Author Topic: Power up and down (Read 6748 times)

kelLOGg · « **Reply #20 on:** January 22, 2006, 08:24:17 PM »

Quote from: summerjob on January 17, 2006, 09:22:44 AM

Has anyone added power up and down to their manual WM. WM says that it can't be done to an LT 25, but I believe where there is a will there is a way. I don't mind any of the other aspects of my manual mill, but after a long day of sawing it gets old cutting 4/4 then having to crank back up to do the next 30" log. That is the only time I mind using the crank, to crank back up for the next log. Any advice on how and what type of motor needed would be much appreciated. I have heard of people using a cordless drill, but when custom sawing I don't want to have to charge batteries.

I modified my Cook's MP-32 with a power up-down (actually gravity does the down part but it would be easy to power it too). I used a 12VDC gear motor from Surplus Center (www.surpluscenter.com) part no. 5-1524 $39.95. I bolted a bracket to the head carriage so there was no welding to the sawmill. It performs very well in my application. I'm not familiar with the LT 25 but if your torque reqirements match the gearmotor and you being handy youu should evaluate it. Current draw is < 20 amps. Good luck

summerjob · « **Reply #21 on:** January 23, 2006, 08:12:18 AM »

I modified my Cook's MP-32 with a power up-down (actually gravity does the down part but it would be easy to power it too). I used a 12VDC gear motor from Surplus Center (www.surpluscenter.com) part no. 5-1524 $39.95. I bolted a bracket to the head carriage so there was no welding to the sawmill. It performs very well in my application. I'm not familiar with the LT 25 but if your torque reqirements match the gearmotor and you being handy youu should evaluate it. Current draw is < 20 amps. Good luck

This really interests me. This seems to be exactly what I am looking for. kelLOGg will the gear motor "free role" to use the crank to lower. How do you lower yours. Is it possible to show me pictures?? When you say gravity, do you use the motor or have a crank also. How do I figure out what torque I am dealling with. Can anyone tell me if the charging system on a Kohler Command 20 can handle the 20 amp draw. Sorry I don't have a camera to take pictures of my setup.
Thanks again You guys are a big help

kelLOGg · « **Reply #22 on:** January 23, 2006, 05:01:57 PM »

Quote from: summerjob on January 23, 2006, 08:12:18 AM

I modified my Cook's MP-32 with a power up-down (actually gravity does the down part but it would be easy to power it too). I used a 12VDC gear motor from Surplus Center (www.surpluscenter.com) part no. 5-1524 $39.95. I bolted a bracket to the head carriage so there was no welding to the sawmill. It performs very well in my application. I'm not familiar with the LT 25 but if your torque reqirements match the gearmotor and you being handy youu should evaluate it. Current draw is < 20 amps. Good luck

This really interests me. This seems to be exactly what I am looking for. kelLOGg will the gear motor "free role" to use the crank to lower. How do you lower yours. Is it possible to show me pictures?? When you say gravity, do you use the motor or have a crank also. How do I figure out what torque I am dealling with. Can anyone tell me if the charging system on a Kohler Command 20 can handle the 20 amp draw. Sorry I don't have a camera to take pictures of my setup.
Thanks again You guys are a big help

Summerjob
I need power only to raise the sawhead - I just release the crank brake
and press the button. (It will actually raise the sawhead with the
brake on but that’s wasteful.) When I want to lower it I just release
the friction brake on the wheel crank and the weight of the sawhead
turns the gearmotor backward. To power the down direction would require
just a DPDT switch but I don’t need it. I can also release the brake
and use the hand crank to raise/lower the head for small distances -
this actually makes it easier to hit the mark for the next cut.
(I know what you mean by cranking up 30" to start a new log. That’s why
I added this gear motor.) The actual measured current draw is 10 amps
and the magneto on my Kohler 16 HP keeps the battery charged so I would think a 20 HP Kohler would do at least as well.
The torque on this gearmotor is 75 in-lbs. To estimate the torque
required to turn the hand crank I hung an empty plastic jug on the
handle and filled it with water until the crank began to turn. I
weighed the jug+water and measured the distance from the center of the
crank shaft and handle (the radius). Multiplying the distance (inches)
by weight (lbs) gives the static torque. In my case the distance is 6
inches and the water weighs 5 lbs - 6 x 5 is 30 in-lbs of torque. This
is a minimum so double or triple it to allow for friction and dynamic
torque. That’s 60 - 90 in lbs and the gearmotor provides 75 in-lbs
continuous. I decided to give it a try. I fitted a sprocket on the
handcrank shaft and one on the gearmotor (required some machine shop
work) and it has worked perfectly for one year now. I used a relay to
operate it so the switch did not have to carry the full 10 amps. I have a .digital pfhoto of it (.jpg file) but I don't know how to insert it yet.

woodbowl · « **Reply #23 on:** January 23, 2006, 08:05:54 PM »

kelLOGg, that method of calculating the inch pounds is pretty slick. I'm gona' remember that one.

.........................

Tom · « **Reply #24 on:** January 23, 2006, 08:09:50 PM »

Fellows

All this use of the quote code is confusing. I am having one heck of a time following the conversation and would really like to be able to read it. Sometimes, especially in a current conversation, it's better to just type what you think rather than repeat what someone else has said. Especially the entire post. Please, please, help me to understand.

summerjob · « **Reply #25 on:** January 24, 2006, 09:56:51 AM »

You've been a big help kelLOGg. Thanks again. On the gear motor it says no key or flat. What did you do to fasten the sprocket to the gear motor. On the gear motor there is a shaft sticking out both sides. Do you think a sprocket could be mounted on one side and a crank handle on the other side. If that could be done, I would not have to reroute my chain at all. I could just add the gear motor to where the current crank is located.

kelLOGg · « **Reply #26 on:** January 24, 2006, 05:24:16 PM »

Summerjob,

Luckily the shaft is machineable steel. I drilled a hole in the sprocket hub and mounted the sprocket on the shaft. (I had to put a sleeve over the shaft to make a snug fit on the sprocket). Using the just-drilled hole as a guide to assure the holes would line up, I drilled thru the shaft and pressed a roll pin thru the hole. (It takes careful mounting in a drill press to keep the assembly steady). Don't use a set screw as it won't hold.

Putting the crank wheel directly on the gearmotor shaft is probably not the best idea because the crank wheel is probably not balanced and when driven bachward due to the descending saw head (by gravity) vibrations will be absorbed directly by the gear motor. This may be a fine point but it's my best guess. Also, remember if driving and driven sprockets are different diameters the torque will change. Keep us posted of your results.

summerjob · « **Reply #27 on:** January 27, 2006, 12:20:15 PM »

It will be a little while until I actually get around to hooking this up, but I did order the gear motor. I am hoping I can just pull the crank rod out of the current sprocket and attach the gear motor with minor machine work. Then I am hoping to just add the crank handle to the shaft sticking out of the gear motor. The crank will only be used to lower the head. If the crank can't be fitted this was I guess I will have to find another location for the gear motor or crank. Can even pull crank off the raise head possibly. Anyone see any major problems with this idea.

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