# Just How Accurate Is A Modern Colchester Lathe



## malmac

I understand that the Colchester Lathe is still considered a bit of an industry standard for quality and accuracy.

Can't justify buying a Colchester lather but would like some data on there accuracy specs if anyone is willing/able to share.

Planning to buy a good quality Taiwanese lathe and would like to compare the accuracy between the machines - to see what I am potentially missing out on.

It is true that there are some really super accurate Taiwanese machines - Cyclematic (on one machine spindle runout of .00125mm) - but somewhere below that are some machines with more modest but still desirable levels of accuracy - that is where I am looking.

Any advice is welcome and appreciated.

Mal
Australia


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## MSD0

I wouldn't get too hung up on the specs. You can still make good parts with tight tolerances on a worn out machine.


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## dlane

Orental machines just need some help to make them ok.


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## Chipper5783

The accuracy of parts made on a lathe is mainly due to the operator.  Same idea holds for many other tasks.  The cheapy import lathes, will readily give a pretty average competence home machinist guy dimensional accuracies of better than 0.01 mm.

The more expensive machines give you about 99% the same result, just faster and with a bit less fussing.

Cholchester has made many good machines, but for the most part, the resulting components won't be any different from a mid level Asian import.

My suggestion is that you don't sweat the brand top much.


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## malmac

I am sure you guys are right - just wanted to  get my head around relative accuracy per cost.

I am looking at two lathes - one has a centre line runout of .015mm and the comparison lathe has a centre line runout of .008

That means the second lathe has a more precise action by .007mm - how much is that improvement worth????
Also how do those figures compare to an industry standard Colchester lathe?

Mal


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## malmac

Thanks Chipper

I am willing to accept that I am not a hot shot machinest. However if I am going to upgrade my lathe I would like to buy the best one I can afford and know why I am paying the extra dosh.

Guess I also like the effect that using precise tools and equipment give me.

When I work on the old bikes I like to build special tools which means I can do the specific job in a calm and controlled space. I experience a pleasure from using a precise piece of equipment - but I do realise that experience really does make a world of difference.

Thanks for your response.

Mal


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## Tony Wells

I'd say those figures are derived from a sampling of their production machines and are based on two primary factors. First and probably foremost would be the bearing quality. It seems to me that this is the easiest way for machine builders to save substantially in their build cost, and they take advantage of that. The other basic contributor to that specification would simply be their own in-house machining practice, in particular the precision of their spindle grinding. That could be ultimately be because of their poor quality grinders, their average operator's accepted performance, or perish the thought, their original design intents and limits. Unfortunately, there is no way to know. You might get a monday morning machine and it be right at, or even out of the spec furnished. Or you may get one where the boss is watching the grinder operator closely right after a threat to their job.....and get one near spot on. Then in both cases, in the end it depends on what the QC department decides to let ship. Or perhaps even checks before shipping. You might just look at it as a gamble, with the odds more in your favor the more you gamble.

All that aside, I have an Acer Dynamic series that I bought new in '97 I believe. I've not mistreated it, never wrecked it.....and I'd say it is every bit as accurate as it was on day one. I regularly work in tolerances less than 0.0005 and have no problem cutting to it, and not having to paper it in. I have no affiliation with them other than a satisfied customer. I have other lathes, so it's unlikely I'll be buying another in the future (other than a couple of smaller Rivetts I am looking at), but should I need another, Acer would be high on the list.


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## mksj

If you look at some of the Taiwanese lathes, such as the PM1340GT, the guaranteed spindle nose TIR is +/- 0.0001" 0r 0.0025mm. I have measured mine, and it is better than this spec., and I would expect similar quality in better built lathes. You do not need to spend big $ to get there. It is all a bit ethereal at the end of the day, when you factor the TIR of a standard scroll chuck is usually around 0.002-0.004" for the better ones, a set-tru is about 0.0004", otherwise use a independent chuck.  This also changes over the clamping range and then you have the accuracy of the Jaw clamping and parallelism to the Z axis. A heavier lathe will have less axial deflection and allow deeper cuts, but at the end of the day one should easily be able to get dimensional accuracy of 0.0005" or better on most of these lathes in the size you are considering. With the lathe it is mostly the operator that determines the accuracy of the final product, assuming the lathe is in good condition. You want a lathe that will fit the scope/size of your work and of good quality and features you need, but there is a point of diminishing return chasing the numbers.


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## Bob Korves

The spindle on my Chinese built Kent USA KLS-1340A is right at .0002" of runout.  Goodbye, alibi!  To get .0002" accuracy on actual work requires some careful fussing and tweaking when using any lathe.  Ultimate lathe accuracy does not really do much for the results of your work, though better machine quality does tend to keep the machine's inherent accuracy in place for a longer time frame with less adjustment and repairs.

