Colchester Student feed help

Hi All

I have just joined the forum as I recently bought a Mk1 (1953/54) Imperial Colchester Student. This will probably be the first of many basic question posts!

I have replaced the motor and added a VFD but I am having trouble engaging the sliding/surfacing feed, it will go into sliding feed only moving away from the chuck and when engaged in surfacing it just clicks and feels like something is worn or misaligned.

Does anyone have a diagram of this type of apron? I can only find the later plunger type.

The other issue I have is that the levers on top that change the gears seem to easily drop out of engagement, even under no load, is there something I can adjust to fix that?

Thanks in advance for any help.

Simon

I believe the early type with the cast levers had detent plungers ,spring loaded in each knob......there should be corresponding holes in the top.The later round plastic knob type have springs and balls engaging detent slots under the pivot...As to your feed issues.....I would think the worm and gear in the sliding engagement shoe are the problem........be very careful with this type of apron ,as it doesnt kick out under load like the later "safety" one.....and you will bust gears if you use a bed stop......Another issue these machines had was the rack coming loose ,too few screws securing ....I have not come across a manual describing this type of apron online,but there are a few parts lists.

I have a 1960 made Colchester and when I tried to get parts I was told by Colchester there are none available. Be careful you will need to make parts if something is broken. What they did have was very expensive.

I have a 17" Colchester (Mastiff??) made I believe in 1975.
The round head, not the square head.
Anyhow I believe the aprons are of similar construction.
On my lathe, the bores in the apron where the leadscrew
and feed rod pass through were egged out. The shafts
run in the iron housing, with no replaceable bearings.
Also, iron housing that the feed lever is attached to,
the one that rides on the feed rod and contains the
worn gear; it's bearing bores were worn out as well.
All this was fixed by aligning the castings on a HBM
and boring the bearing holes in the apron and the feed
lever casting to accept bronze bushings. This took a
while to get everything lined up. Custom size bushings
were made out of aluminum-bronze. Press fit was only
.0005" as they cast iron walls were a little thin to
contain hoop stress. Use Loctite and a slide fit if
you are worried about it. Fit with the shafts was
.002" loose. The reason that the feed rod bushings
wore so bad, is in this lathe, the detent spring that
keeps the feeds engaged bears force on the bushings
of the power feed lever casting, putting a great load
on them when the feed is engaged. I put in a much lighter
spring to help mitigate this with no ill functional effects.
I have studied the schematics of the smaller Colchesters
and I am not totally sure if the detent spring acts in the
same fashion, but something to look at for sure.
I ended up needing a gear and got it from Frank D. Kleinworth
in Texas. I think his business is called FDK.
Hopefully you lathe did not need as much work as mine did.
It was worth it to me, because my 17" has 3.125" through
the spindle and is also a gap bed. Well thought out machine
in my opinion.

--Doozer

In any case,if you pull out the feed rod from the tailstock end,the "shoe" holding the feed gears will drop out........no complex fiddle like the later safety feed...........I see I made a note in my file that the shoe gears can be replaced by a couple of gears from a Burman CP motorbike gearbox.......gone from memory why I wrote this forty odd years ago.....edit.......I might add,the fit of the rod in the apron has no effect on gear mesh,as the shoe is supported at the back by a long bar,and front by the detent......however ,rod fit in the shoe does effect gear mesh,and clearance should be minimal.

This is the style apron on my early rounhead student, is this the same as yours?
Be aware there is also a small shear pin on the drive gear to th feed gearbox which may be giving you intermittent drive.

The diagram is of the "gap bed" setup.....the no gap is different ,the handwheel is at the front,and the gears are different......the no gap has more gears......as mentioned its easy to drop the shoe,not like the later one.