Columbia No 100 portable Arm Parts diagram

[flying500]

I have a Columbia No 100 portable with a sagging arm. The Top bearings are intact but the are none at the bottom.
I am unsure what the correct parts for the bearing assembly should be Can anyone help or post a parts diagram pease?
Many Thanks

[Phono48]

I've never come across a Columbia 100 that DIDN'T have a sagging arm. I've scrapped three because the chances of getting a decent arm are practically nil. The pot-metal bases deteriorate and expand and contract, allowing the bearings to fall out or jam up. How to get replacement bearings in? You have to remove the nut and bolt on the base, insert a thin screwdriver into the tiny gap, and twist until the gap is wide enough to drop the ball bearings through from the base. That's the theory, but in practise, because the pot metal is no longer as pliable as it originally was when new, as soon as you start to open the gap, the base will snap, and as well as the problem you were trying to fix, you now have a broken base.

Barry

[flying500]

Thank you very much for the info Barry.
The Base is in decent condition and the bearings at the top are in place and working but there is nothing other than a sleeve at the bottom which the bottom of the arm fits into. This is a loose fit and 'allows sag'
Was this slleve originally close fitting or is there something missing?
Many Thanks
Jerry

[JerryVan]

I'll start by saying that I've never had one of these apart and I'm only basing my advice on the photos you've shown.

It appears that the inner sleeve is meant to reach up inside the pot metal housing and support the bearings. However, since the pot metal base has grown in its height, (and other dimensions as well), but the steel sleeve has not, the bearing set is now loose, allowing the arm to sag.

Fabricating a taller inner sleeve, or thinning the flange at its base, (by removing material on the flange face adjacent to the body of the sleeve), may improve things.

[Phono48]

It may be me, or the photograph, but there doesn't appear to be a full quota of ball bearings. They should fill the whole circle, and be held in a groove in the black base. They are not held in by the sleeve, which is a loose fit, and only there as an additional guide for the base of the arm but not to support the bearings. As I have tried to explain, when originally constructed, the gap at the back of the base was wider, so that the groove, in turn, was large enough for the bearings to be dropped in from the upturned base. When they were all in place, the nut and bolt was inserted and tightened, thus the bearings were then trapped in the groove and could not fall out. Hard to believe that pot-metal could be that malleable, but when new, it was, but alas, not now. This "saggy arm" problem is not confined to the 100 model, it is also very common on, amongst others, the 202, on which I have luckily managed to tighten the arm without snapping the base, the pot-metal still having a limited amount of "give". Hope all this rambling makes sense!

Barry