16-06-2012, 07:49 PM
Hi,
Thanks Lawrence. Your story sounds rational enough to me and why can't the weather behave rationally.
As it keeps pouring with rain I might as well settle down and add the details of how I made the set of knobs for the desk.
I'm sure David will agree that these small turning jobs give a great deal of personal satisfaction. They are not up to David's gallery standard but pleasing enough to grace the desk with.
Working with lots of small bits of timber can become tiresome so the best way if possible is to do the job in stages performing one operation at a time. An off-cut of oak was selected it being 1.250” thick and just large enough to yield the seven blanks required. I didn't expect to make a mistake so didn't cut extra blanks.
The oak was accurately marked in pencil to give the cutting lines and drilling points. 50mm x 6mm countersunk set screws were to be used. First job was to through drill at tapping size; I don't know the size because I find it easy to select a drill bit by using a nut; 6mm nut in this case as a guide; a drill bit that goes through the nut without play is OK. Counter-boring followed giving a recess to accept the screw head. The oak was then mounted in the big engineering vice and a 6mm second (intermediate) tap run through each hole.
Counter boring and tapping.
The blanks were then cut out on the Startrite band saw and a screw run into each using my Bosch drill but leaving the screw head protruding with some thread showing; a touch of wood glue was added then the screw was run home. Screwing in seven 2” long set screws using a screwdriver would take forever but by using the drill the job was completed quickly.
Screw glued in.
The Jacobs chuck was knocked out of the big drill and then knocked into the Record Power DML 24” headstock this being a 1 Morse taper. I had previously made a new short tool rest but never used it so now was the chance to try it out and it was fitted and adjusted to the blank; the blank was nipped into the chuck by its screw and the blank was hand turned to ensure it didn't foul. I've owned this lathe for over 20 years but don't know it's speed range. Normally I never bother adjusting speed just leaving it at middle.
Blanks ready to turn.
With everything set up and secured the lathe was set in motion but not for long. The lathe is near the garage doors away from the strip lights and as I constantly work in a black hole I couldn't see what I was poking the gouge at so not wanting to lose my front teeth I thought it prudent to improve the lighting. Ideally I would have liked to do this by moving to the Bahamas but had to settle with rigging up a test lamp leaving a trailing cable.
Method of chucking.
I've seldom turned oak and this oak was very tough splintering as it was turned. A trip to the grinder improved things a great deal and by dinner time I had produced a single knob. Most of the time had been spent setting everything up as I don't use the lathe often and it had become buried in junk; the buckets and compressor also needed moving from beneath it. It would appear an easy task to turn a wooden knob but with the blank revolving at speed what design do I want as I hadn't settled on anything special only that it must have a matching Formica disc to its front so I played around with various shapes until it looked right. Adding burnt ring decoration is extremely easy but highly dangerous as a novice turner could lose a finger or two in less than a blink of an eye so I'd better explain how to do the job safely.
Please have a look at the picture of the wire in place over the knob. Observe one end is secured around the lathe bed bar but allowed to slide for positioning. The other end is firmly secured into a short wooden handle. At no point and I stress this at no point must the wire ever be wrapped around fingers or it will be sooner rather than later the fingers are neatly and quickly removed. If accurately spaced rings are to be burned then a touch with the point of a skew chisel will help the wire settle. It only takes a shallow nick with the skew so no fear of a monstrous dig in. The lathe is set in motion and the wire brought up and over the revolving work carefully bringing it into contact ensuring it is aligned or a pretty screw thread will appear as the wire runs to one side or the other. Practice on a bit of scrap first to get the hang of the technique. Once contact is made keep pulling the wire downwards to engage more length around the work this will set up more friction resulting in a lot of smoke and one very hot wire. I find the smell of wire burning to be most pleasant and it lingers for a while. Once the burnt ring has been added then very carefully park the wire where it cannot be caught and turn the lathe off. I simply drop the wire and handle behind the headstock out of harms way but be careful as the wire glows red hot whilst burning and can inflict a similar burn onto skin. It is important that the wire is not allowed to become caught up by anything revolving such as a chuck or face plate as it could inflict serious injury. Once the technique is grasped the burnt rings look very effective and add a nice bit of decoration at no cost. Don't overdo the number of rings or the effect will be lessened. I'm happy to add details of wire burning but don't want anyone to get injured.
Wire burning.
After adding the burnt rings then the knob was sanded to 240 grit and burnished with a wooden stick whilst in motion. Sanding sealer was added by cloth and followed shortly with wax with the lathe in motion.
Nice knob fully finished.
