Making Double sided cuts???

[signtist]

I seem to have a tuff time making double sided parts that get off center!!!
Is there a simple way to get this right?
John www.signgraphics1.com (http://www.signgraphics1.com)

[bleeth]

Make sure you have either fixed blocks or a fixed jig to hold your parts. Make sure your artwork is properly centered.
Make sure your x/y position is not getting altered between flips.

[tmerrill]

John,

A simple, accurate and repeatable method is to drill a couple of holes in the project (in the scrap) and corresponding holes in your machine bed (or sacrificial board). Insert a couple of dowels, flip your project and you should have excellent alignment. When you flip everything to toolpath the other side, just include the holes if they are not in a symmetrical position.

If you have Aspire V3.0, there are two tutorials in the Projects section that describe this technique, as well as how to reference each side should you need an accurate thickness when you are finished.

Pictures below are a couple of recent projects using this method. They came out great.

Tim

[bleeth]

Tim: I think I saw that Shark's brother the other day off Delray Beach!

Nice job on both-Your 3-d work is superb. What bits do you use?

[tmerrill]

Hi Dave,

Thanks for your comment.

For the roughing passes I use the largest size down spiral that works.

For the finish passes, I always use Gary Beckwith's tapered ball nose bits. The back side of the Corpus was done with an 1/8", the front with a 1/16". The shark, which is about 20 inches long, was done on both sides with an 1/8" bit.

I can't say enough about Gary's bits and will try the new coated ones the next time I place an order.

Tim

Here are some more details if you are interested. They would probably be a very marketable item in your area, but require a few hours to machine and finish.
http://www.vectric.com/forum/viewtopic.php?f=29&t=10654

[gundog]

I design in Partworks or Aspire. I use a laser edge finder to locate the part by drilling a 1/8" hole in the scrap portion of the material in 2 places on each side of the material. I machine side one and drill the locate holes. I flip the part vertically every time so I don't get confused which way to flip the part. If you flip the part vertically and flip the part in the drawing horizontally chances are good it won't line up and you will get the offset you are speaking of I learned this the hard way.

Where my table is in my shop the ceiling is 8' so I flip vertically which means if it was an 8' sheet you would roll it on the table I do this because it would be impossible to flip the sheet end for end so it helps me remember even if the part is smaller I use this rule so I don't screw it up. Make a rule on how you flip parts and then stick with it.

I made a couple steel pins that have a 1/4" head and an 1/8" shank I put a X in the middle of the 1/4" head exactly on center with my lathe. I plug the pins into the holes I drilled in side one from side 2. I save the coordinates for those holes when the part was flipped vertical for side 2. I chuck the laser edge finder in the collet and send the machine to the recorded coordinates and line the pins up with the edge finder. I sometimes have to send it back and forth several times but when the dot lines up in both pins on the center of the X it is lined up then I turn on the vac table and the part is ready to machine side 2. This only takes a couple minutes.


Here is a drawing of a set of parts I machine both sides the second hole from the center is a counterbore that is put in from one side and the rest of the part is machined from the other side. If it is off they look like hell and I have to fix each one on the lathe. I have screwed them up before I learned I was flipping the part the wrong way. You can see I have the coordinates for the small holes written on the drawing. you can also see the sheet when flipped places the rollers in a different place. Lining edges would not work these parts are cut from 1.25" UHMW plastic and this small piece costs almost $400.


Mike

[oscarg1971]

I agree with the dowels. One of the easiest ways to register both sides of your project.