Help ! - Fobco Star pulley removal

[PeteCo]

hi folks,
I'm just in the process of stripping down an old Fobco Star pillar drill.
Its not a full renovation - just a clean up and fettling so its in best working order for my workshop.

Made good progress today until I came to try get the front pulley wheel off - it just won't seem to budge off the tope of the front spindle/quill.

There are two grub screws on they pulley wheel which I have removed ( one either side of the pulley ) but I can only get the pulley to move about 6mm upwards , then its stuck and won't come off the shaft. The initial movement ( the 6mm ) is really quite easy - so its not seized or anything - but there is a definite "stop" when it gets that far. I just checked a Fobco Star dismantling video on Youtube and it looks straightforward enough - the guy there used a couple of flat-bladed screwdrivers on either side instead of a gear puller, and his just prised off. Mine won't budge. I don't want to wreck the pulley wheel by being too aggressive - any thoughts ? I think the pulleys are cast iron ( there is some rust on mine , though this doesn't seem to be the problem in lifting it off the spindle.?

Any advice at all would be much appreciated.

cheers
Pete

 

[TFrench]

I take it you dont have a puller? Be careful if you do use one, the sides of a vee pulley are quite delicate!

 

[Robbo3]

Check the grub screw holes. Sometimes they use more than one in each hole.

 

[Distinterior]

Check the grub screw holes. Sometimes they use more than one in each hole.

I was going to suggest the same thing.....Someone had done that on my Startrite pillar drill!

 

[PeteCo]

Many thanks for the suggestions. I've got hold of a gear puller now so will try again today and check for additional grub screws

Cheers
Pete

 

[PeteCo]

A 150mm 3-legged Gear puller worked a treat - the grub screws had been tightened so much that there were dimples in the quill shaft causing burrs and this was what was causing the problem getting the pulley off.

Had to sandpaper the shaft slightly to remove the burr caused by the dimples and now the pulley slides on and off very nicely

Spent the whole day stripping down and cleaning up the parts. Haven't dismantled the spindle and bearings yet because I am not sure about re-seating the angular contact bearings - could use some advice about that . I've got lathes.co.uk Tony's dismantling guide but it's short on info about re-assembly !

Cleaned up the pulleys which were hidden beneath a good layer of rust. They look great now.

Can't wait to get it up and running now that it's been fettled. It's a monster.
Cheers
Pete

 

[Steve Maskery]

That sounds very encouraging, Pete. Good luck.
S

 

[Fitzroy]

Sounds like good progress! I’ve the same drill that has a little more runout in the quill than I’d like, c. 0.2mm, and at some point will take it apart and see if I can improve it. However, when I first got it I had the same problem as you that the pulleys did not come off easily so doing anything with it was put on hold. Great to know that all I need is to check for extra grub screws and then a little welly.

Some pictures of progress and blinged up tools always goes down well with the forum.

Fitz.

 

[Steve Maskery]

FWIW, I have a Meddings Pacera called Lulu (she was built the same year as Shout!, though in hindsight I should have called her Cilla the Pilla Drilla from the same era...). I think she is very similar, and though she is a lovely machine in many, many ways, the pulley assembly is absolute rubbish - just a grub screw on the shaft. Not even a flat, let alone a Woodruff key.
She is a mixture of the good, the bad and the ugly. Fortunately she is very heavily weighted on the left-hand side.

 

[PeteCo]

Thanks for the feedback all.
I realised the pulleys are original after all - only one has a copper sleeve inside. The motor pulley.
It dawned on me that when someone replaced the motor the spindle was metric and they needed to bodge a fix .
Seems to fit very well though in fairness.
Pulleys have cleaned up quite well with very fine grade sandpaper and elbow grease.
I had thought about rigging up an electrolysis bath but just couldn't be bothered and took the labour intensive route instead!

just cleaning up the stand and table and then looking forward to reassembly.
cheers
Pete

 

[PeteCo]

Hi Folks - reviving my own old thread here but Ive been using my Fobco Star for about a year and absolutely loving it.

Its help me build 4 guitars this year ( my new retirement hobby)
But lately its become a bit noisy and I have narrowed this down to at least one of the bearings.
When I bought it I knew I would need to do a complete strip down and rebuild at some point , and with an impending house move in a couple of months I have decided that the time is about right.
Ive managed to obtain direct replacements for the Hoffman bearings from Orinoco bearings in Leeds - who were extremely helpful indeed and who I would recommend to other Fobco Star owners looking for the right bearings.

