06-03-2013, 10:27 AM
Hi,
Many thanks Lawrence regarding mounting the fixed single pulley onto the motor shaft and the variable pulley onto the mandrel. It's interesting kicking ideas around.
I thought the standard variable pulley position would be on the motor shaft and in the case of the Jubilee this would also afford extra length compared to mounting on the mandrel which is limited in length by the two bearing housings; please see picture on post #30.
However the variable drive pulley is mounted it would need to be easily adjustable but as these are spring loaded (?) it brings us back to how to make the belt slip? Yes it would give variable speed and these drives can be very complicated as used in cars making speed changes easy but what I'm trying to achieve is to stop the drive completely whilst leaving the motor at full speed; I can adjust the motor speed from zero to over 11,000 revs using the VFD.
I like your thought pattern though Lawrence as we are clearly both thinking about the options available not only as standard but being modified by us. One thing against the variable pulley in this instance is lack of space; the mandrel looks as though it would accept a much wider pulley but if you inspect the picture (post #30) you will see the pedestal is encroaching onto this space in effect only allowing the width of the stepped pulley.
It would be easier to mount a variable drive pulley onto the motor shaft both because of better access but allowing increased length; the motor would still need to be easily adjustable either by lifting or tilting to allow the belt to either rise or lower on the pulley. I've been looking at the mountings in the links below and I'm surprised just how much distance the motor will need to travel to allow the full speed range if a variable pulley was adopted; this distance on the Jubilee is very limited indeed due to the motor aperture in the pedestal. I could get around the problem of the short motor shaft by simply introducing a counter-shaft.
http://www.speedselector.com/engineering/index.htm
http://www.speedselector.com/products/ad...drives.htm
http://www.comintec.it/Variable-pulleys-...c5_en.aspx
Rather than waste a great deal of time and effort experimenting in the workshop I'll do some research on the web; it's a lot warmer here at the computer than for me to make constant trips between workshop and garage in the cold fog and drizzle.
I know a "V" belt can be made to slip so all I need to do is find out how? Years ago when I had my huge Dominion wood-turning lathe this was powered by a big old fashioned cast iron 2 HP 3 phase motor; power was supplied through a Transwave converter and this set up was horrible; for constant start/stop cycles it was a slow process waiting for speed to come up and this was the reason I ended up selling both my Dominion and Triumph lathes. I installed a long lever attaching this lever to the front of the Dominion head-stock; attached to this lever was a cam which allowed the lever to lift the motor with the cam throwing over center thereby locking the motor in the high position; the lathe was running flat belts so as soon as the motor was lifted it completely broke the drive to the mandrel and as the mandrel was fitted with a very heavy 16" out-board face plate I obtained brake disk pads and installed one of these to the head-stock allowing the pad to bear down hard on the disk thereby giving a very effective brake. So I know for certain if I converted the Jubilee to flat belt and pulleys I could achieve what I'm trying to do.
I also know "V" belts can be made to slip and as I'm working on the Jubilee already set up with "V" belt drive I thought if I could succeed without spending a lot of money my story would be useful to others also wishing to install a clutch onto their lathe?
Keep the ideas coming though Lawrence as all information is useful and I'm sure others will have Ideas I hadn't thought of; these forums are great for exchanging ideas and information.
Kind regards, Col.
Many thanks Lawrence regarding mounting the fixed single pulley onto the motor shaft and the variable pulley onto the mandrel. It's interesting kicking ideas around.
I thought the standard variable pulley position would be on the motor shaft and in the case of the Jubilee this would also afford extra length compared to mounting on the mandrel which is limited in length by the two bearing housings; please see picture on post #30.
However the variable drive pulley is mounted it would need to be easily adjustable but as these are spring loaded (?) it brings us back to how to make the belt slip? Yes it would give variable speed and these drives can be very complicated as used in cars making speed changes easy but what I'm trying to achieve is to stop the drive completely whilst leaving the motor at full speed; I can adjust the motor speed from zero to over 11,000 revs using the VFD.
I like your thought pattern though Lawrence as we are clearly both thinking about the options available not only as standard but being modified by us. One thing against the variable pulley in this instance is lack of space; the mandrel looks as though it would accept a much wider pulley but if you inspect the picture (post #30) you will see the pedestal is encroaching onto this space in effect only allowing the width of the stepped pulley.
It would be easier to mount a variable drive pulley onto the motor shaft both because of better access but allowing increased length; the motor would still need to be easily adjustable either by lifting or tilting to allow the belt to either rise or lower on the pulley. I've been looking at the mountings in the links below and I'm surprised just how much distance the motor will need to travel to allow the full speed range if a variable pulley was adopted; this distance on the Jubilee is very limited indeed due to the motor aperture in the pedestal. I could get around the problem of the short motor shaft by simply introducing a counter-shaft.
http://www.speedselector.com/engineering/index.htm
http://www.speedselector.com/products/ad...drives.htm
http://www.comintec.it/Variable-pulleys-...c5_en.aspx
Rather than waste a great deal of time and effort experimenting in the workshop I'll do some research on the web; it's a lot warmer here at the computer than for me to make constant trips between workshop and garage in the cold fog and drizzle.
I know a "V" belt can be made to slip so all I need to do is find out how? Years ago when I had my huge Dominion wood-turning lathe this was powered by a big old fashioned cast iron 2 HP 3 phase motor; power was supplied through a Transwave converter and this set up was horrible; for constant start/stop cycles it was a slow process waiting for speed to come up and this was the reason I ended up selling both my Dominion and Triumph lathes. I installed a long lever attaching this lever to the front of the Dominion head-stock; attached to this lever was a cam which allowed the lever to lift the motor with the cam throwing over center thereby locking the motor in the high position; the lathe was running flat belts so as soon as the motor was lifted it completely broke the drive to the mandrel and as the mandrel was fitted with a very heavy 16" out-board face plate I obtained brake disk pads and installed one of these to the head-stock allowing the pad to bear down hard on the disk thereby giving a very effective brake. So I know for certain if I converted the Jubilee to flat belt and pulleys I could achieve what I'm trying to do.
I also know "V" belts can be made to slip and as I'm working on the Jubilee already set up with "V" belt drive I thought if I could succeed without spending a lot of money my story would be useful to others also wishing to install a clutch onto their lathe?
Keep the ideas coming though Lawrence as all information is useful and I'm sure others will have Ideas I hadn't thought of; these forums are great for exchanging ideas and information.
Kind regards, Col.
Happiness is a wreck of a cabinet to restore.
