[David Michael]

A good reference for the complete Spindle Drive system is at http://www.fadalvmcparts.com/manuals..._and_Motor.pdf

Start at page 307

Many Fadal customers have lost their original manuals so we have them available at http://www.fadalvmcparts.com/documentation.html for your reference.

[scadvice]

OK...!!! Now I recall you David!(nuts) We met when I bought my 1989 VMC40 down at the Fadal plant!! (You won't recall, but it was the day before the big earthquake in San Fran.) Boy am I slow!:stickpoke
Fadal Error, David ( the 'D' in Fadal David) is your best bet to figure this out!!
Steve

[Fadal Error]

Could it be that the drawbar retention washers are broken?

[scadvice]

Fadal Error - I looked at your vid. tonight and its not the air valve problem I was thinking of. You may be right about it having to do with either the bellview washers or the stud clamping device. The draw bar is moving.
I defer to David's thoughts and ideas.
Steve(nuts)

[denmar]

Some times the two 1/8 ballbearigs holding the Draw Bar Floater are demaged, so when
you push to grab the tool, the Floater comes down alone with the bar, so the 8 1/8 ballbearings won't retract to allow the toll to go in or out...

[Fadal Error]

It really sounds like the air pressure is too low when the drawbar tries to come down. I will check the air valve at the back of the machine again.

[andyb4]

Inside the unclamping cylinder, on the underside of the piston is a magnet witch operates the hall effect switch. I have seen this magnet fall out of the piston, it is only glued in, witch stops the piston from travelling all the way to the bottom of the stroke, as well as the sensor will not see it. I had this experience with a '94 VMC 4020. Just my thoughs.
Andy B

[Fadal Error]

Inside the unclamping cylinder, on the underside of the piston is a magnet witch operates the hall effect switch. I have seen this magnet fall out of the piston, it is only glued in, witch stops the piston from travelling all the way to the bottom of the stroke, as well as the sensor will not see it. I had this experience with a '94 VMC 4020. Just my thoughs.
Andy B

Is this the piston?


This sounds like it could be the problem. Did you see the video?

[andyb4]

I didn't see the video, had trouble opening it. Work networks and all. Will try later at home. The symptoms that you describe seemed about right. Your arrow points to the rod coming out of the bottom of the cylinder. If you remove the lighter coloured block just above the black U shaped support, that is the outside of the cylinder. You may have to remove some other stuf to get all the bolts. 7 or so if I remember. The cable going to the sensor on the left side just above the tail end of the arrow is the sensor for the tool unclamp signal. The magnet should be directly above it. A work of caution, the polarity of the magnet makes a difference. Make sure it works before you epoxy it back in. Hope this helps.

[Fadal Error]

Everything looked good in there. The Fadal tech thought the aluminum plate inside might be cracked. Nope.

[Fadal Error]

I opened up the air valve in back again and cleaned the piston that was sticky. It still seems to be a little sticky. Then I put a gauge on top of the head where there is an exhaust fitting. I was getting about 80 psi when I did a TC,1

[little bubba]

Fadal error, I'll get to your problem in a sec, but you actually paid a FADAL tech to come in and he pulled apart the piston, didn't see a crack and quit? and YOU had to check the pressure afterwards! I wouldn't pay him. If he is coming back tomorrow because he couldn't figure it out in a day, I wouldn't pay him.

There are only a few places that could cause your problem, first air pressure, quickest and easiest to diagnose. Once that is done, you are into the piston, so 15 minutes, you have the sheetmetal off and the piston apart, thats not the problem(moves well, nothing floating around in there etc...), put the piston back together, and you're already down at the drawbar level, which leaves cracked and shifted springs or a wasted drawbar floater and possibly a trashed drawbar.

At this point you pick up the phone and order up a set of bellevilles and drawbar floater, about $100 from fadal, cheaper from others, and maybe the retention clips/rings.

Now a tech (who should have a spring compressor), should have the springs compressed, the retainers released and the drawbar dropped out, 1/2 hour or so. At this point all that is left is to get the drawbar floater out. This is the ONE piece that can royally screw your tool retention and is only $20. They can get seriously messed up. If its in reasonable shape, a few minutes with a magnet to get out the two retaining balls (previously mentioned), if its really screwed, days on your back with a die grinder and a long shank burr trying to grind it out without screwing up your taper.

Getting intimate with that area of the machine, piston, springs, floater is pretty much mandatory with a fadal since the floater and belleville springs are more "consumables" vs "hardware". You don't need a tech. These machines are almost Fisher Price simple to work on, and they were the same for like 20 years. Thats the beaty of them, but.... they do break.