Where I need some help / advice is on how to preload the bearings in the Fobco when I come to reassembly of the quill and housing. The internet is full of Fobco info but very short on info about how to actually refit the bearings and how to get them preloaded with basic workshop tools. I bought Tony's guide from Laities.co.uk, but its scant on details for some processes, to be honest. The strip down section is detailed, but there's nothing on rebuilding, sadly.

Can anyone give a clear A-B-C description on how to replace the bearings? Assume you're dealing with an apprentice !!

Cant wait to get it fully restored.
Any help greatly appreciated

cheers and thanks

 

[Jelly]

Happy to share what I have learned about assembling machine tool spindles, but there's quite a few variations on spindle design, and I'm not familiar with the star...

I've sketched a few sectional views through common spindle designs and attached below, if you can tell me which you're dealing with (or a combination of features from several), I'll do my best to advise accordingly.

 

[PeteCo]

Thank you ever so much - that is amazing help @Jelly

I have found a cross sectional diagram which hopefully will attach here - you will probably be able to make sense of it.

I think its a type 1 looking at your diagrams but I haven't had it fully apart yet, and can't be sure.

The guide I bought from Laithes.co.uk talks about seating the angular contact bearings with a tap from a 2lb lump of brass to get the preloading right - but I guess I could just use a 2lb lump hammer when I get to that stage ? There are 2 normal bearings in the housing that support the spindle / pulley shaft. These look like they will need tapping in from above and below the housing - I guess with a long steel rod from below, and something flat from above. My main concern is how to avoid damaging the bearings / races by doing it right. I'm a woodworker and don't have any real machine metalwork workshop experience.

Anyway , any advice on how best to go about installing the bearings would be fantastic.

 

[Jelly]

Great, looking at that it's a variation on the theme of what I called Type 1, which looks to have been designed with the intent of making it easier to re-assemble without specialised equipment.

If I've interpreted this right, then:

Parts of spindle assembly shown:

Part No.	Description
134	Spindle Outer Casing
135	Spindle Shaft
136	Angular Contact Bearing(s)
137	Spacer (to keep part 135 from contacting outer race of 136)
137a & 137b	2-part Lock Ring Secured by grub screws

Procedure to re-assemble and pre-load:

1. Slide spacer (137) over shaft (135)
2. Slide Bearing (136) with the wider face of the internal race facing down, over the shaft to meet the spacer.
   • If you need to apply pressure because it's a tight fit:
     • Use an arbour press, hydraulic press or f-cramp(s) in preference to striking or percussive force.
     • Ensure you only press on the inner race, do not apply any force to the outer race.
3. Insert the shaft-bearing assembly into the spindle casing (134), and seat the bearing by tapping firmly into place with a soft faced hammer or brass drift.
   • As a reverse of the instructions for the previous step, it's important that you only tap down on the outer race when seating the bearing and not the inner race or shaft.
4. Slide the second bearing (136) over the shaft, wider side of the inner race facing up, followed by the locking ring assembly (137a&b).
5. Seat the second bearing by tapping into place as per step 3.
   • Again, it's critical that you only tap on the outer race when doing this.
6. Using a length of tube and an arbour press (ideal) or an f-clamp (not ideal but do-able), pre-load the bearings by applying very gentle force to:
   • The inner race ONLY of the upper bearing, via the locking ring
   • The opposite end of the shaft
   • DO NOT use a normal workshop hydraulic press.
     • They're not nearly well modulated enough to apply the gentle force.
     • If you have access to one which has a pressure control valve which allows you to accurately limit the force applied, then you should be able to use it.
7. Whilst the shaft is under pressure, secure the locking ring.
8. Release the press/clamp and feel the bearing arrangement:
   • When you spin the spindle, if correctly preloaded it should be ever so slightly stiff, turning freely with minimal force by hand, but not totally free spinning.
   • When you grip the shaft and jiggle side to side, there should be almost no perceptible play from side to side.
9. If the spindle still feels loose, then release the locking ring and repeat from step 5 onwards, using just slightly more force to hold together than the last time.
   • It's better to do lots of little steps to get it right because insufficient pre-load will not cause any harm (unless the machine is assembled and run in that state for any length of time), but too heavy a pre-load can permanently ruin the bearing instantly.
10. Tap both ends of the spindle gently with a brass drift a couple of times, after which the shaft should spin slightly more freely (but still stopping quickly when spun at a low speed).
11. Lubricate the spindle as per the manual (I believe this will mean pumping grease into the spindle via a rather awkward looking nipple visible in the sectional view just above the leader for 134), reassemble the rest of the drill, and run at a medium-low speed for 10-15 minutes checking the region immediately contacting the bearing seats for warmth every few minutes.
    • Slight warming is acceptable, especially during this run-in period
    • If the spindle is getting to be significantly warmer (say around the temperature of a warm/hot bath) than the surrounding components, there may be fractionally too much pre-load and you should disassemble and re-assemble with slightly less pre-load.

