Trunnion table best practices?

[Anonymous]

I have been using Fusion 360 CAM for a while now to make the components of an aluminum injection mold. I have been using multiple setups to do both sides of the parts. That has been working fairly well but does get a bit tedious. (Mostly remembering to  flip the axis when working "upside down", but also finding a place to reset my Z height to after a manual tool change.)

I plan to add a 4th and 5th axis via a trunnion table with a rotary table in the center. These will be driven with 2 decent sized harmonic drives to deal with the backlash issues.

Should I model the trunnion table in Fusion and then mount my part on the trunnion model? I would then use a single reference point to do my offsets from.

I am using the generic 3 axis mill as my machine and controlling it via Mach 3. 

[martha.deans]

Hi spookydad,

I don't think modeling the trunnion is ever a bad idea, and it can help with visualizing for sure.

In the past when I've used trunnions, I knew the distance of the center of rotation (COR) of the trunnion to the bottom of the stock, made a sketch point that distance below the center of the bottom face of the stock, and used that point as the origin. So I didn't have a modeled trunnion or anything, just a sketch point. The tricky part is knowing that distance and having your setup be close enough so that you still have tight tolerances. 

Hope that helps, trunnions are a lot of fun, let us know how it goes!

[Anonymous]

So when you want to do a different side of the part, you rotate the part around that sketch point and do another setup based on the new orientation of the part?

Up until now, I have left the part alone and "flipped" the setup to the other side of the part. Then when it comes to machining, I flip the part in the vise and re-zero the machine according to the new stock position. To keep things as easy as possible, I use the top right corner of the stock as my origin. I keep that against the fixed jaw of the vise. My vise is a double station vise so the fixed jaw is in the middle. My x and z values are all negative while the y values are all positive. (Except for the small lead in and lead out moves). I always look at the tool path that Mach 3 shows me to make sure everything is going up and to the left.

I don't use the g-28 or g 54 currently, but I can see now how having a common reference point is going to become necessary. I want to add an atc to the machine so a tool height setter is going to be a necessity too.

My thought was to put the rotary table on the tilting table as it seems to be the standard way of doing it. Recently I saw a video of a machine with the tilting table sitting on top of the rotary one. Other than needing a huge bearing to sit the whole thing on, do you see any other disadvantage to doing it this way? Any advantages?

[Steinwerks]

Are you trying to make your own 5-axis machine?

[Anonymous]

Yes