I laugh out loud when I see the test report sheets for Asian machines.  For the price they are pushing them out the door for, there can be little real, careful inspection of the accuracy and quality of the machines.  What it is, it is, and those test reports are almost certainly pencil whipped into being.  The numbers reported are usually right at the tolerance limits, with a few entries a bit better.  It is mostly a waste of time and money doing it at all, those completed machines are going out the door if they look like all the components are installed.  Employees do what it takes to keep their jobs, and keeping production going out the door tends to work toward that end better than taking fussy measurements, sidelining marginal product, and refusing to write down the expected numbers, in most factories making things that stay in the earth's atmosphere...


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## chips&more

In the big picture, a lathe is a lathe and it makes round things. The operator of the lathe decides how round the things are, for the most part! And I’m not trying to give credit to import machines. Only that the talent of the operator could be the deciding factor for part accuracy.


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## malmac

An interesting discussion. I have a cheap 1340 Chinese lathe and have found accuracy to be one challenge and quality of build another. So as I have been considering an upgrade I have obviously looked at the experience I have had to date (which I freely admit is modest) is influencing my decision making. I also have a chinese mill which is good up to a point - but if I was changing that (which I don't see happening) I would be looking for rigidity and accuracy as well - the size of the machines I have seem really good - just attempting to quantify accuracy and quality before I part with any more dollars.

Thanks to everyone for your input to date.

Mal


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## mksj

I agree with you on your experience with the Chinese machines that you are discussing. One reason why I do not plan on buying any future machines from China, and am in the process of purchasing a Taiwanese mill.

I have attached a brochure from Kent USA precision lathes, but these lathes seem very close to the ERL and RML lathe models available through different vendors around the world. Tolerances are as follows:
PARALLELISM:
Headstock Alignment
0.0006"/12" (V)
0.0006"/12" (H)
Longitudinal Bedways
0.0006"/40"
Center Line of Spindle
with Carriage Motion
0.0004"/12"
Center Line of Tailstock
with Carriage Motion
0.0006"/12"

SQUARENESS:
Center Line of Spindle
with Cross Slide Motion
0.0006"/12"

RUNOUT:
Spindle Nose
0.0002"
Spindle Flange
0.0004"

That is about as good as it gets, and these are usually maximum allowances.  There are so many other factors that affect precision lathe turning, that these specs are impressive and I would expect these machines to be quite rigid.


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## Bob Korves

Bottom line to me is that you can buy quality and mass in lathes and milling machines, but you cannot buy accurate work.  That has to come from within the machinist.  Much of it is repeatability.  I can do some really accurate work -- sometimes.  But not consistently.  Lots of experience and practice, and keeping work practices and standards high, will gradually but noticeably improve the quest for consistently accurate results.  That quest is mostly in the machinist, not in the machines -- as I see things.

All of us can improve our machines by adjusting the gibs, checking the geometry and adjusting it as needed, and keeping things properly lubed.  The world's best mill still needs to be accurately trammed to make nice parts.


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## malmac

Hi Mksj

Thank you for the brochure. I think we are looking at the same lathe.


Looks the same to me. When I work out how to attach a pdf file I will share with you the precision data sheet I have been supplied with this machine and also a slightly more economical machine (also from Taiwan).


I also have an accuracy data sheet for this machine as a comparison.

There is another factor that I am considering is also upfront sales assistance - Whitelaw is very good in this area. Also hoping they will remain as helpful after the lathe is potentially supplied and I need that rare commodity "after sales service".

Mal
Australia


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## Tony Wells

To me those are Left Hander's lathes. The carriage handwheel is on the wrong side. I have run a lathe like that, but sure seemed awkward. Chips slapping around will make you hesitate to grab that operating handle too. Just me, perhaps....but I wouldn't have either of them.


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## mksj

Tony Wells said:


> To me those are Left Hander's lathes.


Great call, I missed that, assumed they are all the same, but you are correct and I wouldn't want the half-nut lever on the left side of the carriage. Never seen that before. Like the carriage hand wheel guard on the kent RML shown. On the precision note, I was just turning some 3.5"x 12" stock down, wobbled at the end, but turned very nicely and was better than 0.001" to spec. when done. As long as you do not remove it from the chuck you would be fine.


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## malmac

Hi Mksj

So do you already have this lathe you have posted the image of?


Mal


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## mksj

PM1340GT, http://www.machinetoolonline.com/PM1340T.html
Added a VFD and a number of other modifications.  Does everything I need it to do, a number of individuals in this forum own this lathe. I originally was seriously looking at the ERL 1340 and 1440 models, but the budget just wasn't there.
Mark


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## malmac

Yes I hear you on the budget side. Wrestling with my do vs don't muscles as we speak. Will keep you posted.


