Colchester Bantam Mk1 1600

[WarwickWoodshop]

Hi all, sorry to revive this thread again but wondered if any of you with a Bantam could help me.

Firstly, many thanks to Dieselman and the other contributors for the thread - have read it through a few times since it first started and it's been an interesting and helpful resource!

So I'm currently working on my own Bantam, it's not in bad shape where it matters - but as another (I believe) ex-school machine it is covered in the inevitable terrible brushed on silver hammerite (they even managed to get some on the leadscrew ), and 50-60 years worth of dried on oil, coolant and grease.

I'm trying to remove the compound slide for cleaning as it's very stiff, but can't get it off. Everything I've seen seems to suggest it's just a case of removing the two locking nuts for the angle plate and then lifting it off, but it won't budge. The slide and plate will happily pirouette around so it's not seized.

May just be a case of more force needed but wanted to make sure I haven't missed something obvious. One of the locking nuts had been expertly rounded off so took a bit of effort to get it removed and am wary of causing more damage!

Thanks in advance for any advice.

 

[WarwickWoodshop]

As a picture paints a thousand words and all that, for clarity this is what I'm trying to remove

 

[Beanwood]

I don't have one. But .... on this post Bantam Swivel Slide it shows a nice picture of it 'removed'
There are also a couple of members on that thread that have first hand experience? @martin62 and @Mark Davison maybe?

 

[WarwickWoodshop]

Cheers, it does look from that photo that there should be nothing stopping it lifting free once the bolts are undone from underneath.

Think that's a Mk2 from the handles but I was under the impression that they are mechanically pretty much identical, so maybe mine is just gummed on there with old grease etc!

 

[Martin-Sy]

Yes, undo the two locking nuts and it should lift off.
Does it swivel OK?
Are the washers on the locking bolts burred and catching in the threads?

 

[Martin-Sy]

Excerpt from the manual in case you don't already have it:

Mine is also a Mk1 BTW.

 

[WarwickWoodshop]

Thanks Martin, yes it swivels freely - however I didn't notice any washers when the nuts dropped free so that could be it, might be stuck to the top hidden in gunk and catching. I'll go and have a look shortly. I have got a copy of the manual cheers, although reading the diagrams correctly is a bit of a learning process for me!

 

[Keith 66]

Some years ago i stripped cleaned & rebuilt one of our college lathes, i seem to remember the two bolts that hold the compound slide on can only be withdrawn with the slide swiveled to a certain position.

 

[Agroshield]

Wind it forward until it is half and half over the cross-slide and pry it gently and evenly upwards. As you are a woodshop, you will know the utility of hardwood folding wedges.

Alternatively, wind the cross slide off its leadscrew, turn it upside down and see if the locating pivot for the compund is visible (I cannot remember if it is a through hole) and tap on it.

...I seem to remember the two bolts that hold the compound slide on can only be withdrawn with the slide swiveled to a certain position.

He is not asking about removing the bolts. He is asking about the prior stage to this, removing the compound from the cross slide. Once this is done, he can turn it upside down and see the place where the botls can be removed.

 

[WarwickWoodshop]

Thanks guys, appreciate all the responses and suggestions. It definitely doesn't want to budge! Weird how it's happy to spin through 360° but not lift off.

My gut feeling is that all is potentially not well underneath somewhere - combination of the rounded locking nut, compound handwheel chewed up by pliers/grips, the fact it's incredibly stiff even with the gibs wound right out.....and a couple of other small bodges I've found elsewhere make me wonder if it's been 'fixed' in the past.

The cross slide is much better so I think I'm going to go down the route of taking that off and having a look from underneath as suggested. Need to pull the lathe out from the wall to get it off though so will have to wait till tomorrow!

Thanks again for the help, will post back what I find in case it's useful to anyone else.

 

[Agroshield]

It definitely doesn't want to budge

Just in case you did not know, a lot of Bantam parts are identical to Chipmaster ones. Also the Harrison 10AA was a re-badged Chipmaster, so manuals for both those machines can be helpful.

