Member postings for Oily Rag

Not just hardware either - wheat prices have risen 3 fold from around £55 ton last year to £180 per ton this year, weather has affected the harvest (although the UK harvest has been / is being pretty resilient this year) in the USA, Canada and much of Europe the yield is poor.

This will knock on to higher food prices (bread, meat by way of higher feeds for animals, and beer!)

So not just metal prices are being affected.

Martin

.....Except by the 'span' measurement across a number of teeth!

Look up Ash Gear, Novi, Detroit for their excellent website which has a gear tooth span formula for calculating the pressure angle of a sample gear.

Martin

Well that's got me flumuxed! DRP maybe the clue to where it was used and I would hazard a guess that the D stands for 'Deutcher' as in Germany. Over to any other suggestions from forum members.

A very nice instrument in beautiful condition may I say. Your late cousin was a very astute 'magpie' !

Martin

Thank you Jason - one is never too old to learn something new every day!

The only experience I have of model engines is as a schoolboy with a 1.5cc ED diesel - still got the three scars on the back of my hand where the prop caught me! Other than that we had a 2.5cc piston /rod and barrel assembly modified with a reed valve head as an air compressor on an F1 engine in the early '90's (the air was used to supply the air springs for the valve mechanism - excess air was bled off to pressurise the coolant system to 6bar.

Martin

Just a question of prudence here - would it not be best to lap the bore using a dummy piston (I'm thinking here of, say, a brass bar turned to a suitable oversize ) and then running the piston in to the lapped bore? After all the bearing points for the piston will be the ring(s) and the lower piston skirt. Is the piston aluminium, CI or steel?

I would point out here that I have no knowledge of the 'art of model engines' so am willing to learn something new here; so if my point is stupid - don't be afraid to say!

Martin

Never a good idea to have drive dogs with parallel faces, any drive gear dog worth its salt will have a subtle back taper on the drive faces (look at a motorcycle dog box for an example ). Stops the gears jumping out under load as well! Interestingly M/c dog gears have way more than 0.030" backlash between 'on drive' and 'off drive'. This primarily helps with under power gear changes, not something you will be interested in though I suspect!!

Martin

H & K were the UK agents for Wohlhaupter if I recall correctly. Now a shadow of their former glory being no less than a logistics company I believe. They were based at Rugby and a lot of there 'goodies' were supplied to the BTH (latterly AEI but again now a multitude of car exhaust and tyre centres plus innumerable Tanning Studio's ) works there manufacturing turbines for power stations.

Bev - A bit of a background of where your cousin may have picked up such a tool may be helpful, where did he live? what major industries were in his area? Could be a start to finding where it may have come from. Are there any other markings on it? which could give a clue to where it was used (R or RR usually indicates Rolls Royce for instance, AS = Armstrong Siddeley, CT = Courtaulds Textile, etc,. )

Martin

Howard,

Well yes indeed, the collet system for the Aciera is Schaublin W20 which uses a delightful drawbar thread of 19.6mm dia x 1.66mm pitch. At least this system is shared with a few other machines, few being the operative word. Getting an item like an ER25 or ER32 collet system to mate with a W20 spindle means going to Rego-Fix, no options for Charlie's parts here!!

Michael,

But dreams can soon turn into nightmares - having said that I bought 2 F3's for far less than new Charlie built machines and they are so well made that they are a 'dream' to work with, even after nearly 60 years old for one and approaching 40 for the other. The shear range of optionals gives the ability to manufacture just about anything.

NDIY,

The male taper I have - so it is easier to measure that than dropping ball bearings down female tapers. I mounted the male taper on a sine bar to measure the included angle on a surface plate and with a digital height gauge. I then double checked by measuring with my clinometer the Sine bar taper and correcting against a measure of the surface plate orientation. The taper on the Sine bar stack measure came out at 4 degree 2' 20" (by interpolation against Tangent tables) The clinometer after correction for surface plate gave 4 degree 1' 50". The Tan values for 1' at these small angles is ³⁄₁₀ of a thou so 20" is therefore equivalent to ⅒ thou. The Clinometer is a 'double bubble contra' movement with readings taken off a graduated wheel to 10" (ex RN gun laying calibrator ). So I'm pretty happy to guess a 2 deg taper is a good start point followed by a bluing test! Other than that I'll mount the taper in the lathe between centres and 'clock it off the top slide'.

Martin

We ran aluminium inlet valves and titanium exhaust valves in the F1 engine (helps with that 28mm lift! ) but valve temperatures were reduced by the applied coatings (not ceramics by the way, which did not work, the coating needs to be intermolecular ). Intake temperatures were at sub zero in a 25C ambient when we ran carbon fibre intakes, this caused ice formation and insipient misfire due to fuel vapourisation issues, so we had to revert to aluminium tracts to get some heat into the fuel air mixture to aid the 'vapour gas exchange' process. Exhaust gases run at approx 950C in the exhaust port just after the valve head, turbos can get to over 1080C for short periods. The piston is the hardest working component in the engine though, through the cycle it can go from over 450C to less than 150C in 3 millisecs, the limiting factor is the average temperature through the cycle has to be below 320C for RR56 or about 360C for MPL 3 alloy.

Good point about valve seat distortion Howard, we often saw power figures deteriorate under prolonged full load runs due to seat distortion. A short timed fuel pulse was added to 'cool' the engine internals. This was a big problem on the Mulsanne straight at Le Mans in my days working on WSC cars, far more than at any other track, cured when they decided to put the roundabouts into the straight!

Martin

Well, after the overwhelming response to that question it looks like there are very few Aciera owners out there!

