colchester bantam

[keith russell 4Participant @keithrussell4]

Hi I wonder if someone can help me, I have been trying to screwcut on my Collchester Bantam, have set up the appropriate change gears, selected the correct position on the "joystick" control,and the the tool does not track the correct pitch, I am obviously doing something wrong, I tend to try and use really slow

speeds for the mandrel ..Help please!!!!

Big Jack

[keith russell 4Participant @keithrussell4]

help with screwcutting

[Ady1Participant @ady1]

Have you done any screwcutting at all before now?

Have you been turning on the lathe for very long?

Tell us what you do know so far

[Tony RayParticipant @tonyray65007]

Jack,

How are you putting on the cut ? If you are using the usual power feed that is where you are going wrong. When threading you put the cut on by engaging the feed nuts yes I have been there !

other than that if the pitch is incorrect there is something wrong with the ratio between the mandrel and lead screw.

There are various things that could be wrong but let's tackle them if we need to.

Tony

[RobonthemoorParticipant @robonthemoor]

Have a chat with AL204 he has one & I think he had a problem when he first started. He is mustard on threading now acme the lot.

rob

[Clem SayersParticipant @clemsayers49444]

Hello All,

I hope this is the right place to ask my question and seek advice.

I've just acquired a Bantam 2000 and have got it up and running and have even taken a quick facing test cut with it and it all seems OK.

However, I am having some difficulty with trying to change the feed rate. It seems that, whatever combination of the screw cutting gearbox levers I engage, the speed of the feed shaft doesn't change and nor does that of the leadscrew (I've tried to explain this clearer in the pictures in my next post). Both shafts turn and transmit power OK and the levers feel like they're engaging properly (I get that having-to-wiggle-the-spindle-to-fully-engage-the-levers feeling when I'm engaging them) so I don't think anything's broken. I feel like I'm missing some crucial step but don't know what. Can you offer any advice, please?

[Clem SayersParticipant @clemsayers49444]

Further to my earlier post, I'm afraid that I couldn't work out how to attach the pictures (I'm a bit new to the whole forum thing).

[Thor 🇳🇴Participant @thor]

Hi Clem,

I don't have a Bantam so I can't help you with the lathe problem, however Inserting photos has been explained earlier, hope that will enable you to post photos so others can help you.

Thor

Edited By Thor on 26/12/2014 17:32:08

[Phil WhitleyParticipant @philwhitley94135]

I would check the gears in the end case, it sounds like you have the wrong gears, or the wron order of gears on the banjo, this is a common problem, and is not at all obvious to a beginner what is wrong. Having said this my Colchester is a roundhead student! Have you got a bantam manual so you can set it up in standard gearing?

Phil

[MuzzerParticipant @muzzer]

Looks as if the Bantam 2000 is essentially a Harrison 250 otherwise I might have been able to help to some degree as a Bantam 1600 owner. They are completely different beasts.

Calling all Harrison owners?

Murray

[JasonBModerator @jasonb]

The Mk 111 Bantum is the same as a M250 but the Mk11 2000 is not the same as a M250, really need to know which one you have.

J

[Clem SayersParticipant @clemsayers49444]

Hello All,

My lathe is a Mk 2 Bantam (see 2nd attached picture).

Thank you very much for your replies. I bit the bullet and pulled the covers off the screw cutting gearbox to have a look. I think I've worked out the problem (see attached picture with notes). Bit of a funny one but I'm going to try my solution out over the next few days and see what happens. I'll let you know the outcome.

Thank you all for considering my dilemma and sharing your ideas.

Cheers,

Clem.

[BrevaParticipant @breva]

.

Your lathe is probably similar to the above, but note the above has a metric leadscrew.

First, There are three different sets of gearing ie. N, P or Q as seen on the bottom left of the front cover. See above. These are set on the left end of the lathe.

Lets assume you want to cut a 1mm pitch thread. On the panel it shows that a 1mm thread can be cut using either the combination PS1 or NR3. Choose one of these and check that thats the gearing setup that is actually in place under the end cover on the left. Lets say you pick gears P. (as in PS1). Set the two appropriate levers on the gearbox front, ie. to S and the joystick to 1

Set Lever A to the required direction of cut. Engage the dog-clutch C. Use lever B to engage/disengage the half-nuts.

Use lever D (red knob) to drive the cutting tool to the left, and when the cut is finished withdraw the tool and use lever D to reverse the tool back to the start of the cut. (Leaving lever B and the half-nuts engaged).

Do not use the clutch lever on the front of the apron while screwcutting.

John

[JasonBModerator @jasonb]

Looks like you should have more than one gear in place in the left hand photo, there is a better photo of the front panel 2/3rds down this page

[Clem SayersParticipant @clemsayers49444]

Thank you for all your replies. It'll be a week or so before I get it all back together (I'm waiting on some new oil) but, when I do, I'll let you know how it all works out.

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