Pinnacle A2F Mill

[indy4x]

Bought this just over a year ago, eBay purchase from a local electronics firm. Visually it was in pretty good condition but is about 22yrs old.

It came with a 2 axis DRO but only had a scale on the y axis and power feed on the x axis.

It has seen some use since it came into my possession but has always suffered with chatter. Had a pretty good idea it was down to the gibs needed adjusting and there was also some lateral play in the quill.

Other projects kept getting in the way including extending the garage to make room for it and my M300.



So it's now time to sort it out. The play in the quill has been bugging me so made a start on it last night. Dug out a DTI and did some measurements on the quill. With an ER32 collect holder in the spindle I was getting about 10 thou of lateral movement when measured against the collect holder. If I did the same measurement against the quill I had no detectable play which pointed to a possible issue with the bearings and or spindle.

Stripped the quill out last night which turned out to be a fairly straightforward task



Tonight the quill got stripped, little apprehensive as the only manual I could find was for the modern version badge as Grizzly in the USA and there are some minor differences.



Nose on the quill is threaded where as the Grizzly diagrams do not show this but once the nose is off the spindle drifts out fairly easily



Once the shaft was out the source of the play looks like the bearings needed adjusting but someone has definitely been in there before me, photo was taken after I started undoing the locking ring

 

[penfold]

That's definitely had some passionate attention.

 

[zzr1200]

Indy, I take it that old lump of bar stock might stand a chance of getting attacked in earnest soon?

Also any chance of some close up photos of the quills fine feed dial if it's imperial...please

 

[indy4x]

@zzr1200 yes it will, mill still isn't getting my ful attention as need to finish off some work on the D2 but soon

Mine is all metric so probably not much use taking pics, can do if required

 

[indy4x]

Bearings are standard sizes, it has 2x 7207A and 3x 6209ZZ. As its apart I will probably change them as a matter of course.

There are some differences compared to the Grizzly manual, main one being there is an inner (128 in diagram below) and outer (128 in diagram below) spacer ring that sits between the bearings against the inner and outer races however in mine it only has the outer spacer ring. Don't know it this is a later modification as don't have the inner spacer ring in mone or its been apart before and lost or forgotten to put back in?





I'm assuming its a later modification so you nip up the bearing nut and the spacer takes care of preload and end float but on mine I would need to adjust the collar to do the same. If its the latter I have no information as to how tight to go?

 

[indy4x]

Some progress made, setup the spindle in a 4 jaw chuck, revolving centre on the other end and after a couple of light cuts the locking collar is now looking loads better

Before




And setup and done

 

[indy4x]

Next up was to make a replacement spacer for the lower spindle bearings. As the original was missing I have assumed it needs to be the same thickness as the outer spacer

Didn't want to waste some of my larger dia bar and it was too big to fit down the spindle bore so had a go using a fixed steady. This posed 2 challenges, one, it has been seized up since I got it so needed pulling apart, cleaning up all the bits and then putting back together. Second problem is I have never used a steady on a lathe before. Nothing ventured etc



So I now have a slightly oversize spacer which needs to be slimmed down to match the thickness of the outer spacer.

 

[indy4x]

Am also trying to find what bearings need to be fitted. Manual just lists the basic part numbers but no info as to the precision required or for the lower angular contact bearings what built-in preload

Have posted on the 6x26 Mill group and had a little info back but not enough to nail it. Looking at the manuals for both the VM-F and VM-C mills they actually share the same quill and bearings.

Was in one of my local hydraulic and power train supplier and they gave me a few pointers

Have bought replacement bearings for the top of the spindle and they supplied me with C3 but reading up on these it seems to suggest they are for high speed or high temperature situations, to my mind I would have thought CN would have been a better option

For the lower angular contact bearings I think I'm going to have to suck it and see however it could be an expensive experiment

 

[zzr1200]

So I now have a slightly oversize spacer which needs to be slimmed down to match the thickness of the outer spacer.