One decision I found difficult to make was how many knobs to make; one knob centrally mounted per drawer or two? I wondered if a row of six drawer knobs would make the desk top resemble an organ but then a single knob per drawer might look a bit odd? I'm now happy I decided to go two knobs per drawer as they appear more balanced.
In the afternoon the other six knobs were turned with great care and patience; they are not perfect but in a way this adds to their charm as they are each hand turned and not spit out by an automatic lathe. I did try to get them pretty near to each other but it wasn't easy as the style chosen was not the best for rapid cloning by hand.
Near enough alike.
Cutting out the Formica discs was a test of my patience. The recesses in the knobs were quite near regarding diameter to each other but a digital vernier calliper was used in conjunction with a pair of compasses to accurately determine the disc size for each knob. Masking tape was added to the Formica face and the first circle was drawn. I wasn't at all happy having my fingers so near a big band saw blade whilst cutting to the line. A zero clearance throat plate had been added to the saw. With the rough disc cut out then it was brought to size on the grinder. After doing two such discs I decided I wasn't happy using the band saw. After a bit of thought I ended up using the big tin snips which cut the Formica very cleanly leaving little tidying up on the grindstone. These discs are not perfect but once again the doom and gloom made the work difficult. Had my engineering lathe been running I could have made a single point fly cutter to produce perfectly accurate discs but I had to make do and compromise which goes against the grain with me.
Evostik impact adhesive was used to secure the discs; I thought positioning might be a major problem because this adhesive grabs and doesn't let go but the discs dropped into place with no trouble whatsoever being pressed home with thumb pressure.
Knob in place.
The knobs are 1.250” deep and 1.250” maximum diameter. At first I thought they appeared a bit too deep but now I'm happy with them. The knobs cost nothing other than my time and they were turned for this desk rather than buying in a set of mass produced knobs. A small finishing touch but well worth it and I gained a lot of satisfaction out of turning them. If I spent as much time as David on the lathe then I would add better lighting and buy decent chucks; the length of the Jacobs chuck combined with the length of the blank gave rise to chattering with a bit of chipping out; this chipping out isn't serious but to me could have been prevented by better mounting. After turning the first three knobs I adjusted the drive belt to give top speed something in the region of 3,000 revs; this gave a cleaner cut and heated up the burning wire more hence the slightly darker rings on some knobs. It's all trial and error but most enjoyable.
Roll on summer.
Kind regards, Col.
Thanks Lawrence. Your story sounds rational enough to me and why can't the weather behave rationally.
As it keeps pouring with rain I might as well settle down and add the details of how I made the set of knobs for the desk.
I'm sure David will agree that these small turning jobs give a great deal of personal satisfaction. They are not up to David's gallery standard but pleasing enough to grace the desk with.
Working with lots of small bits of timber can become tiresome so the best way if possible is to do the job in stages performing one operation at a time. An off-cut of oak was selected it being 1.250” thick and just large enough to yield the seven blanks required. I didn't expect to make a mistake so didn't cut extra blanks.
The oak was accurately marked in pencil to give the cutting lines and drilling points. 50mm x 6mm countersunk set screws were to be used. First job was to through drill at tapping size; I don't know the size because I find it easy to select a drill bit by using a nut; 6mm nut in this case as a guide; a drill bit that goes through the nut without play is OK. Counter-boring followed giving a recess to accept the screw head. The oak was then mounted in the big engineering vice and a 6mm second (intermediate) tap run through each hole.
Counter boring and tapping.
The blanks were then cut out on the Startrite band saw and a screw run into each using my Bosch drill but leaving the screw head protruding with some thread showing; a touch of wood glue was added then the screw was run home. Screwing in seven 2” long set screws using a screwdriver would take forever but by using the drill the job was completed quickly.
Screw glued in.
The Jacobs chuck was knocked out of the big drill and then knocked into the Record Power DML 24” headstock this being a 1 Morse taper. I had previously made a new short tool rest but never used it so now was the chance to try it out and it was fitted and adjusted to the blank; the blank was nipped into the chuck by its screw and the blank was hand turned to ensure it didn't foul. I've owned this lathe for over 20 years but don't know it's speed range. Normally I never bother adjusting speed just leaving it at middle.
Blanks ready to turn.
With everything set up and secured the lathe was set in motion but not for long. The lathe is near the garage doors away from the strip lights and as I constantly work in a black hole I couldn't see what I was poking the gouge at so not wanting to lose my front teeth I thought it prudent to improve the lighting. Ideally I would have liked to do this by moving to the Bahamas but had to settle with rigging up a test lamp leaving a trailing cable.
Method of chucking.
