Im looking at a Clausing Colchester 13X40 6500 series SN F3/57607 1966/1967 with 45 inch threading box. Is this machine capable of cutting metric threads? If so how much of an expense and hassle would it be to switch back and forth from inch to metric? My only experiance has been with machines that can be shifted back and forth. The price seems fair but I'm not sure if I should keep looking since I require both threading profiles.
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Metric Threads with Clausing-Colchester lathe
- Thread starter Home Body
- Start date
- Replies 18
- Views 16,007
gradstdnt_99
Hot Rolled
- Joined
- Aug 17, 2004
- Location
- USA, Midwest
I have an 8000 series Clausing Colchester lathe 13 x 40. It is capable of metric threading but you can not disengage the half nut from the feed rod. This makes the threading dial useless. You have to run the machine in reverse to move the carriage back to take multiple passes. What this really results in is a pretty close approximation of metric threads using an English feed rod. I've done it and it works on the rare occasion I've needed to perform this task. If I was working exclusively in metric, I would opt for a machine that is designed with metric threading rod.
PixMan
Diamond
- Joined
- Jan 30, 2007
- Location
- Central MA USA
The situation that gradstdnt_99 has described is how almost all manual lathes destined for the US market are configured. They almost all have "inch" lead screws (4, 6 or 8 tpi most often). You'd need a "millimeter" pitch lead screw to be able to use the half nut even on machines shipped with a set of change gears.
metric threads
Thanks !!
That helps me in my decision. Decisions arent exactly my strong point. I think I might keep looking for a while. Shifting a lever sounds much easier on my brain. Too bad though, it looked like a pretty nice little lathe.
Thanks !!
That helps me in my decision. Decisions arent exactly my strong point. I think I might keep looking for a while. Shifting a lever sounds much easier on my brain. Too bad though, it looked like a pretty nice little lathe.
Finegrain
Diamond
- Joined
- Sep 6, 2007
- Location
- Seattle, Washington
Well, if you get a lathe with a metric leadscrew, you won't be able to use the threading dial when cutting English threads. Without some sort of dual-leadscrew setup, you can't just lever back and forth and still use a threading dial for both.
Regards.
Finegrain
Regards.
Finegrain
Finegrain
Diamond
- Joined
- Sep 6, 2007
- Location
- Seattle, Washington
Huh? How does reversing instead of disengaging the halfnuts cause some approximation error? PLZ elaborate.
Mathematically, once you transpose in the end gearing using a 127/100 tooth gear, the movements of the carriage are in exact millimeter increments relative to the spindle. There is no error. If you use a different ratio like 80/63 or 47/37 , then there is some error, on the order of .0002"/inch of thread length. This is entirely due to the ratios being not quite 1.27, and have nothing to do with the mechanics of the halfnuts or reversing of the works.
Regards.
Finegrain
rockfish
Titanium
- Joined
- Aug 27, 2006
- Location
- Munith, Michigan
I have to agree with Finegrain. You either have a machine with a metric lead screw or one with a inch lead screw. I've never seen one yet that can lever between the both AND be able to disengage the halfnuts using a threading dial.
Frank
www.randolphmach.com
Frank
www.randolphmach.com
Clive603
Titanium
- Joined
- Aug 2, 2008
- Location
- Sussex, England
Home Body
Better check again what you are looking at.
As I understand it a 13 x 40 Clausing 6500 series is a re-badged "roundhead" Colchester Master. By 1965/67 probably a Mk11 with flat top head-stock just to confuse matters.
The normal Colchester English box has some metric threading capability built in, from memory something like 45 English threads and 25 metric. As far as I know the all English, Dominion, version was only made in short 27" bed form with Colchester badge. Dunno whether Clausing specified the Dominion box on longer bed machines tho'.
As usual www.lathes.co.uk has plenty of pictures and info.
