Colchester Bantam Mk1 1600

[Agroshield]

...a key that followed the spline, but I cannot see anything, and the inside is smooth so how do they lock together to rotate?

The apron on a Bantam is the same as on a Chipmaster, so that will provide another avenue where you might find a solution.

Have you dismantled the apron and removed part A? If not yet, be very careful dismantling the shaft behind it, the one with the worm on it. It is preloaded with springs and the tension on the springs sets the automatic feed knock off. If you make the springs too tight, the feed knock off will not work properly. It might push the bedstop along the bed resulting in a crash or spoiled part. It might shear the shear pin further up in the drive train. So when reassembling it, err on the side of making the preload too little. If the auto trip trips too early, you can always tighten it up a little.

Anyway, yes there should be something to transmit the drive. Clean the part very well and you might see how it is constructed*. The drive key or drive pin is unlikely to be made integral with the part as that makes it very difficult (and expensive) to manufacture. So, if it is a pin, you will see the hole through which it is inserted from the outside. If it is a key, you will see the keyway at one end or the other of the part.

If you cannot find it, drill a hole and loctite in a pin the correct diameter to go in the keyway in the leadscrew.

*Spray it with brake cleaner and sometimes a damp line will appear at the join - it is a poor man's version of a die penetrant test.

 

[indy4x]

If you make the springs too tight, the feed knock off will not work properly..

I never knew this was a thing, although there have been times when machining up to the bed stop where I had thought it would be a useful feature

Anyone know if the M300 has this feature

Sorry for thread drift

 

[Dieselman 63]

I never knew this was a thing, although there have been times when machining up to the bed stop where I had thought it would be a useful feature

Anyone know if the M300 has this feature

Sorry for thread drift

Same as if you put that little indented piece of steel back to front or upside down.

Two apron gearbox strip downs til I got it right. What a nightmare!

 

[Dieselman 63]

Honestly can’t even remember how it all works, best bet is to download the spare parts book, it’s out there on the internet somewhere for free. My drive shaft was seized in the gearbox and it was a total pain to free it. It’s a bit of a puzzle but I’m pleased that I worked it out myself! That parts book is your best friend, it has all the answers.

Can’t remember springs in there, just bearings - there are two springs in the front of the apron that have the piece of steel with the chamfered detent in it, and if that can’t slide the power feed will lock on. Not good and a pain to fix cause it’s apron off etc.

 

[Pembrotinker]

Many thanks for replies , I had removed wormdrive pinion to examine inside which is when I saw it was smooth . and no evidence of a hole to put a pin . And I had seen on attached parts drawing there is no pin shown . and yes that parts book is great apart from this detail
My friend who donated the Bantam to me also has a chipmaster but I dont think he will want to dismantle it to get the answer , even mates have a limit .
So unless someone has the official Colchester answer I will drill my own hole and pop a pin in .(thanks to Agroshield for suggestion)

 

[Agroshield]

Many thanks for replies

If you get really stuck, there is a guy on eBay, 52kr, who is parting out a Chipmaster. He might be able to supply the part.

Can I change my suggestion to drill and tap for a dog point grubscrew held in with weak loctite? Try to locate it in a place you can get at without dropping the apron if ever you need to change it.

Go over the keyway in the second shaft and tune it up best you can. If the old drive key has been worn away, the shaft might not be great and you want the life of your new pin to be as long as possible.

If you need to adjust the trip spring tension, pull the interlock bar out. That allows the lever to hinge downwards and you can get at the adjustment screws. You can test it with the interlock bar removed, but be careful. The interlock stops you engaging power feed and halfnut at the same time.

 

[Agroshield]

My friend who donated the Bantam to me also has a Chipmaster but I don't think he will want to dismantle it to get the answer

Find yourself a more faithful friend

 

[Dieselman 63]

Find yourself a more faithful friend
View attachment 377584

View attachment 377585

Dedication!

 

[Pembrotinker]

Many many thanks Agroshield , mystery solved !!

I have attached photo and that line is all that is left of the key

The bushes and support bushes are completely shot so I guess as they deteriorated the key was put under extreme pressure and failed .

Luckily the spline shaft is undamaged.

I will try one of blondiehacks (

) to cut a new keyway and fit a new key ,adapt some new oilite bushes and make the support bushes true ( or remake from scratch ) .

Good excuse to learn some new skills.

 

[Agroshield]

...adapt some new oilite bushes...

Have a good look through the manual for the part reference for the bushes: in one Chipmaster manual, the part number is 10-929 which denotes a standard off-the-shelf bush. However, having said that, it is not listed in the standard parts list.

For the support bushes, maybe bore them out 2mm oversize on diameter, loctite or soft solder in a plug and then bore back to size leaving a 1mm wall.

Try George Lodge Direct for the oilite bushes as they carry a good line of imperial ones.

It is worth joining the Colchester group at groups.io as they have a manual for the US Clausing version of the Bantam in their files section, which contains more detail thatn the UK manual.

 

[Pete.]

Many many thanks Agroshield , mystery solved !!

I have attached photo and that line is all that is left of the key

The bushes and support bushes are completely shot so I guess as they deteriorated the key was put under extreme pressure and failed .

Luckily the spline shaft is undamaged.

I will try one of blondiehacks (

) to cut a new keyway and fit a new key ,adapt some new oilite bushes and make the support bushes true ( or remake from scratch ) .

Good excuse to learn some new skills.

View attachment 377629

Talk nicely to @doubleboost perhaps he will take a look at repairing it and feature it on his channel?

 

[Dieselman 63]

Talk nicely to @doubleboost perhaps he will take a look at repairing it and feature it on his channel?

He used to have one, didn’t he?

 

[Pete.]

He used to have one, didn’t he?

Not sure I know he had a Boxford before his Harrison.

 

[Pembrotinker]

Here's an update on repair incase it helps anyone else in similar pickle.

I cleaned up support bushes using bored out nylon to hold in chuck .



Then removed worn out brass bushes in pinion by boring out till wafer thin and peeling out remains


then hammered in nylon66 and bored that out to suit cleaned up support bushes



I drilled a slot and hammered a key in place , those bolts will be replaced with tiny tig welds when I get oilite bushes to replace nylon66 bushes




running really nicely , many thanks for advice guys

 

[Dieselman 63]

I bought a replacement cross slide - don’t need it, but I did want that T slot table on the back. The things seriously rusty but it’ll come clean with time and effort.

 

[Martin-Sy]

Somewhere I have a sketch of the rear toolpost that fits on that if you want it. Many years ago I made one for mine but I had a genuine Colchester one to copy. Made the base out of a bit of cast iron too.

 

[Agroshield]

Somewhere I have a sketch of the rear toolpost that fits on that if you want it.

There is a drawing of it in the files section of the files section of the Colchester IO group. If it hasn't surfaced by this evening, I can find a copy and post here.

 

[Dieselman 63]

There is a drawing of it in the files section of the files section of the Colchester IO group. If it hasn't surfaced by this evening, I can find a copy and post here.

Yes, keen. The toolpost is an easy thing to knock up for me, the T slots less so.

 

[Martin-Sy]

Over 30 years old and faded! I've gone over a few bits with a pen. Apologies for the mix of metric/imperial dims!
Bolts are UNC not whit.

Post here again or PM me if there's anything missing or wait for @Agroshield if there's a proper drawing on the Colchester Lathes group.

 

[Agroshield]

Found them. The one above from Martin-Sy is nicer.