log clamps on home built mills

[flip]

I am nearing the completion of the "fabrication" part of my band mill and am starting to gather parts for the hydraulics.  Does anyone have a good system or pics. of a log clamp system.  I want to use a high torque hydraulic motor to clamp the log.  Up and down adjustment will be come manually.  Thanks in advance for any help.

Flip ???

[Tom]

Welcome to the forum, flip. 

I don't have any pictures, especially of the design you describe.  I would say that you should consider 2 small rams rather than a hydraulic motor.  You might have to build the stress parts of something substantial but having two rams working in two different planes will provide you with a clamp that will also perform minor (and frequent) turning duties.  It'll be just like the "Big boys". :D

First hand will tell you more than pictures.  See if you can get a look at the clamp on a WM or Baker to see what I'm talking about.

[flip]

Sounds like a good idea Tom.  Like you said, I havn't been able to get any good close ups of other mills.  I'm in south west Indiana and the nearest mill that I know of is 25 miles away.  My frame is super heavy so strength is not a big issue, just the design and set up.  Log turners would be nice!!

[flip]

Just to give everyone an idea my mill is 20ft long (18ft cutable).  Outer rails are 6" C chanel and the cross braces are 6" I beams.  My carriage is similar to the Timber king with the cutterhead on the inside of the cage.  The head is my varriant of Linn limber's with 19" wheels and my own "special" hydraulic tensioning system.  If I can figure it out I'll try and post some pics. in a few days.  Thanks, for all the help.

Flip in Jasper, IN

[flip]

Oh, and I forgot, it is mobile and has 6 jacks.  Should I have any levelers?   ???

[Larry]

Welcome flip!

Here is the WM 2-plane clamp.  Really cool....just wish I could afford the clamp with the mill attached.

Somebody smarter than me will have to explain the operation if your interested...it's really best if ya could see one in operation.

[flip]

I think I understand the principal.  I think your right, I need to see one in operation to understand how the pivot system works.  Hummmmm, more ideas, this is bad. :P

[GF]

Here is a picture of one of my hydraulic clamps I made.  The square tube that the ram is connected to 2 1/2" x 2 1/2" thick wall, the smaller piece of square tubing that slides in it is 2" x 2" thick wall.  At each end of the square tubes is a pivot point one is on the solid crossmember, and on is on the clamp device (has the 3  bolts on right) that slides back and forth down a 3" or  3 1/3" square tub, cant remember the size exactly.

The ram pivot on points on the larger 2 1/2" tube and at the very ende of the 2" tube.  When the ram extends the square tubing also extends, keeping everthing connected together.  The three bolts on the right allow you take the side of the clamp device off and remove from the 3" or 3 1/2" square tubing.  So far I have not had any problem with this setup, and it has moves some 36" diameter logs.

I also have a picture below of the log turner I built, the arm was built from 3x5 heavy steel tubing, the chain is 80 pitch and I cut and welded the teeth on the chain, teeth were made from 1" thick steek.  Below the arm is a hydraulic ram you cannot see that raises and lowers, the tuner chain is powered by a high torque low RPM hydraulic motor mounted below.  It has lifted and turned some 36"+ diameter logs with ease.  Some times my 5-18" hydraulic logs stops (can see one in the down position toward the bottom of the second picture)are not tall enough when I am lifting and turning, I have some 2 1/2" square welded on the frame so I can insert some tall 2" tube when I turn a large log.

[flip]

How did you keep the ram from jamming/wedging  against the cross member??  Great work!  Looks really nice.

[D._Frederick]

flip,

The hydraulic 2 plain camp system that WM uses has the clamp moved back and forth by a "V" system. There is a bearing at the bottom of the V and at each top, one side is connected to the track assy. and the other side is connected to the moveable clamp slide. The hydraulic cylinder is connected within the V to increase the distance the clamp can travel.

Hope this helps.

[D._Frederick]

GF,

I guess I don't understand the angle your hydraulic cylinder is pushing/working at what keeps it from destroying your mill frame work.

[GF]

The picture does not show it to clearly.  The clamp on the right side is actually attached to a larger piece (that has the 3 bolts on the right) this is all one piece that clides back and forth over the 3 or 3 1/2 square tube.  The idea is that the ram is postionaled at an angle, as it extends the clamp head slides toward the direction of the angle, and it retracts it does the opposite.  The ram anlong with the arms the ram is attached to is connected with 1" pins they all pivot on.  Not sure if this helps any, if needed I can get a close up picture and post it.