Whatever you buy the thread dial indicator is unlikely to be much use. Metric threads are rationalised in terms of pitch rather than turns per unit length so you have to change the gears on the thread dial for different sets of threads to cope with the lack of common factors. The dial tends to be complex too. My metric Smart & Brown 1024 has 4 gears, 12 divisions on the dial and a spiffy little plate telling you when to engage at 1, 3, 4 or 6 division intervals.
Aaargh!
Try keeping that lot straight that after a liquid lunch!
Leaving the nut engaged is normal practice even on all metric lathes. Many better quality ones have high speed return capability to facilitate this.
Best set-up is, as ever, on the Holbrook. Metric and Imperial on the box with a single tooth dog clutch with trigger release in the drive train so you never need to worry about thread dials or dropping the half nut in time again. Ever.
Clive
Better check again what you are looking at.
As I understand it a 13 x 40 Clausing 6500 series is a re-badged "roundhead" Colchester Master. By 1965/67 probably a Mk11 with flat top head-stock just to confuse matters.
The normal Colchester English box has some metric threading capability built in, from memory something like 45 English threads and 25 metric. As far as I know the all English, Dominion, version was only made in short 27" bed form with Colchester badge. Dunno whether Clausing specified the Dominion box on longer bed machines tho'.
As usual www.lathes.co.uk has plenty of pictures and info.
Whatever you buy the thread dial indicator is unlikely to be much use. Metric threads are rationalised in terms of pitch rather than turns per unit length so you have to change the gears on the thread dial for different sets of threads to cope with the lack of common factors. The dial tends to be complex too. My metric Smart & Brown 1024 has 4 gears, 12 divisions on the dial and a spiffy little plate telling you when to engage at 1, 3, 4 or 6 division intervals.
Aaargh!
Try keeping that lot straight that after a liquid lunch!
Leaving the nut engaged is normal practice even on all metric lathes. Many better quality ones have high speed return capability to facilitate this.
Best set-up is, as ever, on the Holbrook. Metric and Imperial on the box with a single tooth dog clutch with trigger release in the drive train so you never need to worry about thread dials or dropping the half nut in time again. Ever.
Clive
Clausing metric threads
Sounds like it might still be an option as a lathe for me then. It also sounds as though I had better do some more studying on the subject. Now that you mention it, the two lathes at work that I have used are a Tikasawa and a LaBlond. The Tikasawa shows metric threads on the plate by the shifter so I assumed you could shift back and fourth. I've only cut threads with the Lablond and they were engllish.
Is it hard to find the parts that I need to make this lathe cut metric threads? Or possibly it sounds as though if I am not concerned with .0002/inch error, I may not need to buy gears?
Sounds like it might still be an option as a lathe for me then. It also sounds as though I had better do some more studying on the subject. Now that you mention it, the two lathes at work that I have used are a Tikasawa and a LaBlond. The Tikasawa shows metric threads on the plate by the shifter so I assumed you could shift back and fourth. I've only cut threads with the Lablond and they were engllish.
Is it hard to find the parts that I need to make this lathe cut metric threads? Or possibly it sounds as though if I am not concerned with .0002/inch error, I may not need to buy gears?
Finegrain
Diamond
- Joined
- Sep 6, 2007
- Location
- Seattle, Washington
OK, on well-equipped lathes, you CAN shift easily between English and metric threads. but what you CANNOT do is use the threading dial in conjunction with unclasping the halfnuts between passes, for both English and metric threads. A lathe that shows metric threads on the dataplate doesn't necessarily allow the use of the threading dial when cutting those metric threads.
As for what's required to make a 6500 cut metric, it depends on the end gearing configuration. If the end gears run on fixed-position shafts like older Clausing's, it's pretty hard to go metric as you need a special metric quadrant that has shafts spaced properly for the transposing gears. If, OTOH, a 6500 has an adjustable-span banjo, then it's simply a matter of fitting a transposing compound gear with 127/100, 80/63, or 47/37 (among others) teeth. That'll get you .5 mm, 1 mm, 1.25 mm, 2 mm, 2.5 mm, and 4 mm (assuming the QC box has the normal compliment of TPI settings). There are also a few extra gears needed to get the right ratios for the other metric pitches like .7 mm, 1.5 mm, 1.75 mm, etc.
