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CZ 527 Barrel Tenon Thread

Hi All,
A buddy of mine has asked me to re-barrel his .223 CZ 527 to .20 Practical to which i said gladly.
I have since been told that the CZ 527 has a metric reciever thread, which will be a problem for me as my Colchester lathe has an imperial gearbox only so i cant cut metric threads.
Please could any of you guys confirm what the thread is and if it is indeed a metric form before i get into re-moving the 223 barrel, dont exactly want to start the job if i cant finish it.
Many Thanks

Ian.
 
I dont have the answer to your question but I may have the answer to your problem. If your lathe is a Colchester it should allow you to make metric or imperial threads. If you look at your thread chart on your lathe,its the metal chart at the gear selection handles which is usually rivetted onto the lathe,youll
see a list of thread sizes,on one side of the column you should see TPI threads per inch and on the other column you should just see thread pitches which may look like say .5 .75 1.00 and so on, the metric ones will look like 10 12 13 14 16 18 20 21 and so on, these are the ones your after. Im sure you should get the rest of the question answered by someone else. Hope this helps.
 
With all due respect gamma, i know my way around a lathe,
I have been operating Colchester lathes for over 30 years here in the UK and i am what you guys call a master machinist,
My lathe at home is a Colchester Dominion which is identical to a master and will only cut imperial threads but thanks for the pointers anyway.

Ian.
 
Be careful on your way around that lathe,it would be a killer to fall and get hurt and not know whether to use metric or an imperial bandage.
 
CentrePunch said:
With all due respect gamma, i know my way around a lathe,
I have been operating Colchester lathes for over 30 years here in the UK and i am what you guys call a master machinist,
My lathe at home is a Colchester Dominion which is identical to a master and will only cut imperial threads but thanks for the pointers anyway.

Ian.

Ian,

With all due respect, as you seem to live in UK, you can certainly easily get from Colchester the necessary gears set to adapt to metric threads?

We were used this side of the Channel to use metric leadescrews lathes for cutting Imperial threads, using a 127 teeth gear. The reverse option certainly exist from Colchester?

'The world turns on Colchester's' is their advert...with some jams it seems!!!

R.G.C
 
Robert, i know what you are saying but it is not as simple as just changing a gear on this particular machine.
I have looked into changing the gearbox but although my lathe is 50yrs old and many parts are no longer available to buy direct from Colchester you would have to be a rich man.
As an example i got quoted just short of £3500 for a set of head stock gears for a MK1 Student/Master:eek: luckily i found a very good used set complete with shafts on ebay for £65:)
Even used parts are becoming very expensive now.
It would be cheaper to buy a complete newer lathe.
However if a gearbox and lead screw from a MK1 Master becomes available for a reasonable price i will buy it.

Ian.
 
CentrePunch said:
Robert, i know what you are saying but it is not as simple as just changing a gear on this particular machine.
I have looked into changing the gearbox but although my lathe is 50yrs old and many parts are no longer available to buy direct from Colchester you would have to be a rich man.
As an example i got quoted just short of £3500 for a set of head stock gears for a MK1 Student/Master:eek: luckily i found a very good used set complete with shafts on ebay for £65:)
Even used parts are becoming very expensive now.
It would be cheaper to buy a complete newer lathe.
However if a gearbox and lead screw from a MK1 Master becomes available for a reasonable price i will buy it.

Ian.

Ian,

Many years ago, I had to use an old Colchester lathe 'do not rememeber the model, but sure he contributed to WW2 war effort), whose leadescrew was 4 tpi, and no Norton gerabox for the metrics.
I got from a transmission parts stockist new blank gears at very low cost, and had them bored/keyed to suit the shadts of cascade gears of the lathe.
Setting for instance the Norton Box at 4 tp; and using a gear ratio of, for isntance 20/127, 25/127/, 30/127 allowed to cut threads of respectively 1,00,1,25, 1,50mm. All other combinations were possible, using miltiple of 4tpi on sub multiple.

I can tell you this did not cost me a fortune, just some time...

R.G.C.
 
gamma said:
I dont have the answer to your question but I may have the answer to your problem. If your lathe is a Colchester it should allow you to make metric or imperial threads. If you look at your thread chart on your lathe,its the metal chart at the gear selection handles which is usually rivetted onto the lathe,youll
see a list of thread sizes,on one side of the column you should see TPI threads per inch and on the other column you should just see thread pitches which may look like say .5 .75 1.00 and so on, the metric ones will look like 10 12 13 14 16 18 20 21 and so on, these are the ones your after. Im sure you should get the rest of the question answered by someone else. Hope this helps.

Hi gamma, especially for you, please explain the matric thread pitches.

TPI_Chart_001.jpg


Ian.
 

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