Load cell and stepper motor bullet seater!

[#40Fan]

I usually need .001 to .0015 tension to be at 20-40lbs depending on caliber and neck condition.

.002 has put me at 80lbs before.

Might be time to knock the cob webs off of the lathe and make some mandrels.

Beer #2 has me thinking that the arc of the load cell while being pressed might put the seating stem in a bind, but sitting here playing with it, it is nice and smooth with what pressures I can exert with my hands. It wouldn't take much to make a tapered piece to go under the seating die cup so that at 20+ lbs of force, the die is more in line with the load cell and ram. I'll see what beer #3 has to offer.

 

[Jdne5b]

I like how you work.

 

[Rich S]

Very cool.
If your looking to market a system I think you could package a load cell and LVDT along with your graphing to drop in an arbor press such as the KM. I think some folks would prefer to run the press manually to have a feel of the seeting. Id be happy to test it for you

 

[Dusty Stevens]

Id build the load cell to be just a base to run on any press and motorize a good press like a hart or something. Dont think youll sell many of the bottle capper presses compared to a nice arbor press

 

[#40Fan]

Id build the load cell to be just a base to run on any press and motorize a good press like a hart or something. Dont think youll sell many of the bottle capper presses compared to a nice arbor press

Absolutely agree. The bottle capper doesn't scream the precision that the reloaders who would be interested in something like this would be after, but it was what I had on hand. For the beta stage, not too horrible.

Ultimately, something that would convert current arbor presses would be the goal.

 

[#40Fan]

Got it!! The angle of the dangle wasn't right. Dangle = seating cup. Printed out a seating cup holder with a slight angle to it and the next 5 pieces of prepped brass from two or three weeks ago seated perfectly. Beer #2 was right.

It wouldn't take much to make a tapered piece to go under the seating die cup so that at 20+ lbs of force, the die is more in line with the load cell and ram.

Screen capture of the load cell graphs below.

The extra up/downs on the first few are from me holding the button too long......because I wasn't sure it was going to work.

 

[#40Fan]

I finally had the chance to get another video done. Had to record it twice due to light issues and not staying focused.

This has a quick run down of the setup and seating 17 bullets.

In the previous post you will see 5 graphs from 5 previous bullet seatings. I did get the chance to shoot them a couple of weekends ago. In the order they are shown in the post above, velocities were:

3040
3035
3027
3024
3027

I'll hopefully get the chance to shoot this weekend and I'll chronograph these 17 new loads.

 

[#40Fan]

Got my PCB's in today from China. They look awesome and turned my board into a very compact design.



As for my last post, I manage to chrono 4 of the 17 rounds before the battery died on me. Maybe next time.

 

[fguffey]

The first load cell devise I saw was built to be used with a standard press. And then there is the hydraulic press. I continue to see reloadrs insisting on using interference fit between the neck and bullet and then struggling to get anyone to understand it in terms of tension. The hydraulic press measures effort in pounds, I have tension gages, all of my tension gages measure effort in pounds. I do not know that it is an advantage but I have a strain gage. Even with the strain gage I can not get it to shift to tensions.

And then there is the deflection gage, I have one, it measures deflection in thousandths.

And there is no such thing as a standard for tensions based on pounds or interference fit. I sort cases, I keep my cases sorted. I do that to even out bullet hold; I am the fan of all the bullet hold I can get.

F. Guffey

 

[#40Fan]

I am the fan of all the bullet hold I can get.

F. Guffey

Size your 30-06 brass with a 270 die. You'll get all the hold you can muster.

 

[fguffey]

The hydraulic press measures effort in pounds, I have tension gages, all of my tension gages measure effort in pounds. I do not know that it is an advantage but I have a strain gage. Even with the strain gage I can not get it to shift to tensions.

Size your 30-06 brass with a 270 die. You'll get all the hold you can muster.

Why are you so angry? I did not expect anyone to tell me there are X tensions in 10 pounds or 1 pound is equal to x tensions. I have done some heavy duty interference fits, when I wanted to know the amount of effort all I had to do was check the hydraulic gage on the top of the press. Many times it took thousands of pounds to get it started, and then the gage would fall off, if the gage did not fall off I had to make sure the scatter shield was in place.

F. Guffey

 

[Dusty Stevens]

Here is fguffey changing dies in his seating press.

 

[#40Fan]

Why are you so angry? I did not expect anyone to tell me there are X tensions in 10 pounds or 1 pound is equal to x tensions. I have done some heavy duty interference fits, when I wanted to know the amount of effort all I had to do was check the hydraulic gage on the top of the press. Many times it took thousands of pounds to get it started, and then the gage would fall off, if the gage did not fall off I had to make sure the scatter shield was in place.

F. Guffey

Angry? No, not at all.

I too have done some heavy duty interference fits. I think her name was Sharlene.

 

[powderbrake]

#40fan;
Regarding Beer #2, it is difficult to get a compression type system to align with load cells. I designed load cells, and their test equipment for our company which manufactured them.

Yours appears to be a Dual Beam cell, and as such, the vertical deflection at the end should not include any rotation. Errors may be due to the press motion not being sufficiently restrained in the directions perpendicular to the press stroke, rather than the rotation of the end of the load cell. This implies that a good arbor press would not introduce errors. Also the axis of the press may not be perpendicular to the base. If so, your angled piece would correct for this.

The farther the dual beams are apart, the less possibility for rotation at the end. I have a load cell patent (# 4,899,599) where the beams are a couple inches apart, specifically to allow only vertical motion of the end of the beam.

If there is some rotation, then the receptacle could be located over the center of the dual beam, and fastened to the load cell where it is presently connected.

One way to get rid of the problem of a deflection arc is to mount the load cell on a plate and place free rollers (say 1/4 dia balls) between the load cell and the base. This allows the cell to move horizontally to remain under the case. This is a little difficult as you need pockets for the balls on the base and load cell plate.

The other route is a higher rating load cell, which would have less deflection, but your sizing seems perfect for the loads you are experiencing.

Your investigation into the seating forces would probably be advanced by your actuator being attached to a good reloading arbor press. The fact that you have mechanized the force input will help the repeatability of your system. It already provides much greater insight into the seating forces, with much more information than what can be derived from a pressure gauge. Keep up the good work.

As to the semantics battle with Mr Guffey, you, I, and most reloaders have come to express the amount of interference fit on the necks as "tension" and in reality it is some circumferential tension in the brass of the neck. And no, we cannot directly measure it, but we don't care. In reality you don't even measure the seating force in pounds, we measure the amount of strain in the face of the beam........indirectly by measuring the change in resistance of a strain gage.....indirectly by measuring the voltage across a bridge circuit. And again , we don't care, because it works.