Author Topic: Can or should Hydraulic cylinder's be used to raise/lower saw head? (Read 4305 times)

GAmillworker · « **on:** July 13, 2011, 06:59:02 PM »

Can or should Hydraulic cylinder's be used to raise/lower saw head? Has anyone done this before? Would it be accurate?

Thanks
Daniel

Magicman · « **Reply #1 on:** July 13, 2011, 07:21:03 PM »

What is going to hold it in place and keep it from creeping? This is where worm gears really work well.

GAmillworker · « **Reply #2 on:** July 13, 2011, 07:36:52 PM »

Thanks for the reply Magic man.

Read your post on cabin addition. Great work.

The cylinders would be pushing chain up like on a forklift.

Dont know if I can incorporate some type of lock.

tyb525 · « **Reply #3 on:** July 13, 2011, 07:44:53 PM »

Hydraulic drift would be a concern.

ladylake · « **Reply #4 on:** July 13, 2011, 07:56:17 PM »

The TK 2000 uses a hyd cylinder for up-down, it has a check valve to keep the head from dropping. If I was building a mill I might use a hyd motor driving a worn drive gearbox running a roller chain, no creep with the realiability of hydrailics, so long as the gearsbox would stand up to constant up-down. Steve

Kcwoodbutcher · « **Reply #5 on:** July 13, 2011, 08:11:52 PM »

The TK 1600 uses one ( pulls a roller chain), have never had a problem with creep. It's a very robust and reliable system.

GAmillworker · « **Reply #6 on:** July 13, 2011, 08:33:17 PM »

Thanks for the replies.

Does anyone have pics of the TK setup?

I'll do a search.

bandmiller2 · « **Reply #7 on:** July 13, 2011, 08:38:31 PM »

Dan, you bet it works and it works well too.Thats what I used when I built my bandmill,let me explain.A good cylinder and valve, creep is no problem.I used 3/8 wire cable reeved to give me 2" up/down travel for each 1" cylinder movement.Think of it like a rope through a pulley if you fasten one end of the rope and move the pulley up1" the outher end of the rope will move 2".The hyd. cyl. is verticle with two cable wheels in the yoke the cables are fastened to the frame at the top through the wheels to each side of the band head.The feed uses the same hydraulics to move the carriage with a hyd. motor and drum for anouther cable, just kinda pulls itself along.Sorry about no pictures not up to speed on that. Frank C.

Larry · « **Reply #8 on:** July 13, 2011, 08:47:57 PM »

On the TK 2000 there is not much to picture. The hydraulic cylinder resides inside some tubing on the carriage. The only thing visible is a short section of roller chain.

Its one of those things that is simple and works quite well. Drops with the setworks are right on and rock solid.

sgschwend · « **Reply #9 on:** July 13, 2011, 10:04:27 PM »

MM uses a hydraulic cylinder for the setworks.

The valving is such that when the valve is closed the the cylinder is locked from both hydraulic lines.

The challenge I found with the Mighty Mite was manually stopping one the scale. In this type of manual setworks there is a minimum time the valve will open and hence minimum step size versus cylinder speed. The slower the speed the smaller the minimum step size. To control this issue I adjusted the hydraulic flow rate in the cylinder with two flow control valves.

The advantage of this system is the matching lifting force on the sawhead, with a minimum of parts.

Brucer · « **Reply #10 on:** July 14, 2011, 12:57:39 AM »

There's a simple, off-the-shelf device to prevent creep in hydraulic cylinders (and motors). It's a 2-way pilot operated check valve, and it will prevent oil from returning from one side of the cylinder unless the other side is pressurized. Costa about $50 in Canada.

ladylake · « **Reply #11 on:** July 14, 2011, 05:22:26 AM »

Quote from: sgschwend on July 13, 2011, 10:04:27 PM

MM uses a hydraulic cylinder for the setworks.

The valving is such that when the valve is closed the the cylinder is locked from both hydraulic lines.

The challenge I found with the Mighty Mite was manually stopping one the scale. In this type of manual setworks there is a minimum time the valve will open and hence minimum step size versus cylinder speed. The slower the speed the smaller the minimum step size. To control this issue I adjusted the hydraulic flow rate in the cylinder with two flow control valves.

The advantage of this system is the matching lifting force on the sawhead, with a minimum of parts.

I know what your talking about, my old Oliver 770 with a loader has check valves in it's system, the loader will stay in one spot forever but there is no way to lower it a inch or so without it jerking. The TK 2000 has check valves but also has a manuel lever where it can be inched up-down as slow and as little as you want. No idea how it's plumbed. Steve

bandmiller2 · « **Reply #12 on:** July 14, 2011, 06:22:30 AM »

My bandsaw setworks is simplicity in itself an aluminum yardstick and pointer.Its very easy and precise to feather the spool valve and drop the head down to the next mark.Hydraulics make head movement effortless,easy to make multiple cuts lifting the head to go back and over.Feed is easy to control with a cheap needle valve, infinately adjustable feed,full speed gigback.I don't think a solenoid type valve would give fine enough control of the bandhead hight 1/32" control is desireable. Frank C.

argyle1 · « **Reply #13 on:** July 14, 2011, 11:59:04 AM »

I'm using a cylinder to raise and lower the head on my circular dimension mill, but instead of cables over pulleys I'm using 80 pitch drive chain over sprockets.
There is no creep at all, even tho it has a very heavy saw head--if you have a good cylinder and valve, there won't be a problem with creeping

Magicman · « **Reply #14 on:** July 14, 2011, 12:11:41 PM »

We are all learning a lesson, especially me.

ladylake · « **Reply #15 on:** July 14, 2011, 12:17:34 PM »

Seems to me even brand new tractors, skidlaoders etc will let a loader go down over time unless they have some kind of check valve. If you have every thing in good shape there sure wouldn't be much creep in the 20 seconds or so that it takes to make a cut. Steve

tyb525 · « **Reply #16 on:** July 14, 2011, 07:15:30 PM »

One of the basic rules in hydraulics is that you can't trust them to hold up a load 100% of the time. Maybe 99% of the time they will hold just fine, but once a hose breaks or a seal/valve blows or leaks, its game over. That's why a mechanical holding device of some type will ensure there will be no falling saw heads, ever.

I personally knew a guy who was killed when he was working on a planter. The tractor's hydraulics were holding it up, and out of nowhere it dropped fast, he had no time to move out from under it. This was a fairly new tractor, too. I've heard similar stories from other people also.

Does it matter on a saw head? Maybe not. Would it be a great idea to incorporate a mechanical holding device of some sort, since you're in the process of building the saw anyways? I'd sure as heck do it now, rather than in the future if you realize you need it.

Dave Shepard · « **Reply #17 on:** July 14, 2011, 07:54:52 PM »

A system like bucket trucks or LULL type forklifts uses might work. They have a valve in the cylinder that requires full hydraulic pressure to activate the cylinder. It cannot come down by gravity, even if a hose breaks.

beenthere · « **Reply #18 on:** July 14, 2011, 08:56:41 PM »

I have that lock valve on the hydraulic top arm cylinder on my 3 pt tractor hitch. Surplus Center has the lock valves for about $100 or a bit less. I have no problem making very fine (and slow) feather adjustments to that top arm. SC also has the cylinders that include that lock valve plumbed in.

Dave Shepard · « **Reply #19 on:** July 14, 2011, 09:04:25 PM »

That's good info to have, thanks.

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Author Topic: Can or should Hydraulic cylinder's be used to raise/lower saw head? (Read 4305 times)

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