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: Colchester Bantam Lathe|
Colchester users may find this useful,some years ago I bought an all metric Student lathe,one feature which i had never seen before was a dial fitted on the saddle handwheel ,one rotation of the dial was exactly 25mm and it was accurate and useful. It was also fitted with variable speed and was short bed,it was a pain to use so I then bought a master 2500, which was imperial with dual dials,out of curiosity I checked the saddle travel against one turn of the saddle wheel, it moved 25mm so I came to the conclusion that they must be fitted with metric module racks so I took the dial off the student and it fitted my master, so I now had an imperial lathe with metric reading dial for saddle travel.I then sold the student minus dial, Most of the time I work imperial on the cross and topslide and metric on the saddle and it is so useful despite the imp/ metric mix. I then looked at my all metric triumph 2000 the rack was module so I went along to G & m tools and found a suitable metric dial which could be converted to fit the triumph hand wheel. I have Colchester bed stops but they are not reliable as they do slip and never use them now that I have saddle dials. One thing on my ex naval triumph is a 2ft long engraved sign stating "this machine is fitted with a metric threaded leadscrew" I have often wondered if someone made an expensive cock up confusing 0.2inch imperial with 5 mm metric pitch leadscrew. Going back to the student ,the mechanical vari speed and the phase converter was a useless combination ,I asked a machine tool dealer if he had experience with variable speeds ,his comment avoid if possible any variable speed powered by 3 phase conveters.
|Thread: square top Colch / Student|
Cross slide adjustment,I looked at my master 2400 today there are three socket screws plus a ball bearing type lubricator in the centre of the slide ,its about 10 years since I had the slide off so memories a bit rusty,I think two outer screws secure the nut and the centre one adjusts the nut, if its different just remove the slide and have a look how the adjustments work,I found that when removing the cross slide the screw sits in a long recess in the casting,and this recess has no drainage and of course it fills with soluble oil and if one of the more higher performance oils has been used it can corrode the feedscrew ,so I made a new screw as Colchesters wanted around £500 for a new screw and nut. And I drilled a drain hole in the casting. And if your Colchester has a hand operated lubricating pump on the front face of the saddle, while you have the cross slide off make sure the oilways / holes in the saddle and crosslide are cleaned out. Also due to space my master resides along a wall and it is a right pain to remove the cross slide and get access to the suds pump and clean out the tank.
Best bet is to buy a Bison 3 jaw chuck from Rotagrip,its worthwhile to also get a set of soft jaws they can be very useful. I understand that Burnerd chucks are now made by east european manufacturers but have retained their own jaw dimensions. I have 6 inch and 8 inch Bison chucks on my colchester master and they have proved to be very good,at one time eastern european chucks were very good value for money but their prices have risen a lot in recent years,but a lathes no good without a decent chuck ,
Unless you are broke I would not grind a lathe chucks jaws ,as if they are that worn the scroll and the slides where the jaws fit are also worn,plus grinding dust on a lathe does not do the lathe much good no matter how careful you are , I have an old 8 inch 3 jaw chuck mounted to a non swivelling base which can be bolted to my mill table ,ideal for holding round work for milling,the jaws were tapered so with feeler gauges I worked out how much the error was ,set up each jaw in a vice on my surface grinder and ground them true,the chuck then gripped work securely ,concentricity does not matter in this case and the grinding dust stayed on the grinder.
|Thread: First Time Milling Cutter Issues Help Needed Please|
looked at the posts,oh dear, putting 25 mm plate on a small mill is like this and then trying to cut with the side flutes of a 20mm cutter is not good practice and wont do the mill much good. Endmills always cut better on the end face ie the work would be set vertical on a stiff angle plate and the mill spindle would also be vertical, Speed about 250 cut depth about 3mm and cut half the width of the plate. probaly not enough room under your spindle, you could try a fly cutter mounted direct in the spindle which gives a lot more clearance under the head.ok you may say its a bit slow with a flycutter but it will get the job done . If you want to mill pieces of inch plate you require a horizontal mill with a sturdy vertical head with 40 int spindle.
I once saw demonstrated by a well known carbide tooling supplier ,an inserted tooth cutter with just two inserts milling an inch wide bar held in a vice in a bridgeport ,it cut at a very high speed and feed,no lubricant and produced red hot chips it was impressive particularly as the machine is only a light turret mill and the tooling was expensive,plus there is a considerable fire risk plus adjoining operators need protection, the point is it was face cutting not side cutting.
