Engine Turning on Aluminum

[drodda]

I am trying to Engine Turn a full 4ft x 10ft sheet of Aluminum. I can't figure out what to use to get a uniform pattern across the whole sheet. Does anyone know what a person could use in the PC 7518 to make a pattern that would stay uniform for over 4000 swirl patterns on an Aluminum sheet? I have gotten a swirl pattern on small pieces of aluminum but not a full sheet. I can't even get past the second row. If you have any ideas I would greatly appreciate the help.

[Brady Watson]

Cratex (http://www.cratex.com/)

[drodda]

Brady,

Thanks for the reply.
I have used the cratex mandrels. They say that you must reface them every 6 to 10 swirls. This is not acceptable for trying to do 4000 swirls. The mandrels really need to be turned at 700 to 1000 rpm also not the 10,000 that is the lowest on my PC 7518. I have tried an encapsulated brush but really have not found anything to give me a really clean and uniform circle. I have been playing with scotch brite pads also. they give me the best results up to about 200 swirls but then they fall off fast from there. they really get filled with aluminum pretty fast. I am trying to acheive the look that you find with this company.
http://www.fpmmetals.com/architectural.php

[jay]

Dave, why do you have to use the PC 7518?

Have you considered mounting a drill motor in place of or beside your router?

[Brady Watson]

You may want to try using some valve-grinding compound as an abrasive media in conjunction with the Cratex cylinders. I think that you are asking a bit much considering that you can only dial the RPM down to a minimum of 10k. You may want to experiment with mounting a drill or other tool to the Z-axis to get a more reasonable working RPM out of it, like Jay suggests.

-Brady

[drodda]

Thanks for the info. As I am still fairly new to the shopbot I am still having trouble tearing apart a perfectly good working and properly aligned machine to experiment. Unless this is to replace the Pc with a spindle. Still praying that Santa brings me one but very doubtful. I think the spindle would be the solution but not financially ready to go that direction. Need to sell a few more poker tables I guess first.

Maybe a drill piggyback to the router might be a temporary fix in this case.

[Brady Watson]

That *might* work if you are very conservative with your Z move speeds. While the Alpha motors are strong, you may experience some stalling due to the added weight & lack of additional counter-balance from the Z-springs.

Truing up the Z-axis on an Alpha is a walk in the park compared to the older PRT machines...I know where you are in your 'ShopBot evolution'...give it a year or 2 and you will be hacking the machine....like me! LOL! I didn't touch my machine for like 2-1/2 years after I bought it...now I am beyond the 'new smell' and modify it to suit my needs.

-Brady