05-03-2013, 05:53 PM
Hi,
No you are not nuts Lawrence unless I also am. Thanks for giving this project so much thought. Yes a variable pulley clutch would work and like you I considered such a pulley amongst my other options. Unfortunately adding such a clutch would be well outside the scope of the guy in a small home workshop; obtaining such a clutch could prove a major problem and possibly lead to a lot of extra cost. One thing I omitted to add is that this 3 phase motor only has a short shaft not even long enough to fully support the standard stepped pulley which I've reversed on the shaft to bring the 4" diameter pulley over the shaft; I could easily turn an extension bush but I wonder what length of shaft would be required to support a variable pulley? The further away from the motor the drive is the more the motor main bearing is loaded; adding an outboard bearing assembly is possible but given the space problem within the pedestal I would like to keep this Jubilee clutch as simple and cheap as possible. Good idea though Lawrence and we are thinking on the same lines.
Thanks David for adding the pictures of your lathe which is a beauty and I know it gives you much pleasure; Bron and I are happy to display items you have superbly turned on it. You are going back a bit David regarding the Raleigh Ultramatic moped; the only progress from those days has been to introduce gimmicky paint-jobs and lots of plastic; I can't think of anything new in motorcycles apart from electronics which hasn't already been tried and tested years ago. My late father used to own a Mobylette moped and one day he was not at all happy when I arrived home having just bought my Ariel 1.000cc Square Four.
All information is welcome David and is it possible to go "off topic" on this forum? Regarding the modern variable speed lathe burning out its motor or inverter due to heat build up this is very relevant with this Jubilee project and is why I'm wanting to install a mechanical clutch. Standard motors are happiest whilst running at full speed; this allows the motor to be cooled by the fan but once the speed drops but the motor is still giving full power due to fancy electronics you can guess how this affects heat build up? Lathes are constantly subjected to rapid start/stop cycles and although this is bad enough with a 3 phase motor on a single phase motor it can be catastrophic; it's very impressive to blow up a 1.5HP single phase motor due to repeated cycling but also highly expensive as I found out whilst gear cutting.
Where I worked at Book Motors we supplied inverter rated motors and still do but we also supplied FVU's (Forced Vent Units). These units consisted of dedicated motor and fan built into an extend fan cover which directly replaced the original fan cover; this fan then gave correct cooling during low speeds but of course it wasn't a cheap option. also the extra length was added to the motor.
As you will probably know David having a lathe fitted with a remote potentiometer to control the lathe speed from zero to its maximum of around 3,000 revs only encourages knob twiddling; winding the speed up and down using the pot is obviously very convenient but it can also render the lathe scrap if the motor is a special built into the headstock also such a motor/inverter if they fail could cost more than the actual lathe to repair; they certainly are not cheap items.
Thanks Big Al. Your Colchester Chipmaster is a very capable lathe and I know you enjoy owning and using it; at 3HP it will do anything you ask of it and do it well without breaking a sweat. You are right about my Colchester Triumph though; this had a 5HP two speed main motor and even the suds pump motor was rated at 1/2HP. Like your Chipmaster Alan my triumph was also fitted with a multi-plate Matrix clutch; even with the power of the Triumph I once got the clutch smoking whilst turning a big lump of stainless. The drive was transmitted via three "V" belts and in low gear this was not a novices lathe as there was no stopping it.
http://www.lathes.co.uk/colchester/page8.html
I know flat belts can be made to easily slip but the "V" belt on my Jubilee refuses to do so and as access is so very limited I'm having difficulty trying to watch the action of the belt once the motor is tilted; you are right Alan in that these belts can be made to slip but the technique is so far evading me; yes lack of space within the pedestal is causing most of the trouble not only in mounting the motor and getting it to tilt enough but also the belt is enclosed; poking with a stick to see if there is a position where the belt can be made to slip whilst the lathe is under power isn't something I wish to experiment with; had the belt been open then yes I have no problems doing this kind of thing after all aged 15 in the pit I was poking very long flat belts in order to get them back on the pulley and tracking. Novices please do not attempt playing around with a motor under power or you will surely wish you hadn't whilst sitting in A&E.
As you say Alan I could easily obtain information where to attach a remote pot to control the VFD allowing the VFD to be remotely mounted and in part this is what I'm trying to achieve. I want to remotely mount the VFD but not add a pot to control the speed; David has already mentioned the problems of such an arrangement causing overheating; I would be OK with such an arrangement because I'm aware of the overheating problem so would not resort to twiddling the pot every few seconds. The idea is brilliant and it does work but eventually would the motor or inverter (VFD) fail?
