Gas Spring Counterbalance (Swede???)

[bill south]

Hey Guys
I need to counterbalance the head on my benchtop cnc mill setup. The head weighs about 250# and the servo struggles. On the +Z axis limit, the bottom of the head is about 17 Inches from the base. The head is 13.5" tall and has 6.5" travel to the =Z limit.
What I'm trying to learn about is gas springs. Swede, you installed one on your 5bears machine and I'm sure, researched prior to purchase. Can you (or someone) help by explaining how they work so I can size and order one from maybe mcmaster. I need to get this thing going so I can start on some of my planned projects which is to duplicate the 5 bears machine.
Thanks in advance!
billyjack

[DareBee]

Ideally a counterbalance is to make your moving componenent weigh 0, so your servo and screw only have to deal with inertia and cutting forces.
Gas springs have the advantage of maintaining the same force through the range of it's full stroke.
Get a 250# unit with more than 6.5 stroke and mount it rod end down - done deal

[sridharan]

Hi Guys iam also looking for a counter for my new mini cnc mill the trave is around 250 mm and the weight will be 25 kg (including spindle assembly as well the spindle motor) can any one suggest me a counter balance for my z axis with clear picture.

[BobWarfield]

Hey lookee here:

what size stepper to move head?

Page down and MAX711 has springs on his big ole Industrial Hobbies 200lb mill head. He gives a picture, some notes on how well it works (some loss of travel but now he can use a little bitty servo and things are way smoother), and he also gives a part number and vendor to get one.

Best,

BW