Fobco Star drilling machine

Has any one got a drawing of a Fobco Star drilling a machine. I have dismantled mine and found that the top bearing ( next to the pulley) is an angular type, which according to Tony@Lathes said it should be at the bottom. I would appreciate knowledgeable/help comments before reassembling the machine after a good clean up and painting. John/Ted

Hi John, Well it is a bit of a dilemma, but if anyone should know it is Tony@lathes, and an angular type bearing is designed to take thrust in one direction, so not only must it be fitted at the bottom (where the thrust is) it must also be fitted the right way round!

Phil

Hi John

I might have that info I have sent you a PM

I just happened to replace the spindle bearings on my fobco star today.

The quill/spindle contains a pair of angular contact bearings. I replaced mine with a pair of SKF 7202BEP (Replacing the old R&M LJT15's). The bottom bearing is fitted so the angular contact is made when pressing up on the base of the inner bearing race from the bottom, and the top one is placed in the opposite direction, so the angular contact is made when pressing down on the inner race from above. It does matter which way up the bearings go. The top bearing was a looser fit in the quill than the bottom one, which needed pressing.

When assembled, you need to use a piece of tube to put over the spindle and press down on the collar that sits ontop of the upper bearing. Then you need to press down to exert some preload on the bearings while tightening the grub screw on the collar. This keeps the arrangement in place. Angular contact bearings don't work unless they have pressure applied to them.

I initially did this using hand pressure, but got too much movement on the spindle after fitting and had to repeat in the press, just putting extremely light pressure whilst doing up the grub screw. It really was the lightest of pressures in the pres though. That worked a treat.

There is another bearing at the top/front which secures the pulley to the main casting, but I have no details on this bearing. I wonder if something was getting lost in translation between you and Tony as there should be two angular contact bearings in the spindle (one at bottom and one at top) and a standard ball bearing for the pulley.

Note, there are several spindle types, so I am not sure if the different types use the same bearing arrangement. Ive heard of some people saying there is an angular contact at the bottom of the quill and a standard bearing at the top, but I cant see how that would be very successful.

Even without any preload though, as soon as you push down on the quill on a drill bit, the bottom angular contact should seat properly, but I was seeing significant vibration at 4000rpm without proper preload applied so I dont know whether this type of arrangement would work very well.

Hope this helps.

Graham

I should clarify that last statement. Without preload applied, I was seeing vibration in the spindle when running with no load applied. As soon as the drill bit touched down, the angular contact seats and the vibration goes away. As soon as the load is taken off, the spindle vibration returns.

If you only have an angular contact at the bottom and standard bearing at the top, I would expect to be able to grab the end of the spindle and pull forward and backward and get some play.

This is tony's advice from lathes.co.uk

"As a point of interest the top bearing in the shaft assembly is an ordinary ball race, but the lower pair are a pair of angular-contact type. When the assembly is rebuilt some end loading is required on the bearings - and this can be done with a length of tubing, the setting being locked by a grub screw through the top collar (ensure that it bits into a new part of the shaft, not the original dimple). At first the bearings will be slightly tight and to correct this it's necessary to seat them properly by giving the end of the shaft a single smart tap with a 2 lb lump of brass. After this the shaft should spin freely and sweetly"

When he refers to the top bearing in the shaft, he is refering to the pulley bearing being a plain bearing, not the top bearing in the quill/spindle. He correctly refers to these as a pair of angular contacts.

Hope this helps

Graham

thank you graham for that excellent advice.

my old Fobco Star has performed very well though the lowest speed is a bit too high for my liking.

on the front of the spindle casting is a grease nipple though my grease gun doesnt fit! anyone know how to oil/grease the quill? im afraid to say that due to the above mine hasnt been oiled/fgreased in over 25years!

cheers,

julian

I take mine out and fit a temp extended one when I grease it.

I made this adapter years ago, the plain part has a nylon ring at the end to seal to the nipple. The thread at the other end fits an old Wanner grease-gun..

Ive just looked at some pictures of the newer version of the Fobco Star Spindle, and I'm now thinking that the bearing arrangement on the later models is significantly different. Perhaps a pair of back to back angular contacts at the bottom of the quill and nothing at the top????? There doesnt appear to be any bearing surface at the top of the wider section. Has anyone split down a later model of the quill.

Thanks

Graham

Edited By Graham Wharton on 04/03/2015 10:49:00

Hi Graham

A while back I replaced the bearings on a Fobco Star for someone and as an earlier poster found these were 7202b angular contact at top and bottom of quill. The bore of these is 15mm. Clearly from the pictures you show the spindles are larger than that. Fobco did other designs of spindle for the Star, I believe Tony refers to a total of five. One of them had a 2mt taper, in fact my own machine has that arrangement and the bottom bearing is clearly larger. I can't speak for the upper bearing as I've never dismantled it. My spindle also has a myford 7 threaded nose as appears to be the case in your lower picture. I have a drawing of the Fobco 7/8 machine head and that does show two angular contact bearings at the bottom and a ball race at the top, so this is clearly a method they used. This latter is shown on the drawing as being on the smaller diameter of the spindle, not the larger. The bearing surface may not be apparent. You have to bear in mind that the majority of these started life in industry and many suffered the most appalling abuse, ( bit of a paradox really considering that this happened during those halcyon days of British engineering of which we often hear ) and the original bearing surface could have been destroyed by a slipping bearing.

Hope this helps

Michael

Many thank to all have responded to my request in particular Stephen who sent me all I need almost by return. Its good to know there are helpful people out there.

Hi John, just took possession of a Fobco. Star, shipped from the homeland to Brisbane. It's in original condition but want to strip, clean and reassemble. The above posts are very helpful. Motor definitely needs bearings. Very impressed with the machine and the British Made label on the front of the table, heavy brute it is, thanks to Howard from Myford for finding this one.