Tensioning method for homemade bandsaw mill

[tnaz]

If anyone is interested I can post some pictures of my progress so far.

Please post some pictures, thats what I live for.  "I ain't got no mill!!!"

tnaz

[matt_K98]

Haha, alright. I will take some pictures tomorrow and post them.

[Ox]

Yep, pics please!  Remember, others in the future will be reading this thread and learning, too. 

[Magicman]

If a blade heats up it is dull and needs replacing.   

[matt_K98]

Here are a few pictures of what i have done,


You can see the two metal plates I welded onto the tube, this worked really well.


You can see on this picture that the plate is now level.


Here is all the hardware that came out of the scissor jack, a 15" long 1/2" ACME rod, and one nut that fits the thread on the rod. The other nut doesn't have any threads, the rod just slides through it.

I bought a little piece of angle iron that I am going to weld onto the sawmills platform, and I will run the rod through.


So this is where I am at right now, I'm just trying to figure out how this will all work.

If anyone knows how I could set this up from the pictures above, please let me know.  ???

[Ox]

Sorry, but I'd have to be there in person to see the stuff in real life.  I'm not very good at seeing and imagining things in 3D.  Someone smarter will be along soon!

[Kbeitz]

Will that rod be pushing or pulling ?

[Ljohnsaw]

My set up was pulling with the rod so it was easy to do.  Yours looks like it will be pushing so here is one way to get 'er done:

You need to mount the threaded "nut" on to the LEFT side of the axle mounting plate in the picture.  You just need to prevent it from spinning.  A couple of small pieces of angle iron welded on each side of the hole will do it.  The piece of angle iron that you drilled a nice hole in - weld a plate on the LEFT side of that so there is a pocket for the end of the rod to ride in.  There will be considerable force on this plate so it should be thick and welded securely.  If you wanted, you could weld the un-threaded "nut" to make the pocket deeper.  Now the question is, with the ACME rod that will be sticking out quite a bit on the left side of your axle mounting plate be accessible to rotate and also not in the way of your wheel axle?

If it will interfere there, you could reverse the installation:  Make a pocket by welding a plate on the RIGHT side of your axle mount plate and put the ACME nut against the RIGHT side of you angle iron bracket.

Its your choice as to how much of the ACME rod you want to use - you would just adjust where you put your angle iron bracket.  The longer the rod (since it is in compression), the more apt to bow under the strain.  Scissor jacks pull, not push.

Hope this makes sense.

[matt_K98]

I can make the rod push or pull, whichever is easier to do.

[Joe Hillmann]

If you make it so the rod is pushing make it as short as possible the longer the piece is that has pressure on it the  more likely it is to bend.  If the rod is pulling it shouldn't matter since it will be trying to pull it straight.

I also don't know if that is a heavy duty enough threaded rod to stand up to the abuse it will receive.

[Ljohnsaw]

I can make the rod push or pull, whichever is easier to do.

With your setup there, I don't see how you could make it pull...

[matt_K98]

I can make the rod push or pull, whichever is easier to do.

With your setup there, I don't see how you could make it pull...

I'm sorry, I don't think I quite understand what your saying about the "pushing setup."

I never posted a picture but I was planning on using a compression spring over the ACME rod, I don't know if that will effect the way I set it up?

Really whatever way I can set it up I will do, I don't want to make this over complicated.

[Ljohnsaw]

I'm making an assumption and you know what happens when you assume...

It looks like the plate must extent out to tighten you blade, correct?  So there is no way you could "pull" with the threaded rod with what you show in the picture.  To make it pull, you would have to jump through some hoops with some fancy brackets.  Doable but try with what you have so far and see how it works.

[matt_K98]

Correct, the plate in the picture is shown pushed inwards so the blade can be installed, the plate extends a few inches out.

[matt_K98]

So here's a little diagram of what my intentions were.

I was going to weld the nut onto the left side of the mounting plate then move the piece of angle iron that I drilled a hole in, closer towards the mounting plate to support the rod, weld it down, then weld another piece of angle iron behind it so the rod pushes against it.

Then eventually weld a handle on the end of the rod.

