Sawmill Setworks

Hello,

Consider me a electronics no nothing. I would like to build a system that controls the movement of my sawmill. Is it possible to imput numbers into a touch screen? Correspond that number to a push button for repeatability and frequent use. Finally use an encoder to verify correct movement amount.

Current system uses hydraulics and limit switches for movement. The hydraulic portion will be staying.

How feasible is this?

Welcome !

what you want to do is a rather large project.

however, all projects do break down into bits and pieces.

the Arduino and touch screen are things you can go on-line and find how to do.

but, your description of your other work is a bit short on details.

if you use an encoder and a roller, you can measure height. you can re-set for each new cut.

you can pre-set the distance, like radio-pre-select buttons in the car. then as you lower your blade (band saw mill, right?) you can have a RED/YELLOW/GREEN led as you get close, it goes to yellow, once on the correct setting it goes to green. to far, and back to yellow or red....

at these early stages, it is assumed you are not trying to set the cutting depth automatically ? that might come at a later point, but to get into that, you need to have a lot more experience with the Arduino.

Since you are also running hydraulics, I assume your feed is also hydraulic you should be able to monitor the feed speed. and report that. blade temperature is also withing the possibilities. as your programming skill and confidence grows, your can add quite a bit of information.

blade speed, cutter feed rate blade temperature water/coolant level hydraulic fluid temperature Hydraulic pressure.

if you put in the width of the log, and note the feed rate, you might be able to predict blade sharpness.

if you put in log width and distance of cut, you can figure our board feet hint, the feed rate at the end of cut changes as does load and blade speed.

There are many things you can work up to. what is your first goal ?

Here's what I had to say about this for a similar request in 2014:

Interesting project. An arduino could certainly do it, although I expect that a wood shop is a noisy environment electrically so you'd need to defend against that.

That you could though, doesn't mean that you should. Atmel has disclaimers against their devices being used in safety critical applications and I'd certainly put automated saws in this category.

The idea of writing a controller for this equipment as your first arduino project is a little scary. Since you say that this is in a workplace means legal liability issues too. Personally, I wouldn't do it.

My opinion hasn't changed.

How long have you been sawing? The experience there will depend greatly on if this is a project that should be undertaken. Those with less experience should not undertake the project or comment.

Which type of mill? Which positions are you trying to work with?

Do you just want a read out or do you also want the system to control the position?

The trick will be to find an encoder that is long enough. A rotary encoder mounted on the motors will have too much play due to the "drive train" to be of much use. Then you will need a way reliably mount the encoder to the mill and mount the electronics to keep out the dust and the moisture. Finally you will need a way to zero the encoder to a know position.

Otherwise, inputting numbers on a touch screen and reading an encoder is within the capability of an Arduino. Even building circuitry to control electro-hydraulic valves is too.

adwsystems:
Which type of mill? Which positions are you trying to work with?

Do you just want a read out or do you also want the system to control the position?

The trick will be to find an encoder that is long enough. A rotary encoder mounted on the motors will have too much play due to the “drive train” to be of much use. Then you will need a way reliably mount the encoder to the mill and mount the electronics to keep out the dust and the moisture. Finally you will need a way to zero the encoder to a know position.

Otherwise, inputting numbers on a touch screen and reading an encoder is within the capability of an Arduino. Even building circuitry to control electro-hydraulic valves is too.

The construction of the device is critical.
a direct measure on the vertical can be a simple grey scale encoder with the printed scale on the frame. the encoder then just becomes a set of IR diodes.
I agree with everyone that your skills with the mill and abilities to make thing so safe that it would automatically shut off if there was even a chance of hurting someone, should be a primary concern.
Simple readout of systems is not rocket surgery, but the accuracy is often more involved with the actual structure of the system more than ability of the sensor.

dave-in-nj: The construction of the device is critical. a direct measure on the vertical can be a simple grey scale encoder with the printed scale on the frame. the encoder then just becomes a set of IR diodes.

Dust. Sawmills make A LOT OF DUST. Did I mention they make a lot dust. They like to fill everything with dust. Eyes, ears, mouth, noise, pockets, shoes, everything. If you need more fiber in your diet, I suggest running a sawmill. I'm not sure optics is the way to go. I was thinking a linear magnetic quadrature encoder. It will have WAY more resolution and accuracy, but better ore than to little.

dave-in-nj: I agree with everyone that your skills with the mill and abilities to make thing so safe that it would automatically shut off if there was even a chance of hurting someone, should be a primary concern.