Regards


Mal


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## Kiwi

Isn't  Colchester (Group 600) also now made in Taiwan I know that some of them were assembled in England in the early days of the Group 600 from my understanding the tolerance claims are from the average of special assembled machines which can be different from production machines  but not by much


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## malmac

I think a quality machine from Taiwan will be more than accurate enough for myself. Though I am going to lurk around the forum for a bit longer before I make a hard decision on exactly which one.
The workshop needs a rejig before any new machines come in and I need to look at my budget for the total makeover and then see how much I have left over for a lathe upgrade.
The lathe actually gets more work than the mill, though that does change a bit depending on what project is in the pipeline. I don't make things for the sake of it - rather when a job needs doing I don't shy away from using the lathe to improve the quality of the solution.

Thank you to everyone who has contributed.


Mal


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## Downunder Bob

MSD0 said:


> I wouldn't get too hung up on the specs. You can still make good parts with tight tolerances on a worn out machine.



Yes it's all in the skill of the operator.


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## Smithdoor

FYI
Back in the 80's the Colchester RUNOUT Spindle Nose 0.0001"
There other lathe that RUNOUT Spindle Nose 0.00005" Dating back the 30's
Most work only needs RUNOUT Spindle Nose 0.001" Other work may need RUNOUT Spindle Nose 0.0005"

Dave


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## Andre

Get a 4 jaw, then dial all that radial runout away. I would only be concerned with minor spindle nose runout if using collets for very tight tolerances. 

Also remember, your spindle accuracy changes as it heats up and the machine warms. Some claim sunlight through a window can affect the performance of a jig grinder, because it heats up and expands the cast iron base.


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## malmac

Well I bit the bullet and have ordered a Colchester, Triumph 2000 with a short bed (625mm between centres) so it fits nicely into my workshop.
I accept that a skilful machinist can make an accurate part on a rather average machine, a great guitarist can make a cheap guitar sound pretty darn good, if you take my point.
However I feel I need all the help I can get as I don't think I have forty years left in me to develop that lifetime of experience that some have already put in. I am a late comer to the party.

I get a lot of satisfaction out of making things on the lathe and mill for my various projects - so I guess I will try and learn as much as I can.


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## Downunder Bob

malmac said:


> Well I bit the bullet and have ordered a Colchester, Triumph 2000 with a short bed (625mm between centres) so it fits nicely into my workshop.
> I accept that a skilful machinist can make an accurate part on a rather average machine, a great guitarist can make a cheap guitar sound pretty darn good, if you take my point.
> However I feel I need all the help I can get as I don't think I have forty years left in me to develop that lifetime of experience that some have already put in. I am a late comer to the party.
> 
> I get a lot of satisfaction out of making things on the lathe and mill for my various projects - so I guess I will try and learn as much as I can.



Well done, I'm sure you'll get a lot of satisfaction and fun from your purchase. 

When I think back, I finished my 5 year apprenticeship in 1966, fitter & Turner / Toolmaker, and then I started learning. You have a lot to lean my friend, but you are also in a position where, to a large degree, you can choose what to learn and and what not to bother with. You will learn as you go only learning those processes that you need to know in order to achieve whatever it is you are trying to achieve, You will still learn a lot, and like many hobby machinists you have the opportunity to become very good at some of the processes.

Good luck.


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## malmac

Bob
I am the first to admit I know very little and will never stop learning. I can't even imagine what a person like yourself has learned in your lifetime of experience as a fitter and turner.

Still they say, one is never too old to learn something new.

Cheers


mal


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## Downunder Bob

malmac said:


> Bob
> I am the first to admit I know very little and will never stop learning. I can't even imagine what a person like yourself has learned in your lifetime of experience as a fitter and turner.
> 
> Still they say, one is never too old to learn something new.
> 
> Cheers
> 
> 
> mal



That's the trick Mal, just keep learning, no one can know everything, And for everything you learn some one else will learn something different. When you come up with a project that you think might be outside your abilities, it probably is, but that's what this forum is for, start asking questions, A few, sometimes many will help guide you through.

There is usually more than one way to skin a cat. So, just because someone says you can't or shouldn't do something a certain way, there may be other ways that are viable. One has to be careful of course, especially when safety is involved, there is no glory in cutting corners for the sake of it. 

Post your projects as you go, you will get both praise and sometimes criticism, but that is how we learn.

I have a few projects on the drawing board, well actually they're in my head, I almost never draw anything, just think it through and then go ahead and do it. I will however post my projects as I get into them with photos.


