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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: Cutting Aluminum Sheet/Plate
19/07/2010 23:47:38
Hi All,
 
Well as Sid has admitted to having a metal bandsaw in another post, it could be that the limited throat  ( his sheets need to be 11"x16")  have stopped that.
 
Would agree that a nice metal cutting bandsaw is a very good and safe way of hacking sheet as the saw holds the work down on the table and you will have the top guide just above the sheet so no exposed blade. But you do need a real Industrial saw to do Sid's job.
 
The jigsaw might struggle a bit with 1/8" Ali- but  worth a try.
 
Like Niloch, don't have an Evolution to hand as I am at home,  but I think the rpm is around 2500.The interesting bit is the tooth config, it appears that the Evolution blade is about  clearance of the cut material and limiting the effective tooth feed. The finish is very good for the small number of cutting tips.
 
If I was Evolution I would want to sell motors with blades.  But  it would be good to know more.
 
Interesting that we all focus on "what power tool", the sheet metal saw is still a good tool  and handy for keeping fit, the wife is now quite good at keeping to the line. But you can run out of metal to cut.
 
 
Regards,
Alan.
Thread: Portable bandsaws - any good?
19/07/2010 22:03:49
Well done Terry!
Perhaps we should start a new movement  for UNpowered tools!  As another near OAP male we do need to keep going to keep going. It is interesting that we now all seem to think of  which power tool we will use rather than consider the whole range of tools.
 
But then if we banned electricity we would not be able to discuss these issues, perhaps an exercise bike with a generator......
 
regards,
Alan
 
PS love the hand held bandsaw, what a great idea! ( for use by others....)
 

Thread: Antivirus
19/07/2010 21:50:47
Denise
The Mac operating system is Unix based. As such it is designed to be networked with all that that implies in terms of security and access levels. It is intrinsically very much more secure than  windows which was never originally designed to be networked. Mac people are normally quite aware of  their situation.
 
You can break into any system that has dumb users who logon as supervisors  and open attatchments without thinking regardless of any AV products. Easy Peasy. Been there with a sysadmin hat on. Currently a windows machine without AV lasts around 30 seconds on b/band before being taken over by someone or other. Some current virii even install a rip off AV product to protect the taken-over machine from further infection. Most spam comes from taken over PC's running windows.
 
You don't have to connect  CAD/CAM machines to the internet. They are best run without  AV  and always offline. AV is always an intrusive set of processes which always costs CPU cycles as well as needing constant updating.  All of our updates are via another online machine, the updates go on a USB stick. Needless to say, if a PC controls a machine tool it should never have  AV  and never go online unless the people concerned really know their stuff and have a good H&S legal fund.
 
As an interesting comparison we have nine Linux PC's running 24/7 without AV and on a very fast fixed IP connection. They have not crashed or been breached once in over 30 machine years.
 
On a more positive note, Hard drives last us around 3-4 years of  24/7 running at present so there are loads of Al castings waiting to be melted down and made into something more interesting. You  do regular backups?
 
Alan.
Thread: Cutting Aluminum Sheet/Plate
19/07/2010 11:05:30
Hi Sid, I would own up to having used a TCT circular saw to cut Ali but the regular blades  designed for wood are far too  fierce- so even a very slow feed rate can be very hairy. Would not recomend at all unless you are very careful, expect large chips flying, full eye protection vital.
 
As Jason has said, a negative rake blade is what is needed,  some triple chip blades are rated for Ali ( they are very good on Perspex and some other 'difficult' plastics too) but there are also some abrasive  blades that are said  to be useable on Ali. The Evolution blade IS fantastic as a cut  almost anything blade and is great on a chop saw however Evolution say that the blade should only be used on their saws- I wonder why?
 
There is always the sheet metal saw- a nice new blade will finish the job  quicker than you will get a new blade and you get a bit off the waistline too.
Regards,
Alan.
Thread: Adjustable v-ledges
15/07/2010 01:36:58
Another way of thinking about the tapered gib is to consider two long thin wedges pointing in opposite directons and held together so that  when the two wedge angles are the same, the outside long faces are parallel. If the wedges are pulled apart the parallel faces are closer, when the wedges are pushed together the parallel faces move apart.
 
