Here is a list of all the postings Nigel McBurney 1 has made in our forums. Click on a thread name to jump to the thread.
|Thread: Slitting saw|
|Hi slitting saws do have clearance,they are slightly hollow ground,do not use driving keys or pegs better a slip than a shattered saw, coarse tooth saws cut better and tend to cut straighter,when I was an instrument maker usual practice on slitting brass tubes was to apply tallow as a lubricant,watch out on thick tubes,internal stress can cause the tube to spring shut and pinch the saw at end of cut,when doing one offs always hand feed ,power feeds should be left to production jobs.|
|Thread: Logging on & post failures|
|Hi thanks Chris I tried it and it worked but not really not what I expect on me website, this time I deliberately logged on just before i answered but it still logged me out before I finished, Who ever runs this site please fix it,|
|Thread: Jones & Shipman Surface Grinder|
Hi I have a 540 very good machine well liked by toolmakers and trade shops,hydrauics usual problem is dirty or choked filter in oil tank,the hydraulics do not look to be very complicated,one problem can be air in system after machine left standing ,remedy is to let table operate over full travel for a few minutes ,this is recomended in the handbook.Golden rule with grinders do not strip any part unless it is essential,as it is all too easy to get particles of grit in the works.If you hand feed the table
the slide ways have to be lubricated with oil can as during normal operation there is a bleed off the hydraulics to lubricate the bed ways,under the table there are two pockets which catch oil that drips from the slides,clean these out as they attract airborne grit and can turn the oil in the pockets into a grinding paste and damage the slides.wheel nuts are left hand.A j and s service engineer once told me that lubrication nipple for the cross feed slide hand wheel must not be greased ,it must be oiled,very commom problem cross feed stiff,usual cause filled with grease. The automatic feed has been found to be assembled incorrectly,which can cause the feed too operate when the table reaches one end of its travel,it should operate when the table reaches either end.hope info is of help.
|Thread: Tap Magic|
|Hi trefolex is good for most tapping,its very similar to the old method of using a mix of sulphur and tallow which was common during my apprenticeship 50 years ago , for very small taps the Rocol rtd paste is very good probably better than the liquid RTD. I do as I was taught ,when using 10 BA taps a drop of spit works wonders. when tapping cast iron the old method was to use plain tallow.|
|Thread: bonded crankshaft|
|Hi Best way for small i/c cranks is machine from solid in free cutting en8. I have seen two made for the model gardner in en24 they are superb. I have made a replacement crank for a full size 1 hp replica engine,I shrunk fit the webs but found that unless there is a fair amount of metal around the bored hole the effect of the fit is reduced as the metal in the web stretches,i also secured with large taper pins ,parallel pin will work loose. Ic engines particularly slow speed singles have lots of torque and the crank has to be sound,A friend repaired a crank for a 1920s 5hp engine,he bored the web of crank,press fitted a new shaft and then welded around the web,its about 4.5inch stroke with 33inch flywheel,after some running the weld parted and the press fit loosened. Hit and miss engines put more strain on a crank than a more evenly firing throttle governed engines.|
|Thread: stuart s50 build|
|Hi there are lots of ways to do any job,but on model engineering size equipment and very often on full size m/cs as well ,invariably the best results in boring castings are obtained by rotating the work with stationary tools provided the work is balanced,also I have read in the above posts and in ME recently the use of soluble oil on cast iron, recomended practice since engineering began is to cut dry,the carbon/graphite in the iron acts as a lubricant,if you find that the life of the tool is improved by coolant then you are cutting the material too fast ,80 ft per minute surface is correct,in over 50 years in the business I have only seen cast iron machined using soluble once and this was on a very high tech fully automatic machining line ,totally computer controlled to machine a range of castings,and when asked why use soluble the answer was swarf removal,it was the only way they found at the time to get rid of the swarf as there were no operators involved in the operations. Cast iron swarf mixed with soluble will rust solid very quickly,ok you may keep the machine clean but it will get under the lathe saddle and other inaccesable places. .when I was apprenticed most of our work on centre lathes was cast iron or non ferrous and none of them were fitted with soluble pumps,this was deliberate ,so there was no mixing of swarf and soluble. I f problems occur when reaming cast iron then tallow was applied to the reamer.|
