17-03-2013, 01:46 PM
Hi,
What fun I'm having with this Jubilee clutch job. I thought it would be very simple to get the belt to slip breaking the drive to the mandrel but it's so far proving impossible and over the last few days I've tried lots of ways.
Having the motor hinged gives lots of belt slack but it still drives even though I've tried to separate the belt from the motor pulley using metal rods as fingers; bearings and even strip metal guides all to no avail; to compound the problem I'm unable to gain easy access or to even see the belt in motion as it is enclosed in the head-stock pedestal. With the belt very slack I can't deflect the belt using wooden battens or screwdrivers talk about stubborn; these "V" belt drives are very efficient; had it been a flat belt drive it would easily stop driving with a slack belt. I've also tried to brake the mandrel whilst the motor was fully tilted but there was no stopping it.
Hinged motor mounting.
I've already gone to considerable trouble in making a decent job of hinging the motor and this worked perfectly giving at least an inch of lift. As an experiment I grasped a spare new "A" belt in my left hand engaging it into a pulley held in my right hand; all I needed to do was to move the pulley an eighth of an inch allowing the pulley to be turned by hand; moving the pulley an inch in the lathe doesn't stop it driving?
It's time I tried something different? Last night this problem kept me awake for hours in bed whilst I was thinking about all kinds of weird and wonderful solutions. I had considered a variable drive pulley and Lawrence also kindly suggested such a pulley in an earlier post but I dismissed the idea because I wanted to break the drive completely not to vary it.
I then started to think about a "split pulley" one that had a fixed cheek and a sliding cheek arranged in such a manner as to allow the cheeks to fully open thereby preventing them grabbing the belt as is currently happening; I believe the problem to be a wedging effect where the two cheeks are pulling the belt in rather than releasing the belt? If the cheeks could be made to open then the wedging effect would disappear or at least I hope it would allowing the belt to run free as it drops to the center of the pulley.
I've just spent a while browsing the web for split pulleys but found nothing so far I would consider suitable. I have however found a fascinating site showing pictures of how a steel "Split pulley" is manufactured ; this isn't the kind of split I had in mind as I wanted a two part pulley but nevertheless it is interesting;
http://www.scag.com/splitsteelpulleys.html
Being tight I tried to use the original stepped pulley but the unwanted steps kept getting in the way so I dug deep and bought a "Taper lock" insert for a cast iron pulley I had in stock. I was taking Bron to a craft shop in Batley so decided to do a detour in the opposite direction to visit Huddersfield Bearings on the outskirts of Huddersfield. I grabbed the pulley from the garage and bought the correct insert costing £5 (Minimum order) then visited the craft store.
In the afternoon I realized my mistake; I had got a pulley the correct diameter with correct insert but I now had a SPZ with the wrong belt size when in fact I needed an SPA; oh dear I need to slow down but nothing lost because I can still use this SPZ pulley on another project.
The day after I visited Huddersfield Bearings once again and this time simply asked for the SPA pulley and insert I needed the cost was very reasonable at just over £12. I had asked for a 75/80mm SPA pulley with a 19mm bore insert; the pulley supplied was 80mm.
For members unfamiliar with pulleys these taper lock pulleys are truly a delight to install. Insert the key into the motor shaft; slide on the pulley with the taper facing outwards; slide on the taper insert; align and install the two grub screws and tighten; job done. To remove the pulley removed the two grub screws and tap the pulley towards the motor to break the taper. I like these pulleys. Just for interest a couple of years ago I wanted a pair of Whale Tufnol head-stock bearings these being very basic with a single shoulder each; I sent details of the single main bearing to Tufnol and was quoted £150 plus VAT for this one bearing which I thought ridiculous ending up turning both bearings in my garage from a Tufnol blank for under £20; by comparison these taper lock pulleys are dirt cheap.
SPA & SPZ pulleys; SPA pulley installed.
I'm still practicing CAD and this morning used Emachineshop CAD to produce a basic drawing of a pulley I have in mind which I could machine in the garage. This pulley has a fixed cheek on a boss but the second cheek is designed to slide on the boss located with a shaft key to prevent it spinning on the boss; a thrust bearing is added and the fixed cheek is given a spacer allowing both cheeks to come together giving the correct belt spacing; I need to do more work on this but I'm thinking on the lines of a car clutch for activation using a forked lever to engage the thrust bearing?
My split pulley design.
I'm also considering turning two new flat pulleys because a flat belt can easily be made to slip so I still have options open to me. To add to the problems the motor shaft is very short but problems have solutions if I dig deep enough.
Short motor shaft.
All I want is to be comfortable to play in the garage but I believe snow is forecast; this climate spoils many of my projects taking a lot of the interest and enjoyment from them. I'll keep having a go at this project and I'm not in a hurry.
Kind regards, Col.
