Oriental Screens

[jaum@alltel.net]

Have an order for Oriental screens for room dividers (large) and background pieces for Saki Rice, Tea sets (small). It involves cutting an oriental pattern through .75 material. Problem is that area or space that is cut out is so small they can't be sanded from a practical standpoint.

How can I get the best possible (Unsanded finish), I'm currently using .25 upcut spiral, at 1.7 in per min, and a .25 z cut each time. Any suggestions would be appreciated.

[bjwat@comcast.net]

There are a few ways that I would go about it. It is possible to get a nice finish if you separate the toolpaths as climb (use on insides if you want a nice finish and you are discarding the islands) and conventional (if you want to keep the islands)

I learned the hard way that the edges will appear with snipe if you don't discern between Climb and Conventional. This is especially true when using the tabbing command. Often if you are cutting on the outside of a rectangle, for instance, and it does a Z move on a tab, it leaves a mark on the finished piece...be sure to select a conventional cut if doing this on an outside profile cut to avoid edge marks.

I am not sure what software you are using, but in regards to getting a nice finish...If possible, offset the design (in CAD) in a little bit (maybe like .05) and do a hog out contour pass with your spiral bit. Then go back and do a profile pass of the entire 3/4" depth on the original vectors with a straight non-spiral bit. There won't be any stepdown marks on the piece and if you select the right direction of cut, there won't be any snipe marks (edge ridging), top or bottom tearout...AND best of all...NO SANDING!


Hope that helps.

-Brady

[jaum@alltel.net]

Thanks Brady, For some reason the conventional vs climb issues didn't pop in my head till you mentioned it. I know that will help. We are using ArtCam 6 which a little bit overkill on this project but it works!

I'll also try your suggestions on offsetting towards the scrap pieces for all three cuts, then a straight spiral for a final full cut. No Tabs or bridges, we are clamping the piece in place.


Thanks again.

Jim

[john]

You might try a compression spiral bit, we like them as they leave a clean edge top & bottom hence no cleanup sanding.

[elcruisr@bellsouth.net]

We use a 1/4" compression spiral for things like this as we get a clean edge top and bottom. I favor the Onsrud with a very short upcut, it helps keep parts on the table. I also find that compression bits don't always follow the regular / climb cut rules so you need to do a test cut to see which direction works best. Also using lead in moves if there's room and a finish pass will help. Another trick would be to keep the rpm's a little on the high side which will shorten tool life but give a smoother finish.

[jumbaugh]

Brady, John and Elcruisr,

Tried all of your suggestions. Much Much better. The Onsrud 60-307 was a big improvement over the spiral upcut but the series 60-246 had an even better "unsanded" finish. Reduced image to less than 25 kilobytes but it doesn't seem to want to post.

[gerald_d]

Image must also be less than 400x400 pixels on this new board.

[bill_thorpe]

It seems to me that posting photos to this message board is a stumbling block to most users of this board (including me). Can't help but wonder if there is a way that the message board software could automatically resize uploaded photos. Lacking that what easy method might there be to resize a photo for posting?

[pappy]

Bill,

I have a small program on my desktop called
photoresizer that I can e-mail you if you want.

[gerald_d]

Bill, that "stumbling block"is not unique to this message board - it applies to nearly everybody who has taken a digital pic (or scan) and who then wants to mail that pic or share it over the www at a reasonable speed.

Here is a download site for that freeware PhotoResizer.