Auto saw stop

Hi

New to this stuff but very keen to learn i would like to build a automated saw length stop that would work by entering a size in to a keypad and lcd or touchscreen and the stop moving to that size to make the cut

thinking of a dc gear motor running along a rack with encoder my question is would i get an accurate size with this or would a large steper motor be better when i mean accurate i mean 0.5-1mm would be fine but more would be nice, the length is fairly large ranging for 0-4000mm

if this works out i hope to add a powered feed table that feeds the stock into the stop and that would control a numatic clamp to hold the work

any help ideas or feedback would be great
thanks again

Your post leaves just a wee bit many variables in it's description.

For starters: a table saw?

If you can manage, a picture would help replies be more consistent and on target...

:wink:

Is the saw a circular saw, a band saw or a reciprocating saw?
If circular, what is the diameter of the blade?
What moves, the work piece or the blade?
How is it moved? By hand or powered?
What is the saw cutting? Wood, metal, stone, plastic, etc?
As 1:1 stated, there are too many unknown variables to give you an answer.

Something like one of these? http://www.sawgear.com/Applications.aspx

if you cut a section, you have a zero. if you feed your material with rollersa such as a power feed all you need to hace is a rotary encoder on your part.

should be prettey straight forward.

using a belt with a stop could be done as well. timing belts and steppers can delivers the accuracy you are looking for with stock parts.

0,5 - 1 mm accuracy over the distance of 4 meters using timing belts? I would not bet on that being achievable.
When people say "saw" I think of wood, but getting 0,5 mm accuracy in wood is hard even on small workpieces.
If we are talking metal, things get even more complicated.
Also, most common usage of the word saw, at least to me, implies a cut through the entire workpiece, not partial, so you'll have to elaborate of what exactly and how are you sawing.

CNC machines of that size cost tens of thousands of euros/dollars/pounds, because this is not a trivial requirement. Even if you need only one axis and divide the cost of a CNC machine by 3, you still get a huge bill.

Hi Thanks for all the replys

Sorry I'm cutting steel sections with a 300mm 3ph band saw the saw will be fixed and the stock will be pushed by hand thought the saw to the stop for now i was thinking of a rack and dc gear motor or servo motor just wanted to see if anyone has done something like this

Thanks the sawgear link is what i would like to built also tigerstop but both products are £5500 - £6500 a pop

Don't let the work feed determine the amount of cut. Just let it push, hit a stop, then slip until a timeout or until it actually senses it's at the stop.

The stop can be on a linear encoder, distance referenced with the blade (average or point of largest 'wobble').

Then your pneumatic clamps can swing into action.

Separate projects really - you can integrate as you go.

Thanks

yes i was thinking that the switch on the stop would turn off the feed rollers with a small time delay to acount for any bounce this could be reduced with a sensor mounted slightly forward of the end stop to slow the feed rollers down the last 100mm - 200mm then clamp the work then i could operate the saw bye hand for now (but would like to automate this in the end ) then release the clamp when the saw is raised to the fully up position

thinking about the sensor to slow down the feed rollers maybe a problem when cutting small bits as it will have to be mounted forward of the stop mayby a sensor on the stop that can detect the work approaching it ???

Thanks for the help

This is what I am wanting to accomplish as well except exactly like my miter Saw job site set up. Any progress with this?

615306:
This is what I am wanting to accomplish as well except exactly like my miter Saw job site set up. Any progress with this?

yes,
start your own thread and be detailed about what you want to achieve.
go to the link in post #3, and in your new thread, mention that you went there and what you thought