Regards.
Finegrain
As for what's required to make a 6500 cut metric, it depends on the end gearing configuration. If the end gears run on fixed-position shafts like older Clausing's, it's pretty hard to go metric as you need a special metric quadrant that has shafts spaced properly for the transposing gears. If, OTOH, a 6500 has an adjustable-span banjo, then it's simply a matter of fitting a transposing compound gear with 127/100, 80/63, or 47/37 (among others) teeth. That'll get you .5 mm, 1 mm, 1.25 mm, 2 mm, 2.5 mm, and 4 mm (assuming the QC box has the normal compliment of TPI settings). There are also a few extra gears needed to get the right ratios for the other metric pitches like .7 mm, 1.5 mm, 1.75 mm, etc.
Regards.
Finegrain
Last edited:
Thanks so much for your time! I have asked for some better pictures of the headstock and carriage as I am having trouble positively identifying this. If I go look at it tomorrow (Saturday) What is it that I need to look at axactly. I dont know what a metric quadrant or adjustable-span banjo is. It might make more sense to me if I were looking at the machine in person.
Thanks again!
Thanks again!
Clive603
Titanium
- Joined
- Aug 2, 2008
- Location
- Sussex, England
Home Body
If you haven't already done so check out the Colchester section at www.lathes.co.uk. There is a Clausing number link which will take you to the right general type of machine. More info than you need and plenty of pictures.
As to adjustable span banjo / metric quadrant these are components needed to allow different size gears to be put into the drive train between spindle and threading gearbox (or lead screw on plain back gear screw cutting lathes). Almost invariably the drive from spindle to gearbox or lead screw is via an open train of gears, under a cover at the left hand end on any reasonably modern lathe. Part of the gear train commonly resides on a slotted arm of banjo (ish) shape with a hole in the "body" enabling it to be clamped on a boss surrounding the gearbox input or lead screw drive shaft. By sliding the gear mount(s) along the slot and rotating the banjo about the mounting boss different sizes and sets of gears can be bought into engagement. Clearly if the input and/or output gears are changed or gears of different sizes pinned together in driven / driver pairs fitted the overall gear ratio in the system can be changed. The transposing compound gear pairs mentioned by Finegrain above alter the ratio so that the lead screw moves the carriage in mm (or fractions thereof) per turn of the spindle rather than the standard inches.
Besides fitting the transposing gear it may be necessary to change other gears to get the right ratio for certain threads.
Metric quadrants are an alternative form of banjo usually associated with back gear screw cutting machines which don't have a threading gearbox. Because all the gear ratios have to be built up from loose gears (change wheels) there usually isn't enough space on the single slotted arm of the banjo so alternative forms having two (or more) arms or slotted plates of varying complexity are used. For some obscure reason these are usually called quadrants although they pretty much never are. Metric quadrants are alternative versions with different angles between the arms or slot arrangements to accommodate the transposing gear on lathes whose standard imperial version doesn't have room being made to accommodate only the smaller gears used for common imperial threading. Not something you need to worry about with a Colchester or any other post war designed industrial size lathe although a few smaller gearbox equipped lathes need them e.g. Myford, SouthBend Heavy 10. All rather silly as a metric quadrant always does OK for imperial duties so why make two.
The general term is pretty much always banjo, whatever its shape or position.
Clive
If you haven't already done so check out the Colchester section at www.lathes.co.uk. There is a Clausing number link which will take you to the right general type of machine. More info than you need and plenty of pictures.
