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colcehster bantam 1600 mk2

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glinner 8113/02/2015 14:48:54
6 forum posts
6 photos

Hi All,

I have just broken a long time rule of mine and im afraid ive paid the price - i bought a lathe on the internet without viewing it first.

when i got it delivered i set it up and plugged it in - the seller told me it was single phase and that is one of the reasons i bought it. Plus i have felt that a bantam mk2 is the perfect size for my requirements and space available.

when i lift the apron lever up the chuck turns. however when i push it down nothing happens. as you know the apron lever should dictate the spindle direction. when i set the leadscrew lever to either forward, reverse or neutral it makes no difference. I have found out that the high/low switch is now infact set to control the spindle direction. low being forward and high being reverse.

it is a good lathe otherwise not too much wear on the beds and the spindle is relatively quiet. BUT to me this is a big issue as i really need to use the automatic feed / threading capabilities.

has anybody any ideas how i could fix this or do you think it is now simply a gearbox - less lathe??

any help appreciated

Tony Ray13/02/2015 17:26:41
179 forum posts
43 photos

Hi,

I don't have a Bantam but a Harrsion the operation of all geared head lathes is bascally the same.

Lets see if we can break this down into chunks

1. The "apron lever " usually called the third rod switch only lets you run in forward ?

2. The high/low switch now controls spindle direction. ?

3. The leadscrew lever does nothing ?

Issues 1 & 2 are electrical and are related.

Now onto issue 3.

I think 1 & 2 stem from the fact that the lathe was originally 3 phase and has been converted (arguably not that well) to single phase. Reversing 3 phase motors is easy and required less switching than single phase ones.

When you switch your high / low switch does the third rod switch then allow you to run in the opposite direction ?

If so apart from the slightly unconventional set-up you can achieve both direction or rotation.

Originall your lathe had a two speed 3 phase motor - the high & low switch controlled which of the motor speeds was being used. This is was made redundant when they fitted the single speed motor so they used it to change spindle direction.

Your third rod issue can be fixed but it sounds like you don't have much electrical experience and need an electrician - be warned your standard domestic sparky may not be able to help you. You really need someone familliar with motor switching controls, its not difficult but someone doing this all the time will have it sorted out quickly.

The lathe has two gearboxes - one to control spindle speed the upper one, and anothet - the lower one to control the leadscrew speed and therfore feeds for surfacing and screw cutting. As you are getting nothing it sounds like there is no input power to the lower box. If you take the end cover off you will see a gear train and I suspect that the input shaft to the screwcutting box is not connected to the rest.

If you can post some images of your machine that will give everyone a better idea of the model - and take one of the geartrain inside the end cover.

Don't despair nothing sounds too serious to me

Tony

3 is mechanical


Muzzer13/02/2015 18:10:05
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2904 forum posts
448 photos

Have you actually got the full manual for this? I don't follow what you are saying but if you indeed have a Bantam 1600, it has gearboxes for both the spindle and the leadscrew as well as power feed on the saddle and cross slide.

Could you post a photo?

I have a 1600 MkI but AFAIK they are basically the same. PM me if you want a PDF of the manual, parts list etc - if nobody has the manual for the MKII.

Murray

Les Jones 113/02/2015 18:21:35
2255 forum posts
156 photos

Hi glimmer 81,
When you say "when i set the leadscrew lever to either forward, reverse or neutral it makes no difference." do you mean that the leadscrew does not rotate in any of the three positions or do you mean that the saddle does not move ? If the leadscrew is rotating then are you sure the half nut is engaged ? Sorry for such an obvious question but as this is your first post I have now way of knowing how familiar you are with lathes.

Les.

glinner 8113/02/2015 20:58:54
6 forum posts
6 photos

Firstly, thanks to everyone for the replies, its good to know there is help.

right back to business - Tony,

When you switch your high / low switch does the third rod switch then allow you to run in the opposite direction ? no it still only runs in the direction which is set by the high / low switch (low is forward, high is reverse) and the apron lever will only work when you pull it up, pushing it down does nothing. i will post some pictures in the morning.

