Re: [CAD_CAM_EDM_DRO] Re: How Would You Design question

Hi Tim:
You will probably need to stabilize the material on both sides of the
cut if you want to hold 0.0025"
Best way I can think of for the free strip is a vacuum fence.
If you just let it hang out in space the saw will recut it every time it
curls or flops around.
You'll never hold tolerance without the vacuum fence.
So long as you can adjust it dead nuts parallel and exactly to width, you
may not even need anything more elaborate than just the fence.
It's worth a try anyway ( cheapest part of the whole rig, assuming you've
got a decent saw and a top quality planer blade.)
If you want to get fancy, then you can set up a panel sawing frame to run in
the miter fence slots, and top clamp the stock.
You still need the vacuum fence though (but it becomes part of the sliding
frame.)
Cheers

Marcus

----- Original Message -----
From: "Tim Goldstein" <timg@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Wednesday, April 24, 2002 7:16 PM
Subject: RE: [CAD_CAM_EDM_DRO] Re: How Would You Design question


> Lots of considerations in this besides the ease of cutting. A knife edge
> band saw will cause crushing of the wood towards the surface and drive
> up the density while reducing the stiffness. There is also the problem
> that a band saw blade wanders and would make the thickness inconsistent.
> Reducing the waste is not a concern. Turning 50% of the raw stock to
> dust is OK if the resulting product is very smooth and consistent, not
> sawn, and has the absolute minimum fiber damage on the surface. From all
> the ways of cutting I have tried using a circular saw blade produces the
> proper product. You have to take off your engineering hats on this part
> and accept that marketing says it has to be cut that way. Not put the
> engineer hat back on to work on the design for this.
>
> I am leaning to using a timing belt to drive the feed for the cutting
> and a lead screw on the advance feed. I am thinking that the best way to
> avoid lash on the advance feed it to spring load it to apply pressure
> against the screw. This avoids the need to use zero backlash type
> systems and should work fine as there is no load or pulling in this
> direction. The part I am still hung up on is how to arrange the length
> feed so that the + - .0025" thickness requirement can be met without
> building a monstrosity. Something like the 80/20 stock is appealing, but
> I doubt that it can be consistent down the length. I like the idea that
> someone threw out to have a stop that controls the cut thickness as the
> precision part than just becomes the slide against that.
>
> Tim
> [Denver, CO]