Sub-plate and 4th axis question

I have a 1.940" thick, cast aluminum sub plate that I am trying to mount on my Speedio.

In order to mount the 4th axis and give room for the clamps, I would have to extend the 4th completely off the table. The sub plate would hang about 6.5" off the table itself.



This would give me the option of leaving the 4th axis on the machine all the time so I don't need to re-mount it when running it. That would tend to give me incentive to run more 4th axis jobs as compared to just doing it the way I always did it and use vises and multiple setups so I could avoid the re-mounting and dialing in of the rotary face since that is a pain in the butt to get perfectly square.

Do you think this is going to be too weak or flexible? I have laid this out 9 ways to sunday but in order to get the face of the rotary even with the X- travel, it just has to fly out there. My only option would be to bump the rotary over 2-3 inches so about half of it is above the table, and just deal with losing 3 inches of table travel if I choose not to pull the rotary. If I HAD to have those inches, I could pull the table and do the parts, then remount the table.

I really only want to do this once. What do you think?

If you don't have a tailstock pushing against the rotary then I would be willing to do it. If you have a tailstock pushing 380 pounds against the face then I would be pulling the rotary onto the table some.

No tailstock currently. I do have a trunnion table that I can add, but that doesn't push any against the rotary.

I think I have it now so that the RH edge of the rotary table is about 1-1/2" to the right of the table edge. I sure hope this is not going to bite me in the ass over the next year. I guess worst case is I just have to push it over another couple inches, re-mount it and deal with the lost travel.

You have a couple inches of extra space between the way cover and the overhang of your subplate, add some stiffening ribs underneath it and hang the rotary all the way off.

Edit: You can mount an indicator to the table/machine and measure the deflection when you load the rotary table. That could quickly alleviate your concerns, or maybe make you rethink your whole strategy.

2" thick? I think you're fine. Like the others said, if your worried put an indicator on the plate and load you part(s) to check for deflection. Enjoy!

The ass end of my 4th on the Hurco is overhanging about 2.5" on a 1" aluminum sub plate.
I've had the 4th since 2008, and no problems related to the sub plate.

Doug.

I set them so that the face of the rotary is flush with spindle C/L. No reason to have any further on than that.
Looks like your sub is awfully thick! Flex shouldn't be much of an issue there.


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