|Thread: Brown & Sharpe Machine?|
|Brown and sharp were one of the best known American manufacturers of first class machine tools,they invented the horizontal mill/universal mill as we know it around 1870,principally to produce twist drills by spirall milling they were also the principle developer of the cylindrical grinder,the turret or screw automatic lathes plus the whole range of precision hand tools, they had for a time a factory in Plymouth Devon.They published a number of very good handbooks including''A practical treatise on milling" 'a treatise on gearcutting' and instigated the tables used for setting up dividing heads for spiral milling still in use today,their machine tools were known in the uk well before lend lease,i have uk catalogue dated 1924|
|Thread: Milling cutters with screwed shanks|
|Hi Agree with above, the thread is 20 tpi for all diameters,The thread on the cutter was part of Clarksons patent and if a cutter was ordered from a say a specialist cutter manufacturer and the Clarkson thread was specified on the drawing a royalty had to be paid to Clarksons for every cutter which I think was one shilling.( in approx 1960) My employer told me that until the Clarkson holder was invented there were lots of methods of retaining cutters in milling spindles but the main problem was getting them out after use,they usally jammed tight,the Clarkson scheme made the release a lot easier,plus cutters were prevented winding down into the work by the thread. The more recent use of multi slotted collets was brought about by the need to grip plain shank solid carbide cutters.|
|Thread: Microscope objective thread|
|HI objective thread is 36 TPI Whit form, dias were given in decimal imperial But its 40 years since I worked as an instrument maker and I cannot remember the exact dias,Most instrument making was make to a good fit rather than precise dimensions,but the objective threads were always made to gauge as they had to be interchangeable.|
|Thread: Brass Shell Case|
|Hi Do not attempt to machine it,when I worked as an instrument maker ,telescope tube was always sawn using fine tooth slitting saws in a saw table mounted on an instrument lathe. Then mounted on an expanding mandrel ,the ends faced and then threaded by chasing for the optic mounts,I personally would finish it with a file,use a new one on brass.if a steady is attemted then fill the inside of the tube with wood or plaster of paris or it will collapse and wreck the steady.|
|Thread: Back plates for Harrison lathe|
|I have used in the past a company called ROTAGRIP lodge rd ,Hockley ,Birmingham,I assume they are still business,so many firms are disappearing.They supplied me with chucks and backplates for my colchester master,the chucks are eastern european and are quite good ,apparently there are currently no chucks made in the uk.The fitting is usually designated L0 or L00 depending on size of spindle,they will know what you need,I have found them most helpful,they also have a large range of soft jaws to fit most chucks.Their phone no is 0845 1001566 I last bought a chuck from them in 2005. Hope this is of help.|
|Thread: Cutting tool protection,|
|HI The product you require is called Crocell,there are suppliers listed when I did a google search.|
|Thread: Brake Screw|
Hi I made my Allchin brake screw about 40 years ago,all the above is good advice,but they have forgotten clearance on top of the thread,make the tap about 6 thou larger on the outside diameter and also cut the thread depth a few thou deeper on the tap,a little side clearance is also required on the thread,about a thou or two or it will bind in the nut. A long tap with a slow taper is good advice. In recent years I made a screw and nut for a full size seven ton Aveling and it was probably easier as both thread and nut can be screwcut.On some old machine tools and the screws on old antique dining table the thread was machined and the nut was cast around the thread using white metal.
On normal square threads clearance between the top of the screw thread and the thread in the nut was a standard ten thou irrespective of screw dia.
