Programming on a tombstone

[z.alexander616]

Hello guys, I have a question about getting the correct code when programming a part on a tombstone.

So I am basically setting the workoffset on the part at A0 then adjusting the tool orientation on the toolpaths that should cut at A90 in this case. I have the offset in the center of the part, and I am leaving it there and just adjust the Z direction for the paths that should be at A90. It is posting out the A90 but the X Y location does not look right and I think I know what it is. I believe I need to be able to tell it an axis in which it rotates around so it can calculate that out. 

Any help on this would be great! 

[Anonymous]

My understanding is that tombstone is mounted on B axis, which rotates around Y axis, so what happens if you set origin at center of tombstone?

I would expect that all coordinates would be automatically adjusted for any angle just as in case of 4'th axis work on vertical mill when origin is set at center of A axis, which rotates around X axis.

I have zero horizontal mill experience but it seems to me this makes sense.

[seth.madore]

So....

Tombstone programming is a bit rough, in my opinion.

First, lets' fully understand a few things:

1) Machine and post processor used?
2) Method of WCS setting. Does each part get an offset, relative to the part itself, or is everything set to center of rotation

3) For your -B- values, do you expect to have A0, 90, 180, 270? Or can you live with a G54 B0., G55 B0. G56 B0. etc etc

[seth.madore]

@Anonymous that's the expected workflow, based on how Fusion works. However, when this software meets reality and how things ACTUALLY should work, that whole idea tends to fall apart pretty quickly...

[Anonymous]

As noted, I have no actual experience with horizontal mill and was referencing my comment in relation to what a colleague sad to me awhile back,........ his exact words ....." If I set origin in center of tombstone, I always know where that part is".

Shop is acquiring horizontal mill and I will soon be able to pick a brain of new mill programmer just for sake of understanding it but don't anticipate ever actually dealing with it I have center role in tougher part of the deal with ongoing project.

[seth.madore]

Understood!

Yeah, I was more railing against the "way things are". I'm not a huge fan for "center of rotation" setups, as...well...what do you do when you have to re-machine your softjaws or fixture? That part is no longer where it's expected. At that point, you're back to running separate offsets for each part/tombstone face.

Center of rotation is great for the 5 axis setups and DWO/TCPC setups. I too would like to engage with someone (RE tombstone) about how it works and what the benefits are. Who knows, maybe the way I think I know is completely all wrong and inefficient

[franky.the.pierre]

Could you put a snapshot of the setup, at this point it is unclear if you have a vertical or horizontal mill.  I do tombstone work for years on a regular basis, on horizontal 4-axis machines (B axis) and 5-axis with tailstock (both A-C and B-C), so I think I can help.  I do this with Inventor CAM, which works exactly the same as Fusion.  It's pretty much as @Anonymous said, you set the setup WCS to your 0 angle, and for any operation not at this angle, you set the tool axis within the operation.  The angle will get output correctly.  (Do not activate tool axis orientation in the operation if the orientation is same as WCS, that screws things up, even if you set it exactly same as WCS.  This is reserved for operation with angles different than WCS).

For the WCS location, you can set it on center of rotation, but really don't have to.  You can set it anywhere you want, so to make it easy to pickup.

You can also output the angle in the program, or you can output WCS for each face (which i think is not what you are after, but this is possible).  I don't see any problems @seth.madore , been using it steady for this exact workflow for years without problems.

If you want more detailed info on how to get Work offset output for each face, let me know, there are some specific steps that need to be done, but it works just fine.  Otherwise, I think it has been explained correctly so far, let us know if you get it working or what issues remain please.

[engineguy]

@z.alexander616 

Mostly it depends on the make of the machine but a basic Horizontal machine would usually have a configuration like this looking from the back of the spindle :-

Z Axis =  Z- move out Z+ move back

X Axis = X- Left X+ right (These may be reversed eg Bridgeport)

Y Axis = Y+ Up Y- Down.

B Axis rotates around what would be the Z Axis on a normal 3 Axis VMC

So you will need to set the centre of the Tombstone to Rotate around what would be the Z Axis, because the rotational axis is the centre of the Tombstone then all calculations for things like Clearance Heights will be calculated from that rotation point, that should work for you 🙂

Stay Safe

Regards

Rob

[Anonymous]

What about one time run or running forgings in fixtures that never gets recut ?, I have seen people run multiple parts in vises and fixtures mounted on tombstone, complete parts in 4 operations or less.

Concept of programming such work was never part of what I do.

[franky.the.pierre]

A picture is worth a 1000 words, hopefully this explains.  The orientation is important, the actual point can be anywhere on the part.  Z points to 0deg face, so anything in this orientation would be B0 in this example.

 

[z.alexander616]

Thanks for all the feedback! I will have to sit down later and read through all of this better. For now I will explain a little more and add a couple images. One shows the orientation at A0 and the other shows it at A90 which would be working on the top side of the part (Machine rotating forward at A90).

