8ERD4?gclid=CMvW3K2cy7oCFQcSMwod_wkA2A&cm_mmc=PPC:GooglePLA-_-Hand%20Tools-_-Specialty%20Safety%20Tools-_-8ERD4&ci_src=17588969&ci_sku=8ERD4&ef_id=UY0UlgAABdTl8Vt4:20131104131957:s

In terms of accuracy, it really depends on how anal you are, and yes, I am pretty anal. Here is what I do.

First I weight the case with primer attached and note it down in my Excel spreadsheet. Next I weight the powder as accurate as possible, yes to the last 0.02 grain. I then pour the powder into the case and then re-weight the combo. I put this into my spreadsheet and it automatically subtract the weight of the case. At this point, the calculated weight has to be within 0.02 grain of the targeted weight – i.e. if I was aiming for 40.20 grain, then it cannot be more than 40.22 or less than 40.18 grain. The slop is to account for slight drift of the scale which is acceptable. I have found that anything more or less is because the actual powder weight is off. In that case, I pour the powder back in and re-adjust. Sounds like a lot of work but the balance is so good that you only have to do this about 10% of the time. It also gives you a double check should you have a brain fart and put in a significantly more powder than you plan – yes this happens when you are doing a lot of weighting….

 

[BaconFat]

One thing I've noticed about my scale is the weight with the powder pan removed varies. My pan weights 58.16gr. After weighing my powder and removing the pan to pour the powder in the case the scale will read anywhere from -58.10gr to -58.22gr. When I replace the pan back on the scale, most of the time, returns to zero. So I have to wonder, did I actually get the weight I wanted or something else.

I guess I need to weigh my cases empty and full to see what I'm getting so I can have confidence in what I doing.

Although I've never seen one of those spatulas I do use a 1/8 teaspoon to deftly pluck a kernel or two to get my weight right. Which then causes me to wait for the scale to react. Never occurred to me to use it as a little persuader to get the scale to recognize the addition more quickly.

 

[jlow]

BaconFat – Have you done your calibration with the pan off? That may be your problem with drifting.

About using the empty case double check, what I find is it is easy to get confused especially if you are doing something like an OCW where you are weighing quite a few different weights. It is so easy to make a mistake that is why I do what I do. FWIW, I actually add another column in my spreadsheet where I have to physically reenter my powder weight I am weighting (it’s already on the left) that way it is another reminder.

What I do is I put the case on the balance, enter the weight in the spreadsheet, pick the case up and look at the scale, if it does not come back to zero, I zero it and put the case back on, repeat until it goes back to zero, that way you don’t have that slight 0.02 grain error in your final calculation. Again it sounds tedious but you only have to do this sometimes. Once this works out, I go to the next column and enter the weight of the powder I am going to weight – Check, and then I go weight it.

You don’t need the spatula in the link. That is what we use in the lab. If it is small and not heavy and it works for you, it is perfect.

 

[thumper4fun]

Another thing that may help, at least it helped me, is to get rid of the little plastic weigh pan. It is a static magnet. I use the pan from my chargemaster wiped down before each weighing session with a dryer sheet.

 

[savageshooter86]

I have the choke I put on the power cord from Radio Shak and also I just recently put a flat piece of tile under the scale and leveled it. Lately I have not had the scale drift on me at all. But I will tare the scale maybe every 15-20 cases just to make sure everything is close.

I also will dump the powder and let it settle to a reading then lightly touch the pan with the tweezers. Then when it settles and gives me a reading this is what I go off of. Then trickle a few kernels and immediately touch the pan so it tells me the weight instead of having to wait 5-15 seconds for it to read the few kernels.

I actually leave mine plugged in all the time unless it is suppose to rain or be bad weather.

As the stated above I also wipe down weighing pan with old dryer sheet before each session. And usually do the platform too.
I also calibrate the scale before each time I begin a session. I do this with check weights and also against a loaded round that I weighed on a Denver Instrument APX-200 scale. If it does not read what I have logged as the weight for that, I will re-calibrate the scale. Then begin reloading (my scale reads 0.02 gr off of what the big scale did)

 

[snakepit]

After reading everything that you guys are going through to use your GemPro 250 in weighing powder makes be realize more than ever that buying a FX-120i was the correct thing to do.

 

[savageshooter86]

Spending $3 on choke and free piece of tile and taking the time to calibrate it and level it sure seems to be worth saving $530+ vs the FX 120i scale YIKES

OP- still most likely if your scale moves on you, it is still going to weigh more accurate than a beam scale(0.1 vs 0.02 gr). I have not had mine drift more than 0.02 gr during a session

 

[jlow]

I am sorry but you have confused what we are doing as something specific to the GemPro 250. The truth is when you are dealing with balances, yes, even mechanical ones especially ones that can get down to the 0.02 grain area, you are going have to take measures to deal with responses and static.

Not going to be any different with the FX-120i. Heck, I used electronic balance in the multiple thousand dollar range and it’s the same thing. It's the nature of the beast that when you are trying to measure ANYTHING that small or light, a lot of enviromental factors come into play.

 

[snakepit]

Spending $3 on choke and free piece of tile and taking the time to calibrate it and level it sure seems to be worth saving $530+ vs the FX 120i scale YIKES

As I mentioned I did use the choke, in fact I put one on each end of the power cord. I did put it on a piece of lexan and leveled it. I did calibrate it every time I used it and usually several times during a loading session. I only paid $400 Canadian for my FX120i which was about $390 US for it from Cambridge Scales Of Canada. Since last summer when forum member "lil evil" posted this price numerous and I mean a lot of forum members have purchased this scale at this price. There have been several threads about this scale.

Since I paid $140 for my GemPro and $390 for my FX120i the difference is only $250 not the $530+ you mentioned you saved by purchasing the GemPro over the FX120i. Maybe you should shop around a little more or use the search function on this forum.

To me the time and frustration saved and not doubting the accuracy of the GemPro was worth the $250.

 

[savageshooter86]

Was comparing apples to apples on the easiest site to find scales. Did not search high and low for lowest price for comparisons. Either way it is still $250 more dollars I could have spent on components to shoot. You say you still did most of the setting up steps I mentioned that may help. So not seeing the value in spending more $ than I already have to

Not trying to hurt feelings by stating that I am happy with results of my $122 scale vs your $390 scale that both weigh to the 0.02 gr

 

[snakepit]

Not trying to hurt feelings by stating that I am happy with results of my $122 scale vs your $390 scale that both weigh to the 0.02 gr

I know that the GemPro is capable of measuring 0.02 gram, my GemPro did it. It is just the hassles and wasted time involved vesrus the smooth operation of the FX120i. Was the change worth it, absolutely. I will say one good thing about GemPro, they did refund me my money.

 

[jlow]

Snakepit – Not saying the FX120i could not be better than the GemPro 250 but could you elaborate what in your experience was the pros and cons? Been using mine for many years and I have not found anything significant compared to the super expensive electronic analytical balances I have used.

To put things into perspective for you guys, just about everything reloaders use i.e. $1,000 or less would be budget in nature. Real analytical scales goes for thousands of dollars.