This depends greatly on what the OP wants to control. I assume either the vertical head position for a bandsaw mill or the cutting position of the truck of a circular mill. In neither case am I assuming he is trying to control the head (or truck) traversing the cut. There isn't much point in that. With that said, a simple set of limit switches for end of travel and a timer to detect the lack of encoder change when command (stuck, jammed, or loss of signal)

dave-in-nj: Simple readout of systems is not rocket surgery, but the accuracy is often more involved with the actual structure of the system more than ability of the sensor.

I suggest direct measurement (linear encoder) opposed to indirect (interpreting and converting motor rotations to linear position). Most mills use chain, cable, or belt drive in the drive train. All of which have a lot of play and backlash and lie between the motor and linear position, there by making indirect measure almost impossible.

Forester09: I would like to build a system that controls the movement of my sawmill.

If this is a machine that is capable of cutting someone's hand off then the FIRST thing you need to do before you make any modifications is get written approval from your liability insurer.

Frankly, I doubt if they will give it.

...R

Robin2: If this is a machine that is capable of cutting someone's hand off then the FIRST thing you need to do before you make any modifications is get written approval from your liability insurer.

Frankly, I doubt if they will give it.

...R

Are you assuming this is a commercial business application?

Robin2: If this is a machine that is capable of cutting someone's hand off then the FIRST thing you need to do before you make any modifications is get written approval from your liability insurer.

Frankly, I doubt if they will give it.

...R

I guess the same warning would go to somebody who wants to put an oil pressure sensor in an automobile after all it's being put into a device or a machine that can kill people and as we know more people die of cars every year than they do have guns

dave-in-nj: I guess the same warning would go to somebody who wants to put an oil pressure sensor in an automobile after all it's being put into a device or a machine that can kill people and as we know more people die of cars every year than they do have guns

That may be as insurers can be picky. If the pressure sensor was badly fitted and allowed oil to spill on the road it could cause a crash.

However I suspect the chances of that are far smaller than the risk of injury from a saw that is out of control.

...R

Bandsaw mills are run in price from 2k USD (Harbor Freight) to 70k USD, with the low end commerical saws around just 20k. Though the OP is not clear, it is likely this is for personal use, and not retrofitting something in a commercial business therefore there is no "liability insurer" to contact. If I had fewer projects on my plate, I might bite on this as well.

IMHO, to add sensors for measuring distance, or oil pressure, or temperature, does not rise to the concern of personal injury.

One of the problems with most saw mills in the lower end are that the height adjustments are manual and are not repetitious. Heaven forbid the Woodland Mills / Horror Fright machines should come with a decent blade. Blade temperature would help to extend the life or make better cuts.

I can see the desire to want to make a run of boards that are all 5/8"" and do so with some level of accuracy.
measuring is not a particularly dangerous sport.

I have not see the same level of concern for actually controlling laser heads, or CNC milling and drilling machines.
things that actually do bite or can cause permanent damage.

The risk of adding sensors is about as benign as measuring the sames sort of things in a garden.
temperature, humidity, pressures, levels, etc.

And up to now, there has been no in-depth discussion about automating the machine.

oh, and I would like to add to the list of sensors:

  • metal detecting on the log that is being cut. It will not detect bricks, but it would (should) be able to detect metals.

Up to this point, I think it is more dangerous to plug into a mains outlet to power your NANO. Real risk of electrical shock there, ones hands being so close to the mains voltage…

dave-in-nj:
One of the problems with most saw mills in the lower end are that the height adjustments are manual and are not repetitious. Heaven forbid the Woodland Mills / Horror Fright machines should come with a decent blade. Blade temperature would help to extend the life or make better cuts.

Most mills only come with 1 or 2 blades. Even the mid-range blades (I don’t use the more expensive blades that may last longer for fear of cutting into metal) only last 3-4 hours. Whether they provide a decent blade or junk, is almost irrelevant as you are going to have to buy more blades by the end of the first day.

P.S. There is a hilarious video on YouTube of a guy testing a Harbor Freight mill with the stock blade and an “aftermarket” Lenox blade. He states how awful the Lenox blade is. If you look carefully, the blade is on inside-out/backwards. :o

dave-in-nj:
oh, and I would like to add to the list of sensors:

  • metal detecting on the log that is being cut. It will not detect bricks, but it would (should) be able to detect metals.