Some information on the set up. Machine is a vertical mill (Doosan DNM4500) with a fanuc control. The 4th is A axis and I have made a few small changes to the post that seem to work fine. The numbers that post out seem to make since if the angle of rotation is around the point that is selected, I was mostly curious if I could set it up like this and specify where the angle of rotation is (Center of tombstone) and have it post it correctly. 

So my options seem to be:

A - Set the work offset in the center of the tombstone so it post everything correct 

B- Set a work offset for each position that it rotates too

For B, if I rotate to A90 and set a new offset in the correct location, then I think the code looks correct right now for that. 

Let me know what you think based on this additional information

[franky.the.pierre]

A- only if you want to.  You can set origin anywhere you want, but orientation X-Y-Z is critical.  Z points up away from table, like you did.

B-If you set a work offset for each face, meaning a setup for each face in Fusion, it will always output A0.0 because the setup would be oriented that way.  I don't think you want that.  If you want a work offset for each angle, then you create just 1 setup, like you did, then create 1 folder for each face, and set the work offset in the folder (under post process tab, check the box and input the work offset you want).  then you change the tool axis in the operations, and then the angle will output correctly.

[z.alexander616]

@seth.madore  I added a couple images below in a previous reply of mine and hopefully that helps you see what I am talking about.

I am wanted A90 and A270 for this particular program as of now. When it post the A90 right now, it take the Y to a position that would be the center of the part based on that offset in place (Y +0.9), but I am wanting to see that Y value be about -6.0 in this case because the tombstone would rotate the 90 degree to the front of the machine and then do the work on the top of the part. 

But as of now it wouldn't know where the axis is that the 4th is rotating around so I wasn't sure if I can leave this set up and specify that information somewhere or what. I hope this makes a little more sense or at least gives an idea of what I am looking for. 

[engineguy]

@z.alexander616 

If all you want/need is a simple 4th axis rotating around the X axis then the attached file is a simple example, no multiple WCS just simple Tool Orientation which can be used to machine parts/fixtures/soft jaws etc, real easy to use. (I didn`t draw the Faceplate or Tailstock in, got lazy) 🙂 🙂

Make whatever you want, it is just for an example, works fine and with the PP I use it outputs the correct code no problem so you can play around with it as much as  you want 🙂 🙂 🙂

Top is A0, next is A-90 next is A180 and last is A90, code is attached.

Stay Safe

Regards

Rob

[z.alexander616]

@engineguy  Thanks for this. This makes perfect sense to me with it being in the center of the tombstone. That is actually what I am trying to avoid. I want to place it where ever I want (as I did in the images) but not sure how to let it know where it is rotating around. Sounds like its possible so I am just be missing something easy. 

[z.alexander616]

@engineguy 

Thanks for this. This makes perfect sense to me with it being in the center of the tombstone. That is actually what I am trying to avoid. I want to place it where ever I want (as I did in the images) but not sure how to let it know where it is rotating around. Sounds like its possible so I am just be missing something easy. 

[seth.madore]

---

@z.alexander616 wrote:

..I want to place it where ever I want (as I did in the images) ... 

---

And I think that's where I'm getting hung up as well. I need to be able to pick up the part wherever it's located on any side of the tombstone, but I also want to have my A/B values posted absolute to the machine, so A0, 90, 180, 270.

If I go the separate Setup route for every part, I only get A0., requiring a manual post edit (very bad idea). If I program it all in one file, using folders, that does give me the ability to have separate work offsets, but...I guess I need to spend some more time with folders and NC Programs...

[engineguy]

@z.alexander616 

@seth.madore 

Hmm, seems to be a case of stock selection, I was able to do the two parts in the image below with the WCS set to what is in effect the rotational centre of the two Stock blocks, first one is set to G55 and the second one to G56 and they output in the code OK.

It is a simplified example but might act as a pointer.

The movements of A0, A90, A-90 do seem also to post out correctly using this method 🙂

@z.alexander616 

Whether this is exactly what you want I am not sure but I think it may be close enough for you to finish off 🙂

Stay Safe

Regards

Rob

[DarthBane55]

---

@z.alexander616 wrote:

@engineguy 

Thanks for this. This makes perfect sense to me with it being in the center of the tombstone. That is actually what I am trying to avoid. I want to place it where ever I want (as I did in the images) but not sure how to let it know where it is rotating around. Sounds like its possible so I am just be missing something easy. 

---

You can place the WCS where you want as @franky.the.pierre  mentioned a few times.  The software doesn't care about the actual rotating axis LOCATION, it cares about the rotating axis ORIENTATION only.  So if you orient the X parallel with your rotation axis in the WCS, you can put it anywhere, it will output the angles correctly when you choose tool orientation in the operations that are at a different angle.  In @engineguy sample file, move his WCS to somewhere other than center of rotation, but keep its orientation, the code will be perfect in relation to the WCS you chose.  The only difference to the code will be all the X-Y-Z values, because the WCS moved, but both codes would produce the same result on the machine (of course you need to set the work offset accordingly in the machine).

[z.alexander616]

I feel like I am still missing something somewhere, which I am sure its something easy I am overlooking lol. But I do think the folders will work at least now that I get that. Ill follow up if I still need help!