[flip]

I guess my ?? is how can the sleeve slide the clamp instead of wedging against the tube?  An overhead pic. or measurement from frame to pin on clamp would be great.
Thanks,
Flip

[D._Frederick]

GF,

An interesting way to move the clamp back and forth, how much force does the cylinder produce this way? Will it move a log up against the squaring posts?

[GF]

D._Fredrick
I have moved 36" Red Oak with this design with no problem, and the engine at idle, not sure of the force the ram pushes at 7850 lbs force and retracts at 5300 lbs.


Flip
The one oend of the ram near the clamp slid is not actually connected to the clamp slide, its looks like it but its not.  Its actually connected to the smaller square tube that extends out.  Basically the ram is not connected to either the frame or the clamp, its connected to the square tubing that extends.  The square tubes then only have a single pivot point at each end one at the framme side and the other on the clamp.   Since the ram is at an angle it does not bind it will slide on the tube back and forth.

[flip]

Do you know what the angle is or did you just experiment?  How wide is your track frame?  I'm trying to get an idea what size cylinder you have and how much travel you have.
Flip

[GF]

I just experimented on the angle.  What I did was connect air to the ram to test with instead of hydrualic fluid, once I knew that 120PSI air would work, then I knew the hydraulic pressure would work just fine. 

[flip]

I see, makes a lot of sense, a lot less moving parts than the motor, screw, chain etc.  I bet it has a lot more clamping force too.  What size cylinder and psi did you use?
Flip

[Tom]

Flip,

You keep talking about clamping force.  I just want to make you aware that squeezing a cant with extreme pressure can be detrimental.  It can tear the wood as well as cause the cant to pop up off of the mill.  This is especially true when you are cutting down close to the bed and have less than an inch of clamp in contact with the bottom of the cant.

Finesse is more important than PSI in most cases. (not all)    Also having a direct horizontal pressure against the clamp will keep the cant from raising from the mill.

While pressure is important, especially if used to help turn cants and hold down tensioned boards, you would be  best to consider how much control you offer yourself in applying. it.

Logs are heavy and not as easily moved around as you might think when properly dogged.   Too much pressure can actually push your dogs out of alignment and cause you to cut "diamond" cants.  These are cants that form parallelograms rather than rectangles.  They are kinda like a leaning square and aren't good if cutting construction lumber.  You have to be able to apply only what is needed so that you hurt neither the cant nor the mill.

[flip]

The pressure only concerns me to the point that there is enough to push a big cant against my stops.  I know probably no more than a couple hundred MAX psi is needed.  This is where I'm having the dilema, to use a hydraulic motor and a couple of chain driven clamps as opposed to 1 or 2 rams.  The chain/motor system uses a lot more parts but I think would be more controlable as opposed to the ram.  I just remember KISS (keep it simple stuipd) that's where the ram idea intrigues me.  My neighbor uses manual cam type clamps and is a real pain in the you know what to keep adjusting all the time.  I would also like to incorporate, like you said, a log turner into the clamp, kill 2 birds with one stone.  I could use a modified WM set-up like the above pic.  So many ideas, so little brain.
Flip

P.S.  Tom, I really enjoy your site, I have spent several hours reading and looking at pics.  It's nice to see someone that likes sharing their life with others.

[GF]

Flip,
    I dont have a problem with the rams destroying the wood due to the force, I feather the hydraulic lever when I get close to the stops and apply only enough pressure to get it there, and clamp in place.  If the saw is cutting square the backside of the log will hit all the stops the same.  I can also clamp a round log in place with all the force the rams have and pnetrate the wood slightly.  I am know way an engineer or even close, my theory is that by having the ram angled the force applied is much less, than having the ram in straight line with it.  In other words the ram extends 1" but moves the clamp 2" due to the angle, this tells me that if the ram has 7000lbs push at a straight force, it now is 3500lbs of pushing pressure.  As the ram and the clamp extend further they run more purandicular to each other, as this happens the pressure does start to increase back up. 

   I do have my 1/2" log stops that are welded to the frame every 2' apart and they are about 2-3 inches long.  I also have 6 longer log stops attached to a single ram that are adjustable until I get the log squared up. 

   I have failed to put the logs stops up and pushed a log off the backside.  Alot of time I use the log turner to move the log back and forth on the deck, and I also clamp with it with squaring up a log. Since the log tuner is centered for a 12' log, I am able to move either end left or right by have one or the other end hit one of the log stops and turn the log chain in either direction.