Portable Log Mill

[scottbrrtt72]

Hi All,

It has been a long time since I have posted progress on my sawmill. This project has taken a while for me to build and I’m not done yet. I am at a point where I need some of your help. The attached photos should help explain what I am trying to do. I will post individual photos along with the questions I hope you all can answer. The first photo is a general picture of the frame and the cutting part of the sawmill.

 

[scottbrrtt72]

This second photo is where I am having the problem. As you can see from the first photo I am using a winch and pulley to lift the cutting part of the sawmill. The cutting part slides up and down the tube steel to the required height. The frame is 2-inch tube steel and the cutting part frame is 2-½ tube steel. The problem is when I want to lift the cutting part of the mill the 2-1/2 tube steel kinks on one side of the 2 inch frame. When it does this it will not lift at all. I have tried numerous things to try and correct this problem. I even added casters to the sides to keep it from torquing to one side. This seemed to work for a little while. When it did work, it seemed like there was a lot of resistance. The whole cutting part, including a 100 lb motor, shouldn’t weight more than 225 lbs. The lifting capacity of the winch is 1500 lbs. Anyway, is there a way to add additional pulleys to make the cutting part lift level and smoothly? Any ideas would be greatly appreciated.

 

[scottbrrtt72]

Here is another photo.

 

[scottbrrtt72]

Another photo.

 

[scottbrrtt72]

This is the old saw mill. I will be using the same log carriage but different cutting head.

Hope you guys have some good ideas! I am getting fustrated with this part of the project....

 

[RobS]

Kind of hard to tell from your pictures Scott. Are all the various square tube pieces square and parallel where they need to be? Can you get it in a gravity-neutral position and try to slide it by hand to feel for binds? Is your lift mechanism lifting evenly or is one side/end being favored? How about grease?

Looks like a neat project. Maybe a wider angle photo would help us picture it better /forums/images/graemlins/smile.gif

 

[rockinmywaypa]

like Robs says it's hard to see but I think the problem may lie in your lifting point being off the centre of gravity.Consider where the motor is and all weights and then sort of think in terms of a piece of plywood hanging on a rope with the rope coming up through the centre of the disc. You have to find that centre point in relation to the spread of weight or counter balance the platform to balance it out, then you will have very little twist on the sliders as it goes up and down. in your case I think your cable may have to move farther back towards the motor pulleys to do the lifting and maybe closer to the motor end.

 

[scottbrrtt72]

I think that is the problem. When the winch starts to pull up, it binds on the left hand side all the time. That is why I tried putting in the casters to reduce the binding on sides of the frame. Like I said, it worked for a little while but there was a lot of resistance. Everything is level and parallel. I know the side where the axle resides is heaver than the other. That said I don’t think it is well balanced. Do you think adding additional pulleys would help? Or does the weight on both side have to be equal for the pulleys to work?

/forums/images/graemlins/confused.gif

 

[missourihick]

check out bakers sawmill. You might get some ideas there. I am buying one. Baker wood buddy sawmill Send for their info and video,it's free and it shows some very good details.

 

[wroughtn_harv]

Grease will make a ton of difference. You can buy grease zerts that you just pound in. You drill a quarter inch hole. Then, I use a socket over the zert, hammer it in place.

But with the sawdust grease presents a myriad of problems, staining, collecting sawdust, etc.

When you look at the amount of bearing--resistance surface you have a ton, buku square inches of it, two inch times four sides times height. There's plenty of room for trouble. Also your bind is always doubled because it happens at each end.

A viable alternative would be to limit the bearing--restance surface area. If you went up in size to three inch for the outside and put bearings on the top of your outside and the bottom of your inside piece. Then your contact patch would be cut by umpteen percent and it would be converted to a rolling resistance instead of a rubbing one.

Good sealed bearings aren't that much. Plus with your resistance cut down times hundreds everything else, winch etc, will live longer too.

I like your concept and attention to detail.

