Hydraulic feed question?

[isassi]

I have been giving a lot of thought about bandmills and may build my own or modify a manual mill (cheapskate here ;) and since I have zero experience with them except watching a TK 1200, I wonder when I read the literature, how do they accomplish feed with an electric motor? I presume the hydraulic mills use a motor that can be speed varied? So, here is my thought: My Ditch Witch uses a variable control valve for the ground drive motor, foward and reverse and I'm a thinking that this would work great on a band head, rather then a valve lever that requires operator pressure? Any thoughts or am I way off target here?

[highpockets]

I am not sure just what you are going to do but I built a full hydraulic mill several years ago.  I have learned a bunch of stuff and since I own a machine shop, I am still modifying. 

I used a 5 h.p. engine to drive a 4 g.p.m. pump. There are eight circuits that do everything from loading the logs to moving the (feed) sawhead.   The biggest problem I had was getting a good controlled speed on the feed.  The other day it dawned on me that the old International Cub Cadets with hydrostat drive had a neat system.  The engine fed into the pump-motor arrangement. One could use an engine to feed in the Cub's hydrostat pump and also belt drive a separate pump for the other controls.  The little pump-motor has a small lever that can control the speed from 0 to whatever. 

On the lifting of the sawhead I used a hydraulic motor into a 40:1 gearbox and fed this out to a shaft with two chains that lifted the sawhead.  This ain't the best. I recently changed it and used a cylinder which I don't like. The cylinder can leak down letting the sawhead drop. I am not going back with a Acme 1-5 thread screw and powering it with the original hydraulic motor. 

[jpgreen]

Woodmizer uses these drum control switches, and a reostat kinda pot control on the feed rate.

Look pretty slick and not all that expensive.  I'm replacing mine.

I would look at buying a used mill and modifying it as with the cost of materials and time, you could soon be over the cost of buying one adding up the nickle and dime rate.

[footer]

I think most band mill use dc electic motors to move the head up and down and back and forth. Easy to controll the feed rate. Just remember you might want your return speed a lot faster than your feed speed. The hydrost drive sounds like it might work too, but maybe a bit overkill, but if the price is right....

[isassi]

The variable ground drive valve is a simple speed/reverse control..kind of like fingertip control. A cub Cadet like we owned used a hydrostatic/ variable displacement pump. That is what allowed them to use full system pressure at any speed with dispacement governing ground speed. It would work great also. Since I haven't done anything with a bandmill, I was curious exactly how for instance TK mills do it since I can see they have a spool valve...so I guess the operator uses hand pressure on the valve...I think the idea of a 5TPI acme to lift the head would work better then the winches on the less expensive mills. I am still playing with the idea of building or modifying an existing mill.  :P

[footer]

Not sure about the TK but WM uses dc motors not hydraulics to move the carrage.