Ok I know some of you say you dont need any help with the stepper and ballscrew and some say you do so on that note. So far I have tried 2 different gas struts from the parts store both were to strong. The first one was the correct length and had the correct amount to travel but with 270 lbs on it it wouldnt move. Took it back and this time actually checked to see if I could move the one I picked and it was stong but I could compress it. Installed it and its to stong made the motor grunt to have to push it down. (305oz stepper) You guys that have them did you buy them from LMS or did you get them at a parts house. If from the parts house would it be possible to tell me from where and possibly a part # or manufacturer name. Also do you get the same or more travel than the torsion spring that is currently on mills like mine. The travel is the reasoning I am wanting to do away with the torsion spring. Thanks in advance.
Rick

I just determined the appoximate weight of all the moving parts and then took off a little more than half of that. I was just wanting to stop spin down when the power was cut. If you use a spring that is too strong, then you are over working the motor to push down. I let gravity help in that direction. Thats why I went with a little less than half the weight.
I estimated maybe 65 to 70 pounds on my Z axis. I bought 30 pound gas springs.
These were actually bought for a different project that got canceled. I just used one on my machine. More travel than you need is okay depending on how you mount it. If you have plenty of room, then thats okay. It helps to consider location and the action and location of the spring throughout the travel too.
I had to move mine back from it's initial spot. When I was milling some stuff that was max size for my table, the spring was in the way a little.
Also mount these with the shaft down and the tube up.

Here is where I got mine.

http://www.surpluscenter.com/item.asp?UID=2008013005591187&item=1-1676&catname=hydraulic

You can see how I used it toward the end of this thread.

http://www.cnczone.com/forums/showthread.php?t=32609

I have been trying to find them at local auto parts houses. The ones that were the required size so far have been to strong and the ones that are to short are the closer to the poundage required I think. I havent yet found a site that would give full specs on the cylinders (full length, stroke and poundage). May have to place another order with surplus center.

maxboostbusa,

I do not have one on mine and I am one of those that does not think it is nessesary on a stock CNC conversion. I don't have a problem, with it wanting to screw down even if I try to force it down with a fair amount of force when the power is off. I think if you make something that has a heavy head like Hoss's X2 Freak with all the attachments he has, then I belive it would be nessesary to use one, in fact, he has 2 of them. Try talking to Hoss and ask him his opinion on the matter.

BTW - Do you have a Busa?

Thanks
Bill

I have an Power drawbar and belt drive on top of the mill so far and will have an engraver bracket finished up soon. I am thinking about doing something for tilting the head like Hoss has except maybe without the front to back tilt. I'm not to fond of the tilting column on the mill now and probibly will add some bracing to it to lock it into position.

On the Busa I was a jockey for a guy doing some top speed, drag and a little bit of ol' street racing. He got rid of his bike and I havent ponied up for another one YET. Probibly will do another turbo bike soon. Its fun to run 140 in 6th and snap the throttle open and smoke the tire for a mile. That bike was fast with around 460hp at 24lbs of boost but if I do another one it will probibly make around 600 or so. Planning on making some of the billet parts for the kit on the CNC when I get everything all together.