 

[rockinmywaypa]

It will be a great running machine when you're done. Is there any way that you can put a bottle jack under the platform and experiment with finding the sweet spot for lifting to eliminate the binding then add a piece to the toprail to crane the winch out over that spot and drop the cable down to a ring in the platform?

 

[mrcaptainbob]

Lifting it at both ends simultaneously would do it. Similar to venetian blinds. Cable from both ends over pulleys at the top and then the two cables to your winch. As long as the cables feed at the same level, (no overlaps of one cable and not the other), it should work fine.

 

[Egon]

You could also try and set up the lifting attachment like a single tree used for horses. Bar across the top attached at either end with chain and a pivoting mid point the winch pulls on. And grease.

Egon

 

[theonlybull]

try and add some counter weight to the light side of your frame. if you get it to ballence at the point your lift cable attaches, it will slide alot better.

 

[moeh1]

I agree with MrcaptainBob. You have to get a setup where both ends move up the same distance simultaneously. You indicated that one end is heavy, I'm sure you are cocking the assemby almost instantly each time you try and lift. I probably would have gone for 2 screws with a chain drive between them to assure that they are together, but thats just me. I'm sure you can get a cable to work, just haven't had enough coffee to figure it out on the fly.
Good luck looks like a fun project. /forums/images/graemlins/cool.gif

 

[scottbrrtt72]

Thanks for all the suggestions. I will try a few ideas today. /forums/images/graemlins/smile.gif

 

[SPIKER]

Scot:

a couple insites of things I see:

1. try to remove the slideing part and bevel the top & bottom edges of the 2.5" tubes so that it can't DIG IN the edges are nice and square which will catch and attempt to grab the upright tubes.

2. add wheels to the top and bottom sides. wheels on one side only will not help you very much. the next thing would be to use some chuncks of UHMW (plastic stuff very slipery and easy to work with) and mount them as blocks on top.

3. consider mounting the blocks not only inside & outside but front and back so all 4 sides are captured around the 2" square.

4. get the LIFTs center for weight distrubution even so that if you were to ballance the saw part on a pin it will stay flat & level on all 4 planes (left, right, front, back, and twisting motions should be as neutral as possable.) this will go a long way in making it help.

5. add some toggle clamps to HOLD it in place on each side after you are set in postion so it does not MOVE freely on its own. that is if it is not being HELD in place already but (you're design) doesn't yet appear to have it. must keep the blade from twisting up or down as the blade starts going through the tree! which it will do if the unit is not held ridgid correctly.

6. maybe think of one of the jack screw machines to raise/lower it. http://www.surpluscenter.com has some that are 110 vac and some DC now for aobut 60 bucks with a lot of travel witch have 600~900 lbs of lifting price was 25 to 70 bucks + shipping.

I'll keep helping as needed. keep posting new pics as problems arrize.

Mark M

http://www.bright.net/~pfryman is my show where I work, built suff similar but I don't ahve any GOOD photos of them in the material handeling sections.

 

[scottbrrtt72]

I want to thank everyone for there ideas. This is what I did today. Pulling from both ends seemed to work well initially. Once I put the motor on it became unbalanced again. Once the motor was on it kinked the same corner (where the motor is) every time I tried lifting it up. Looks like I’m back to the drawing board again. I have spent so much time on this one part of the project. Talk about frustrating. I even mounted a few more casters to help take some of the weight off areas I thought were causing the most friction. Didn’t seem to help. I will try and round out the tops of the 2 ½ tube stock. That seems like it would help reduce the amount of friction. Any more suggestions would be great.

/forums/images/graemlins/confused.gif

 

[scottbrrtt72]

Here is another photo. When I used the cable (stretched from corner to corner) to lift both ends together I lost a little lifting height. I went to a being able to mill a 30-inch diameter log to a 25-inch because of the slack in the cable.

 

[scottbrrtt72]

Forgot the photo. It's been a long fustrating day.