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Member postings for Billy Mills

Here is a list of all the postings Billy Mills has made in our forums. Click on a thread name to jump to the thread.

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Thread: Grinding on the side of the wheel
13/01/2012 21:29:20
Agree with David, I have used diamond wheels for several years on HSS and carbide and am very happy with the performance. I use the wheels to keep sharp tools very sharp, I don't attempt to do heavy metal removal, just maintain edges that are little worn.
 
The use of Brake Dressers is crazy for home workshop use. Like buying a T & C grinder for sharpening small twist drills- totally uneconomic, better to buy new wheels or drills.
 
The diamond wheels that I have bought from the well known suppliers run very nicely as you might expect from the way they are made by CNC machining. In contrast, sintered wheels have to be dressed true because sintering is a much cruder process.
 
I looked at the Childs site. I am a long-term Tormek user which is a slow speed wetstone machine for sharpening steel. I cannot agree with some of his comments about this machine. I am a very happy user of wet stone machines -indeed I now have two set up for different jobs.
 
 
I know a number of Professional woodworkers who use these kind of machines to keep their HSS edges razor sharp, it takes moments to do and the sharpness is way beyond any tool as supplied. The machine is expensive however it has clones that are affordable These machines are designed for side stone grinding, the side is flat and the stone very wide, rotation is about 120 rpm.
 
Billy.
Thread: Laser centreing
13/01/2012 20:55:31
Chris- one further thought. If the laser is mounted off centre and is able to move then you can adjust the circle diameter by changing the spindle speed.
 
Billy.
Thread: To CNC or not to CNC - that is the question.
11/01/2012 21:56:02
I would go with the given advice, start milling - there is quite a bit to learn- and then decide what you want to make in the future. Many people on this forum are set against CNC for various reasons however it is the right tool for many jobs. CNC milling allows you to make complex curved shapes which would be impossible by hand and produces the same item every time.
 
There is quite a bit to learn with any CNC software package, some of which needs milling experience so I would suggest milling first then you are in a much better position to decide what you want in a CNC machine if you feel the need. CNC milling of wood and plastics can be very good too - you are not limited to metal. It can also be very creative at a level objectors don't always understand.
 
One detail already mentioned is that mills sell for not much less than the buying price so even if milling looses it's appeal little is lost on the price of the mill. You will find that cutters, vices, clamps and the other vital bits do add up however you can then make some fantastic things. Years of fun!
 
Billy.
Thread: Grinding on the side of the wheel
10/01/2012 18:29:56
There's a lot to be said for diamond wheels for touching up edges, no chance of any breakage and works great on carbide without the short life and mess from green wheels.

They are also cheap and at no risk from damage in shipment or over tightening and sold by many retailers to our hobby.

Billy.
Thread: Wheel Cuting thin tooth?
08/01/2012 16:14:21
Did you turn off the cutter drive while the cutter was in the last slot before retracting the cutter ? or always retract before turning off. If both then it could be that the cutter is moving the few thou when driven so most slots are cut with a rotating cutter approaching the slot. On the last slot if power is removed after the slot is cut the cutter could move over whilst slowing down and shave the last tooth.
 
It could be something like this because you have proven that the equipment and the operator can produce good wheels.
 
Billy.
08/01/2012 12:37:49
If the three wheel pictures are the latest cut and given that the second has a thin tooth then something is loose or the cutting procedure has changed for the second wheel. It would be good to mark the first notch when cutting the next wheel and the starting position for the index plate. With a cut wheel mounted how much can you turn the wheel- i.e. how much backlash in the pin/plate/mandrel/ wheel system? How much can you move the culler along the spindle axis?
 
It could be that the apparent rotation is in the first cut or the last cut . Not at some other position because that would produce two bad teeth, but it has not happened every time. So the evidence suggests that the plate is good but that some other gremlin sometimes moves stuff at the beginning or end.
 
