11-12-2011, 04:42 PM
Hi,
Yes Alan; it was perishing in the garage yesterday but I get so fed up with this climate that I decided to make a start and sort the frost bite out later.
Oh dear; poor Tim will have an empty wallet for Christmas but with luck Alan you will have access to a belt grinder shortly.
I was back in the garage just after 9 o’clock this morning as I’m now keen to make this belt grinder. I left the car in the garage and worked around it which isn’t my favourite pastime but I didn’t want to pull it out again to give it a soaking. It’s another black hole today but although it was cool in the garage I soon forgot about this and settled down to some serious work.
Tight squeeze in garage.
I already had a plan of action for today as I was awake at 4 am thinking about the job and the plan for today was to make the two alloy belt rollers. The picture shows cutting the roller blanks out using my big Startrite bandsaw. Cutting round stock on such a bandsaw if not done with care can easily result in injury or blade breakage as the blade will grab and rotate anything round possibly dragging fingers into contact. To avoid this I always clamp supports and these can be seen preventing the bar being rotated. I’m glad I didn’t have to cut this with a hacksaw. The blanks measure 2.5” Dia x 2.5” long to allow truing in the lathe.
Cutting blanks using Startrite bandsaw.
It was a tight squeeze at the lathe after moving a bit of kit out of the way. The first blank was chucked in the three jaw and gently tapped until it ran true bringing up the tool bit each time to test until the tool rubbed all the way around. It was faced then centre drilled; a 6.8mm drill bit was then run through followed by an 18mm drill bit. This gives inner shaft clearance once the roller is mounted on its bearings.
Running through with 18mm bit.
Whilst still in the chuck the end was opened out using a boring bar to give a nice friction fit for the 6202Z bearing. With the new bearing recess cleaned up to depth the blank was turned around in the chuck and again faced and opened up for the second 6202Z bearing. A great deal of care is required when the bearing housing is approaching correct size as it is so easy to take just one more cut and end up with a sloppy fitting bearing. I had tried to “crown” the roller to aid belt tracking but it was a hit and miss affair so rather than keep trying and losing metal at each attempt I thought I’d take the longer option and turn a dummy mandrel between centers.
Top roller ready for bearings.
The first part of the mandrel (tailstock end) was turned to a nice sliding fit then it was increased slightly in diameter by a couple of thou and this would allow the blank to be gently knocked on with a hammer and bit of wood to lock it to the mandrel. With the blank now knocked on and locked it was much easier to crown the outer circumference; the top slide was adjusted by trial and error until it removed a taper from zero in the middle of the roller to fifty thou (0.050”) at each end. All the measurements were taken with a digital vernier caliper. The bearings were squeezed into place using the big engineering vice ensuring they went in straight. That took care of the top free running roller (idler).
Crowning top roller mounted on dummy mandrel.
Next job was much easier and this was the second blank that was to be the driven roller (Bottom). Again the blank was set to run true and faced then the hole bored out to 18mm. whilst in the chuck this roller had its bore reamed out to ¾” to suit the drive shaft as it will be the fixed roller. I stopped at this point because I don’t have any ¾” dia bar stock and I need this in order to mount the blank to crown it ensuring concentricity.
I bought the alloy blank ages ago and think it cost £5 cash. This blank has now made two rollers and enough is left to make a pulley if required. These rollers are available but rather expensive and I think mine compare well. Compare prices below.
http://www.beaumontmetalworks.com/
In spite of the gloomy weather once I got stuck in this morning I’ve enjoyed tinkering around today and have something to show for it.
Top roller completed; bottom roller still to crown.
I know a number of members now own engineering lathes whilst others are interested in buying a lathe. I wouldn’t be without either of my lathes. For novices to engineering lathes they will appear strange at first; it’s not just a case of sticking a lump of metal in the chuck or between centers and producing first class work immediately. The simplest turning job requires a bit of forethought and planning but experience is quickly gained with practice. The usual mistake is to remove too much material making an outside diameter too small and an inside diameter too large. My chum David has said it a number of times that putting on a cut of say ten thou (0.010”) doesn’t remove just ten thou it actually removes twenty thou (0.020”). A lathe is the daddy of all machines and a joy to own and use. Today has been good.
Kind regards, Col.
