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- เผยแพร่เมื่อ 12 ก.ย. 2024
- Refilling and bleeding the down feed cylinder on a HF/CM 97009 7"x12" horizontal /vertical band saw.
Over the last few years, the down feed cylinder has been slowly loosing it's effectiveness. There are no obvious oil leaks that I can see, but it has lost oil out of the cylinder.
I found a video on TH-cam that showed how to refill the cylinder on a different model saw:
• Horizontal band saw cy...
But that saw had a separate bleed screw, unlike my saw. But I remembered a trick from an old car mechanic who showed me how to bleed a clutch master cylinder that had no bleed screw. Simply crack the fitting at the highest point in the system open and use that to let out trapped air and excess oil.
I think this cylinder must have a one way check valve in the piston that lets oil flow back easily when you pull the piston out. Then that valve closes and forces oil back via the flow control valve when it compresses.
Bandsaw listing on HF:
www.harborfrei...
I used some Bar's Leaks Jack Oil with Stop Leak:
amzn.to/3UD4LPc
Be sure to rate, comment and share
And as always, thanks for watching
Intro:
Louisiana Fairytale by Austin Rogers
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Thank you for the video! I was trying to solve the "bounciness" in my feed cylinder when completely extended. I don't know how air could get inside over time!
I filled the cylinder with hydraulic oil the way you you did, it was better but not perfect. I still had some air at the top of my cylinder that I couldn't purge no matter what I tried causing bounciness again.
To solve my problem 100%, what I did is, with the cylinder as full of oil as I could, and mounted on the saw, I raised the saw completely, and held it in place to make sure that the cylinder was completely at the top of it's stroke. I then removed completely the feed screw on top of the cylinder... (while still holding the saw up) ...because mine has 2 o-rings inside the feed screw, so even if I loosened it 3-4 turns like you did, it was completely sealed. I then manually, slowly lowered the saw by hand (with the valve open of course) until oil overflowed by the feed screw orifice. I had some hydrolic oil on hand in a squirt bottle, so I refilled the cylinder. I had the same problem as you. The oil would not go down, so, when the hole was full I raised the saw little by little, forcing the oil inside like a syringe would, keeping the hole full at all time to avoid sucking in air. I continued until I was at the maximum stroke of the cylinder. I then replaced the feed screw and thightened it. This way the cylinder was COMPLETELY full! Absolutely perfect! Like new!
I was also looking at the 150$ cylinders online before trying this, so I'm very happy!
Sounds like a good filling procedure, thanks for posting.
THANK YOU!!!!! You saved me $149 for the cost of a replacement cylinder! I was recently given a 20-year old cut-off saw and one of the things that was a bit hinkey was the erratic operation of the down feed cylinder. It would only work for the last inch or two of the cut or sometimes not at all, and it wouldn't always reset itself when the saw was raised. While there was no sign of damage or leakage, I decided to try refilling it after seeing your how-to video. Come to find out the problem was low oil and after topping it off just like you did, and then bleeding it (my unit has a bleed screw), it now works perfect and like new.
Glad you were able to fix your cylinder. You're lucky to have a bleed screw, makes that easier.
Brilliant! Been putting off looking at my cylinder, but after seeing how simple it is I'm gonna finally fix mine
Good luck! One of these days, I need to tear apart the valve and see if I can fix the leak that seems to be there as I need to top off the oil once a year or so.
I was looking for hydraulic jack diy. It was great vid.
Glad it was helpful. I think I watched a jack video to get the idea for this fix.
My down feed cylinder isnt working properly, and I think this my be the ticket. Thank you for sharing!
Yes, seems to be a fairly common issue on these saws. I've had to top mine off a time or two since this first refill. I think they leak through the valve.
What you should have done is get a 3/8" clear tube and stuff it in the needle valve opening. Then get a plastic mayo jar with lid with hole for the tub to fit snug and only goes in a 1/4". Fill jar with fluid. Close jar. With the rod all the way out and cylinder horizontal, tip jar upside down and hold over the cylinder. SLOWLY push rod in a little bit. Air from cylinder will compress in jar and force fluid down. Pull rod back out , air rise while fluid descends. You can let it gravity feed or you can slowly pump the rod to get it done quicker. You will know when you are done when no more air bubbles come out. Lower jar below the cylinder as you put the cylinder vertical. Crack the jar lid open and this will start a syphon, let it bleed just a bit then , crack the tube at cylinder. Remaining fluid should dump back into jar and any fluid that would have spilled out at cylinder would be pulled back in. You can also push the rod in just a bit and as you crack the tubing off pull the rod out, sucking any fluid in , instead of falling out.
