Gentlemen,

I've got a very interesting job that's being presented to me and I'm rolling it around in my head on how to produce the parts. I've signed an NDA but I believe I can talk about the parts without disclosing the product.

I have to machine 80,000 strips of oak that will be a 1/4 x 3/4 x 78" long with about 8 holes drilled and countersunk, one end with small radiused corners, the other end with a 12 degree bevel and the top edges eased all the way around.

No problem producing the blanks, it's radiusing, the bevel and easing the top edges in an efficient manner.

I have a pod rail router and could make numerous holding fixtures and machine the parts one at a time, but I don't want to tie the machine up just to run that job.

I've considered ganging parts together and beveling the ends in lots of 10 or more on a shaper and doing the same for the radius's on the other end, then drilling all of the holes on a drill press set up with stops. Not excited about that process.

I'm not opposed to buying another machining center to run this job either. The money is quite good.

I've never run a flat table router and am thinking that maybe I could put a lot of pieces on the table and let the machine do the work and have a guy just sit and load.

Is this a possibility? Will a vacuum pump hold those pieces if I put them on an 1/8 or a 1/16" wider then needed and let the machine do the final sizing and all of the drilling?

What are your thoughts? I am open for suggestions.

Thanks

Mark

Could you do all the machining on the CNC on a single board and then rip the board into your strips? This would solve the hold down issue plus take a lot less CNC time.

BH Davis

BH,

I can't.

I'm starting to think that I can cut out the shapes in a piece of 1/8" tempered hard board to act as a locator and place multiples on a flat bed router and machine them like that.

What do you think?

Mark

I have used wedges to hold multiple pieces into fixtures on a flat bed router (1 1/2" x 7/8" x 96"). I wasn't concerned about keeping the pieces absolutely flat on the table though. You could use a thin sheet of hardboard to accurately place the parts but you will have to devise a method to hold them flat to the table. Vacuum alone will not be reliable for so small a surface area and thinness. It could be a series of spring loaded aluminum dogs that can turn 90° to release the work or Destaco clamps as long as you can assure yourself that you won't run the router through them.

Mark,

I think you mean you could cut out spaces for the strips to sit in the sheet of 1/8" hard board.....correct? I think that's a good idea with the caveat of how you're going to hold them down. Just sitting in openings I think is going to let the parts move as soon as the bit hits them. Plus the parts would have to be dead flat. Even so I doubt a spoil board vacuum is going to hold them down. Easy enough to try though.

A modified plan along those lines might be to cut part shaped recesses into the surface of a 3/4" sheet of PVC. Then cut a 3/16" channel all the way around the part near the perimeter of the recess for a 1/4" round gasket to press into. One end of the part recess would be near the end of the sheet of PVC so that you could drill an access hole into the recess from the edge. Then you could run tubing from the edge holes to a rotary vane vacuum pump and pull say 18" to 26" of vacuum on all the recesses. The combination of the recess and the full vacuum suction should hold the strips.

Your 1/8" hard board idea gives good perimeter support but poor suction while the PVC method would give the same perimeter support while adding a sealed vacuum suction to the bottom of the part.

BH Davis

BH,

Thanks for your suggestion. I'm going to run a test. I can build the fixture and try it on my rail and pod machine.

Without having any experience with a flat table router, I don't/didn't know if the vacuum pumps could hold those parts while being machined.

Mark

Mark,

Right......I forgot you said you had a pod and rail machine. So you already have a true vacuum source through the pods. That makes it a lot easier as you can just through bore from the center of each PVC part recess down into the center of a pod location. Makes for a very easy setup.

Thinking about it a 24" x 96" piece of 3/4" PVC would give you easy access from one side to all the parts and simplify height uniformity issues that might arise with a 4x8 sheet.

BH Davis

BH and Tom,

Thanks for both of your your responses. I was wondering if there was enough vacuum that could be pulled through a spoil board to hold those thin parts down while being machined. And it sounds like that won't work, so I'll quit barking up that tree.

BH, I'll start tracking down some 3/4" PVC and and give that a test. This job could be large enough to merit a second, maybe used, rail and pod machine to keep up with it.

Mark

Mark,

If your regular panel provider doesn't have it you might find it at a lumber yard. We have one around me that carries it. Also Home Depot and Lowes might be a source.

The reason for the PVC is that it is a relatively inexpensive non-porous sheet good product. It can expand and contract but not significantly in relation to what you are doing. I actually used it to make the grid work hold down system on my retirement home shop 4x8 CNC. If you used MDF for this purpose you would have to seal all surfaces and edges after cutting in the recesses.

BH Davis

I used to work for a company years ago that did thousands of lineal ft of 6mm or 1/4 inch solid birch edging for birch cabinets for schools and institutions.
To make the 6mm we would run solid boards through the shaper with a multi cut or gang style blade set up, then we ran the strips through the widebelt sander to get the finished thickness. It was very fast.
I think once you had your blanks done you could set them in a hardboard jig like you mentioned and drill all the holes and some of the machining on a flat bed cnc. You could tape poly on the hard board and then all your vacuum would be at your pieces. I think you are going to have to do some handwork on every piece with the ends of the pieces though, use a laminate trimmer maybe?
1/4 inch thick is going to be delicate to work with.