[mflux_gamblej]

I need to install a positive air curtain on my VMC-20 that I just put a new spindle in as documented on another thread here. I bought a kit to do this. The kit has:

1/4" air polyline
5/32" air polyline
1/4" tube push to connect, to 1/4" NPT 90 deg elbow
1/4" tube push to connect, Y-splitter
5/32" tube push to connect, Y-splitter
grayhill black solid state relay
fuse
solenoid controlled air valve (watts brand) that has 1/4" air in, and just a filter on the output, presumably to leak air when you want to, this doesn't have an air line output on it.


This doesn't match up with what is going on in my VMC-4020 machine which has the air curtain installed. On the 4020, there is a 5/32" line installed on the mac air valves where shown in the maintenance manual to do so. At the spindle there is a 1/4" air tube covering / slipped over the 5/32" air line. The 5/32" line seems to go straight from the mac valves to the spindle. There is no watts valve or anything installed on the 1100-2 board. I am supposed to be hooking up that watts valve to the 1100-2 board to control it at wires 15, 16. Maybe this extra 1/4" valve has something to do with newer machines that maybe didn't use the same air setup? My machines are early to mid-90's vintage, and they have the Mac air valves at the air box on the left side. no watts brand at all.

wtf!?

anyone know about installing the air curtain, why do I need to put this solenoid controlled valve on my 1100-2 board in the spindle drive cabinet? what do the 1/4" tubes hook up to? its pretty confusing to me at this point.

in the maintenance manual page 318, section 08, there is a picture of the 'air positive flow system'. which very vaguely shows the setup. they show the mac air block in the air box, they show where to install the 5/32" air line, then to plumb that to the spindle, just like on my 4020. then they also show 1/4" air line, the drain valve, and y connector, but they do not show where to hook it up at all! there is also a regulator in the picture which is odd. there are no written instructions there, just the pictures.

[mflux_gamblej]

I went ahead with the installation to copy my 4020 machine. I ran 5/32" from the air box / mac valves, up thru the cat tracks and head, etc, down to the spindle and installed it there as 5/32", but also with a 1/4" line covering it for protection like the 4020. This produced the identical result to the 4020 machine; it runs air all the time, but turns off when the spindle is oriented (M19, or tool change). I still have no idea what that watts valve, and the 1/4" Y's and the instruction to install something on the 1100-2 board is all about. Would someone look at their machine and comment?

I also installed a regulator so that I can put the pressure down a bit. It was really blastin' the air out, even more than my 4020. So no I can set the pressure to sound similar to the 4020.

[vertcnc]

On the air curtain, where does the air exit? The only thing I have is the air blast that flows down through spindle during tool changes. Its operated by the Mac Valve.

[mflux_gamblej]

On the air curtain, where does the air exit? The only thing I have is the air blast that flows down through spindle during tool changes. Its operated by the Mac Valve.

The air comes out of the interfaces at the nose of the spindle. 'Through the cracks.' The air is applied inside the spindle to create a positive pressure. That intends to keep coolant and or dust out of the seals between the housing and rotating parts of the spindle.

You would know if you have it installed because as soon as you power on the machine there will be what sounds like an air leak. A lot of people don't like it because it consumes shop air. Well let me let you know that you're gonna like this air dumping a hell of a lot more than a spindle swap. I just went thru that, and it was very expensive and time consuming. A caveat is that you need clean dry air, or you will be pumping water vapor directly into your spindle. I have a refrigerated air dryer and a long line set of copper coming out of my compressor prior to that. I don't see any water in my compressed air these days.

You will want to install the air curtain too if you don't have it. The fitting to supply air is at the upper one which is nearer the underside of the head (up near the coolant bar). The other fitting on the right side of the spindle down nearer to the spindle nose (but still on the side of the spindle) is for dowfrost if you have a chiller.

Seems like fadal skipped installing the air curtain on some machines to save money? Geeze, it was pretty much free. I just had to run an air line - so it was that and a few fittings.


I'm still unsure about why I was sold a watts valve, 1/4" tube and all this other sh*t as a kit to do this.

[vertcnc]

Thanks for explaining it, I have a VMC 15 and it doesn't have it. Just the spindle air blast during tool changes. I will have to look into it. I know of a few that have switched the fan around on top of the spindle motor so it blows down through the motor and doesn't suck all the coolant mist up through motor.
I am not sure I have seen a spot to connect a line for the curtain. I have a 10,000 rpm spindle with spindle coolant so it could be different.

[mflux_gamblej]

Thanks for explaining it, I have a VMC 15 and it doesn't have it. Just the spindle air blast during tool changes. I will have to look into it. I know of a few that have switched the fan around on top of the spindle motor so it blows down through the motor and doesn't suck all the coolant mist up through motor.
I am not sure I have seen a spot to connect a line for the curtain. I have a 10,000 rpm spindle with spindle coolant so it could be different.

On the spindle motor fan you do not want to push down with the air. That goes against the 'chimney' effect and it could create a situation where parts of the motor are not being cooled. That being said, theory land says that you don't want this, but in reality it may be that the heat doesn't build up in that way to a magnitude where it would cause trouble.

Also, on the air blast during tool change, I think that's just air you are hearing leaking by up in the drawbar assembly. There is no plumbing for a thru spindle air blast. If you have coolant thru, they may have arranged for that, but on a machine that doesn't have coolant through, you're just hearing air near the spindle, its not pushing through deliberately.

The fitting for the positive curtain is on the right side, right up near the seal with the underside of the head casting. The ball valve that shuts off the coolant is right next to it. It maybe indeed be possible that your spindle doesn't have that 1/8th NPT tapped hole there. I guess fadal did a lot of spindle design changes over the years.

[vertcnc]

I will look and see if there is a 1/8 npt plugged hole.
The air blast I am referring to deftly comes down through the spindle. I am not sure if that was the intention. I have read that Fadal had something like positive pressure inside spindle drawbar area to keep coolant out. Maybe it just is vented when tool is released. Sure doesn't leak when tool is in spindle though?

[mflux_gamblej]

Since installing the 5/32" portion of the air curtain - which is the air curtain really - I have been getting 'waiting on air valve' errors when trying to change belt ranges. If I drain the air from the system, the error clears.

This is trouble obviously, but it is even worse because when you drain the air, the belts go slack. The motor starts up right when the error clears - this is when there is no air in the system. Then you apply air, and bam! the belt knuckle slams the belt into the already turning motor pulley. This isn't a good thing at all.

Maybe that watts valve is designed to avoid this problem somehow.

I purchased the kit from ITSCNC. I asked them to tell me where to install that valve, and why, and I haven't heard back from them yet in over 1 week.

I'll keep posting when I find out about it and solve my air valve / belt range error problems.

[mflux_gamblej]

I will look and see if there is a 1/8 npt plugged hole.
The air blast I am referring to deftly comes down through the spindle. I am not sure if that was the intention. I have read that Fadal had something like positive pressure inside spindle drawbar area to keep coolant out. Maybe it just is vented when tool is released. Sure doesn't leak when tool is in spindle though?

You are right about the air thru spindle. it enters the drawbar inside the drawbar air assembly through a hole in the side it seems. - so what I said before about how there was no plumbing was wrong.

makes you wonder how the coolant thru setup works

[mflux_gamblej]

I am still waiting on a response from ITSCNC. I even spoke with them on the phone, they haven't bothered getting back to me.

it looks like that watts valve is supposed to go somewhere inside the spindle head / z-axis head. I still don't know where. I talked with someone at fadalcnc.com and he said that it goes up there, but didn't give me details or didn't email me a circuit diagram or anything. its still a mystery to me.