Yes Alan; it was perishing in the garage yesterday but I get so fed up with this climate that I decided to make a start and sort the frost bite out later.
Oh dear; poor Tim will have an empty wallet for Christmas but with luck Alan you will have access to a belt grinder shortly.
I was back in the garage just after 9 o’clock this morning as I’m now keen to make this belt grinder. I left the car in the garage and worked around it which isn’t my favourite pastime but I didn’t want to pull it out again to give it a soaking. It’s another black hole today but although it was cool in the garage I soon forgot about this and settled down to some serious work.
Tight squeeze in garage.
I already had a plan of action for today as I was awake at 4 am thinking about the job and the plan for today was to make the two alloy belt rollers. The picture shows cutting the roller blanks out using my big Startrite bandsaw. Cutting round stock on such a bandsaw if not done with care can easily result in injury or blade breakage as the blade will grab and rotate anything round possibly dragging fingers into contact. To avoid this I always clamp supports and these can be seen preventing the bar being rotated. I’m glad I didn’t have to cut this with a hacksaw. The blanks measure 2.5” Dia x 2.5” long to allow truing in the lathe.
Cutting blanks using Startrite bandsaw.
It was a tight squeeze at the lathe after moving a bit of kit out of the way. The first blank was chucked in the three jaw and gently tapped until it ran true bringing up the tool bit each time to test until the tool rubbed all the way around. It was faced then centre drilled; a 6.8mm drill bit was then run through followed by an 18mm drill bit. This gives inner shaft clearance once the roller is mounted on its bearings.
Running through with 18mm bit.
Whilst still in the chuck the end was opened out using a boring bar to give a nice friction fit for the 6202Z bearing. With the new bearing recess cleaned up to depth the blank was turned around in the chuck and again faced and opened up for the second 6202Z bearing. A great deal of care is required when the bearing housing is approaching correct size as it is so easy to take just one more cut and end up with a sloppy fitting bearing. I had tried to “crown” the roller to aid belt tracking but it was a hit and miss affair so rather than keep trying and losing metal at each attempt I thought I’d take the longer option and turn a dummy mandrel between centers.
Top roller ready for bearings.
The first part of the mandrel (tailstock end) was turned to a nice sliding fit then it was increased slightly in diameter by a couple of thou and this would allow the blank to be gently knocked on with a hammer and bit of wood to lock it to the mandrel. With the blank now knocked on and locked it was much easier to crown the outer circumference; the top slide was adjusted by trial and error until it removed a taper from zero in the middle of the roller to fifty thou (0.050”) at each end. All the measurements were taken with a digital vernier caliper. The bearings were squeezed into place using the big engineering vice ensuring they went in straight. That took care of the top free running roller (idler).
Crowning top roller mounted on dummy mandrel.
Next job was much easier and this was the second blank that was to be the driven roller (Bottom). Again the blank was set to run true and faced then the hole bored out to 18mm. whilst in the chuck this roller had its bore reamed out to ¾” to suit the drive shaft as it will be the fixed roller. I stopped at this point because I don’t have any ¾” dia bar stock and I need this in order to mount the blank to crown it ensuring concentricity.
I bought the alloy blank ages ago and think it cost £5 cash. This blank has now made two rollers and enough is left to make a pulley if required. These rollers are available but rather expensive and I think mine compare well. Compare prices below.
http://www.beaumontmetalworks.com/
In spite of the gloomy weather once I got stuck in this morning I’ve enjoyed tinkering around today and have something to show for it.
Top roller completed; bottom roller still to crown.
I know a number of members now own engineering lathes whilst others are interested in buying a lathe. I wouldn’t be without either of my lathes. For novices to engineering lathes they will appear strange at first; it’s not just a case of sticking a lump of metal in the chuck or between centers and producing first class work immediately. The simplest turning job requires a bit of forethought and planning but experience is quickly gained with practice. The usual mistake is to remove too much material making an outside diameter too small and an inside diameter too large. My chum David has said it a number of times that putting on a cut of say ten thou (0.010”) doesn’t remove just ten thou it actually removes twenty thou (0.020”). A lathe is the daddy of all machines and a joy to own and use. Today has been good.
Kind regards, Col.
Happiness is a wreck of a cabinet to restore.
