4th axis position on table-Fadal

ripperj · Apr 2, 2021

I fussed around aligning the new to me 4th axis on my Fadal, setting the offset and then realized the servo would come blowing through the door glass on max Y positive. I have about another .250” of +Y when the end of the servo hits the door window.
I tried moving the axis to the rear slot but it hits the Z ways with minus .3” travel left.
So... I either need to move my cold start or remember to open the door

Anyone see this before. My Y axis CS position indicator does seem to be maxed out to the front, so there is probably a .250 adjustment.

Any issue with moving the cold start 1/4”?
Thanks

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ripperj · Apr 2, 2021

I should mention I replaced the Y screw a while back, I don’t believe I had to move the cold start indicator, I had marked the screw coupler and tried to match the old and new screw ball nut positions when I coupled the motor back up.
Maybe I can pull the motor and rotate the screw one or two turns( I don’t recall the pitch)

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Bobw · Apr 2, 2021

Just don't go to max Y+.

I wouldn't mess around with trying to move your cold start position.
That could just get you into trouble and end up with a blown driver board.

ripperj · Apr 2, 2021

I think I’ll just leave it as is , thanks for the reply

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Garwood · Apr 2, 2021

Nothing to do with Fadal specifically, but I always use a subplate and cantilever the 4th off the table. I like to put the face of the indexer at max/min X travel so I don't waste any travel, but I can mill anything I bolt to the face.

Subplate lets you position it wherever you want in Y so you can center it.

A friend has a nice Mori vertical with a 4th that hits the enclosure in one place. I have gotten used to it, but I still hate it. Several oh shit moments where I stopped it just in time.

ripperj · Apr 2, 2021

I do want to eventually hang the 4th over the rightX cover. I had a sub plate on the mill, but kept having to pull it off and re oil to keep corrosion at bay, it’s large enough to gain 6” of X travel

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Mud · Apr 2, 2021

Is there a limit switch that can be moved to keep it from hitting?

ripperj · Apr 2, 2021

Mud said:
Is there a limit switch that can be moved to keep it from hitting?

Good idea, but no limit switches, you cold start the machine on index marks so the control has a starting reference and then the control just counts ball screw turns to get to the limits

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mmurray70 · Apr 2, 2021

The window should flex 0.250"

Might as well get used to looking for crashes like that. Never ending with the 4th axis on table. It will always be in the way, tool holders will always want to hit jaws, coolant nozzles getting moved etc etc. Need to watch everything way closer then with 3 axis.

What size Fadal is that? I have a 4020 and thinking about adding a smaller one too.

Really sucks the way they have the whole cold start thing rigged up. Wish they would of came with proper home/limit switches like every other machine in the world.

aarongough · Apr 2, 2021

Is this a DC servo machine? If so then I believe rotating the resolver relative to the servo will move the cold start position up to 1 thread pitch of the screw, not sure if that will be enough to give you clearance though!

I would second the recommendation for a sub-plate! Seems a shame to waste so much X travel!

Bobw · Apr 2, 2021

mmurray70 said:
Really sucks the way they have the whole cold start thing rigged up. Wish they would of came with proper home/limit switches like every other machine in the world.

What is cool though, is that the only machine I've never had a limit switch problem with, was a Fadal..
Unless you count the tool changer.

One more thing to break, one more thing to fix, and when it was new, one less thing you(they) had to pay for.

On a 4020, you have plenty of room(Y axis) with a vh65. I'm guessing this is a 3016.

ripperj · Apr 2, 2021

DC control VMC 20

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xyzzy · Apr 6, 2021

Not sure how ambitious you are but this is how I dealt with the same problem with a VH65 on a 3016. Nice to be able to move the 4th out of the way, as well as get some X back. You could make something similar offset in Y without a subplate.

ripperj · Apr 6, 2021

Thanks for the reply
I can’t really make out the second pic, does the 4th mount to a dovetail base that slides in X (adjustable?)

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xyzzy · Apr 6, 2021

Yes, sorry for the confusion, you got it right. The second picture is the back of the 4th axis, looking in from the right side of the machine. I have a collet closer hanging out the back of the 4th, so the limit on moving it x+ off the table is when it hits the right hand window. I basically get the entire table when it is "parked." Hasn't been off the machine in years (taking the VH65 in and out, and messing with connectors and the control is a PITA.)

ripperj · Apr 7, 2021

That’s pretty cool, thx

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wesg · Apr 7, 2021

Leave the CS in the center, and set the home position at 7.5. Easy to change back to 8 if you want the table closer without it. Just need to remember.

mhajicek · Apr 7, 2021

Use steel for your subplate so you don't get galvanic corrosion.

trochoidalpath · Apr 10, 2021

mhajicek said:
Use steel for your subplate so you don't get galvanic corrosion.

Anodizing should also work, I think? (I remember anodizing being electrically insulating.) Probably better to be hard anodized so it's a little more resistant to scratching when the subplate gets mounted.

Garwood · Apr 10, 2021

trochoidalpath said:
Anodizing should also work, I think? (I remember anodizing being electrically insulating.) Probably better to be hard anodized so it's a little more resistant to scratching when the subplate gets mounted.

Type 3 is great, but the trick is it adds about .0015" to .002" to all surfaces.

I have been using Slide no rust to stop the corrosion under aluminum subplates and it seems to work.

4th axis position on table-Fadal

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