X3 counterweight

[DICKEYBIRD]

ajhutchin sent me a PM wanting some more pics of the counterweight rig I cobbled up for my X3 to make it easier to wind the head up & down. I figured someone else may want to see them as well so I decided to post them here. If not, just ignore & go back to your regularly scheduled programming.

The pulleys were pulled from my scrapbox...I think they were spares for a carwash machine at work; just inexpensive plastic pulleys with crude ball bearings. You could make your own from scrap aluminum and rollerblade bearings...or no bearings at all prolly. The 2/1 compound pulley system is important to keep the total amount of counterweight down

The cable is plastic coated 1/8" stranded steel cable bought at Home Cheepo. I picked up the eyebolts, ferrules and end-loops there as well. The straps & bushings were cobbled out of the scrapbox. The "crane" was made from a piece of rusty pipe I picked up on the side of the road.

The counterweight itself is a couple of used up auto front brake discs and several chunks of scrap bolted together. Sorry, I don't know the total weight, I just kept hanging more junk on it until the handle turned about the same both ways....just a tad easier going down to make depth adjustments more consistent.

I chucked a 14mm socket in my old Makita 7.2v drill and it runs the head up & down in a flash. Remembering the shoulder pain I had during the 1st couple months I owned it makes me smile every time I do it.

[Teyber12]

thanks for posting this! this is really nifty!

looks like you took apart a bowflex for the parts hehe

[DICKEYBIRD]

Yup, running the head up & down changing a stock X3 between a drill chuck & a collet several times in a row makes you feel like it's an exercise machine!

[scudzuki]

Great that you could find new life for old brake rotors, too. Excellent "parts-bin" engineering. If this setup were for counterweighting a CNCed column, I would beef up the arm or reinforce it with a strap from the ceiling at the loose end... I bet rapid acceleration/deceleration and direction changes induce a bit of oscillation that does not affect manual operation, but would wreak havoc with a stepper or servo tuned near the limit. This is why gas springs are so good in this application as they have a bit of damping inherently that inhibits harmonics.

Joe

[ajhutchin]

DB, thanks for posting the pics. I've been going back and forth trying to decide whether to do a weighted counter balance or use two gas springs. I figure with the weighted counter balance, the attachment point on the head can be placed close to the balance point to reduce the torque on the gibs.

My only concern with the counter balance is the effects of flex in the counter balance frame on the head if i CNC'd the mill at some point. In all likelihood the machine will remain a manual milling machine for a long time so this isn't much of a concern right now.

On a side note, I just purchased my X3 last month from Grizzly and was surprised that it didn't come with a single gas spring mounted on the back of the column. Is this a recent change made by the manufacturer?

Thanks,
Hutch