calculating maximum area question... (circumscribed square?)

[Peachfuzz]

So The Lt 10 is really ripping along well and I just had a friend of mine drop off a few cord of cedar to play. I'm looking to get the most I can out of these trees, so I dusted off the old geometry book and looked up how to measure the area of a circumscribed square, and solved for the length of the side of the square. Now I take this number and subtract it from the diameter of the narrow end, divide by 2 and I now know what I'm peeling off to get my square cant. In other words:
L = 1.414R where L is length of side of square and R is radius of small end of log.
(D-l)/2 = total removed per side for a square cant.

I was playing with this today, it seemed to work, but I ended up doing 2 cuts per side so I'd be able to rip that extra 1x whatever out of there. Anybody else out there do it like this? Is there a better way? thanks in advance for any feedback.

The math if anybody wants to see what I did:
Let d = diameter of log, and Diagonal of square
Let L= Length of side of square
L^2+L^2=D^2= (2r)^2
(2L^2=4r^2)/2
(L^2 = 2r^2)sqrt
L = sqrt2R = 1.414R
(d-1.414r)/2

 

[hamish]

Hell use an online board foot calculator, or a widely available sliding rule. Keep it simple.

 

[Dave Boyt]

Interesting approach, but you are applying rigid geometry to a highly irregular and variable material-- knots, bumps, areas of rot, taper. To get the most out of a small log, you might consider leaving live edges on both sides. Clamp the log down, saw boards half way down, flip the log over and repeat. You can decide whether to straight rip or use the natural edges after it is dry and you are ready to use the lumber. The best estimator of log volume is the International 1/4" scale, then add 15%, since the band blade takes a thinner kerf.

Be thinking about the next step--drying. Ther are a couple of ways of doing it, depending on how you saw the lumber. Here is a link: Drying Lumber. The first photo in the link shows cedar cut with live edges, as described above.

Glad your band saw mill is cutting well-- keep us posted on your projects. Now you need more chain saws, a bigger tractor, winches, cant hooks, Advil, and a good chiropractor.

 

[Peachfuzz]

Thanks for those links. I looked at my math vs the international log volume and tried to plug those numbers into the equation and they seem really close. I'll bet those two extra boards i pull off squaring the cant are where the missing bd ft are.

The reason for all the fuss is my log clamp leaves a lot to be desired. I can't fletch boards to save my life, that bloody clamp won't stay. I had some success using a carpenters clamp to supplement, but it leaves a lot to be desired. I'm putting pen to paper now to try and redesign the clamp to my liking. I like the idea of a log clamp on acme rod that turns in the same way every time. I figured in the mean time if I could fletch the boards while it was still a whole log I wouldn't have to fight that damn clamp.

I hear you on the chiropractor. Fortunately for me most of this cedar I'm milling is going to finish my neighbor's sauna, so I've got that going for me anyway. Thanks for your help

 

[Mac88]

The reason for all the fuss is my log clamp leaves a lot to be desired. I can't fletch boards to save my life, that bloody clamp won't stay.

What's the issue with your clamp? We have an LT30 (my BIL's) and have no problem dogging down anything we mill. I'm assuming your LT10 uses the same mechanism. Pics?

 

[hamish]

Use an appropriate sized backing board (ie 4x4 or 4x6) against you log stops to give support to your flitches. Carpenters spped clamps are the cats meow for this application and are very handy on a manual mill.

View attachment 265397View attachment 265398

 

[Peachfuzz]

View attachment 265519View attachment 265520

What's the issue with your clamp? We have an LT30 (my BIL's) and have no problem dogging down anything we mill. I'm assuming your LT10 uses the same mechanism. Pics?

The issue is one of either too much or not enough. I can never get the slop out of the clamp just right so I either end up reefing on it or it'll come loose when I'm sawing. The other problem I have with it is that if the clamp is not perfectly level with the supports on the other side the cant will rise as I clamp down. Then it's back to fighting with the clamp to get just the right amount of pressure on it and try again. It's really slowing me down. I'd take any help I can get at this point as I'm a little frustrated with it.

I should note that the clamp works fine when it's still a log, it's only when fletching or trying to clamp a square cant down low.

 

[Mac88]

View attachment 265519View attachment 265520

The issue is one of either too much or not enough. I can never get the slop out of the clamp just right so I either end up reefing on it or it'll come loose when I'm sawing. The other problem I have with it is that if the clamp is not perfectly level with the supports on the other side the cant will rise as I clamp down. Then it's back to fighting with the clamp to get just the right amount of pressure on it and try again. It's really slowing me down. I'd take any help I can get at this point as I'm a little frustrated with it.

I should note that the clamp works fine when it's still a log, it's only when fletching or trying to clamp a square cant down low.

I see that's quite a bit different than on the LT30. I would have expected they would at least be similar. The 30 uses a horizontal cam on top of a vertical tube. The tube goes through a series of holes in the crossmember, depending on log size, and is held tight by a spring loaded chain. I know that's a little hard to picture. I'll post a pic in the morning, if you're interested. You might be able to fab up a similar setup if you have access to welding equipment. It works great on the 30, we've even used it to dog some rounds (on end) that we cut wafers off of.

 

[Peachfuzz]

I am a pictures man... I've got a welder... Right now I'm thinking about how I can adapt a bench vise style approach to the situation. If I bought some 3/4 acme rod and nuts I could make a log clamp that slid across the rod and then just tighten the nut (double nut = better). I can weld a piece of rerod on the outside nut so the handle is always on the clamp.

