[manakawari]

my job just added a roland mdx40a milling machine and i just cut my first couple test cuts..i have a job that needs to be done for tomorrow and im having trouble and was hoping someone had a solution...i am trying to mill out small .5 inch triangles out of sheet metal(brass)...i created the file and i have the settings that seem to cut very well but i cant seem to figure out how to attach the sheet metal to the bed and have it stay,..im using double sided tape and it mills the outside of the triangle just fine(thats the first step) but when it goes to mill out the center of the triangles i guess theres not enough material left to sufficiently hold it to the bed and the triangles move out of place and i need to abort the milling....the logical solution i guess would be to somehow change the file so it mills the center of the triangle out first but i cant for the life of me figure out how to do that and i absolutely need this job finished tomorrow morning so i cant spend all day on the phone with roland trying to solve that problem so i was hoping you guys had a solution for me to fix the sheet metal more firmly to the bed so i can cut out tiny shapes without having them move while cutting.

please i absolutely need a solution for this tonight!!...thanks!!!!

[mactec54]

manakawari

It is hard to say what you can do without the size/shape of the inside of your part, you could mill out the center first, mount that on a fixture the same shape as the cutout, hold it in place with a small washer & screw, mill the outside

You could also mill a fixture to hold/clamp the outside shape,then mill the inside

[ErnieD]

Just a thought. Is it possible to mill out the center triangle first and then the outer triangle. If the tape still does not hold it, make a layout of the triangles then drill and tap holes in a plate where the center of the triangles fall. Then after you mill out the inner triangle (first) put some sort of a clamp and bolt to secure the stock and mill out the outer part of the triangle. If this is a little confusing, I am tired and sleepy. Good luck. As to cutting the center triangle first, if you are doing this as a contour, select the center first and the outside last. That should work if tour software will allow it.

Ernie

I typed too slow!

[awerby]

It seems that even if you changed the order of the operations, the parts would shift when you did the outsides instead of when you did the insides. It sounds like you need a better way to hold your parts down. Mactec had some good suggestions; another would be to use a vacuum pod, which would be screwed to the base of your mill and would hold the parts down by suction. It would probably help to design your parts with tabs that keep them attached to the sheet during the cutting operation; that will help prevent them from flying away as they're cut loose, and would maximize the surface area holding them down. Remove the tabs later by hand.

One thing I should mention, though - the MDX40A was not designed for cutting metals. The open structures at the bottom will fill up with chips and jam. So be very careful to collect all that swarf before it gets down there and gums up the works.

[manakawari]

The triangles are only .5 inches so creating a jig like you suggest seems terribly difficult. ..id love to mill out the center first but dont know how...perhaps a stronger double sided tape??? But i dont know of one...its really bothering me as i just cant seem to figure out how to mill out the center on this roland software. .ugggg

[ger21]

Glue the brass sheet to a scrap piece of wood with CA glue (crazy glue). After cutting, remove with acetone.

[manakawari]

thanks im doing that now..i imagine this will work im just worried about the work removing the glue...i wish there was a tape that held tight enough...i heard about some tape 3m makes thats super strong....anyone use that and think that might work for something like this in the future?

[rowbare]

Mitee Grip by Mitee Bite might do the job.

Their site uses frames so I can't give you a direct link. Mitee-Bite Products Co. Click on Products then find Mitee Grip.

You might also try machinable wax or parrafin or beeswax. I am not sure it will be strong enough bit it could be (Mitee Grip is wax based). Make a fixture plate, heat it in a frying pan, and coat it with a thin layer of wax. Press your material into it and when it cools machine away.

This is also pretty cool: http://www.ibagna.com/pdfs/Freeze_Chuck_PDF.pdf. You might be able to make a freeze clamping fixture from a peltier module.

bob

[aarggh]

That freeze chuck looks real interesting! That would make a really neat little project for small machining jobs.

cheers, Ian

[Pleine]

Late to the party. I hope it worked out for you!

I frequently use setters pitch / setting cement from jeweler supply houses to hold things.

Cheers,
Pleine