Muzzer,

i do have a photocopied manual but it is only numbered to page 23 - after that it goes into a parts manual that is not labeled.

Les,

When you say "when i set the leadscrew lever to either forward, reverse or neutral it makes no difference." do you mean that the leadscrew does not rotate in any of the three positions or do you mean that the saddle does not move. i mean that the leadscrew doesnt move at all in forward or reverse but when i move the leadscrew selector on the headstock i do feel it 'click' into place, i can feel it mesh with gears in the box. Having read all of your replies it sounds like for whatever reason the powertrain to the leadscrew/screw cutting box has been disconnected. I will have a look tomorrow. I will also take some pictures.

I am not overly familiar with lathes or the electrical gear,,,,this is my second lathe, my first is an ML7 with imperial box. a nice little machine but as I am into building model steam traction engines I just find it harder to make some parts that I was hoping the colchester would make easier....

Muzzer13/02/2015 21:45:03
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2904 forum posts
448 photos

Both the leadscrew and the slotted feed shaft are driven by the (threading) gearbox. The slotted feed shaft is what provides the power feed to the cross slide and carriage. The leadscrew is for screwcutting and has a manual dog clutch to disengage it and reduce wear when not in use.

Take the gear cover off and check whether there are any gears between the shaft directly under the spindle and the input to the gearbox (mounted on the banjo). I suspect you'll find the problem there. I assume you have drive to the spindle itself.

Sounds as if the high / low speed switch was rewired when the single phase motor was fitted. Quite what the “apron control lever” does now is for you to figure out, but it may not be capable of reversing the motor in this arrangement. No loss - my Bantam no longer has this lever - I simply control the motor from a pendant switch that controls a VFD.

It's a nice "little" lathe, so once you figure out how to use it, I suspect you'll be very happy with it

Murray

Check your inbox - I have PM'd you a link to some manuals.

Edited By Muzzer on 13/02/2015 21:47:46

Rex Hanman14/02/2015 14:09:23
96 forum posts

I have a Bantam Mk2 but it is an 800 so can't help much with the electrical problems. However, a couple of thoughts re lead/feed screws.....

Assuming there is indeed drive to the input side of the gearbox check the following. Are all the leavers on the front of the headstock fully engaged? Any one of them in a "mid" position will result in no output from the gearbox. In particular, make sure that the 6 position "joystick" is pushed left or right. In mid position you get nothing.

If all is well, both the leadscrew and the feed shaft should turn but if the feed shaft does and the leadscrew doesn't check the small dog clutch on the left hand end of the leadscrew, just against the gearbox.

Many years ago the school workshop had a couple of earlier Bantams. They were Hawk and Eagle models. Both of these had a shear pins in the drive. The kids regularly managed to shear them, I was constantly replacing them. However, I can not see any shear pins on mine so maybe Mk2s didn't have them.

Hope this helps.smiley

glinner 8114/02/2015 19:44:33
6 forum posts
6 photos

hi all,

here are some pics of my bantam :-

20150214_184225a.jpg

20150214_184153a.jpg20150214_184413a.jpg

Muzzer14/02/2015 21:07:21
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2904 forum posts
448 photos

Definitely a Bantam! The MkII is little more than a superficial facelift over the MkI, so mechanically almost identical.

Check that the forward / reverse gear selector between the spindle and the 42t gear is properly engaged in one direction or the other. And the shear pin Rex mentions is fitted behind the 42t gear (remove the nut). The 42t gear should turn at the same speed as the spindle in either direction.

If the gearbox input is turning, make sure both the 3 position and 6 selectors are fully engaged. You can change positions with the machine running slowly (<2-300rpm) and they can be a bit notchy. Can't imagine the gearbox is actually broken, so you should be able to sort this out easily enough. Famous last words.

BTW, the gearbox(es) and slides are lubricated with ISO 32 hydraulic oil which you can buy easily and cheaply from motor spares shops. They don't sell the recommended Telus oil any more but this is the modern equivalent.

Nick_G14/02/2015 21:38:58
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1808 forum posts
744 photos

.