As to adjustable span banjo / metric quadrant these are components needed to allow different size gears to be put into the drive train between spindle and threading gearbox (or lead screw on plain back gear screw cutting lathes). Almost invariably the drive from spindle to gearbox or lead screw is via an open train of gears, under a cover at the left hand end on any reasonably modern lathe. Part of the gear train commonly resides on a slotted arm of banjo (ish) shape with a hole in the "body" enabling it to be clamped on a boss surrounding the gearbox input or lead screw drive shaft. By sliding the gear mount(s) along the slot and rotating the banjo about the mounting boss different sizes and sets of gears can be bought into engagement. Clearly if the input and/or output gears are changed or gears of different sizes pinned together in driven / driver pairs fitted the overall gear ratio in the system can be changed. The transposing compound gear pairs mentioned by Finegrain above alter the ratio so that the lead screw moves the carriage in mm (or fractions thereof) per turn of the spindle rather than the standard inches.
Besides fitting the transposing gear it may be necessary to change other gears to get the right ratio for certain threads.
Metric quadrants are an alternative form of banjo usually associated with back gear screw cutting machines which don't have a threading gearbox. Because all the gear ratios have to be built up from loose gears (change wheels) there usually isn't enough space on the single slotted arm of the banjo so alternative forms having two (or more) arms or slotted plates of varying complexity are used. For some obscure reason these are usually called quadrants although they pretty much never are. Metric quadrants are alternative versions with different angles between the arms or slot arrangements to accommodate the transposing gear on lathes whose standard imperial version doesn't have room being made to accommodate only the smaller gears used for common imperial threading. Not something you need to worry about with a Colchester or any other post war designed industrial size lathe although a few smaller gearbox equipped lathes need them e.g. Myford, SouthBend Heavy 10. All rather silly as a metric quadrant always does OK for imperial duties so why make two.
The general term is pretty much always banjo, whatever its shape or position.
Clive
Clausing metric threads
That makes sense. Im just waiting on some more pictures and an email from the seller. Its fifteen below zero here this morning so I might be better off to stay in the shop today. Guess weather never stopped me before.
That makes sense. Im just waiting on some more pictures and an email from the seller. Its fifteen below zero here this morning so I might be better off to stay in the shop today. Guess weather never stopped me before.
As some one thats just cut there first ever gears i can honestly say there easy to make if you cant just buy them. A 40 Tooth is pritty quick, A 127 toother is a lot longer and far more boring affair to cut! Now if i had a dividing head not a rotory table it might have been easyer. The gears have a priity easy life and when you look at it dont have to be made to all that exacting of requirments.
As to leaving the half nuts engaged i have never yet had a chance to cut a pitch of thread that alllowed me to disengage them - or a lathe with diffrent indicator gears. For some reason ever thread i cut has the most obscure pitch known!
As to leaving the half nuts engaged i have never yet had a chance to cut a pitch of thread that alllowed me to disengage them - or a lathe with diffrent indicator gears. For some reason ever thread i cut has the most obscure pitch known!
gradstdnt_99
Hot Rolled
- Joined
- Aug 17, 2004
- Location
- USA, Midwest
On my lathe there is no gear to transpose. I can cut metric and english threads without change gears. Everything is done in the quick change gear box. I figured the metric threads were not spot on but had some level of roundoff error.
davycrocket
Hot Rolled
- Joined
- Jul 10, 2005
- Location
- UK
Metric to English threading
Hi
I have a much used nifty little English made Denford Viceroy lathe with a screwcutting gearbox. It is all metric. As well as the quick change gearbox there is a set of gearwheels, one of which placed at the output of the reversing gear cluster enables a range of tooth pitches, the total range being from 0.25 mm to 6 mm.
I also have the metric to imperial conversion including a different Banjo and a very large wheel with 127/135 teeth which gives very accurate English TPI. The wheel with that large number of teeth has had the DP changed from 16 to 18 to get it into the end cover. There is a replacement 18DP set of the above mentioned gearwheels again giving a wide range of TPI from as low as 4 , and as high as 84.