I've seldom turned oak and this oak was very tough splintering as it was turned. A trip to the grinder improved things a great deal and by dinner time I had produced a single knob. Most of the time had been spent setting everything up as I don't use the lathe often and it had become buried in junk; the buckets and compressor also needed moving from beneath it. It would appear an easy task to turn a wooden knob but with the blank revolving at speed what design do I want as I hadn't settled on anything special only that it must have a matching Formica disc to its front so I played around with various shapes until it looked right. Adding burnt ring decoration is extremely easy but highly dangerous as a novice turner could lose a finger or two in less than a blink of an eye so I'd better explain how to do the job safely.
Please have a look at the picture of the wire in place over the knob. Observe one end is secured around the lathe bed bar but allowed to slide for positioning. The other end is firmly secured into a short wooden handle. At no point and I stress this at no point must the wire ever be wrapped around fingers or it will be sooner rather than later the fingers are neatly and quickly removed. If accurately spaced rings are to be burned then a touch with the point of a skew chisel will help the wire settle. It only takes a shallow nick with the skew so no fear of a monstrous dig in. The lathe is set in motion and the wire brought up and over the revolving work carefully bringing it into contact ensuring it is aligned or a pretty screw thread will appear as the wire runs to one side or the other. Practice on a bit of scrap first to get the hang of the technique. Once contact is made keep pulling the wire downwards to engage more length around the work this will set up more friction resulting in a lot of smoke and one very hot wire. I find the smell of wire burning to be most pleasant and it lingers for a while. Once the burnt ring has been added then very carefully park the wire where it cannot be caught and turn the lathe off. I simply drop the wire and handle behind the headstock out of harms way but be careful as the wire glows red hot whilst burning and can inflict a similar burn onto skin. It is important that the wire is not allowed to become caught up by anything revolving such as a chuck or face plate as it could inflict serious injury. Once the technique is grasped the burnt rings look very effective and add a nice bit of decoration at no cost. Don't overdo the number of rings or the effect will be lessened. I'm happy to add details of wire burning but don't want anyone to get injured.
Wire burning.
After adding the burnt rings then the knob was sanded to 240 grit and burnished with a wooden stick whilst in motion. Sanding sealer was added by cloth and followed shortly with wax with the lathe in motion.
Nice knob fully finished.
One decision I found difficult to make was how many knobs to make; one knob centrally mounted per drawer or two? I wondered if a row of six drawer knobs would make the desk top resemble an organ but then a single knob per drawer might look a bit odd? I'm now happy I decided to go two knobs per drawer as they appear more balanced.
In the afternoon the other six knobs were turned with great care and patience; they are not perfect but in a way this adds to their charm as they are each hand turned and not spit out by an automatic lathe. I did try to get them pretty near to each other but it wasn't easy as the style chosen was not the best for rapid cloning by hand.
Near enough alike.
Cutting out the Formica discs was a test of my patience. The recesses in the knobs were quite near regarding diameter to each other but a digital vernier calliper was used in conjunction with a pair of compasses to accurately determine the disc size for each knob. Masking tape was added to the Formica face and the first circle was drawn. I wasn't at all happy having my fingers so near a big band saw blade whilst cutting to the line. A zero clearance throat plate had been added to the saw. With the rough disc cut out then it was brought to size on the grinder. After doing two such discs I decided I wasn't happy using the band saw. After a bit of thought I ended up using the big tin snips which cut the Formica very cleanly leaving little tidying up on the grindstone. These discs are not perfect but once again the doom and gloom made the work difficult. Had my engineering lathe been running I could have made a single point fly cutter to produce perfectly accurate discs but I had to make do and compromise which goes against the grain with me.
Evostik impact adhesive was used to secure the discs; I thought positioning might be a major problem because this adhesive grabs and doesn't let go but the discs dropped into place with no trouble whatsoever being pressed home with thumb pressure.
Knob in place.
The knobs are 1.250” deep and 1.250” maximum diameter. At first I thought they appeared a bit too deep but now I'm happy with them. The knobs cost nothing other than my time and they were turned for this desk rather than buying in a set of mass produced knobs. A small finishing touch but well worth it and I gained a lot of satisfaction out of turning them. If I spent as much time as David on the lathe then I would add better lighting and buy decent chucks; the length of the Jacobs chuck combined with the length of the blank gave rise to chattering with a bit of chipping out; this chipping out isn't serious but to me could have been prevented by better mounting. After turning the first three knobs I adjusted the drive belt to give top speed something in the region of 3,000 revs; this gave a cleaner cut and heated up the burning wire more hence the slightly darker rings on some knobs. It's all trial and error but most enjoyable.
Roll on summer.
Kind regards, Col.
Happiness is a wreck of a cabinet to restore.
