Shooting Rig Upgrades (Advice Needed)...

[jmace]

Currently, I am using gear motors to control both horizontal and vertical movement on a shooting rig (http://jimmace.com/main/default.aspx...rs&out_c=shoot). These motors are controlled via a joystick. My current problems are that the gear motors are very slow and when engaged they turn at full speed, and they are noisy. I would like to make some upgrades to my current system as follows:

Variable speed motor control from a joystick.
Increased range both horizontal and vertical.
Reliability.

I looked into using linear actuators for vertical movement (elevation), but they are pretty bulky. Therefore, I was thinking about using stepper motors with an Acme threaded rod similar to what I have now. The total weight that the system will have to move is well under 20 pounds. Will a stepper motor fit this need. What other components will I need besides a motor controller and a joystick with potentiometers?

I am not an engineer, just a simple computer programmer, so please keep the explanations somewhat simple...

[turmite]

jmace,

First off welcome to the forum. Second you have my attention. My site is
www.turnercustoms.com Take a look and you will see why you have my attention. If there is anything I can do to assist you, ask!

Steppers may be too noisy for you since you are using this is a hunting situation. Do you have an idea of weight the screw will be lifting in the vertical? This would dictate the size of the stepper needed.

Now another idea might be hydraulic. (sp) I have a friend who use to have a benchrest set up that used hyd for both the windage and elevation. It did require the turning of a screw, but that could be accomplished via a small stepper or servo.

Let me know if I can help in any way.

Mike

[jmace]

Mike,

That Barracuda is absolutely mean looking... :-)

About a year ago I was looking into hydraulics or pneumatics, but it was hard to find miniature components. My heaviest rifle weighs 9.5 pounds and the plate that everything sits on is less than 5 pounds, so we're not moving anything super heavy. I just want to build something that is robust enough to handle the recoil of a Magnum, say 375 H&H. I do plan on going to Africa in 2008.

Would you happen to have any pictures of your friends benchrest set up?

[turmite]

Thanks for the compliment. I no longer own or make the Barracuda but I can promise you something better called the Supercuda is coming!

I don't have a pic of the rest but the principal was simple. The turning of the screw was in essence the same thing as a cylinder moving a shaft. The screw was the cylinder and the shaft. There was a little piston resting on the bottom of the vertical that when the screw was turned the fluid moved the piston. I don't know if it was a completely enclosed system or if it had bleed-off's in it. I will try to do a little research and see if I can find the man that made it. Maybe he could be enlisted to help. It was a very simple system though and that is always good......especially if you plan on taking any dangerous game.

Mike

[jmace]

No dangerous game for me this trip. I mostly going for plains game.

Thanks for the interest in my project. I will try to use more research as well.

Jim

[wolfmetalfab]

imo if you plan to use something like a 375 H&H, you might want to think about planning some sort of system to absorb some of the recoil because it may be enough to cause the mount/turrent itself to break/bend, open sights or long eye relief scope might be a good idea as well to use with a cannon like that

if you could post/email me some detailed pics of your current turrent setup and what its going to be mounted to ie wheelchair or used off a bench for target/sight tuning (trust me with a 375 h&h sighting it in would be better with it bolted down to something other then yourself ) the hydraulic idea sound like a good one as well, I'll start tossing some ideas around for the mount and drive systems, but someone else will have to help with the control system

few questions to start the gears rolling in my head, how much swing do you want for the vert/horiz and I'm going to guess that you would want the thing to be able to fit most rifles/shotguns/blackpowders right?

[turmite]

Hi Jim,

I haven't forgot you. Here is a copy of an email I got from a man that has made one of these before. There are a couple of other contacts I haven't made yet but will keep trying. If you want to contact this guy I send you his email address.

Mike

"Mike,
Sorry to take so long to get back with you. I have made a hydraulic rest for a fellow in Australia. It used hydraulic cylinders to move windage and elevation. The hoses ran back to a block where there were two hydraulic cylinders with threaded thumb screws. A rest like this will be around $500 plus shipping.

Thanks,

Scott"

[jmace]

That would be great. I will get some detailed pictures of my rig tonight, hopefully.

[wolfmetalfab]

well that hydrolic setup doesnt seem too hard the more I think about it, what has me thinking is the mount and recoil management, after looking at the vid of you shooting with your current rig (30-06 right?) and thinking about the recoil of a .375 H&H Mag. (270 grain at 2690 fps MV 9.0lbs of rifle is 36.1 ft lbs 16.1 fps free recoil velocity from chart found here http://www.chuckhawks.com/recoil_table.htm )
I have some ideas for the top half of the mount, see about getting it on paper by next week and attempt to get something built in the next few weeks
oh and I can range test my ideas when I build it w/ a 458 win mag or with a 12ga 3 1/2" mag (about 70+ ft lbs of recoil)