Sawmill cnc ideas and input.

Hi my name is Shaun and I’ve been playing with micro controllers off and on for a few years so I am a beginner with programing. What I’m looking to do is automate this mill and make it more user friendly. I have done several things to make it more user friendly.

Now the mill has a motorized deck to raise & lower blade and I’m working on motorized bed travel.

What the plans are to have the micro controller counting the encoder steps on the bed and deck travel. Just a few inches before the log and a few after the log on the bed. After each cut drop an inch or what ever I’m needing cut on each pass.

Well you get the idea. Any input

OK. What do you want help on?

What do you think would be the best way to input info and some type of visual conformation of what was entered. Say I wanted one log cut in inch planks what would be a good way to enter in, touch pad, push buttons, twist encoder knob to select thickness of whats to be cut. Should it be just predetermined thickness like in 1/8 increments or would some type of input be easier to program.

What would be super nice is if someone has already done something similar and I can see what and how they did it.

It all depends on your requirements. Are you satisfied with just one thickness option, or do you want more options for thickness?

I think a 16x2 character line display would be ideal to give the user some feedback. Maybe a rotary encoder to allow the user to dial in values. These could be preset increments as appropriate to what is being adjusted.

A simple menu system and jobs a goodun. If you want something really nice you could perhaps even go for a 3" touch sensitive display. I still like the rotary encoder idea to dial in values though.

Oooo yes I would love to do a touch screen with a TFT LCD. With little spinning gadgets and blinking lights on the LCD but that's way beyond my knowledge. A 16x2 character line display will work and that's a great idea using a rotary encoder idea to dial in values. I have about till march before I will need it so I have the time to learn and play.

Usually I cut 1" planks on some wood but other wood 1 1/2 structural wood. Some people want 1/2 and 3/4 planks and some want 6" thick slabs.

As for the motorized bed travel chances are its going to be dual 12v motors and a chain spanning the distance of the bed on each side. The motors will pull the carriage along the bed one motor on each side. I will add an encoder to one side to give a position to the controller. The motors will be regulated with a speed controller to slow the carriage depending on the wood hardness.

if you drive the motors on a gear on the sled and the chain is fixed, you can use some sort of spring tension to keep up the slack. the great thing is that you can also use that tension as feedback to the motor to tell it the blade is dull or the wood hard.

mounting the motor on a leaf spring would allow minimal movement with the give needed to protect the blade.

Have you discussed this project with your Liability insurers?

If not, do so before you spend any more time on it.

...R

what ever you do it will need to be very well protected I have not worked on band saws but when I was young I spent every weekend and holiday working on a 3/4 saw with 3 blades the 3rd blade was motorised the motor and controller had to get changed quite a few times because of the saw dust, rain, blade coolant and dust was always getting in some how. in the end it got changed to a hand control.
also the carriage was controlled by a capstan for going forwards and backwards

The motors will pull the carriage along the bed one motor on each side. I will add an encoder to one side to give a position to the controller.

When you have two or more of something they will rarely stay naturally synchronized. Wear on the motors, a knot in the wood, even a difference in power cables will cause the motors to move at different rates. I suggest you either have one drive motor with appropriate linkage or use two encoders.

thinking about this. I like the idea of a keypad. like a calculator, you can put in the basics, saw tooth set distance (Kerf), and the expected cut error. these could be built in and changed after your sharpen or change blades.

then you could have it set to the board thickness for your repetitive cutting.

as others have mentioned, alignment of the carriage as it moves is important. a single drive axle at the end of the unit with a cable or chain that moves would keep the carriage in alignment at all times.

if you use a hydraulic blade tensioner, you could add a sensor for that.
with a tachometer on the drive wheel, you could calculate blade speed.

Robin2:
Have you discussed this project with your Liability insurers?

If not, do so before you spend any more time on it.

...R

I'm not concerned at all about liability. I have spent two years of my life learning and I am not a person.

TO: Shannon
Unfortunately the carriage has to be pulled from each side. It will bind up if only moved only from one side. Now if some one can come up with an idea to move it along the bed with one motor that would be great.

I have spent two years of my life learning and I am not a person.

:o :cold_sweat:

vffgaston:
:o :cold_sweat:

Yea that was a confusing sentence for some, give it a few and lets wait and see if its recognized.

Yea just pushing it from one side is a pain, you can do it but its not nearly as smooth as pushing from around the center of the carriage. When the blade is sharp and the rails are clean you can push it with two fingers.

It the future I would like to have the controller monitor the current to the drive motors and regulate the speed of feed.

TO: Shannon

In which case, I will assume you prefer to be addressed by your forum ranking rather than your moniker. As you wish. :wink:

TO: Newbie

Unfortunately the carriage has to be pulled from each side. It will bind up if only moved only from one side. Now if some one can come up with an idea to move it along the bed with one motor that would be great.

Well, two motors, each with their own encoder, would certainly work (with a bit of software).

Greensprings:
what is a shannon member, is that like Wu Tang

Google Claude Shannon

...R

Lol I see the error in my ways master

Mmmm why two encoders?

One for each motor. You increase (decrease) power to the motor that is running slower (faster) than the other. This is a common problem / solution with mobile robots that have two or more drive wheels. I suspect you can even find an off-the-shelf tandem motor driver that takes care of some / most / all of the details.

The problem with stepper motors (all motors) is, without feedback, there is no way for the controller to know when it slips or stalls. Which are very likely to occur with this application. Once feedback is added (an encoder) there is no point in limiting the motor choice to just steppers.