|Thread: Logging on & post failures|
|hi What am I doing wrong,currently 50 % of the replies I have made to readers questions have failed,a few days ago,i logged on .answered two questions without problem then typed in another answer and the message came up please log in,so my effort in typing was wasted as when you log in your answer just disappears ,is there a log on time limit ? .today I logged on ,read somebody had a problem,typed an answer and again message appears please log on and again my effort wasted.not worth the bother.|
|Thread: why cant you silver solder in the workshop?|
|HI a long time ago I started on an Allchin boiler and bought a propane torch kit,first time I tried it out in my workshop on annealing some copper,I did it on some firebrick on the concrete floor,it was all going well and getting nicely red hot until I got up off my knees and looked at my tools and the brand knew Myford,in that relatively short time there was a yellow rust film on most of the bright steel and cast iron surfaces,the rise in air temperature and the moisture frome the burning propane had caused instant corrosion.As I was annealing it was only the propane that caused the rust,I have never heated work or silver soldered in my good workshop since. I have an outer workshop for rough work with double doors and a mobile steel bench and position it behind one of the doors so that the work is in shadow so that I can see if it is hot enough and keep the other door open for ventilation.Electric welding is always done outside ,the fumes can then be carried away by the wind.If I silver solder a large job like a boiler I would do it in the open air to avoid the fumes .|
|Thread: Bench Drill Press speed|
Hi I have a Fobcobench drill for 40 years and had the same problem,and thought a lot about finding a way to get a low bottom speed,but never found an ideal solution as the speed changing must be quick and easy to operate,and there is not much room within the existing belt guards to mount a speed change system.about 15 years ago I solved it easily,I went out and bought a surperb Meddings one inch capacity 3 mt pillar drill in very good condition ,bargain at £320 solved all the problems as its got a two speed gearbox plus five belt speeds,of course you could used an electronic type speed control of the motor of your drill,but it can cost as much as buying a drilling machine,I got mine in the last recession and now might be another good time to find one.Aother way would be say find another smaller cheaper machine and arrange a system of belts with a counter shaft to get a single speed of 100 rpm and only use it for low speed jobs,it will not take up too much room
|Thread: HTS Bolts|
|hi I assume that you were attempting to part off a threaded portion of the bolt shank,well a ht bolt will have some heat treatment plus probable work hardening from rolling the thread,best advice is cut it off with a hacksaw,then just face it in the lathe,why ruin a good parting blade or expensive tip and its quicker.the factory where I worked as an apprentice only used tee nuts ,thee eigths and half inch whitworth.and had a large assortment of bolts so the correct length could be selected ,and we were instructed to make sure the bolts did not bottom out in the tee slot,there were no tee bolts,also studs were only used on special purpose fixtures,I understood that the reason was someone had had an accident caused by long stud projecting well out above a clamp,so the boss preferred bolts and in such matters his workshop practice was good.Too prevent overtightening only short series spanners were allowed in your toolkit.None of our machines or equipment had a damaged slot,but after I left my first job I have seen a lot of damage to tee slots and machine tables,particularly in trade shops.|
|Thread: Gear milling|
|Hi words of warning,The majority of gear cutters that you will come across either have a pressure angle of fourteen and a half degrees or twenty degrees,common practice for at least the last fifty years is to use twenty degrees and usually this is engraved or etched on the gear,a lot of cutters available are unmarked and others have fourteen and a half degrees etched on them and there are still a lot of them around at dealers and auto jumbles,it is of course good practice to mesh gears which have been cut with cutters having the same pressure angle.So specify when purchasing that cutters must have twenty degrees p/a etched on them,I also understand that a lot of lathe change gears continued to use fourteen and a half p/a long after it went out of common use.when cutting on small lathe/mill set ups it is best to take two cuts on steel or cast on dp gears up to 12 dp.first cut two thirds of gear tooth depth ,second cut one third of depth.|
|Thread: Just bought myfirst lathe now what?|
|hi why make a milling spindle when the first class lathe spindle is available,boxfords made a vertical milling slide and a t slotted crosslide these do come up for sale but may prove more expensive than a small milling machine,it all depends on available space,if you go for a mill a small s/h uk built machine will be far better than the far eastern rubbish.|
|Thread: lathe tool advice|
Hi The worst of the common materials to machine are steel water pipe then rolled steel plate,they are not really tough but very stringy.forget carbides use good hss with 15 t0 20 degrees rake and SLOW cutting speed ,around 40 to 50 ft per minute using soluble oil or even slower on the first couple of cuts,if as you say your lathes bottom speed is 120 then you are attempting to cut rough steel at at nearly 200 ft a minute which will destroy any tool,your lathe speed should be 25 to 30 rpm.I know there is some low quality hss around,but no hss will last on good steel if you exceed 100 foot a minute surface speed,possibly 120 on soft leaded freecutting material,the tougher the material the lower the speed,thats why carbides were introduced,to enable higher speeds to be used to keep cost down,but they are intended for use on suitable machinery and nice clean known materials under ideal cutting conditions,not rough jobbing engineering .thats why a Myford and my Colchester have low bottom speeds of 25 rpm.Use ordinary soluble oil at 20 to1 mix,The above is not theory I earn my living on jobs like this.
ps dont go using grinding wheels and angle grinders on your lathe.
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