Edit:

Having now done a little research, it would seem there are quite a few variations on the fobco star spindle arrangement from the sounds of things.​

​

There's a thread on the Model Engineer forums giving advice similar to my own (and substantiating my guess about greasing the spindle via an awkward nipple) for the style you've shown, where other posters are discussing the variety of different configurations they've found on the Star.​

​

Reading that thread it would seem Tony's advice given above is valid for some of the earlier designs of star, but not all of them as the design changed significantly over time.​

 

[PeteCo]

Thank you @Jelly - I really couldn't have asked for more detailed instructions, that's a huge help and I now feel confident tackling it, and that I won't have a ex-Fobco lying in bits for ever !!

It might be a few weeks before I have chance to fully disassemble it - but I'll see if I can at least get the quill dropped out to do those bearings soon.

I might be back for more help when I do the pulley bearings, but I'm hoping these will be a case of removing the pulleys ( which Ive done before with a puller) removing the circlips and tapping the two bearings out of the cast iron housing carefully - though I thought I would have to tap the outer races using suitable rod (adjacent to the housing) rather than the inner ones for that ?

cheers

 

[Fitzroy]

Thank you @Jelly - I really couldn't have asked for more detailed instructions, that's a huge help and I now feel confident tackling it, and that I won't have a ex-Fobco lying in bits for ever !!

It might be a few weeks before I have chance to fully disassemble it - but I'll see if I can at least get the quill dropped out to do those bearings soon.

I might be back for more help when I do the pulley bearings, but I'm hoping these will be a case of removing the pulleys ( which Ive done before with a puller) removing the circlips and tapping the two bearings out of the cast iron housing carefully - though I thought I would have to tap the outer races using suitable rod (adjacent to the housing) rather than the inner ones for that ?

cheers

If that diagram is part of a brochure or similar could you photo it all and upload it? I have a Star and have searched for info before and found nothing.

Cheers

Fitz.

 

[PeteCo]

Hi @Fitzroy Its just a single page I found on the web when searching for a Fobco manual. I bought the guide from Laithes.co.uk, but it doesn't have any other drawings specific to the star - only the other machines in the Fobco range. I don't know if there was ever a manual as such.
How is your Star ?

 

[Jelly]

I might be back for more help when I do the pulley bearings, but I'm hoping these will be a case of removing the pulleys ( which Ive done before with a puller) removing the circlips and tapping the two bearings out of the cast iron housing carefully - though I thought I would have to tap the outer races using suitable rod (adjacent to the housing) rather than the inner ones for that ?

You're right that in getting the pully bearings out you'll want to apply force to the outer races to get the best effect.

If the bearings (which from the diagram look like standard sealed BB rather than angular contact, so much cheaper) are being replaced with new, I'd be inclined to chance using a bearing puller on the inside race pushing off a steel bar placed across the top of the assembly, or better yet equal force on both races using two tabs of steel (one threaded one with a through hole) a length of threaded rod and four nuts to break them loose as per the diagram below.

DIY puller for removing bearings from bores:

Method of employment:

 

[PeteCo]

thanks @Jelly Dont think the diagram attached unfortunately.

I bought some more expensive original Hoffman bearings for the pulleys so I need to get it right ! The pulley bearings were nearly twice as much as the angular contacts but they do look the business though.

 

[Jelly]

thanks @Jelly Dont think the diagram attached unfortunately.

I bought some more expensive original Hoffman bearings for the pulleys so I need to get it right ! The pulley bearings were nearly twice as much as the angular contacts but they do look the business though.

I have just edited to add them back, sorry.

Pulling the old bearings you can do pretty much anything, so long as it doesn't mar the bore (and even then you can hone it out), it's only the reinstallation step where you have to ensure you follow a sequence that lets you do it without damaging the races/cages.

Looking at the assembly diagram of the pulley bearings I'd be inclined to fit them by:

1. Installing bottom circlip (157)
2. Press fitting bottom bearing (155) to bore (pressure to outer race only)
3. Installing spacer (156) concentric with bearing ID bore
4. Press fitting top bearing (155) to just inside bore, (again pressure to outer race only)
5. Compress top circlip (157) into bore and place directly on top of outer race
6. continue press fitting top bearing (ideally applying pressure to outer race but not circlip if possible) until circlip click into place
7. Placing pulley (158) in top compartment of freezer
8. Placing bore assembly on top of a radiator on full
9. Waiting several hours/overnight
10. Drop pulley into ID bore of bearings/spacer
11. Leave to warm.