Travelling around many machine shops in the 1960/70s the operators favourite tool on the turret mills was the single point fly cutter on smaller batchwork , some operators loved a bridgeport as the controls are all to hand and the machine easy and quick to use particularly if a bonus system was in use . others preferred a lot sturdier mill for heavier cutting , though you did not see much side cutting with larger end mills,the shorter stubbier clarkson deadlock cutter was more popular. Also the clarkson threaded cutters in their clarkson holders were in widespread use as the end mills did not move as they were lock solid. I have collet holders on my large turret mill and universal mill but when I am cutting tougher steels the Clarkson auto locks are set up they are far superior as collets will let the cutter slip. The popularity of collet systems has increased with cnc and solid carbide cutters which have plain shanks.
|Thread: Chamfering on the lathe|
Chamfer tools as per the 90 degree pointed tool shown above with no top rake are ok for brass or cast iron ,to get a good finish on steel or bronze a chamfer tool cuts better with top rake, I use a Dickson toolpost and have a 6 inch long ,half inch square HSS tool bit permanently fitted in a toolholder , looking at the tool holder from the top,it is set parallel to the cross slide ,the toolbit has a 45degree angle ground right across the tool and top ground onto it, in this position small edgebreaks to wide chamfers can be machined on outside diameters. Now to machine chamfers on bores the toolholder is positioned parallel with the lathe bed ,the other end of the toolbit now protrudes towards the chuck this end also has a 45 degree chamfer with top rake,though more clearance on the front face has to be ground as it is boring type tool,so say a tube can have its outer edge and bore chamferred by just indexing the tool post through 90 degrees, The toolholder is marked with yellow tape so that it can quickly identified from the other dozen or so toolholders. I have used this method for twenty odd years on my Colchesters and it is quick and convenient particularly when earning a living at it.
When I trained as an instrument maker ,the use of files for breaking edges was more common than using a graver,the files were classed as super smooth and were either 6 inch and or long narrow 8 inch pillar files the tooth angle was normal . On the other hand a turner in a machine shop would not use a file ,he would be expected to achieve finish and size by turning , When I moved to a small toolroom cum model shop,it was noticeable that my colleague trained as a fitter and turner never used a file on a lathe but always used the power feed whereas I being an instrument maker nearly always fed by hand on mill and lathe on the smaller work,and even now rarely use power feed on my ton and a half mill if the travel to machine a job is less than 6 or 8 inches,you can feel what the cutter is doing and I cannot see why so many modellers want x,y power feed on small mills. z feed on the knee would be far more usefull but is rarely fitted
|Thread: strange taps|
Yes they are thread forming taps,they require larger tapping holes ,ie about 65% thread ,the threads are stronger due to the forming action,
Advantages virtually no swarf,less tap breakage ,high operating speed ,ideal for cnc work particularly with electronic solid tapping with pitch control,reduced cnc machine downtime and very few scrapped castings. needs high performance soluble oil with regular control of lubricant strength.
No good for any other work,they are a high speed production tool
|Thread: Stuart 'No.1' : a beginners tale..|
Setting a boring tool is difficult,one way to get over the problem is to bore the hole as close to size as you can,then turn the shaft to suit, or bore the hole to within a few thou and finish ream to size.When restoring stationary engines I always bore the cylinders and get a new piston cast and then turn it to fit the bore.When using a between centre boring bar first check the tailstock is in line with headstock,particularly if the tailstock has been set over for taper turning at some time,The between centre boring bar has the advantage that it bores a constant diameter,though a bore may be found to be tapered this can be is due to tool wear so when taking the final couple of cuts make sure the tool is sharp. In the past when this country did proper engineering long boring bars were mainly used on horizontal borers the tools held by wedges ,screws or taper pins,and the tools adjusted by a special depth micrometer mounted on a special vee block,the vee block was held on the boring bar and the amount the tool protruded from the bar measured by the micrometer, in more recent times adjustable tool holders could be screwed into the boring bars and a index ring provided micrometer adjustment and carbide insert used for cutting,they were very good but were limited to larger bores.
|Thread: Milling cutter damage - what am I doing wrong|
It would be helpful if the type/make of mill was stated and the spindle size,A mill with int 40 spindle would take cuts to full depth 5mm easily,a 30 int spindle should take a cut to full depth but if the mild steel is flat plate it can sometimes be stringy so a cut 2.5mm taken ,the centre cut should be no problem but if you try to climb mill the outer cuts then the mill can grab a bigger bite and damage the cutter , mild steel round bar always machines easier than flat drawn bms,black hot rolled is not tough just stringey and difficult to get good finish. Not knowing the machine ,it could be the machine is to light to take a 16mm cutter and the table is jumping about and breaking the teeth.
