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Sharp SV2412 drawbar removal

pianoman8t8

Hot Rolled
Joined
Nov 14, 2012
Location
Maine, USA
I think I've narrowed it down to something within the drawbar assembly is keeping the drawbar from going all the way down. It was changing tools just fine a couple days ago, now the drawbar only goes down about 75% of the required distance and won't release the tool. I took off what I could to try to get at the spring washers but am not there yet.
 
Wow cool. I use the sv2412 every day and just took apart an entire carousel that had some pieces in it crushed.

Will ask boss on Monday about your situation.

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I'm still waiting to hear back from Sharp, but there is where I left off last night. Not sure what to do with this pc on top with the threaded holes, according to the parts diagram, it looks like it threads in place. I made a custom spanner wrench thing last night and threaded a couple bolts into those holes, but it wouldn't budge.

SV2412 drawbar.jpg
 
Got the drawbar removed last night, everything on it looks just fine. It actually compressed down just fine and released the tool that was in the spindle, after making a steel plate and using a couple long bolts and using it as a drawbar pusher. Anyway, now I'm wondering if the problem is with the air/oil cylinder that pushed on it. I didn't check the level of the little oil reservoir before removing it, and I know I lost some oil while handling it, but it does show a little low now. Not sure if that would cause this situation?
 
More updates... Drawbar finally out, everything was fine with it. Put it all back together, topped off oil in reservoir, fired up machine, put in JOG, pressed manual tool unclamp, drawbar went down all the way, and upon clamping again (drawbar going up) it blew the cap off the oil reservoir, spewing oil about. So, it's back-feeding air into the oil reservoir, at a steady rate in the clamp position. Guess it's time for a cylinder rebuild! Anyone on here ever rebuild one of these cylinders? I haven't, but I can't seem to think it'd be too difficult... Waiting to hear back from Sharp regarding a rebuild/seal kit.
 
See if you can find some manufacturer numbers on the cylinder, and go direct, you will save lots of time and money potentially. May also be locally available.
 
It's a Chen Sound Industrial brand air over oil cylinder. I suspect they're pretty much direct from overseas. Currently looking into disassembling and seeing if the seals are off-the-shelf McMaster items.
 
If you have a hydraulic shop near by they will likely have needed seals in house (or close enough), it should be a quick and easy job for them to disassemble and replace the seals.
 
Hey guys and gals, finally figured out the problem, half-assed a solution to get by until the new assembly arrives. So the drawbar was fine, but a royal pain to get at. The cap on top was very tight, used a 1.5ft long aluminum flat bar with the hole pattern drilled into it, but then had to add my 2ft adjustable to the end of the aluminum bar and even then, push on it with BOTH hands, while the spindle was being held via the vise (cringe). All the spring discs (Bellville washers?) were fine. Re-assembled, thinking OK maybe it's the cylinder that pushes it all down upon tool release. After putting it all back together minus the head cover, topped off cylinder reservoir with oil, and the initial push down went fine, but when it retracted, blew the top off the reservoir and most of the oil as well. Subsequent cylinder activations were less and less successful since not it's compressing air in the hyd cylinder instead of displacing fluid, then pushing the piston down. See photos below. Problem: deep rust pitting on lower cylinder wall, causing air blow-by, which was then forcing it's way past the hyd piston seal, since both are not pressurized at the same time. Hydraulic pressure to push down, then air on the bottom pushing up to get piston end off drawbar end. I filled in the voids with JB weld, bored smooth, and added a groove in middle of piston which lines up with proximity switch plate for easy air escape if it did still leak. Put it all back together, works great now.

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I've only had this machine for a few months now, and I do have a refrigerated air dryer for my compressed air supply. This looks like it's been a problem for quite a while now, since there was also scratching on that cylinder that would've suggested someone took a screwdriver to scrap off rust previously.
 
At my last shop we had similar trouble with what looks to be the exact same unit on an amera seiki vmc. We polished the cylinder and installed new seal from a hydraulic shop and worked find after.

Id say your fine with a refrigerated dryer. Place it before the regulator for best results. Maybe an inline lubricator might help stop the rusting by keeping a film of oil on it.
 
That mill comes with a lubricator, but it doesn't mean the previous owners kept oil in it.

It does look like water in the air though.

I put a new SMC filter/regulator and oiler on my SV2412 a couple years back, the OEM part that came on the machine is pretty cheesy One day I was trying to adjust the pressure and the damn thing blew to pieces.
 








 
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