[Smokey911]

I am wondering what is the best way to hold down thin stock like .125 or so on a mill. I have a 14 by 7.5 window and with big clamps I can bring that unfortunately down to 11.5 by 7 very easily and I want to keep my window so I can use every inch of my stock.

Is there anything on the market inexpensive to hep me out here. In the past at job we used double back sticky tape. That was somewhat messy and I had to use acetone and other chemicals to get up the tape from machine and part itself...

[txcncman]

Use a sub plate. Clamp at outside edges first and drill any through holes. Drill at tap at through holes for socket head cap screws to hold down. Apply screws then remove outside edge clamps and finish machining.

[Smokey911]

I think I follow. Are you saying make an aluminum plate and lock it to table. Then put piece on it lock piece down. Then I assume before I did that think of ways to strategically put a few holes in part so that when I drill threw my part to start into plate, immediately tap that hole or holes to hold piece. Then take off clamps and do my part.

Will I reuse this plate over and over? I assume it will have random holes all over it and maybe at some point get used up.... Is their any video on this, I tried looking it up and I saw people selling plates. Could not get total picture... Any info will help, I think I am getting closer to a solution, thanks...

[txcncman]

You could also use a vacuum plate: Vacuum Fixture Plate on my HAAS TM-1P - YouTube

Basically you need to make a fixture(s) to hold your part(s). Sometimes you will need one fixture for each part. Sometimes you can have one fixture for many parts.

Here is a video that is for wood working, but a lot of it applies to machining any type of material: [ame=http://www.youtube.com/watch?v=ajARYPiHXOg&feature=related]02-04-12 (Full Video) Jigs and Fixtures by Jim Dion (1h33m23s).wmv - YouTube[/ame]

Some people make and use what they call a tooling plate: [ame=http://www.youtube.com/watch?v=3SgAc67DwaI]12x20 Tooling Plate - YouTube[/ame]

Hope that gives you ideas and visualization.

[Flateric]

Unless I am missing something here, this sounds like an excellent job for the use of a vacuum table.

(LOL, as the post above me states. I had an old version of the thread tabbed and did not refresh before posting)

But yes, I agree with all of the above. It's a great fast and very strong form of work piece holding. Does however have a few limitations to be considered so your piece doesn't lose vacuum pressure when milling through your material.

[Smokey911]

okay great info... I see I will have to make a plate. I want to use it over and over for a while at least 20 or so pieces. My problem is I am cutting in to my plate (all the way through. Wont that mess it up for the next piece? The air plates wont work when you cut all the way through, although I saw a vacuum chuck system with a rubber throw away mat that would let you, still to costly to start ($1,000 or so). If I can only use my fixture once I will have to just do that but if that is the case I might as well clamp it down and lose machining area. For the plate, I could skim off the top surface after every sheet for a while until I have skimmed all I can off....

You could also use a vacuum plate: Vacuum Fixture Plate on my HAAS TM-1P - YouTube

Basically you need to make a fixture(s) to hold your part(s). Sometimes you will need one fixture for each part. Sometimes you can have one fixture for many parts.

Here is a video that is for wood working, but a lot of it applies to machining any type of material: 02-04-12 (Full Video) Jigs and Fixtures by Jim Dion (1h33m23s).wmv - YouTube

Some people make and use what they call a tooling plate: 12x20 Tooling Plate - YouTube

Hope that gives you ideas and visualization.

[Smokey911]

Yes, and the losing vacuum because I am cutting through is the problem... And the system I saw that worked if you cut through was costly... I think I will just have to make a fixture...

Unless I am missing something here, this sounds like an excellent job for the use of a vacuum table.

(LOL, as the post above me states. I had an old version of the thread tabbed and did not refresh before posting)

But yes, I agree with all of the above. It's a great fast and very strong form of work piece holding. Does however have a few limitations to be considered so your piece doesn't lose vacuum pressure when milling through your material.

[txcncman]

okay great info... I see I will have to make a plate. I want to use it over and over for a while at least 20 or so pieces. My problem is I am cutting in to my plate (all the way through. Wont that mess it up for the next piece? The air plates wont work when you cut all the way through, although I saw a vacuum chuck system with a rubber throw away mat that would let you, still to costly to start ($1,000 or so). If I can only use my fixture once I will have to just do that but if that is the case I might as well clamp it down and lose machining area. For the plate, I could skim off the top surface after every sheet for a while until I have skimmed all I can off....

If every part is identical or even very close to the previous part, you should not have to resurface the fixture plate between parts. Just make sure the clamps and hold down screws are in solid areas and not causing the part to buckle up. The cut through only needs to be just a few thousandths of an inch to give a smooth edge. I have also done this where I purposely did not cut through, leaving about 0.005" of material. Then break away the material and clean up the edges with a file or belt sander as needed. There are many, many different ways to machine parts. You have to choose what works best for you in your logic and with the tools you have available. As far as that goes, I have also used lay out ink and a scribe on sheet material and then cut out the part on a band saw and then sand and file the saw cut edges to finish. Not quite as accurate as milling the part, but it gets the job done.

[Smokey911]

Thanks for all of the help. I am ready to proceed now!

[skray775]

Here is a short video of a small fixture plate with a piece of .09" aluminum bolted to it.

The fixture is drilled and tapped and mounted in the vise. A pre cut 3"x5"x.09" work piece is clamped to the plate on the ends with small C clamps. Then I drill and counter sink the inside 4 screws, pause, then screw the work piece to the fixture plate and remove the C clamps, then proceed with the operations as needed.

I hope that helps

Small Fixture Plate - YouTube

[Smokey911]

Thanks! Great to see it in action!!!!!

Here is a short video of a small fixture plate with a piece of .09" aluminum bolted to it.

The fixture is drilled and tapped and mounted in the vise. A pre cut 3"x5"x.09" work piece is clamped to the plate on the ends with small C clamps. Then I drill and counter sink the inside 4 screws, pause, then screw the work piece to the fixture plate and remove the C clamps, then proceed with the operations as needed.

I hope that helps

Small Fixture Plate - YouTube