View attachment 131673

The bearings are supposedly "Precission Bearing" and appear to require some "Preloading", but what the difference is in between the inner/outer spacer I have no idea.

 

[indy4x]

@zzr1200 yep, that is what's proving to be the challenge. From what I've read the spacers should be the same thickness but the bearings are available with 3 levels of preload, which one I actually need is still to be confirmed as no one seems to know

 

[indy4x]

@zzr1200 I did get the Warco manual off eBay and it hasn't really helped, if you want a copy will get it scanned for you

 

[zzr1200]

@zzr1200 I did get the Warco manual off eBay and it hasn't really helped, if you want a copy will get it scanned for you

I found a manual badly photocopied with just "A2F on the front sheet on Fleabag, if yours is a readable copy I am interested, please.

 

[zzr1200]

@zzr1200 yep, that is what's proving to be the challenge. From what I've read the spacers should be the same thickness but the bearings are available with 3 levels of preload, which one I actually need is still to be confirmed as no one seems to know

If you type "7207A taper bearing" into google you can check the bearing manufacturers web sites for spec sheets which do list preloaded spec.
Some list Dynamic, Static and/or Axial loads, I used to setup diff pinion preload with a spring balance years ago but haven't done that for many years now.

7207A taper bearing specs

7207a taper bearing preload specs

Hth

 

[indy4x]

Picking this up again

Spindle and quill were sorted back in March and the head has been reassembled, also added an oil pot to the side of the head to lube the quill

 

[indy4x]

Now that the spindle play is sorted time to move on to the table. It is seriously gunked up and while the oiler is working and getting oil onto the ways there is some play in the table that shouldn't be there. Stripped it tonight ready to cleanup

 

[indy4x]

Been a while since I posted on this thread, it's once again been left unloved while other projects got in the way but spent a little time on it tonight

Table was refitted a good few months ago along with the power feed etc. Have lost the key from the left hand side handle so need to make one but for now I can use the right hand handle and power feed

Also stripped and cleaned the vice, it was full of circuit board dust from its previous life

Tomorrow nights job is to clean and lube the screw from the vice, refit and then square up the head and vice ready to make some chips

 

[Pete.]

Those spacer rings are preload setting rings so whilst they are apparently the same width they will actually be different but the amount of difference is so small you couldn't match it by turning in the lathe. I suggest turning one of tow courses of action:

1. Turn a pair of rings, face them in the lathe then put them on a surface grinder and grind both faces then set the pre-load by grinding them a tenth or two different. If the spindle runs warm when you build it you can always give the inner ring a lick on the grinder to ease the load.
2. Fit modern bearings which have the pre-load inherent in the design, like the ones I just put in my Hardinge lathe and grind the pre-load rings exactly the same so that your bearing spacings are correct.

 

[indy4x]

@Pete. I did have them ground. Dropped them both off at a local engineering place and they did it for me for a donation to their tea and biscuit fund

I did post a message on a few forums and spoke to a local bearing supplier but didn't get an answer that made sense.

I then dropped a message to Arc Euro Trade looking to buy new bearings and a very pleasant chap asked me to ring him. We discussed bearings at length even tho there wasn't a sale in it for him and his advice matched your post above

I have made the assumption that the preload was designed into the bearings and the spacers were ground so they were the same thickness and then rebuilt it with the original bearings.

Will find out tonight what the outcome is and if it runs warm then will get it apart and grind the spacer rings to reduce the preload

Cheers

Chris

 

[Pete.]

I think that's a fair assumption for modern bearings and I don't think you could approach it in a much better way than you did. My HLV bearings were designed for a specified pre-load and the nut torque specified. One thing that surprised me was how little grease they held 4.6cc. Put in too much grease and they get hot.

 

[indy4x]

+1 on the grease, it was something else the guy at Arc mentioned was do not pack too much in there as it will get too hot, they don't need much to keep them happy

Unfortunately the manuals I have found for the Mill don't go into detail on how to do any of this stuff