One thing I hadn't given much thought to was to how the speed was adjusted on this Jubilee when it left the factory? The motor mounting is a fabricated heavy steel unit solidly mounted to the pedestal using two very big set screws and washers with the motor mounted directly to this making it one solid unit; the mandrel is obviously in a fixed position so how was the speed changed? Forcing the belt to jump steps in the pulley is sure to result in trapped fingers and many of these lathes went into schools?
I've not yet given up on this slipping belt clutch because as Alan says it must be able to be made to work so I need to find out how to do it? Simply lifting/tilting the motor fails as I've now found out but I believe the problem is the belt location once the motor is tilted; the belt must remain in such a position drive still continues even though the belt is very slack; it's highly possible the solution would be to arrange some kind of belt deflection removing the belt away from the revolving driving pulley? I added a video in an earlier post showing a lathe with a slipping "V" belt clutch but there is very little to give away how this has been achieved; I'm stubborn enough to carry on until I solve this because I'm now fully committed to installing a clutch whatever it takes and however long.
Had the weather not been so bad for most of the year I would have enjoyed scrambling around scrap yards in search of raw materials; I'm thinking on the lines of obtaining an assortment of timing pulleys from car engines; with a pair of these installed in the Jubilee I could order a flat timing belt of correct length but how about this for an idea; as the new timing belt will be toothed then why not turn the belt inside out to present the original outer flat section to the pulleys? As the belt will be flat against flat pulleys then surely it can easily be made to slip?
I've also given more thought to the limited amount of motor tilt; at the moment the "T" box fouls the pedestal but it won't if I remotely mount the box running the leads directly into the motor adding a suitable blanking plate? This would allow a lot more tilt but I believe the belt is slack enough even with the limited motor tilt so I need to experiment a bit; as I'm unable to experiment with the lathe this doesn't mean I can't experiment with a dummy set up on the bench using the motor but driving a spare pulley? OK Jubilee do your worst because I'm now on your case.
Out of interest; I keep complaining about my personal black cloud and how the weather dogs my activities; below is a picture of our sunset taken just now as it is setting at 5.30; we are in a black hole and it's been very cold here all day; this morning I took Bron over to Pudsey and it was lovely and sunny so why do I deserve this lousy weather year in year out? Our forecast for today was 10 degrees and sunny once the early fog cleared?
Kind regards, Col.
No you are not nuts Lawrence unless I also am. Thanks for giving this project so much thought. Yes a variable pulley clutch would work and like you I considered such a pulley amongst my other options. Unfortunately adding such a clutch would be well outside the scope of the guy in a small home workshop; obtaining such a clutch could prove a major problem and possibly lead to a lot of extra cost. One thing I omitted to add is that this 3 phase motor only has a short shaft not even long enough to fully support the standard stepped pulley which I've reversed on the shaft to bring the 4" diameter pulley over the shaft; I could easily turn an extension bush but I wonder what length of shaft would be required to support a variable pulley? The further away from the motor the drive is the more the motor main bearing is loaded; adding an outboard bearing assembly is possible but given the space problem within the pedestal I would like to keep this Jubilee clutch as simple and cheap as possible. Good idea though Lawrence and we are thinking on the same lines.
Thanks David for adding the pictures of your lathe which is a beauty and I know it gives you much pleasure; Bron and I are happy to display items you have superbly turned on it. You are going back a bit David regarding the Raleigh Ultramatic moped; the only progress from those days has been to introduce gimmicky paint-jobs and lots of plastic; I can't think of anything new in motorcycles apart from electronics which hasn't already been tried and tested years ago. My late father used to own a Mobylette moped and one day he was not at all happy when I arrived home having just bought my Ariel 1.000cc Square Four.
All information is welcome David and is it possible to go "off topic" on this forum? Regarding the modern variable speed lathe burning out its motor or inverter due to heat build up this is very relevant with this Jubilee project and is why I'm wanting to install a mechanical clutch. Standard motors are happiest whilst running at full speed; this allows the motor to be cooled by the fan but once the speed drops but the motor is still giving full power due to fancy electronics you can guess how this affects heat build up? Lathes are constantly subjected to rapid start/stop cycles and although this is bad enough with a 3 phase motor on a single phase motor it can be catastrophic; it's very impressive to blow up a 1.5HP single phase motor due to repeated cycling but also highly expensive as I found out whilst gear cutting.
Where I worked at Book Motors we supplied inverter rated motors and still do but we also supplied FVU's (Forced Vent Units). These units consisted of dedicated motor and fan built into an extend fan cover which directly replaced the original fan cover; this fan then gave correct cooling during low speeds but of course it wasn't a cheap option. also the extra length was added to the motor.