|Thread: fuel tank|
As the tractor has a high tank a carburretter having a float chamber with a float to control the fuel level ,should be used,
Most hit and miss farm engines had a tank lower than the carb and had a non return valve on the fuel pipe,
|Thread: Cast Iron Tips|
For a job like this use HSS toolbits ,with no top rake at a cutting speed of 80 ft per min, final cut should be about a thou. the fit of chuck to backplate should be a "knock" fit ie they should go together with a knock from the handle of a plastic screwdriver handle,make sure the chuck seats fully on the backplate and does not ride on the edges of the spigot, if you make a cock up and the chuck is a sloppy fit on the spigot ,dont worry set the chuck true with a dial gauge and really tighten the allen screws,the chuck will not move a unless you accidentally hit it hard with the saddle or toolpost ,
I read a lot on here about people always moaning about machining cast iron,perhaps our current generation do not like getting their hands dirty,they should have worked in machine shops up to the 1970s,some were like coalmines, cast iron machines nicely,no cutting lube ,though tallow was sometimes used for tapping and reaming.Though you did see slideways on well used machines that looked as if a big cat had used them for a scratching post .
I have only once seen soluble oil used in high volumes on cast iron (mill and lathe beds)on a futureistic automated machining cell where cleaning was impossible unless the line was stopped so the lubricant was used to flush away the swarf and it was very noticeable that there was no black dust anywhere.
|Thread: Tool Post Material|
big problem ,if you grind holder plus tool,then replace it on lathe what happens to the grinding dust that will get behind the tool and on the threads of the screws of the toolholder. The dust will get onto your lathe slides and will soon wear out your lathe. When grinding your toolbits by hand always wipe any cutting oil of toolbit and then after the tool is sharpened wipe off any dust before replacing in the lathe.
|Thread: Why did my Flywheel Wobble?|
I have often thought most flywheels have six spokes,and a awful lot of other castings/forgings were six sided yet most faceplates have two master slots set at 90 degrees making it easier for four spoke or square workpieces,though after a century or so Colchester did make six slot face plates by which time nobody was making flywheels. all the above are good comments though I will add some more, beware of workpieces that are stiffer than the faceplate overclamping will distort the faceplate. Holding work on stub mandrels can cause chatter problems as the bore on most flywheels is small relative to diameter. My method is mount three alloy blocks on the faceplate spaced two thirds up each spoke, then use three clamps on the spokes directly over the blocks,on heavier flywheels a further three blocks are mounted equispaced onto the face plate near the rim , three bolts screwed into the blocks are screwed outwards ,like chuck jaws , to just touch the inside of the rim.This helps to keep the flywheel in position and takes any radial strain off the spoke clamps . rough machine bore .o/dia and face ,sometime if the flywheel is spaced away from the faceplate the other face can also be machined .then relax the spoke clamps ,this allows any stress in the casting to be relieved but it remains in position ,held by the three bolts. Then leave as long as possible,tighten the clamps Finish by machining the rims and the bore last, on small wheels the hole should be bored a fewthou undersize and finish by reaming.
Use HSS tools for finish boring ,I have machined a quantity of flywheels from 6ins to 2 ft for steam and ic engines plus refaced rusty stationary engine f/wheels .
|Thread: Poor surface finish|
I dont know how experienced you are,but I would suggest you try to find a really experienced turner for a second opinion ,if they cannot get good results then I think that you should dump the lathe on warcos doorstep stating that the machine is not fit for purpose, the tailstock height difference is a fault that should reject a lathe, I googled the lathe type and it appears tp have a vee and flat bed,a saddle traversed on this type of bed should not cause any of the deflection described particularly when traversing by hand .
refering to the comment on chatter and ringing when turning thin tubular shapes, this will occurr on any lathe,its the nature of the bell like shape, the work needs some vibration damping applied, during my aprenticeship I was making some 3 inch dia micrometer drums in brass . I bored them out ok but when turning the od and the taper where the numbers go it really sang and vibrated ,foreman showed me what was apparrently an old trick,fill up the Inside Dia with a thick greasy rag and ram it tight with a screwdriver handle ,vibration ceased, Of course depending on the job ,internal chatter on a thin bore is more difficult to cure ,a damping material can be clamped on the outside dia, or a larger piece of material used,bore to size,vibration should not occurr with the thicker wall material ,then turn the od to size.
A lot of precision machine tools (lathes ,grinders ,jig borers )sit on three feet so there is no chance of bed distortion or rock. If a modellers lathe vibrates when sitting on 3 out of 4 feet ,it probably the lathe is at fault rather than the mounting, its usually the spindle assembly or chuck out of balance ,If the workpiece is out of balance then the operator should balance the work or reduce speed.
Why should a new lathe require adjusting? as you have checked most of the commonly known faults have a look at the three jaw chuck, the severe chatter on the work is quite common on well worn or strained chucks where the jaws are gripping at the back of the chuck but not gripping at the front,of course it should not happen with a new chuck ,the chuck jaws may not have been ground parallel to the axis of the chuck. ( perhaps the far eastern makers have a rubbish grinder or operator)I have assumed that you have fitted the chuck correctly onto the spindle. First try fitting up the four chuck,mount the steel bar and turn at the same speed and feed and see what results you get . you could also try mounting the bar between centres and turning, though with 1 inch bar between centres speed should be reduced to 200/250.rpm.