[Ljohnsaw]

That should work great.  Two things, keep the rod as short as possible and brace the left angle iron really well.  You don't really need to weld the nut to the plate, just capture it between two bars.  That way if you change your mind, you don't have cut it off.  Plus, if you weld it, there is the chance of destroying it.  Don't ask me how I know about things like that... :

[Kbeitz]

Just so you know what kind of pressure your working with...
This is my setup. I'm using 1/2" all threaded rod.
I had a chunk of 1/2" water pipe welded to the hidden end of
the rod. One of the long bolts that clamp the sliding part
had the chunk of pipe over it. When I first tried it out the
pipe snapped in too. I had to weld a 1/2" thick steel plate
with a hole drilled in it to keep it from snapping in too.
The  all threaded rod is what pulls on the long bolts that
slides everything.



 

[matt_K98]

I worked on the wheel tensioning a bit more this morning, I welded everything down and then I put a blade on the wheels and tested it. It works great, the only issue I am finding is that the ACME rod is wanting to bend since there is nothing supporting it, just like @Kbeitz said would happen. So I will weld a piece of steel with a hole drilled through it, onto the tube that's attached to the mounting plate.

The other issue I am having is with the blade tracking. Just to test the tracking I ran the wheels parallel with the frame, put a blade on then tightened it down. It did not track very well and wanted to roll off. I then started to mess around with the "toeing" of the wheels, it still did not want to track very well. So I will keep adjusting the wheel toeing until the blade wants to track. (If anyone has any tips to do this that would be great!)

Here are a few pictures of the bolt tensioner,


I took this picture before I welded a support onto the angle iron, I found that when the rod was putting pressure on the angle iron that it wanted to bend, so to fix that I got a 2"x2" 1/4" thick piece of steel and welded it onto the back of the angle iron. Eventually I will secure the nut and then weld a handle onto the end of the rod. I may order a 3/4" ACME rod just to be on the safe side. (As you can see, I'm not the best welder out there  ;))


Here is the wheel mounted and the blade under tension, this is when I had the wheels parallel to the frame.

[Ljohnsaw]

Matt,

Not to throw the proverbial wrench in the works...  With you blade on, I noticed something and you need to verify.  The motor MUST pull the blade through the cut, not push it.  The teeth on the blade on the bottom of the wheels should be pointing toward the powered wheel.  Is your engine running the correct direction to do that or in the direction that the blade is currently shown.

The reason is that the blade needs to be under constant tension.  If you are "pushing" the blade, the tension will wander up and down as the tires flex under the load (as you begin to cut) and will adversely affect the quality of your lumber.  The shaft on the adjustable side looks long enough to mount the drive pulley there if you need to swap sides.  However, the blade tension adjustment will also affect the drive belt tension unless you have other arrangements.

Also, I don't see it in the pictures - how are you adjusting the toe-in on the wheel?  Shims?  If so, you really need a bolt-like adjustment.  You will find you need small changes and you need to be able to do it while it is running.

[matt_K98]

The way I mounted my motor, the shaft is facing behind the sawmill, my engines shaft runs counter clockwise, so the blade will be spinning to the left. (When you are standing behind the mill.)

I totally forgot to check if the teeth on the blade are facing the right direction, but If they are not, then I can always flip the blade inside out so the teeth are facing the right direction.

[matt_K98]

For the toeing adjustments, I am putting washers behind the pillow block bearings to angle the wheels outwards.

It seems to be working good, but maybe I do need a fine adjustment, I may have to tinker around and see what I can do.

[Ljohnsaw]

The way I mounted my motor, the shaft is facing behind the sawmill, my engines shaft runs counter clockwise, so the blade will be spinning to the left. (When you are standing behind the mill.)

I totally forgot to check if the teeth on the blade are facing the right direction, but If they are not, then I can always flip the blade inside out so the teeth are facing the right direction.

Perfect!  I just didn't want you going down a bad path.  Don't forget to flip the blade - they don't cut so well the wrong direction :D

[Ljohnsaw]

For the toeing adjustments, I am putting washers behind the pillow block bearings to angle the wheels outwards.

It seems to be working good, but maybe I do need a fine adjustment, I may have to tinker around and see what I can do.

Here is a wild hare thought.  Make another plate to mount the pillow blocks on and have a rod welded in the middle, vertically on the back side of it.  If you use long enough bolts on the pillow blocks, they will extend through your original mounting plate (might have to elongate the hole a tad).  With nuts on the back of your original plate, you can teeter-todder the secondary mounting plate.  A nut on the opposite side would be snugged up when you have the correct toe-in.

[matt_K98]

That sounds like a good idea!

Now do you think it would make a difference if I mounted the rod in the center of the plate or near the front that way I can use a bolt on the back end to adjust the toeing.

Here is an example of what I mean,

[Ox]

That'll work!  I think it's similar to Bill Rake's design.