What fun I'm having with this Jubilee clutch job. I thought it would be very simple to get the belt to slip breaking the drive to the mandrel but it's so far proving impossible and over the last few days I've tried lots of ways.
Having the motor hinged gives lots of belt slack but it still drives even though I've tried to separate the belt from the motor pulley using metal rods as fingers; bearings and even strip metal guides all to no avail; to compound the problem I'm unable to gain easy access or to even see the belt in motion as it is enclosed in the head-stock pedestal. With the belt very slack I can't deflect the belt using wooden battens or screwdrivers talk about stubborn; these "V" belt drives are very efficient; had it been a flat belt drive it would easily stop driving with a slack belt. I've also tried to brake the mandrel whilst the motor was fully tilted but there was no stopping it.
Hinged motor mounting.
I've already gone to considerable trouble in making a decent job of hinging the motor and this worked perfectly giving at least an inch of lift. As an experiment I grasped a spare new "A" belt in my left hand engaging it into a pulley held in my right hand; all I needed to do was to move the pulley an eighth of an inch allowing the pulley to be turned by hand; moving the pulley an inch in the lathe doesn't stop it driving?
It's time I tried something different? Last night this problem kept me awake for hours in bed whilst I was thinking about all kinds of weird and wonderful solutions. I had considered a variable drive pulley and Lawrence also kindly suggested such a pulley in an earlier post but I dismissed the idea because I wanted to break the drive completely not to vary it.
I then started to think about a "split pulley" one that had a fixed cheek and a sliding cheek arranged in such a manner as to allow the cheeks to fully open thereby preventing them grabbing the belt as is currently happening; I believe the problem to be a wedging effect where the two cheeks are pulling the belt in rather than releasing the belt? If the cheeks could be made to open then the wedging effect would disappear or at least I hope it would allowing the belt to run free as it drops to the center of the pulley.
I've just spent a while browsing the web for split pulleys but found nothing so far I would consider suitable. I have however found a fascinating site showing pictures of how a steel "Split pulley" is manufactured ; this isn't the kind of split I had in mind as I wanted a two part pulley but nevertheless it is interesting;
http://www.scag.com/splitsteelpulleys.html
Being tight I tried to use the original stepped pulley but the unwanted steps kept getting in the way so I dug deep and bought a "Taper lock" insert for a cast iron pulley I had in stock. I was taking Bron to a craft shop in Batley so decided to do a detour in the opposite direction to visit Huddersfield Bearings on the outskirts of Huddersfield. I grabbed the pulley from the garage and bought the correct insert costing £5 (Minimum order) then visited the craft store.
In the afternoon I realized my mistake; I had got a pulley the correct diameter with correct insert but I now had a SPZ with the wrong belt size when in fact I needed an SPA; oh dear I need to slow down but nothing lost because I can still use this SPZ pulley on another project.
The day after I visited Huddersfield Bearings once again and this time simply asked for the SPA pulley and insert I needed the cost was very reasonable at just over £12. I had asked for a 75/80mm SPA pulley with a 19mm bore insert; the pulley supplied was 80mm.
For members unfamiliar with pulleys these taper lock pulleys are truly a delight to install. Insert the key into the motor shaft; slide on the pulley with the taper facing outwards; slide on the taper insert; align and install the two grub screws and tighten; job done. To remove the pulley removed the two grub screws and tap the pulley towards the motor to break the taper. I like these pulleys. Just for interest a couple of years ago I wanted a pair of Whale Tufnol head-stock bearings these being very basic with a single shoulder each; I sent details of the single main bearing to Tufnol and was quoted £150 plus VAT for this one bearing which I thought ridiculous ending up turning both bearings in my garage from a Tufnol blank for under £20; by comparison these taper lock pulleys are dirt cheap.
SPA & SPZ pulleys; SPA pulley installed.
I'm still practicing CAD and this morning used Emachineshop CAD to produce a basic drawing of a pulley I have in mind which I could machine in the garage. This pulley has a fixed cheek on a boss but the second cheek is designed to slide on the boss located with a shaft key to prevent it spinning on the boss; a thrust bearing is added and the fixed cheek is given a spacer allowing both cheeks to come together giving the correct belt spacing; I need to do more work on this but I'm thinking on the lines of a car clutch for activation using a forked lever to engage the thrust bearing?
My split pulley design.
I'm also considering turning two new flat pulleys because a flat belt can easily be made to slip so I still have options open to me. To add to the problems the motor shaft is very short but problems have solutions if I dig deep enough.
Short motor shaft.
All I want is to be comfortable to play in the garage but I believe snow is forecast; this climate spoils many of my projects taking a lot of the interest and enjoyment from them. I'll keep having a go at this project and I'm not in a hurry.
Kind regards, Col.
Happiness is a wreck of a cabinet to restore.