Does the compound lift up at all (i.e. can you create any gap)? If you can make any small gap, a drastic solution is to slip a hacksaw blade in there and saw off the boss on the underside of the compound.

Mystic Meg says that you will turn the cross slide upside down and find someone has added a screw and washer underneath.

There is a free ads. site www.homeworkshop.org.uk where you could put a wanted ad. for parts. There is also a Colchester group at groups.io . You can browse the message archive without joining the group, If you do join, there is good infomration in the files section.

 

[WarwickWoodshop]

Well.... Curiosity got the better of me so I'm back out in the garage - as suspected I think someone has been here before!

Not sure it would have left Colchester in that state, and guessing the hacksaw slit in my cross slide nut shouldn't be there either....

So with some gentle judicious use of a punch and hammer I managed to unscrew from underneath using the same holes that were presumably gouged in to tighten it

What a mess - but hey at least it's apart!

Now I just need a working lathe to remake the part to fix my lathe!

 

[Agroshield]

So Mystic Meg was correct.

Maybe the machine's origin in a school explains the modification. If the little darlings forget to tighten the compound after rotating it, the extra security of that part would stop it ripping the T-bolts out of the casting and the compound landing on little Johnny's foot. His foot would heal, but a new base casting would consume the entire school budget for the year.

The split in the nut could be a crude anti-backlash measure - use a feeler gauge to determine the width of the slot and then force in something 0.001" or 0.002" wider.

You will see from how the T-bolts slot into the casting that there are two angular positions of the compound where one of the bolts will drop out when you try to tighten it. Take note of those angular positions and write them in the manual. Never try to clamp the compound too near to or in those positions (the inverted view shows maybe 30 degrees of arc where the T-bolt would not have full bearing).

 

[WarwickWoodshop]

Yep that could be it, or maybe to repair some damage caused by an incident similar to what you describe!

Either way it's not the end of the world, at least I can now clean up/adjust the compound and reinstall it as-is, then when I have the time to make up the parts maybe return it to the stock locating pin configuration. I'll need to find and buy a couple of new nuts for the T-bolts to replace the rounded one but hopefully that'll do for now!

The cross slide backlash is pretty respectable for a 60 year old lathe so that explanation may well be correct too, can have a little play with it at some point to see if I can improve it further.

Just to make sure I understand your last point correctly, I presume you mean not to tighten the compound with a bolt in the area circled - or roughly 180° from there when the other bolt would be in the same area?

Thanks again!

 

[Agroshield]

Just to make sure I understand your last point correctly, I presume you mean not to tighten the compound with a bolt in the area circled

Correct. It is only something you see from underneath.

With the nuts, it may pay to make your own from a bit of 13mm hexagon bar. You can make them deeper than a standard nut and then dress them down with a file to fit the jaws of your chosen 1/2" open ended spanner a little more snugly than a standard nut-spanner fit. That will help prevent rounding in future. Finding or modifying a spanner to have a tall (up and down) but narrow (left to right) head also puts maximum spanner jawage on the nut, still allowing it to turn in the restricted space.

UNC allthread coupling nuts are available in 5/16" size and could also be used as a basis for something with maximum height:

UNC Hexagon Zinc Plated Steel Threaded Bar Connectors 10-24 - 1/2"

UNC Hexagon Zinc Plated Steel Threaded Bar Connectors 10-24 - 1/2"

www.spaldingfasteners.co.uk

 

[Dieselman 63]

Hello,

Good to see this thread is still alive and kicking, and being used as reference. When I originally wrote it, there was zero information about the Bantam other than before and after pictures, so I aimed to make a very thorough thread with heaps of pictures. I think it's pretty cool it has now got over 83,000 views!

That compound dial is one of the worst-designed pieces of metal on the Bantam, it's extremely brittle. I forked out $500 for a new one (brand new old stock) which was the same price I paid for the entire machine. If you over-extend the compound and take a cut the machine doesn't like, it'll pull the compound and rip the poor dial from the cross slide.