If you achieve a good finish then its the 3 jaw chuck at fault, to confirm it place some paper between the jaws and work piece at the front of the jaw and see what the bar machines like. I have a 10 inch four jaw on a Colchester master, I bought the chuck second hand and for years it has only been used to hold castings and irregular parts,customer wanted a quick job so to save a chuck change I used the chuck to grip a 1.5 inch bar and got a result similar to the chatter in the photo.The work was only gripped at the back of the jaws, change chuck back to near new 3 jaw and back to normal .One may ask why have I got a crap chuck ,well I also have a Colchester Triumph which I bought at an ex gov sale and it came with a brand new set of chucks ,faceplate ,centres etc so I do have a lot of options ,though I find the Triumph hard work being well past retirement ,the Master is my preferred lathe.
|Thread: What Size 4 Jaw Chuck|
probably the best option would be a narrow bodied Burnerd 200 mm four jaw with direct fitting D-3 mount,they can be found ,but their popularity results in high second hand prices, the narrow body and direct fitting reduces the overhang and resultant load .on the front of the spindle, New direct fitting Bison 200 mm fitting chucks are available but their cost has risen so much in recent years that they are no longer really viable for the average model maker,
|Thread: Easy Machine vice location|
The company where I first worked had all the machine vices fitted with keys held by csk screws,one keyway run parallel to the slot the other keyway was at 90 degrees,this allowed the vice jaws to located either parallel to the table slots or right angle to the slot,the keys had to be unscrewed and fitted in the other keyway , if keys were looked after, location was within about one thou.Saved a lot of time.
|Thread: Total newbe|
A six inch burrell single model based on an 8nhp prototype will weight about 2100 kilos a suitable trailer around a thousand kilos so can be towed by land rovers and discoveries,a road loco model will be another 500 kilos requiring a small lorry for transport, flywheel is up to 30 inches diameter ,a lot of the parts can be completed on a 7.5 inch c/height colchester triumph ,the flywheel and final drive gears,diff and winding drum will need a lot bigger machine , the cylinder block really wants a mill a lot sturdier than a bridgeport,.Why not try a to use a large engine as a prototype and try 4 or 4.5 inches to the foot,.
A six inch model is heavy ,needs a lot of storage space lifting equipment ,a big trailer,and will take an awful lot of spare time and skill.and cash lots of it. take time and really think about it before tackling such a large project,A lot of enthusiasts start a project but very few have ability to finish one.
Though I have the skill and a lot of equipment and by the time I was in the position to build one I had run out of years,so I bought a big one,had some fun but now I can no longer easily manage such a large engine though it is nice to have a big engine which two people can sit on easily ,bags of power,and a big easily managed fire.So if you must have a big engine do it now before age takes its toll
|Thread: Cutting Speeds/Feeds|
80 to 100 ft per min on mild steels is a good guide for hss cutters,any faster and the cutter life is rapidly reduced,you can go a lot slower,it takes longer though the cutter life is extended,
|Thread: Imperial fractions on drawings.|
I started my apprenticeship in 1958 as a scientific instrument maker,the drawings were all imperial,but our boss was a firm believer in metrication,he felt that continental optical instruments were finer as the use of one mm and half a mm was better than one thirty second and three sixty fourths,particularly for the widths of small steps and widths of knurls on items like eyepieces,when I completed my apprenticeship I was presented with a Roche Etalon vernier and I had the choice of separate imperial scales for internal/external readings or two scales metric and imperial for the external measurement and subtract the jaw width for internal measurement,the boss recomended that i have the imp /metric version as he declared that metrication would be with us within ten years,also he said never lend your vernier to anyone they are all to easily damaged, I still have it and it is superb no batterys to run down or false readings though its initial cost was a weeks wages for a skilled man, within a couple of years I got a desk job so all my tools went home for model engineering and how I wish that my vernier had the dual imperial scales. Most of my time was spent with metric drawings as a desk bound engineer yet I still prefer imperial , my home workshop has an all metric triumph 2000 and a master 2500 with dual dials and an imperial super 7plus two mills one of each measurement, Though I am familiar with both systems I am far quicker when using the imperial machines. The one item that more use should have been made of was metric drills in imperial days ,when working imperial the 64th step was often too large when reaming or requiring a small amount of clearance on a drilled hole,its a lot easier to use a metric set in regular 0.1 steps than the irregular steps in number and letter drills.
Science labs in scools and universities in the fifties and earlier were metric ,98% of our instruments which were mainly for school labs had metric scales, I learnt in all metric labs at school,imperial units at tech,and then when we as a country turned metric,the metric units were all different to the ones I had used at school,crazy.
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