One wedge is then the tapered gib, the other wedge is cut into the female dovetail on one side only. So by pushing the wedge into the dovetail the male part can be clamped between parallel sides so that  sideways movement is prevented but the male can slide along the dovetail.
 
The tapered gib is far more rigid than the conventional gib strip because it is supported along the whole inside face of the dovetail, it is also a great deal simpler to adjust. But it is far more demanding to make  because it has to be accuratly made as opposed to the normal gib strip which relies on many screws being adjusted to take out build errors.
 
Tapered gibs are found on some quality lathes and mills, often with a single screw adjustment ( and locking device). Seem to recall a recent project in MEW that used a tapered gib.
Regards,
Alan

Thread: powerfile bands
27/06/2010 23:45:13
Nope it added http:// onto the line, Perhaps it's time to read the instructions!
 
regards,
Alan.
27/06/2010 23:43:01
Sorry Hansrudolf,
Used the chain link  icon then ctrl-v to paste the link but seems to have invisably picked up the http:// as well - probably my fault.
Anyway typing the address takes you there or googling 'sanding belt jointing' will keep you reading for ages. There is a magic tape but it comes from Australia!
 
regards,
Alan.
 
The following is a quick ctrl-c ,ctrl-v   without using the 'link'  but I will have to post it  so here goes.
 
 

Edited By Katy Purvis on 01/06/2015 09:29:29

27/06/2010 16:56:08
Hi All,
All adhesives fail when heated, just a question  of how hot, what adhesive and stress .  I was thinking that Paul would glue a cloth patch over the back so that there would be a good bond area each side of the  join rather than attempting to butt joint the belt.
 
The belt gets a lot of air cooling so I don't think it will be a bonding failure. However this has got to be one of the toughest gluing jobs. Sounds like finding out about the splice it yourself tape is the very best bet. It  might come from an Abrasive Company ( so they might be a bit rough to deal with.)
 
 
Sorry,
Alan.
 
 
 
and lots more
 
 by googling sanding belt jointing.
 
 
 
 
 

Edited By Katy Purvis on 01/06/2015 09:25:33

Edited By Katy Purvis on 01/06/2015 09:45:40

26/06/2010 18:27:20
HI again,
A solid setting glue will not stand the flexure. A rubber based glue might be better- evostick original is the easy to get one. Would go for  the original -rubber in solvents- not the latest water based glue. After you have let it dry then clamped the joint let it cure for  days before you do the destruct test.
 
There are some very specialised industrial adhesive suppliers that you might Google up, I used to deal with a Company  in Hemel Hempstead that  had give away reel ends of fancy cloth based tapes. The 3M website might give a clue,  they have some very strong industrial tapes and transfer adhesives.
 
 
regards,
Alan.
26/06/2010 15:35:21
Hi All,
Yep I'm a beltsander fan as well. The B & D powerfile is very handy for all sorts of  'adjustments' and clean ups. It is very good on wood too for mortices, lock fitting and door hanging when you encounter the difference between approximate dimensions and reality while holding up a kitchen unit.
 
There was a narrower belt  accesory  which was a replacement arm and roller to run about half width belts.
 
Makita make a 1" wide handheld beltsander  9030 which is a seriously useful- more industrial tool- and has a good range of belt grits available.
 
I have never had a belt come apart on the B&D or Makita machine although have worn many out. As well as the direction it would be worth checking that the rubbing block has a slight chamfer- not a sharp edge- where the belt starts to rub  the block.  Have had the block fall off the Powerfile. ( The Makita has a steel ski shaped strip to support the inside of the belt- it seems to last forever)
 
If the belt tension was very high then the belts would not last too long, The only other cause might be if the belts had been stored at a high temp or in sunlight  that could weaken the bond or if the belts were very old. Think that the Powerfile has been around for well over 30 years- could be 40+  
 
One last thought, when the grits get a little smooth it is tempting to apply too much pressure, better to change the belt and save the smoothie for  de-rusting.
 
Regards,
Alan.
 