Looking at the change wheel photograph it is very similar to my Boxford STS (as many, many other lathes) When I first got mine one of the first things I did was crash it in a right royal fashion. blush

I thought I had goosed it in an equally royal way. - The change wheels were turning but no drive was coming out of the gearbox. I went to bed convinced I had rendered the gearbox 'fubar' !!!

The morning brought a clear mind and I discovered that part of the splines that the gears sit on was a brass 4mm sheer pin. This had done it's job and sheered. So it gave the impression it was turning the gearbox when in reality it had protected it's self from a clumbsey twonk ................... i.e. me.!! wink

I am wondering if your Bantam has a similar arrangement of sheer pins somewhere as mentioned by others. Mine are behind the splines so you cannot actually see them until you take it apart.

 

Nick

Edited By Nick_G on 14/02/2015 21:42:05

glinner 8115/02/2015 00:14:04
6 forum posts
6 photos

im going to be in work until wednesday so hopefully by thursday i will remove the gear and have a better look at the shear pin, i really hope it is something simple like that...knowing my luck it is bunched crying 2

Nick_G15/02/2015 00:24:24
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1808 forum posts
744 photos

.

Think positive. yes

Here is a **LINK** to the Boxford arrangement. I know yours is a Bantam but the principle 'should' be similar.

On this drawing there are 2.

Regards, Nick

Breva15/02/2015 20:09:35
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89 forum posts
7 photos

PM me if you would like a copy of the US Clausing version of the Bantam manual. It is useful on the nuts and bolts aspect of maintenance and adjustments.

This page gives info on the shear-pin mentioned by other posters.

John

bantam.jpg

glinner 8115/02/2015 21:21:25
6 forum posts
6 photos

thumbs up thank you

Jon15/02/2015 22:31:49
1001 forum posts
49 photos

Shear pin may have gone but first check by manually revolving chuck. I had same problem on a Harrison turns out the actual indexing knob didn't line up with inbuilt indents.

Revolve chuck juggling the H selector, direction, X or Y traverse under cross slide high probability and feed lever in centre of apron. Quite normal to select a gearbox pitch and the gears not mesh, revolve chuck and either the levers will drop in or just work. Soon as you see the acme revolve your in business.

Rex Hanman19/02/2015 15:19:00
96 forum posts

Breva, PM sent. laugh

glinner 8120/02/2015 10:48:50
6 forum posts
6 photos

hi all, so i got a spare hour yday (time is precious with 2 kids under 10 and full time job!)

i removed the top gear - which came away without too much hassle. the splined sleeve is a completely different matter. it will not come away. i modified a bearing pullers and i got maybe 1mm of movement but there was a lot of pressure on the pullers. i wasnt sure if this was normal so i didnt force it anymore.

can anyone who may have removed one before say if this is normal or should i apply enough force to pull it off?

i have attached a pic with the top gear off. you can see the top of the shear pin clearly.

20150219_181415a.jpg

Ian Parkin20/02/2015 11:10:28
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1016 forum posts
236 photos

If you turn the chuck by hand the shaft should turn ( the part with the thread on) when the lever at the front is set to forwards or reverse there is a neutral position in between

If the shaft turns but the spline doesnt the the shear pin is broken

If the shaft doesnt turn then its inside the gearbox or the selecter mechanism thats failing to engage

But the splined sleeve should pull off but no need to unless the shaft is turning but the sleeve isnt

Rex Hanman20/02/2015 14:15:30
96 forum posts

Not wishing to harp on about this but both of you photos of the lathe show the 6 position joystick in the upward position but central. It must be pushed either to the left or the right. If you have since done this then apologies for repeating myself. thinking

Muzzer20/02/2015 14:18:54
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2904 forum posts
448 photos

As Ian says, without the shear pin the splined carrier should spin freely on the shaft and pull off easily. If the threaded shaft doesn't turn with the main spindle, there's no drive getting there through the gearbox.

First of all - is the forward / reverse selector properly and fully engaged in one direction of the other? This whole thing could simply be due to you not having engaged it fully. If that isn't the problem, it sounds as if your gearbox is bu99ered. The US Clausing manual mentioned by Breva in the thread above may help you to investigate further within the gearbox. It's not something I've needed to delve in to myself.

Murray

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