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## Uglydog

Well done malmac.
I scored a 15" Colchester a month ago. Still rewiring her down from 440v and changing out all of the oil.
I believe that this thread is true in every way.
I've got several reasons that the Col is here, as I continue to need to justify selling the Boye&Emmes. 
1. She came to me very, very affordable. As I left towing the trailer I was watching to see if the police were gonna pull me over for theft!  
2. I needed to be able to turn metric threads.
3. I wanted to have higher RPMs available.

I suspect that you will likely find her very enjoyable!
I have a contact who may have some parts available for your machine. If interested PM me for his contact info.

Daryl
MN


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## Dinosaur Engineer

The big difference between a Colchester and an Asian import is that the Colchester is made to last in a production environment for at least 40 years. The Gamet spindle bearings in the square head colchesters were state of the art and were very expensive.


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## malmac

Well have had the machine up and running for a couple of months now.

What do I like?
Pretty much everything - especially the DRO - have not had one before.

What have I learned?
Well all you chaps who said accuracy is in the operator - are 100% right -
The good thing is I no longer blame the machine when I fail to hit the mark. I have a lot to learn - the really good thing is I am excited about each project - even the small ones.
Like machining up some new bushes for my grandson's billy kart's wheels. Also made him a little tow ball and put in brass steering head bushes while I was fiddling.

Yesterday machined up some pieces to use with the rotary table on the mill -

So yes I am happy - did I need to spend so much money? Heck no - I think I could have got a perfectly adequate machine for half the price -

Mal


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## Bob Korves

Goodbye, alibi!  A real, honest craftsman never blames his tools...


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## Downunder Bob

Bob Korves said:


> The spindle on my Chinese built Kent USA KLS-1340A is right at .0002" of runout.  Goodbye, alibi!  To get .0002" accuracy on actual work requires some careful fussing and tweaking when using any lathe.  Ultimate lathe accuracy does not really do much for the results of your work, though better machine quality does tend to keep the machine's inherent accuracy in place for a longer time frame with less adjustment and repairs.
> 
> I laugh out loud when I see the test report sheets for Asian machines.  For the price they are pushing them out the door for, there can be little real, careful inspection of the accuracy and quality of the machines.  What it is, it is, and those test reports are almost certainly pencil whipped into being.  The numbers reported are usually right at the tolerance limits, with a few entries a bit better.  It is mostly a waste of time and money doing it at all, those completed machines are going out the door if they look like all the components are installed.  Employees do what it takes to keep their jobs, and keeping production going out the door tends to work toward that end better than taking fussy measurements, sidelining marginal product, and refusing to write down the expected numbers, in most factories making things that stay in the earth's atmosphere...



Yes most definitely, it is what it is.

Prior to buying my lathe I looked at many chinese made and some supposedly Taiwanese made. they were usually "big brothers to some of the more common Chinese ones.

OOPS. 

Don't know what I did, but it appears the second half of my comment disappeared, so as I was saying.

After much looking and comparing. I decided that none of the chinese machines (I include the chinese/taiwanese hybrids) was up to the quality I wanted. they mostly felt stiff and gritty when turned by hand, some of the machined surfaces had visible defects. 

Looking further afield I found a machine importer/distributor in Melbourne, some 500 miles away. that claimed to have a range of quality 100% taiwanese made machines, after further research I finally decided to buy one of these machines. And yes they were very good to deal with and have provided after sales support with my many questions,and a few extra parts.

Although I haven't had the time to use it much, so far so good. the machine has  a great feel and appears to be defect free. All movements are firm but free with no discernable slack or slop anywhere. The fully geared headstock is fairly quiet, as is the norton style feed gearbox>

The lathe is fitted with an imperial leadscrew as was my request but is capable if metric threads with the classic 120 x 127 change wheel provided, It is claimed to produce some 24 metric threads and 40 imperial threads, including the often missed 13 TPI. 

It cost about 50% more than a similarly specced chinese machines, but I believe I have the better deal. And yes I am happy just need more machine time.


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## Downunder Bob

malmac said:


> Well have had the machine up and running for a couple of months now.
> 
> What do I like?
> Pretty much everything - especially the DRO - have not had one before.
> 
> What have I learned?
> Well all you chaps who said accuracy is in the operator - are 100% right -
> The good thing is I no longer blame the machine when I fail to hit the mark. I have a lot to learn - the really good thing is I am excited about each project - even the small ones.
> Like machining up some new bushes for my grandson's billy kart's wheels. Also made him a little tow ball and put in brass steering head bushes while I was fiddling.
> 
> Yesterday machined up some pieces to use with the rotary table on the mill -
> 
> So yes I am happy - did I need to spend so much money? Heck no - I think I could have got a perfectly adequate machine for half the price -
> 
> Mal



That's what we tried to tell you.


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