Thread: Myford alternative
25/06/2010 16:58:11
Mark,
The 'Lathe buying advice' on www.lathes.co.uk is very sound. The site is filled with useful information about  mills,  lathes and other machines and is an invaluable reference for old but excellent machines. There are also some great machining tips.
 
Kwil's recomendation of a M250/300 is wise, I would add one of the more recent Colchesters. Once you get your hands on a Great British Lathe, smell the oil and metal, make the stuff that is too big for the imports and just enjoy every moment of it all then you will understand what machining should be. You can then look forward to an afterlife in  which you have your very own-just run in - DS&G and an infinite personal metal storeroom.
 
Even if you don't find the right machine straight away,  get hold of something and enjoy your turning. You really need to find out what you need in a lathe by turning the stuff you want  to make. Only then can you appreciate your real needs. Tools are personal.
 
regards,
Alan.
Thread: mock up materials
24/06/2010 22:12:35
David,
Why not use MDF? it is readily available in sheet from 3mm up, easy to cut and glue into any size block you want. You can saw, turn, bandsaw, drill, tap,mill and sand the stuff. If a bit does not work make another for pennies.  You can also shape it by sanding or carving when the model is assembled. But do wear a dust mask.
 
I have used lots of the stuff over the years for all sorts of lash-ups and jigs. It is often a good stand in for test foam for CNC checks and is free of the grain issues with real wood or ply and tends to be quite stable. It is very useful for vac form moulds too.
 
Regards,
Alan
 
 
Thread: Countersinking - guidance please...?
24/06/2010 21:30:52
One good use for the cone and hole type is in countersinking thin sheet- especially in thin soft materials. Because the hole type cuts with very low feed pressure you don't get  a dome on the back side of the sheet.
 
Like others, I'm a convert to the single hole countersink. The cut is always chatter free, you can use higher speeds and de-burring could not be neater. This is a tool that seems to convert most users.
Regards,
Alan.
Thread: mock up materials
24/06/2010 17:02:33
Sam
Perhaps you have made an error in recommending the plastic burn test on this forum which is open to all. If you are not experienced in the test then you will not understand the smell and it's implications. If you know about the method then you don't need to be told about it.
 
There are many common materials such as PVC and PTFE that should NEVER be burnt by untrained people. Both plastics produce deadly gasses. Simplistic chemistry  is very dangerous,  Carbon and Nitrogen are  common elements in plastics , one compound produced by burning is cyanide. Chlorine containing plastics like PVC will produce HCl which will -when breathed in- produce hydrochloric acid inside your lungs.There are many other very dangerous compounds formed by low temp burning in air.
 
I would advise that -unless you really have the experience to understand sample burning- you NEV ER attempt this very dangerous process but get your materials from reliable sources.
 
Back  to the thread, hardwoods do thread but the grain limits the load. The real question is what do you want to do with the model? If it is a visual mock up then foamed polystyrene plastered and sanded is dirt cheap  and will allow clearances and form to be seen.
 
 Foam board and card are also easy, cheap and quick for a non working model.
 
Unless plastic or ali is scrap it might cost as much as the finished model but it would be approaching the stiffness of the final product , is that what you want?
 
 
regards,
Alan.
Thread: Highly sought-after Aciera F1 and Sixis mini-mill
22/06/2010 13:18:37
The F1 is a very small mill, it is intended for watch and instrument work and will often be used with magnifiers or a sterio microscope. So the levers are a good way to operate the slides whilst looking at the workpiece.  If the table is used with stops and jigs then small batch production of very small parts becomes easy.
 
The vertical motion can be compensated to ease the load on the vertical lever. It is as simple as that. The compensator is like a large clock spring in a drum, the wire rope is on the outside of the drum so the rotation of the hellical spring is smal so the rope tension is fairly constant an set to partially cancel the mass of the table and slide ( which is VERY heavy) 
 
I think that the real design lesson is not the compensator but the whole machine and it's milling performance. The Aceira's /Deckel/ other euro mills leave everything else in the shade due to the exceptional stiffness of the design, that is why they are so sought after.
Lates.co.uk has good articles on Aciera and Deckel mills.
Regards,
Alan.

