POTD- PROJECT OF THE DAY: What Did You Make In Your Shop Today?

I put the FINAL coat of white enamel on the mill head castings! I'm too sexy for this mill, too sexy for this mill...

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Public Service Announcement - This Rust-oleum Professional enamel goes a LONG way dang! Given the size of this bed mill and oil based enamel being banned, yeah I purchased 2 more gallons just in case. But with multiple coats on a few parts I barely dented the first gallon. Now I feel like I'll have 2 gallons left over. It's not your typical house wall paint is it.

Public Service Announcement - White Rust-oleum Professional spray enamel is a different color than White Rust-oleum Professional enamel in a can, which is quite a bit whiter. DOH!
 
coolidge said:
Public Service Announcement - This Rust-oleum Professional enamel goes a LONG way dang! Given the size of this bed mill and oil based enamel being banned, yeah I purchased 2 more gallons just in case. But with multiple coats on a few parts I barely dented the first gallon. Now I feel like I'll have 2 gallons left over. It's not your typical house wall paint is it.
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Say what? I pity the foo who bans the good paint.
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But seriously. Rustoleum enamel is alkyd paint, which is classified as an oil-modified paint, and it's solvent is mineral spirits which is a SVOC not a VOC. So what 'choo talkin bout? You got some messed up wires or something, or are you privy to some of that A-Team secret intelligence that Mr. T uses to go after the bad guys who be treadin' across his real estate?
 
Cleaned up the no name 4-jaw that came with the lathe
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Rust remover and ultrasonic cleaner leaves kind of a parkerized finish
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Mounted on the lathe. Lot of back and forth adjustment but I managed to get it within.0005 or so of runout with a 3/4" dowel about 2 1/2" from the jaws.
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Next up was the Bison 4 jaw scroll
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soaked the jaws in rust remover and gave the body a scotch brite rub to clean.
need to make a backing plate for this one. IMG_9005.jpeg
 
Firstram said:
I think you mentioned they were 120 lb struts? How did you couple them together, I can’t quite tell in that backlit picture.
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Yes, apologies for the crummy picture. I didn't realize the flash didn't work until I was back in the house.

What I did was bore out some heavy wall pipe for a close fit that let the strut tubes slide inside. Then welded on a butt cap on one end. Turned it all back down to a nice consistent O.D. and drilled and tapped for the threads on the end of the strut. This left enough exposed threads to put a locknut on the outside.

I milled a flat spot on the outside of the tubes so they were easier to clamp and weld. This also got the center lines of the struts closer together. The tubes are 5" long which is the amount of overlap I needed to get everything to fit. It is also sufficient to transfer the twisting forces along a good length of the strut in an effort to keep them from wanting to bend.

The struts are rated at 130# of push with a breakout force of 160# when collapsing. The two struts connected together don't add any force, only travel length. Putting a set on each side doubles the lift to 260# and the breakout force to 320#. I must have gotten that about right because just before the knee starts to come down it gets lose on the dovetails of the column. This is with nothing more than the 6" vise on the table. If I throw the rotary table on too it might be about perfect.
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Nice! The combined force plus breakout threshold is now 290 lbs, not 320 (but who's counting, right? ). Are you springing the knee for a CNC conversion, or just an easier time cranking?
 
pontiac428 said:
Nice! The combined force plus breakout threshold is now 290 lbs, not 320 (but who's counting, right? ). Are you springing the knee for a CNC conversion, or just an easier time cranking?
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I just wanted to take some of the wear pressure off of the lead screw and nut. At some point in the past the casting that holds the nut got busted where the bolts fasten the nut to the casting. The bolts are still in there, but I have no idea how much holding power they actually have so I am trying to protect the torque on the nut from doing any more damage to the casting. The easier cranking is an added bonus as apparently I am not 25 years old any more....

I am curious how did you come up with the 290 pounds of force? Did I do wrong by adding the two sides together? I'm the first to admit that my math/geometry skills are few. As an example I explained to a friend that I was worried about the center line of the struts not being in the center of the forces and that it might cause everything to twist and possibly break the mounting studs. We did some measuring and he pulled out his scientific calculator and told me that the cross component force was less than 10# at the ends of the rods. I have no idea how he came up with that number, something to do with trigonometry I suspect. I'm always curious about such stuff, even if I don't understand it.
 
Can someone provide a link to someplace I can read an explanation/definition of breakout force/threshold? My Google Fu is failing me.

Alternatively, is it equivalent to "stiction" in pneumatic cylinders? Is it because the seals, at rest, tend to take a set and grip, so there is a higher force required to break the seals loose when the cylinders are required to change length relative to the force required to keep the piston/rod in constant motion?
 
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