Billy.
08/01/2012 01:45:53
Changing the diameter of the wheel does NOT alter the angular position of the gaps cut. Imagine having a double sized blank and cutting the 115 gaps, the gaps would look a little lonely but they would be in exactly the same angular relationship as a correct size blank. That is because they are in exactly the same relative angular position as the holes in the plate.
 
That assumes that the cutter has not moved relative to the axis of rotation of the blank however you would think that the cutter would be secure and would not move the same four times running and the rest of the equipment would stay put. If there are loose or slack components you would think that it would have been noticed. Wear or eccentric mounting would not cause the one tooth error, the cut would smoothly vary 1 cycle around the wheel, not all be at one end.
 
 
 
Billy.
07/01/2012 18:42:28
Quick thought, support the plate horizontally above the bench on a jam jar with a torch bulb above so that the light goes through every hole onto the bench to give overlapping circles of light. Is there an irregularity in the overlap somewhere around the circle?
 
 
Billy.
07/01/2012 18:36:29
Richard, we both suspect the same cause. Peter has checked the spacing however I think that despite the checks the first and last holes are out. When you are trying to find the answer to a mystery the simplest most direct tests are often the best- but don't trust assumptions-one of them has let in the error.
 
Out with the verniers and check the hole spacing!
 
Billy.
Thread: Bandsaw blades
07/01/2012 16:12:24
Sitting down Mick ? Around 25,000 psi for a bimetal blade so its that figure divided by the cross sectional area. You can get tension measuring gadgets but most people "twang" the blade by ear. In practice would suggest as tight as you feel comfortable with on your own saw, perhaps around 5mm total deflection in the center over a 100mm distance for a hefty push and pull, that would be kinder to bearings and guides than the full Monty tension in the home workshop. Perhaps only the big machines run anywhere near the blade makers tension.
 
Some larger bandsaws do have tension indicators but some are about as accurate as weather forecasts or politicians. Would advise taking off the tension between sawing sessions as good practice, essential if you have rubber tyres on your wheels ( mainly on woodworking or general use bandsaws).
 
Glad you like the bimetal blades, made the conversion long time back, as you said chalk and cheese.
 
Billy.
Thread: Wheel Cuting thin tooth?
07/01/2012 15:54:24
Although Peter has tested the plate I don't see that it is likely to be anything else. It is interesting that Peter DID NOT use the plate with a rotab, the rotab was used to make the plate then the plate was then used on it's own as a direct index to cut the gear.
 
As Peter has cut four identical gears with one bad tooth it is something very predictable creeping cutters or eccentric mounting would hardly fit, a worn or eccentric pin in the plate would not fit the fault. Relative movement between the cutter and the indexing axis would fit but the same movement four times?
 
Two questions for Peter- did you always start cutting from the same starting hole in the indexing plate? Was the thin tooth always the last tooth?
 
Billy.
06/01/2012 20:24:23
Peter
Did you take 360/115 as the increment between holes then make a table of multiples when making the plate? That could explain the problem as the rounding error would accumulate around the cut gear. The error in the plate would not be that visible until the last tooth is cut.
If the final error was around 1/10 of the spacing we only need a step error of 0.003 degrees per step.
 
Another way is to calculate the individual tooth position as n*360/115, rounding errors should then be well distributed.
 
Billy.
 
Thread: Laser centreing
05/01/2012 01:10:46
Pins work fine for locating centres up close however lasers can be used to check the alignment of all sorts of machines at various distances. The fuzzy spot can be down to excessive brightness and is easily reduced by stopping down or by crossed polarisers.
 
The trick of rotating the pointer turns the fussy blob into a fuzzy ring, the centre of the ring being the true centre of rotation. It is very easy to see the centre. Defects in the beam shape also don't matter with this method.
 
You can greatly improve the sensitivity by using a round or conical target, eg a dead centre in a rotary table or a steel ball. When the cone from the rotating pointer forms a horizontal line around the centre's point then you are on axis. Same works for checking lathe alignment with a tailstock mounted centre along the ways. Nothing expensive needed.
 