See the problem with a plain ole bench vise approach is what do you do with all the rod travel? For every inch of travel in a vise there's an inch of the vise that's now sticking out the back. If I used a clamp that slid across the threaded bar, the bar never moves, just the clamp nuts when the clamps in position. I hope I'm explaining this well, as I can't draw for all the tea....

 

[Peachfuzz]

Use an appropriate sized backing board (ie 4x4 or 4x6) against you log stops to give support to your flitches. Carpenters spped clamps are the cats meow for this application and are very handy on a manual mill.

View attachment 265397View attachment 265398

I like this approach. I had my speed clamps out yesterday and they did help. The only thing I noticed is that I had a lot of trouble with them when the cutting height got below 2". The way I've been cutting i seem to get all the board feet out while doing my fletching while the cant is still whole. Where I get all tangle up with my clamping is when I take my boards with the live edges and start cutting stickers. That's when all the cussing usually starts - lol

 

[Mac88]

I am a pictures man... I've got a welder...

I'll get you a picture in the morning.

The only thing I noticed is that I had a lot of trouble with them when the cutting height got below 2".

I thing the dog on the 30 will let us cut down to 1".

Here's some of what we do:

Oak

Walnut

 

[Peachfuzz]

I'd love to have some walnut to play with, that's pretty stuff. Curious to know if you've run a smaller mill before, and if so, how do you like the extra power on the 30? When the blades are sharp that mill will whistle through cedar, but I ask myself with that cherry is more power needed? Nice thing about having to push the mill through the cant is I can really tell when those blades start getting dull so I don't over use / over heat trying to force my way through. I think that would be a little harder for me with a bigger mill. I can get a little throttle happy at times =)

 

[Mac88]

I'd love to have some walnut to play with, that's pretty stuff. Curious to know if you've run a smaller mill before, and if so, how do you like the extra power on the 30? When the blades are sharp that mill will whistle through cedar, but I ask myself with that cherry is more power needed? Nice thing about having to push the mill through the cant is I can really tell when those blades start getting dull so I don't over use / over heat trying to force my way through. I think that would be a little harder for me with a bigger mill. I can get a little throttle happy at times =)

Milling is pretty new to me. The 30 belongs to my BIL and he brought it over so we could mill up some logs here. I'm just getting a handle on operating the thing. I recall he said it's around 15 hp. You can pretty much tell when the blades start to dull, even with the power feed. This mill has everything from cedar to hedge run through it, and handles it all.

Here's the pics of the dogging clamp. We're shut down at the moment and everything's under tarp, so please excuse the pics.

Dogging clamp:

The tubular section extends through holes in a double cross member. The knobs on it allow you to set the height.

Clamp in use:

This is just a mock-up pic. The spring loaded chain keeps constant tension on the dog. I set it a little high for the pic but it will go down to about 1" and still clear the blade support.

 

[Peachfuzz]

hmm... Got my brain juices flowing now... I'm going to take pics of whatever I come up with and post them back here. Gonna take me a couple of days to get things together.

 

[Mac88]

hmm... Got my brain juices flowing now... I'm going to take pics of whatever I come up with and post them back here. Gonna take me a couple of days to get things together.

Good luck. I'd be interested in seeing what you come up with.

 

[Peachfuzz]

Good luck. I'd be interested in seeing what you come up with.

Here's my update:
It took awhile to get the threaded rod. I used broken sockets and cut the bottoms off so they would slide on the rod. I decided on my hole placement and drilled the holes in the mill frame. Conveniently there is enough space for me to use nuts instead of weld to the frame, so I decided to do that in case i want to move the clamps later for some reason. I installed the rod and the slider, then measured from the top of the slider to the dog on the channel. I grabbed a broken wrench out of the scrap bucket and cut it up at the right height and welded it on to the sliders. This gives me a threaded clamp the height of the dog ear, and I will cut extensions that will drop down on the wrench and give me a taller clamp.
Other than that I just cut some tabs for the clamp nuts and welded them on to make wingnuts so I don't need tooling. In retrospect if I was to do it again I might set the clamps a little further down the frame to allow for a larger handle. Here are some pics of the clamp, I'll have more tomorrow of it on the machine.View attachment 269269View attachment 269270

 

[hamish]

Have me lost with your intent............................appears to be a labour intensive clamping system, try a simple cam.

View attachment 269282

 

[Peachfuzz]

I installed the clamps on the mill today. I threw some boards on there to try them out and take pictures. I'm extremely pleased with how easy they are to operate. They take any slack between the boards out and best of all is I have perfect control over my clamping pressure. I'm going to make a couple of extensions for the clamps so I can use them with more than square cants and fletching boards.
Just to recap: my original problem is that I have an lt10 with a bed extension, and 1 factory log clamp. The factory log clamp works fine with logs and cants until the start getting smaller. Below 4 inches of cut height I have a 50 percent chance the factory clamp will let loose in the middle of a cut. The only way I can make it stop it to overtighten it, which immediately brings the cant out of square with the mill deck. I have adjusted it a bit and it did help, but it's entirely to time consuming and irritating to operate.
Enter my solution - a threaded rod with sliding clamps and wingnuts for tool-less tightening without the headache I currently have. I mostly mill 6, 8, 10, 12 inch boards, so I used acme thread(same stuff in the benchvise in your shop), nuts, and broken wrenches and sockets for the clamp. Woodmizer wanted $120 dollars for another log clamp according to their website, and it was the same one I already don't like. The clamps I made didn't cost me but about $15 a piece, and they're solid tool steel. I could have welded them in place, but I had the clearance to bolt, so that's what I did, in case I wanted to adjust later.View attachment 269400View attachment 269401View attachment 269402View attachment 269403

 

[Mac88]

:msp_thumbsup: