iDRY Vacuum Kilns

Sponsors:

Homemade sawmill questions

Started by cowhead5065, January 11, 2022, 06:55:42 PM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

cowhead5065

First off thanks for letting me join. I have been lurking in the background reading every post I can about homemade bandsaw mills I can find. I started my build about two weeks ago and am close to being finished. I have sooo many questions. I hope I am just way overthinking things but would love guidance from those of you who are more knowledgeable than myself. 
I am building a two post lift. Running Surplus Center 16" wheels with B- belts. 205" woodmizer blades with a 19hp lawn mower engine. From the calculations I have done I hope my running speed is about 4200ish fpm??  I will post the pulley sizes when I find my paper work. 
Ok on to the questions:
I am using a harbor freight winch to raise and lower the cutting head. When I raise and lower the head I put a digital level on the frame and it varies from 1/10-4/10" out of level stopping at random intervals. Is this within tolerance?
I have yet to power this thing up because I'm scared to death the blade is going to fly off. I have spun the wheels probably a mile by hand as fast as I can and it seems to track perfectly. 
Where should the blade rest on the wheels? It seems to be just off the center line of the blade on the crown of the v-belt. 
Sorry for the long post I will be asking questions rapidly. I will post pics too. 
Thanks in advance 

cowhead5065


fluidpowerpro

Quote from: cowhead5065 on January 11, 2022, 06:55:42 PM
Ok on to the questions:
I am using a harbor freight winch to raise and lower the cutting head. When I raise and lower the head I put a digital level on the frame and it varies from 1/10-4/10" out of level stopping at random intervals. Is this within tolerance?

Where should the blade rest on the wheels? It seems to be just off the center line of the blade on the crown of the v-belt.

Thats a nice looking saw.

Unless you plan to cut shingles, I would think you would want to hold better than 1/10"-4/10". Something must be wrong with the cable routing or maybe your head is hanging up on one side.
As far as blade placement on the wheel, I can only speak for what is recommended on my mill (A Hudson) and that is that the back of the blade should be even with the back of the wheel.
Change is hard....
Especially when a jar full of it falls off the top shelf and hits your head!

cowhead5065

Thanks for the info. I believe as the cable winds in the drum I get inconsistency. Just wondering how people have worked out this problem. I can't believe it hasn't happened to someone else. 

cowhead5065

Ok brain fart. I have 1/10 to 4/10 of a degree out, not inch. The digital level is displaying degrees. Sorry for the confusion 

Old Greenhorn

Quote from: cowhead5065 on January 11, 2022, 06:55:42 PM
........
Ok on to the questions:
I am using a harbor freight winch to raise and lower the cutting head. When I raise and lower the head I put a digital level on the frame and it varies from 1/10-4/10" out of level stopping at random intervals. Is this within tolerance?
I have yet to power this thing up because I'm scared to death the blade is going to fly off. I have spun the wheels probably a mile by hand as fast as I can and it seems to track perfectly.
Where should the blade rest on the wheels? It seems to be just off the center line of the blade on the crown of the v-belt.
Sorry for the long post I will be asking questions rapidly. I will post pics too.
Thanks in advance
As FPP said, those tolerances are not going to make you good lumber. OK, just saw your update but I am not sure how that angle relates to the variation over the width of you widest cut, anyway to figure than out? Best take time to figure that out now before you button it up. Seems like your frame is allowing the sliding head to 'cant' as it travels, and that shouldn't happen. In addition to the out of level condition, this will also likely translate into movement during the cut and if it is in more than one plane you will go crazy trying to fix it later. It should ride up and down smooth and rigid.
 If you rolled that blade many times, you should be fine to run that engine. Just pulse it a couple of times getting it up to speed. Guaranteed to make you smile. If your guards are made up, put them in place before you crank it up. If everything is tight and there is no movement, you should be golden.
 The blade should track so that the teeth are not on the wheel, but just in front of it, and the back of the blade should be around the back edge of the wheel.
 Nice job so far. Looks like it will be solid and cut pretty wide. Keep up with the photos as you go along. 
Tom Lindtveit, Woodsman Forest Products
Oscar 328 Band Mill, Husky 350, 450, 562, & 372 (Clone), Mule 3010, and too many hand tools. :) Retired and trying to make a living to stay that way. NYLT Certified.
OK, maybe I'm the woodcutter now.
I work with wood, There is a rumor I might be a woodworker.

cowhead5065

 

 Thanks old greenhorn. Here is a picture of where the blade is riding on the wheels. The head slides up and down smooth as can be. It's hard to believe that 4/10 of a degree would make any significance, but this will cut a 45" wide log so maybe over the span of 45" that comes into play. I am a carpenter by trade and I know that none of the homes I have seen built had tolerance like that, so that is kind of where I'm coming from. 
I built this as cheap as one has probably been built, and I'm not crazy about the winch doing the head lifting, but it's what I had on hand so.... 

rusticretreater

 

 

On my Woodland Mills saw, the clearance between the back of the blade and the roller guide bearing is .038 to .042 inches.

