Fobco spindles and tapers advice please

[Falcn]

Hello, I'm hoping some kind soul out there might give me some advice on my new purchase. I've bought a Fobco Star. I also bought the Fobco collection of manuals/guides an dbrochures.

It looks to me as though my piller drill has a long extension between the end of the quill and the chuck, maybe 2.5" long. There's a Jacobs chuck on the end. (photos will be available this weekend when I have sufficient light to take them).

In the guide the description says

On early versions of the drill three choices of spindle end were available: a ordinary Jacobs No. 6 taper (to carry no. 34 Jacob chuck) or a long external taper having either a No. 1 or No. 2 Morse insert. While the latter two were adequate for light work, because the bottom speed was too high for use with larger drills it was decided (in the early 1990s, and rather late in the day) to modify the assembly by making that section of the head holding the clamp-on chuck guard an integral part of the casting. This increase in diameter and length allowed a larger, 25 mm ID bottom bearing to be fitted together with a bored-out quill assembly to take a spindle with either internal No. 1 or No. 2 Morse taper - or an external chuck-mounting Jacobs fitting. The later quill and spindle assembly can be used as a direct replacement in the earlier machines and substantially improve their drilling performance.

I understand bits of this but I'm not confident I fully understand all of it.

My questions are:
why would there be a long extension?
doesn't that simply reduce the capacity of the drill?
would it be better to replace this with something shorter?
what would you recommend as a replacement?
am I just stupid to think this way?

any help appreciated.

 

[flh801978]

The extension houses the Morse taper the earlier ones had a JT taper so you could only mount a chuck and not MT drills

The bearings in the quill were not large enough to bore for the MT directly hence the extension

Yes you lose 2.5 inches of capacity
Get a longer column !!!

Ian

 

[ArthurH]

Hello, I know this thread is over six years old, but it touches the same subject so I thought it better to continue it than start another.

A few years ago, I inherited from my father, a Fobco Star bench pillar drill. My father was a toolmaker by trade and made great use of the machine - including some very light milling of aluminium.
It does have a shortcoming - it was on his list of 'things to do', but he ran out of time..... I appologise in advance, if I don't use the correct terminology, I find confusing the subtleties between Quills and Spindles, External Tapers and Arbours. I have attached some photos* that may help, but reading posts in this and other forums makes me believe it has a Jacobs no.34 Chuck on a JT6 arbour.

My father (and now I) believe the original taper was always 'marginal', and is now worn out. The taper falls from the spindle quite often, and it is showing signs of scoring and 'pick up', - I have carefully stoned off any high spots, but guess the internal taper must be equally damaged. My father's aim was to replace this with a MT2.

I know one approach could be to replace the entire drill with a heavier duty one, but for soppy sentimental reasons, I don't want to do that. Can anyone please advise what I need to first buy, and then the steps necessary to make this modification?

*Edit - I can't get the photos to upload for some reason - I click on 'Add the file' - it says 'uploading' but then nothing :-(

 

[SteveW1000]

From your description it would seem that your drill has the spindle with either a 1 or 2 Morse internal taper. If you measure the large and small ends of the existing arbour fitted you should be able to identify which taper it is and you can buy a morse taper reamer to remove any high spots from the internal taper. It would also be worth purchasing a new arbour to go in the back of the chuck. Both these should return the drill into a usable state.

 

[ArthurH]

Thanks for the reply Steve. May I ask, what part of my description is pointing you at a Morse Taper as opposed to the Jacobs' taper?

 

[SteveW1000]

You state that the taper falls from the spindle rather than just the chuck. Jacobs tapers are short less than 3/4 of an inch long and go into the back of the chuck.

 

[CHJ]

Thanks for the reply Steve. May I ask, what part of my description is pointing you at a Morse Taper as opposed to the Jacobs' taper?

If your chuck is fited with a standard Morse taper you should be able to check its dimensions against this chart.

View attachment Cone_Morse.pdf

 

[ArthurH]

Thanks for that. I have dropped the chuck from the spindle, but am struggling to see where I make the measurements to tie up with the table.

Better news, I think I have cracked the file upload issue - I have resized them to below the 256Kb forum threshold

 

[SteveW1000]

measure the diameter just after the drill arbour drops down a bit, just need a rough size to identify which morse taper. I would guess that's a one

 

[ArthurH]

OK, thank you. I found the point on the taper that was 12.065 in diameter - it was just a couple of mm from the back of the chuck. As I have no way of measuring the angle, I measured the diameter close to the other end of the taper (40mm along from the first measurement) it was 10.006mm, so by some math I make that an angle of 1.546° or 1° 32' 44" (please check my workings ) These were tricky measurements without specialist tools, so I guess I am close to a no. 1 Morse

 

[CHJ]

Old fashioned check was,
If you can poke your little finger in the hole it's No. 1
If you can poke your index finger in the hole its No.2

 

[ArthurH]

I know it will a lot more effort and expense that refurbishing the no1 MT - but I really would like to press on with my late father's goal of upgrading to a no.2 MT. Can someone point me at what I need?

 

[CHJ]

You need to check that the spindle can accommodated a No.2 Morse socket.

1. Diameter of the spindle, can it accommodate the larger bore of the No.2.
2. Is there enough spindle length to accommodate the longer socket of a No.2
3. Does the spindle have a taper release slot at the rear of the current taper, it may conflict with a new one for the No.2. or entail doing away with this facility.

Assuming sizing OK, spindle will need to be removed and an engineering source located to bore and ream a new socket in the spindle. This may well entail the purchasing of said reamer if they don't have one.

Using adaptors is not an option from No.1 to No.2 for a pillar drill.

No2 to No1 sleeving is possible with a small reduction in drilling depth clearance.

 

[ArthurH]

Thanks Chas, for your quick reply.

Sadly, I am quite new to a lot of this, so may need a bit more spoon feeding :-|

For 1 & 2, is my first step to strip the spindle out of the drill, to enable taking the measurements?

For 3 - does this photo help at all - I'm not sure where the slot for the drift would be?

Are there any vendors that can supply a pre modified no.2 MT spindle for this drill?

Thanks again

 

[CHJ]

The slot I was refering to, you may not have one.

Is for aiding the removal of the Morse taper shaft with suitable wedge..