As you will probably know David having a lathe fitted with a remote potentiometer to control the lathe speed from zero to its maximum of around 3,000 revs only encourages knob twiddling; winding the speed up and down using the pot is obviously very convenient but it can also render the lathe scrap if the motor is a special built into the headstock also such a motor/inverter if they fail could cost more than the actual lathe to repair; they certainly are not cheap items.
Thanks Big Al. Your Colchester Chipmaster is a very capable lathe and I know you enjoy owning and using it; at 3HP it will do anything you ask of it and do it well without breaking a sweat. You are right about my Colchester Triumph though; this had a 5HP two speed main motor and even the suds pump motor was rated at 1/2HP. Like your Chipmaster Alan my triumph was also fitted with a multi-plate Matrix clutch; even with the power of the Triumph I once got the clutch smoking whilst turning a big lump of stainless. The drive was transmitted via three "V" belts and in low gear this was not a novices lathe as there was no stopping it.
http://www.lathes.co.uk/colchester/page8.html
I know flat belts can be made to easily slip but the "V" belt on my Jubilee refuses to do so and as access is so very limited I'm having difficulty trying to watch the action of the belt once the motor is tilted; you are right Alan in that these belts can be made to slip but the technique is so far evading me; yes lack of space within the pedestal is causing most of the trouble not only in mounting the motor and getting it to tilt enough but also the belt is enclosed; poking with a stick to see if there is a position where the belt can be made to slip whilst the lathe is under power isn't something I wish to experiment with; had the belt been open then yes I have no problems doing this kind of thing after all aged 15 in the pit I was poking very long flat belts in order to get them back on the pulley and tracking. Novices please do not attempt playing around with a motor under power or you will surely wish you hadn't whilst sitting in A&E.
As you say Alan I could easily obtain information where to attach a remote pot to control the VFD allowing the VFD to be remotely mounted and in part this is what I'm trying to achieve. I want to remotely mount the VFD but not add a pot to control the speed; David has already mentioned the problems of such an arrangement causing overheating; I would be OK with such an arrangement because I'm aware of the overheating problem so would not resort to twiddling the pot every few seconds. The idea is brilliant and it does work but eventually would the motor or inverter (VFD) fail?
One thing I hadn't given much thought to was to how the speed was adjusted on this Jubilee when it left the factory? The motor mounting is a fabricated heavy steel unit solidly mounted to the pedestal using two very big set screws and washers with the motor mounted directly to this making it one solid unit; the mandrel is obviously in a fixed position so how was the speed changed? Forcing the belt to jump steps in the pulley is sure to result in trapped fingers and many of these lathes went into schools?
I've not yet given up on this slipping belt clutch because as Alan says it must be able to be made to work so I need to find out how to do it? Simply lifting/tilting the motor fails as I've now found out but I believe the problem is the belt location once the motor is tilted; the belt must remain in such a position drive still continues even though the belt is very slack; it's highly possible the solution would be to arrange some kind of belt deflection removing the belt away from the revolving driving pulley? I added a video in an earlier post showing a lathe with a slipping "V" belt clutch but there is very little to give away how this has been achieved; I'm stubborn enough to carry on until I solve this because I'm now fully committed to installing a clutch whatever it takes and however long.
Had the weather not been so bad for most of the year I would have enjoyed scrambling around scrap yards in search of raw materials; I'm thinking on the lines of obtaining an assortment of timing pulleys from car engines; with a pair of these installed in the Jubilee I could order a flat timing belt of correct length but how about this for an idea; as the new timing belt will be toothed then why not turn the belt inside out to present the original outer flat section to the pulleys? As the belt will be flat against flat pulleys then surely it can easily be made to slip?
I've also given more thought to the limited amount of motor tilt; at the moment the "T" box fouls the pedestal but it won't if I remotely mount the box running the leads directly into the motor adding a suitable blanking plate? This would allow a lot more tilt but I believe the belt is slack enough even with the limited motor tilt so I need to experiment a bit; as I'm unable to experiment with the lathe this doesn't mean I can't experiment with a dummy set up on the bench using the motor but driving a spare pulley? OK Jubilee do your worst because I'm now on your case.
Out of interest; I keep complaining about my personal black cloud and how the weather dogs my activities; below is a picture of our sunset taken just now as it is setting at 5.30; we are in a black hole and it's been very cold here all day; this morning I took Bron over to Pudsey and it was lovely and sunny so why do I deserve this lousy weather year in year out? Our forecast for today was 10 degrees and sunny once the early fog cleared?
Kind regards, Col.
Happiness is a wreck of a cabinet to restore.