As for your degree problem, the further away you get from the base angle(vertex), the wider the degree disparity becomes.  If it is at one end of the blade, the other end will be off by a lot at 45". If the vertex is centered on the blade, then both ends will be off the same amount, but in opposite directions.  Even worse.

The sawmill head may be unbalanced and sways from side to side as its moved.  The way the cable wraps onto the winch spool may pull on your cables unevenly if there is free play in the system.(No pictures, so I'm guessing).  I do think that it is likely a combination of both of these.  Can you post a picture of your cabling system?

On my sawmill, they put post sleeve bushings made of HDPE(cutting board plastic) to maintain a clearance with the posts assuring proper alignment.  



 

As a fabricator and woodworker, you're doing a great build!
Woodland Mills HM130 Max w/ Lap siding upgrade
Kubota BX25
Wicked Grapple, Wicked Toothbar
Homemade Log Arch
Big Tex 17' trailer with Log Arch
Warn Winches 8000lb and 4000lb
Husqvarna 562xp
2,000,000th Forestry Forum Post

cowhead5065

Thanks Rustic. Here is the cable system and what I did where the head moves up and down to take away some of the slack. I also used hdpe. 


thecfarm

Welcome to the forum!!
First off, I am not a builder!!
I bought a mill that can cut 20-foot logs. Little did I know this is a big help. I can put a 16 foot log on my mill and I have 4 feet of extra room, not inches like other mills. I have never cut a 20 foot log, but I wanted the option just in case. I have bought stuff and think it's great at that time. Then a year down the road, wish I would have bought something else.  This more room lets me get the head out of the way and lets me put the log anywhere I want too. No need to try to get the log in the correct spot.
So build it long!!!   :)
Model 6020-20hp Manual Thomas bandsaw,TC40A 4wd 40 hp New Holland tractor, 450 Norse Winch, Heatmor 400 OWB,YCC 1978-79

rusticretreater

You mean all that work I did to get you that HDPE image was wasted!  :o ;D

That setup certainly won't work as it doesn't pull evenly on both cables.  The bundle of cable to the blade side of the mill has a larger circumference and pulls more cable per revolution.  If you check, you should see the head canted to one side and the free play in your HDPE shims is taken up when you have a large degree offset.

You might want to tighten them up into a system like the one I posted to put free play at a minimum. But your cable system needs a redesign.  I'm gonna draw a picture to give you an idea, so give me a few minutes.
Woodland Mills HM130 Max w/ Lap siding upgrade
Kubota BX25
Wicked Grapple, Wicked Toothbar
Homemade Log Arch
Big Tex 17' trailer with Log Arch
Warn Winches 8000lb and 4000lb
Husqvarna 562xp
2,000,000th Forestry Forum Post

fluidpowerpro

Maybe 4/10 ths of a degree isnt really that bad. Instead of measuring degrees, just measure actual distance from the blade to a fixed point. That will tell you how close the board will be from edge to edge. 

I think either way though, nows the time to try to improve it. If your like me, and you know its off, it will eventually bug you enough that you end up fixing it later anyway.

I recently modified my mill to use a HF winch also. Based on your picture, I think the issue your having might be because of how the cable wraps on top of itself. When it wraps on top, the drum diameter changes so the distance the cable is pulled changes.
If its directly on top of a cable, or in a valley in between 2 cables will make a difference. 
On my winch, there is a single cable on the drum and because the travel distance is so short, it never wraps on top of itself. Redo the cables so only one is on the drum. Youll probably end up running that cable to the other side of the mill, around a pulley, and then back to the other side. You could also try modifying the winch drum so there are separate sides to it. That way the cables never wrap on top of one another.
Change is hard....
Especially when a jar full of it falls off the top shelf and hits your head!

rusticretreater

As fluidpowerpro said:



 

You might want to make some kind of guide for the metal piece so that it doesn't move around due to the cable stresses.
Woodland Mills HM130 Max w/ Lap siding upgrade
Kubota BX25
Wicked Grapple, Wicked Toothbar
Homemade Log Arch
Big Tex 17' trailer with Log Arch
Warn Winches 8000lb and 4000lb
Husqvarna 562xp
2,000,000th Forestry Forum Post

fluidpowerpro

Also, you might as well plan on putting on a PWM speed control on your winch. I think you will find that without it, when your making height adjustments, its going to be too fast and therefore hard to hit your mark on the visual scale. They are not very expensive and you can get one on line for about $20 - $40. I would also suggest adding a limit switch that shuts the winch off when you raise it up all the way. That way you dont stress the cables when you hit the mechanical limits.
Change is hard....
Especially when a jar full of it falls off the top shelf and hits your head!