If you want to speed things up add a second breath tube in jar that goes all the way down. Problem with that is when you start there will be fluid in the breather that you will have to either dump or blow back in.
Thanks for the suggestion. I'll have to give that a try once I can gather all those materials. My technique has worked well the few times I've used it. I think in my case, the leak is from the needle valve itself. So I need to find the time to open that up and see about resealing it. I suspect there are some small o-rings in there that need replacing.
Very helpful. Got mine working again. Thanks.
You're welcome!
I need to do this on mine, thanks for the tips.
Great, glad the video was a help. I still need to dig into mine and see if I can find/fix the actual leak that is causing the loss of the oil in the first place. I just need a day or so of down time in customer orders where I can tear the machine down and figure out what's going on.
mine leaks at the valve /lever shaft (open -lock valve)
Yes, that's where mine seems to be leaking as well, at least that's where's oil wetness. I need to open that up and see if there is an o-ring or packing that can be replaced.
I'm a bit late to the party but I suspect that tipping the cylinder upside down (or more importantly having the lower port uppermost for the air to rise and exit through) as you push the rod in, would get any trapped air into the area above the piston where it doesn't matter to the operation of the cylinder damping as it compresses.
Yes, that does help. I finally got rid of the plastic piece covering the bottom of the cylinder and now it can fold over almost horizontal. Still traps a bit of air that's easily bled out.
Not knowing a thing about hydraulics, it seems like something clever and useful might be made of a take-off shock absorber that is still good, no?
Yes, might be useful for something like a closer for a heavy lid or a tailgate. Lock it to hold it open then release the lever to slowly lower it.
Thanks! I thought i was going to have to buy a new cylinder!
That's probably what they want you to do :)
But yes, have filled mine up once and then topped it off once. I think the valve on mine is the source of the leak. I need to take that apart and see if it can be repaired or replaced.
R Brown I bought a used wilton 5”x8” and its leaking around the shaft and I looked up rebuild kits but I can’t find it. Hoping I can top it off and it be good
@@The4Crawler Often the seals get ruined when the cylinder rod is pointing up. Metal shavings get stuck and pulled in, ant that ruins the seals.
great video, exactly what I needed.
Thanks for the comment, glad the video was helpful. So far the refill has been working. I think I've found the source of the leak and need to see if I can repair that. If so, I'll be posting an update, so stay tuned for that.
Great vid, but it was of no help- after I pulled my cylinder, I realized that the erratic operation and varying speed of the “drop” was because of the big pin between the base and the C portion of the saw- check yours and maintain it 👍
Great point! Is that the bolt at the top or bottom of the cylinder?
Great video thank you
Glad you enjoyed it
Unless you can push down on the saw during down-feed with zero sponginess it's not fixed.
Good repair. I have the same problem. A new cylinder costs $300.
Yes, I looked up the price on those a month or so ago and found the same thing. I need to try and rebuild the valve on mine, I think that's where it's leaking.
Can you do a overhaul on the feed cylinder? Such as seals?
This thread implies that it's possible:
www.practicalmachinist.com/vb/general/bandsaw-downfeed-rebuild-cylinder-valve-379210/
I need to see if I can fix the leak in the valve on mine, if I can get the cylinder removed from the saw.
I had similar issues, no matter how I fill my cylinder It keeps creating air bubbles that I think it comes through between the shaft and the top cover...but there is no leak during operation. So my question is it normal that it sucks air from top side?
I've not had a chance to tear into the cylinder to see how it works inside. I've not run into that specific issue, I think mine is leaking through the on/off valve.
what do you do when it drops at the end
It may be the oil level is too low and letting it drop or there's air trapped in the piston.
what viscosity to fill in the oil in the hydraulic cylinder
I used a hydraulic jack oil from the local hardware store. It doesn't list a viscosity on it, but it is fairly thin. Added some information on the jack oil I used in the video description.
Need to do a similar repair. Thanks. This video will really speed up my repair.
Glad it helped. I need to tear into mine and fix a leak in the valve. I priced out a new cylinder assembly and it's about US$350!