18/06/2010 21:38:08
Hi Steve,
You can find a F1 manual at :-http://dl.free.fr/updbry0WB  . This is a 140M pdf so not for slow connections. The compensator is  described between p26-30 under " compensation de la coulisse verticale". Although Aceira manuals are always French German and English the English text has been removed- well it is a French site.
 
Like everything else Aceira the compensator is very simple, a spring, drum and wire rope inside the machine. The F1 is a very small mill for miniature work on  watch or instrument parts so the feed forces are very small. The F1 has the built in  option of using levers as "sensitive feeds" so the table mass can be partially compensated to reduce the apparent force needed on the levers.
 
On a larger mill this arrangement would be unworkable, the mass of the table of an F3 - or any other medium sized mill with a  moving table- is huge compaired with the F1.  The mass increases as the cube of the linear dimensions so a tripled table weighs 27 times more.
 
 The vertical leadscrew on the F3 works just fine as it is, there is NO backlash with the table mass pre-load and it is easy to wind the table up and down.
 
regards,
Alan.
Thread: Tachometer design
19/01/2010 20:44:15
HI Gentlemen.
 
Have you considered the LM392? this has a comparitor and op-amp in an 8 pin pack. Many moons ago I used the pack as a Variable Reluctance transducer conditioner. The scheme is to use the opamp as a limiter in front of the schmidt comparitor. With mid level biasing through both amps and negative feedback from the schmidt to bias the op-amp you have very clean schmidt action action at almost the zero crosssing points.
 
The schmidt + preamp combo is exactly the same concept in most scope "Auto Trigger"circuits, with no input it will output a low frequency squarewave. But with the faintest sniff it will quickly produce a nice 1:1 squarewave.  A transistor driven from the schmidt could light a led, with the led flashing slowly there is no input, at half brilliance things are normal.
 
Commercial VR transducers normally have high inductance- many turns- and are often intended to work into a resistive load, above the XL=R frequency, the 6dB/octave rise is countered by the low pass action so the output is almost constant above the crossover RPM.
 
Finally, if Henry Maudsley, John Harrison, Charles Babbage, Armstrong or Whitworth had electronic devices available then they would have used them to great effect. Engineering is about making better machines using whatever methods are available, if it is hydraulic, ropes or chains,steam,gas, sea waves, nuclear or  electrons it is still engineering and of interest to those who love engineering. 
 
 
Thread: Workshop Heating
13/01/2010 23:58:50
Now is a good time to buy insulation cheap, B & Q are selling three rolls of  insulation for £5.00. May not be around many more days though!
 
regards,
Alan.
Thread: What type of oil to use on a Milling machine
13/01/2010 23:51:42
Hi,
Low power heating to reduce corrosion has been around for a long time. A device called a Damp Chaser was fitted ( about 50 years ago) inside some electronic gear to keep the air temp up slightly to reduce condensation. It was about 20 Watts dissipation.
 
Some people use lightbulbs as heaters. Two mains bulbs in series will last almost forever and are easy to source. A good idea for handtools is to keep the tools inside a wooden box with  such a heater, the temp rise will be small but the air inside will be "dry".
 
 Obviously, the heater is most effective when warming a small amount of air that cannot move so an insulated enclosure is good. For a lathe, a cloth  cover will reduce the airflow compared with a naked machine so the air in contact with the metal will be a little warmer than ambient so is less likely to drop the water as condensation.
 
It is worth noting that the average humidity in the UK is about 50% because you can't get more than 70 miles from the sea. When the temp falls air cannot "hold" so much water so the excess falls out as condensation on cold surfaces.
 
If you need to "lay up" a machine to over winter,  grease will be better than oil.
 
 
regards,
 
Alan Gray.
 
 
 
 
 
 
 
Thread: Microscope objective thread
05/01/2010 21:19:15
Hi John and Gang.
Hold an etched rule against the thread then imprint the thread and rule marks onto a lump of plastecene/ staysoft/clay/whathaveyou then count the threads against the scale using the microscope. Any distortion in the media is common to the rule and thread marks so won't matter.
 
OK it's late but Happy New Year anyway.
Alan.
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