Ljohnsaw

Quote from: rusticretreater on January 11, 2022, 10:00:47 PMYou might want to make some kind of guide for the metal piece so that it doesn't move around due to the cable stresses.
Just use a cable clamp.  Then there is no flexing.
John Sawicky

Just North-East of Sacramento...

SkyTrak 9038, Ford 545D FEL, Davis Little Monster backhoe, Case 16+4 Trencher, Home Built 42" capacity/36" cut Bandmill up to 54' long - using it all to build a timber frame cabin.

cowhead5065

Thanks guys. I am still trying to understand the cable route from your drawing, it will eventually click. 
I do have a pwm for the winch. 
Cable clamp is a great idea. 

fluidpowerpro

 

 

Here is a picture of a replacement cable I made for my small Hudson Oscar 18. You can see how a single cable from the winch ends up pulling 2 cables that are attached to the head. 
Change is hard....
Especially when a jar full of it falls off the top shelf and hits your head!

biggkidd

Please first understand I haven't built my mill yet but I do have some bit of life invested in creating things. I think you might want to balance the weight across your saw head a bit closer before you make bigger changes. I think the battery off to one side without it's counter balance could well be your issue or a large part of it.

Build looks great!
Echo 330 T, Echo 510, Stihl Farm Boss, Dolmar 7900, Jinma 354 W/ FEL, & TPH Backhoe, 1969 M35A2,  1970 Cat D4
Building a Band Mill  :)

dustyhat

First i like your winch method, if someone walked into my shop and ask for help with your winch trouble i would replace the drum with a solid round of aluminum all i could get in there, with two grooves a few thousands wider than your cable size , that way your cable can wrap on itself one single wind making a more precision wrap so to speak , dos that make any sense.

Joe Hillmann

Try raising and lowering it with the engine running.  The vibrations of the engine help the same problem on my mill
 What also helps is to always lower the head about a half inch lower then you want to cut then raise it back to your cut point.

What is or isn't good enough is up to you.

Often when I break a big log down into cants I don't worry about precision. Close is good enough.  Then when I break the carts into boards I pay more attention to precision.  Because the boards are usually narrower if the head is a little off level it isn't as noticeable as on wider cuts.  And narrower cuts are less likely to cause my blade to wander.

apm

Is that a vertical shaft engine? how are you changing direction of the belt? 

thanks, 

Greg
Timberking 1600 now

cowhead5065

Thanks Joe, kind of what I figured. I will try it out and see how it works, always going to be making improvements as I go. 
Apm yes it is a vertical shaft engine, it's what I had. Just twist the belt and it works fine. I will be making something to help keep the belt from slipping off just in case. 

JoshNZ

If I'm understanding your format right 4/10 of a degree or 0.4 degrees variation is a thickness difference of over 1/4" across a 40" cut. I'd say that'll annoy you.

The way you have it setup is definitely prone to error, one revolution of the drum will retrieve a slightly different length of each of the cables depending on where they wrap, and hence pull one side higher than the other, as mentioned. Solve it by only wrapping one length of cable on the drum and having the end of that length pull on two cables, one going to each side. One can't be pulled more than the other as they are connected to the same point, as the sketch shows.

Good luck!

Joe Hillmann

Quote from: JoshNZ on January 12, 2022, 11:03:32 AM
The way you have it setup is definitely prone to error, one revolution of the drum will retrieve a slightly different length of each of the cables depending on where they wrap, and hence pull one side higher than the other, as mentioned. Solve it by only wrapping one length of cable on the drum and having the end of that length pull on two cables, one going to each side. One can't be pulled more than the other as they are connected to the same point, as the sketch shows.

Good luck!
I agree with Josh, the way your cable can bunch up differently on each end is part of your problem.  I would look into the cable spools that are used on garage door springs that have a groove for the cable to lay in as it is wound up,  that way it cant over lap.
Here is a picture of how the cable is routed on my mill.


 
The blue points are stationary and mounted to the two upright posts.  The red points are on the part of the head that moves and they go up and down with the head.  This design for sure has issues with not staying level but the vibration of the engine and lowering past my cut then raising back up to it helps a lot.
With this set up there is a 1/2 reduction between how much the winch turns and how much the head moves, which is good because the head got heavier and heavier as I built the mill. 
On the down side, the blue pulley on the top left of the picture is always under strain of 2x the weight of the head of the mill,  so it has to be pretty well built.
This was the simplest/cheapest design I could come up with when building my mill.  The only way to make it simpler would be if the winch was where the top blue pulley was(but mine is hand crank so I wouldn't be able to reach it up there.  With and electric winch that wouldn't be a problem)

Thank You Sponsors!