There are more accurate methods for detecting the cone of light, the resolution is usually limited by  vibration and other noise which can be averaged out, micron resolution is then attainable.  
 
Billy. 
 
Thanks Chris and Jim for your kind comments. 

Edited By Billy Mills on 05/01/2012 01:22:35

Edited By Billy Mills on 05/01/2012 01:31:16

04/01/2012 17:17:50
Chris,
If you mounted any old laser pointer on a rough old bit of wood with sticky tape stuck in a milling chuck then the circle generated when the machine runs would be perfectly aligned with the axis of rotation, size of circle is adjustable by tilting the laser. No expensive German Precision needed, all done by simple geometry.
 
You don't have to worry about the image shape being less than a perfect circle either because the whole image rotates about the axis of rotation. Expect to see your new laser circle generator for lathes, mills and drills at AP, I'm sure it will be yet another beautifully made object of desire.
 
The trick of rotating the source to define a cone around the axis of rotation can be very handy in setting up all sorts of tools.
 
Billy.
Thread: SS Great Britain
04/01/2012 17:00:31
04/01/2012 17:00:19
Don't forget that there were TWO different engines fitted before the second was removed and the SSGB became the Sailing ship GB. Have also had dinner on board the GB and HMS Warrior which is also very interesting to visit. Both (I think) had steam pressures of around 5psi which is why they were so massive. At least the Warrior engine is original and not a mock up.
 
Billy.
Thread: Bandsaw blades
04/01/2012 16:19:54
Bimetal blades last much longer than the price difference against cheapies, also great in hacksaws. Can't see how you could guarantee a blade against the user doing dumb stuff then blaming the blade. Get the right blade and done with it Mick.
 
Billy. 

Edited By Billy Mills on 04/01/2012 16:20:17

Thread: Yet Another Tangential Tool Holder
01/01/2012 11:48:41
Hi Jim, one of the points about the Brunel Cutter is that it took round toolbits so for home metalworkers (who have the odd broken carbide drill or mill  )  there is now another re-cycling route. The Brunel Cutter is also a lot easier to make as you only need to make round holes for the toolbit.
 
Carbide will last longer but for a tangential tool the re-sharpening is so easy and quick that the extra hardness of carbide can be reserved for tougher materials.
 
One other little point about the round bit is that if you turn the toolbit you have a shear tool with a very easy to change angle!
 
Billy.
Hope everyone has a great New Year.

Edited By Billy Mills on 01/01/2012 11:49:36

31/12/2011 01:17:16
Hi Mark - welcome,
The name is Wimberley, the website is here. I think that there is very little difference between this tool and all of the others given that it all started 200+ years ago. If you have a look back on the Tangential tooling posts there has been quite a bit said about this kind of tooling, most of the "angles" have already been tried.
 
With such a long period between conception and rediscovery it is possible that something has been lost in the years between. Brunel and Maudsley were both brilliant engineers, they were setting out the World's first specialised "production line" so when they did something there is every chance that we can learn something from their methods. In this case it could be the extreme ease of maintaining and changing Brunel Cutters for wood and iron.
 
Billy.
31/12/2011 00:49:52
The interesting bit about the Brunel Cutter is that the toolbit is round. The Appendix article shows a clearance flat ground almost vertical so that the cutting edge is straight, not oval. It might be that the flat lasts longer than the oval. Very simple to do, old drills spring to mind.
 
The Holtzpeffl triangular tool is very much like a parting tool however there is the issue of the length of unsupported blade being longer than a conventional approach however if it cuts as well that could be well worth trying as the cutting forces are along the blade rather than across. The basic tool must have merit, Charles Holtzapeffl was a very clever man and a very experienced lathe maker.
 
Anyway following Brunel and Maudsley's footsteps some 200 years later is interesting. The Block Factory is well described on wikipedia.
 
Billy.
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