As others have stated, I can't open the leadscrew nut between cuts or the tool position is lost, never to be found again, and instead, the carriage has to be reversed using the motor.
This works fine, as long as I withdraw the tool right out of the thread because of backlash in the gears. And it's impossible to thread up close to a shoulder though as guessing when to switch of the motor would eventually end up with a tool crash due to the motor/ spindle overun even at the very low speed that one threads at.
Like most machines it apears on www.lathes.co.uk
David C
Hi
I have a much used nifty little English made Denford Viceroy lathe with a screwcutting gearbox. It is all metric. As well as the quick change gearbox there is a set of gearwheels, one of which placed at the output of the reversing gear cluster enables a range of tooth pitches, the total range being from 0.25 mm to 6 mm.
I also have the metric to imperial conversion including a different Banjo and a very large wheel with 127/135 teeth which gives very accurate English TPI. The wheel with that large number of teeth has had the DP changed from 16 to 18 to get it into the end cover. There is a replacement 18DP set of the above mentioned gearwheels again giving a wide range of TPI from as low as 4 , and as high as 84.
As others have stated, I can't open the leadscrew nut between cuts or the tool position is lost, never to be found again, and instead, the carriage has to be reversed using the motor.
This works fine, as long as I withdraw the tool right out of the thread because of backlash in the gears. And it's impossible to thread up close to a shoulder though as guessing when to switch of the motor would eventually end up with a tool crash due to the motor/ spindle overun even at the very low speed that one threads at.
Like most machines it apears on www.lathes.co.uk
David C
Finegrain
Diamond
- Joined
- Sep 6, 2007
- Location
- Seattle, Washington
The transposing gears are in there, I assure you. In fact, you ARE changing gears when you configure metric-from-English or vica-versa. You're just doing it "quickly"
. There may be some pitch errors depending on what transposing ratio your gearcase uses.OK, so there is a way to do it with absolutely no gear switching or shifting -- ELS, or Electronic LeadScrew. Just program whatever you want into a servo motor keyed to a sensor on the spindle. But now we're a bit out-of-the-box, literally and figuratively.
Regards.
Finegrain
Troup
Titanium
- Joined
- Jun 18, 2007
- Location
- New Zealand
I'm completely in agreement with Clive, this setup is definitely the cat's miaow for 'cross-language' threading.
Also available on any machine "having a single tooth clutch arrangement and lead screw reverse control at the apron", which is one definition from years gone by of a Tool Room Lathe.
Available on some tool-room Monarchs, very few American Pacemakers, all tool-room Pratt & Whitneys (speed limited), all (AFAIK) Hendeys & Sidneys (strict speed limit on the latter) & all toolroom Hardinge & clones (NO speed limit), Rivetts & LeBlonds, a few early DSGs, most(?) Lodge and Shipleys (toolroom models), Reed Prentice, some Mori Seiki.
I haven't mentioned speed limits when I don't have specific knowledge but it's a safe bet they are either expressed or implied on any heavy lathe, unless specifically contradicted by the makers. (Even then I'd tread carefully). An inverter added to the drive motor can give you the best of both worlds: slow down only for the start and end (engagement and disengagement of the clutch), speed up for improved surface finish and productivity for the bulk of the distance.
I believe CVA have a single tooth clutch, but not with the control on the apron, nor (what is actually more important) the stop collars which make it possible to thread, at CNC speeds, right up to a shoulder
Thanks to people on this forum from whose collective experience most of this has been drawn. Further O&E welcomed.
j_e_f_f_williams
Plastic
- Joined
- Feb 11, 2011
- Location
- Toronto Area, Canada
Hello,
Just found this thread by searching around for something else. Thought I would just add this for completeness in case someone else comes by the info.
I have a 1960's Colchester Dominion (All english Master) in a 36" bed so they do exist. Still not sure about Clausing selling the same but there are longer bed all engish gear box lathes out there. This one made it here to Canada in the Toronto area. Mine is a round head Mk-I.
TTYL, Jeff