I'm guessing you have drawbar floater/spring problem, especially after checking the inside of the piston.

Here's something to check, take a retention knob and duct tape it to the end of a stud. Turn off all the lights in the shop, lay down on your back on the table with a flashlight in your mouth, have somebody that doesn't mind having your privates pointed at them hold in the 'tool in/out' button. Spend some time in there to figure out why the retention know will not go in.

There are 6 ball bearings up there. (actually 8, but 2 hold the floater into the spindle). The drawbar comes down, the balls ride on the floater, and can now move outwards, allowing the tool to go in/out. The floater "floats" and has already been said, it may be falling when the drawbar pushes down. With a couple of screwdrivers, a flashlight in your mouth and a handy assistant to push a button you can probably figure out what is going on.

I'll gladly talk you through it and post up pics, as I'm sure others would also.

[Fadal Error]

Fadal error, I'll get to your problem in a sec, but you actually paid a FADAL tech to come in and he pulled apart the piston, didn't see a crack and quit? and YOU had to check the pressure afterwards! I wouldn't pay him. If he is coming back tomorrow because he couldn't figure it out in a day, I wouldn't pay him.

No. I talked to a non-factory (and very proficient) technician on the phone and he told me a couple of things to check.

Thank you immensely for your insight and suggestions. I will get on with it tomorrow morning.

[little bubba]

No. I talked to a non-factory (and very proficient) technician on the phone and he told me a couple of things to check.

Thank you immensely for your insight and suggestions. I will get on with it tomorrow morning.

Good thing, sounded like you paid a tech to play with lego's.

Crack into that drawbar, its super simple. It really is easy, I was at a point where I could do the bellevilles and the floater in under a couple of hours.

Really, thats all you have left, is the drawbar area. Since you are cracking into there anyways, replace the springs $60 from CNCpros and the floater, $20, it can transform your machine from a so so machine into a super star with fantastic tool retention.

You will need a spring compressor, I and others have posted up dimensions and possibly pics on here and on Practical Machinist (cnc forum). If need be you can make one on a drill press. They sell one on CNCpros, but I think you still need a gear puller to use it.

You can be up and making chips by Thursday afternoon, Friday at the latest.

[andyb4]

I agree that these are very straight forward machines to work on. If you can't get the tool in the spindle and it is not the cylinder, I would definately take a serious look at the drawbar as suggested previously.

[DareBee]

Like Bubba says - it is probably the retention floater, because even with the error there is a half second window of opportunity for the tool to be installed (if the floater was good).
I also assume we have the correct pull studs in use.

I do want to add that the piston in the release cylinder CAN be put in backwards. Meaning the magnet will not be against the sensor and will give an error. Magnet needs to be on the left side of center.

[Fadal Error]

So I have gotten this far and found that the drawbar was stuck down.


When I pulled up, it came up with a little resistance.


I could push it back down and it would stay down.

[Neal]

Sounds like a possibility of a broken bellville jamming up the drawbar or a drawbar cyclinder not retracting.

Neal

[Fadal Error]

I removed the four screws in the round piece on top (visible in the picture). The half-moon retainers for the spider underneath fell out of the slot. I was trying to figure out the assembly from the exploded view in a pdf of drawbar parts and it looked like the spider should have been under pressure from the belleville washers. It wasn't. So I pried it up with two screwdrivers and the drawbar fell out the bottom. I heard bearings running away, so it should be fun trying to find them. I think the floater is still stuck up there, holding all of the belleville washers in.

[little bubba]

You have one seriously messed up set of bellevilles. Those half moon retainers should be a PIA to get out, and you should have had to use a spring compressor, you will need one to put them back.

The balls you lost, they are just 3/16 ball bearings, 6 of them, don't even bother looking, just go down to the hardware store and get some more, or order them up when you get your new floater and springs. CNCpros is open until 5pm mountain time.

Check your drawbar before you order, make sure she looks ok, the drawbar is expensive and comes in a kit, that includes the floater.

As to the floater, look up inside there, there are two holes, in those holes there are two more 3/16 ball bearings that go into a groove. You can get the balls out with a magnet or a magnetized screwdriver.

IF the balls won't come out, you're screwed. The floater is damaged and you will end up on your back grinding it out, which I can tell you absolutely sucks.

EDIT: on the bright side, with new springs and floater you will have fantastic tool retention and will be able to take cuts you didn't think your machine was capable of.

Also, the bellevilles come out the top, a wire with a loop or a magnet works.