Me too, but unfortunately once the log is on the mill the metal detectors capable of detecting a metal object up to 1 1/2" to 2" below the surface also detect the mill frame, especially toward the back of the mill nearest the back stops (lots of upright metal back there).

dave-in-nj:
I can see the desire to want to make a run of boards that are all 5/8"" and do so with some level of accuracy. measuring is not a particularly dangerous sport.

I have cut as thin as 1/4" at 14" wide making stock to be veneers. But cutting that thin is rare and only available on the clearest (no knots) of wood. Best case, you need 3/16" of material extra for finishing (squaring and planing). So to make a finished board 1" thick (actually 1" thick), the lumber from the mill must be at least 1 3/16", if not closer to 1 3/8" thick.

adwsystems: Quote from: dave-in-nj on Oct 15, 2018, 05:57 pm

I can see the desire to want to make a run of boards that are all 5/8"" and do so with some level of accuracy. measuring is not a particularly dangerous sport.

I have cut as thin as 1/4" at 14" wide making stock to be veneers. But cutting that thin is rare and only available on the clearest (no knots) of wood. Best case, you need 3/16" of material extra for finishing (squaring and planing). So to make a finished board 1" thick (actually 1" thick), the lumber from the mill must be at least 1 3/16", if not closer to 1 3/8" thick.

Exactly the point of adding higher quality measuring.

If you need a 1 inch finish size you need materials to remove with the planer. If you need 1-3/16 but take 1-3/8 you put more wear on you planer blades and if you take 10 cuts, that is an extra 2 inches or possibly 1 or 2 more boards out of a log. higher accuracy is part of what the use of an Arduino is for.

This goes to benefit every aspect. more boards per log, more boards per day less trees needed, less running time for the mill, less CO2 generated, less time sharpening a blade....

As for safety, a loose blade scares me more than one on the machine. Just folding a blade with 1 inch spacing on teeth is a feat best down with thick protective clothes.

dave-in-nj:
As for safety, a loose blade scares me more than one on the machine.
Just folding a blade with 1 inch spacing on teeth is a feat best down with thick protective clothes.

I max that task at 3/4". I hate folding the sawmill blades. There is method called flat packing, kind of like a pretzel. That is what I use.

dave-in-nj:
If you need a 1 inch finish size you need materials to remove with the planer. If you need 1-3/16 but take 1-3/8 you put more wear on you planer blades and if you take 10 cuts, that is an extra 2 inches or possibly 1 or 2 more boards out of a log. Higher accuracy is part of what the use of an Arduino is for.

The Arduino and the additional accuracy is actually only of minimal effect. If the log is clear, the blade sharp, and the planets aligned you can get away with 1-3/16" thick for a 1" finished board. More likely the log is not perfectly clear, the blade is not perfectly sharp, and the planets not aligned in your favor. The cut will need to be 1-3/8", or close there to, to ensure enough material front and back to produce the desired 1" thick finished board. The International Standard (not an international standard but the standard called the International Standard. do blame me I didn’t name it) calls for a 1-1/8" thick for 1" thick nominal (3/4" actual) boards. Hence the 3/8". But when making framing type lumber such as a 2"x4" the cuts are 2" and 4" but the finished board is 1-1/2"x3-1/2" (extra 1/2" each dimension).

Where I can see the Arduino coming into the picture is based on my height gauge. The marker stands 3/8" from the ruler. When starting on a 28" log the marker is above my eye level (likely above my head) and I’m looking up at it. On the final cuts, it is near my waist and I’m looking down at it. The error due to the parallax effect can be huge if I’m not careful. This is why I am pondering the “electronic ruler”.

The OP has not returned, so we do not know if the desire is for and electronic ruler or, as titled, electronic setworks where the Arduino will move the head (likely on command) to the desired height.

There are several different things that I would like to do but let's start simple. The mill itself is a circular mill so my movements will be in and out. I would like to use an encoder to know the distance of the headblocks in relation to the blade. With, the press of a button they will move the desired distance. My thought is if I can master then I can add as I go.

do you have photos or a sketch of the parts you want to measure? if you want to move parts of the machine, how do you plan to move? electric motors ? hydraulic motors?

They are moved no by hydraulics controlled by electric soloniode.

I still vote for the magnetic encoder with an input to enter the current distance. This works better than trying to set 0, because you cannot always get to 0. What is the point of try to saw (or plane, sand, or cut) a board that is 0 inches thick.