However, after some thought I looked closer at the taper angle of the Aciera tailstock centre and have concluded that it is probably a nice round 2 degree half angle which puts it close to a B&S taper of 2 degree 24', whilst all the other long tapers (i.e not Jacobs or B series) are in the range of 1.4 - 1.5 degree half angles.

Guess I'll knock up a 2 degree taper shaft, blue it and try it.

Martin

Howard,

As 4000 rpm equates to 15 millisecs per rev and in a 4 stroke engine a cycle therefore takes 30 millisecs (for the 2 revolutions) the valve will spend a little more than a ¼ of a millisecond on its seat!

Given a typical road tune engine valve period is 250 degrees this will equate to 250/720 * 30 milliseconds opening period (about 10.42 milliseconds) hence leaving 30 - 10.42 = 19.58 millisecond on its seat. Even a race engine with 330 degree valve period will have 16.75 millisecond 'seat time' at this engine speed.

The Neway valve seat cutters are offered in 91 degree included angles, giving as you say, a ½ degree top locator to the valve / seat interface. This is then widened to about a 1mm (0.040" ) seat width during the lapping process.

Single point cutters with powered drive are available from Hunger GmbH - these are also available with 45½ degree blades for ensuring 'top location' seats, 30 degree included angle and 150 degree blades for triple angling.

We employed an 87% to 92% throat to seat constriction with 12 'rivlets' of approximately 1mm deep x 2 to 2.5mm wide. This was developed using low valve lift air flow measurements taken around the valve periphery and produced around 20% increase in low lift conditions with much increased swirl function. Another air flow trick was to produce the valve with a 'disruptor' on the back face of the inlet and on the front face of the exhaust. These again increased low lift flow figures as the disruptor worked in a similar fashion to the Gurney strip used on aerofoil wings to reduce drag.

Now work out how a late 1990's F1 engine managed to have 28mm valve lift and was able to run at 20,000 rpm, valve period was quite mild though at around 270 degree period!

Martin

A lot of this depends on the accuracy of how you cut the valve seat, if you grind it how accurately do you dress the stone? how often do you dress the stone? what is the method of establishing the pilot to the valve guide? If you don't grind it but single point cut the seat again how do you establish the pilot.

First I would suggest you go and look at the Neway expanding pilot system for accurate guide piloting.

Secondly I would decide how you are going to machine the seats, grind, single point or multi cut. For me the only way is either a dedicated motorised single point bench system and as a second best the Neway system. Forget radiused formed seats, they are a waste of time and effort as has been proven by airflow testing, the only 'trick' system to improve airflow over a triple or quad angle seat is the 'rivlet' form behind the valve head over the last 10mm of the throat. If the method is correct the seat will be concentric, its simple! Grinding seats is the wrong process.

Martin

And I thought this was a thread about Flak Batteries from WWII !!!!

The only time I have seen something similar to this was for a line boring bar setting micrometer. The angled rest was set to the bar radius, the readout was hence then converted from a true diameter reading, to a radius reading but this was then converted to a 'cut' diameter reading. That's why I believe the setting tool in the case is a bar rather than the more normal length gauge. From memory they had a very limited measurement range. Used with 'Microbore' tooling generally for very accurate line boring of camshaft and crankshaft bearings.

The one I saw was not made by Hahn & Kolb though; my recollection was that it was possibly a Wohlhaupter.

Martin

Many moons ago I had an acquaintance who was involved in the electro plating business. On a visit to his works he showed me the plating process which was interesting to say the least!

Firstly the parts went into a high detergent wash tank to remove grease and oil, secondly a pure water wash tank, then through a drier before going into Hexavalent Chrome to etch, then a two stage wash, followed by a copper plate solution (which was IIRC copper dissolved in sulphuric acid - copper sulphate in effect ), followed by another double wash, followed by a electro plating copper bath, another wash, then a nickel plating bath, where it was subsequently diverted off line to either a finish wash for dull nickel plate, or a secondary nickel bath for a bright nickel plate. Other parts due for chroming went on their way to the final chromium baths and washes. I was staggered at the amounts of water used in the process - and also just how dangerous Hexavalent Chrome is (was! since it has now been virtually banned ) a piece of paper dipped in the Hex Chrome tank burst into flames when exposed to air!

Martin

To hi-jack Peter's thread, I apologise, but as this is a question about tapers I thought for future reference it maybe the best repository for this question, in the hope that someone will be able to answer:-

I have an Aciera F3 milling machine and have as part of the accessories the Aciera 75mm centre height dividing head and tailstock (tailstock part no 342 ). The tailstock centre (half centre type ) is an unusual taper and roughly measures Big end = <10mm (0.390" ), Small end = 7.2mm (0.284" ) with a length of 39.18mm (1.542" ). these measurements are taken over the engagement length within the tailstock barrel, the full size at the big end actually measures 10.2mm (0.402" ) giving an overall taper length of approx. 42.6mm (1.677" ). Looking at Thor's link this does not match any of the 'normal' tapers - the closest appears to be a #3 B&S or a #3 Jarno (which I erroneously, in an earlier post on this thread, accredited to being of a Northern European origin rather than, oddly, B&S themselves! ).

I can find no mention in any of my Aciera literature as to the taper used in the tailstock barrel, nor is there any mention of alternative centres that were offered for sale. I ask as I need a bull nose centre for a job and was therefore looking to either buy and modify or to make a 'special' to suit my needs.

It would be nice to have the opinions of the forum as to what this taper is liable to be. I'm guessing it may be an extended version of a #3 Jarno.

Martin

Duncan,

the reason I put 'carbon catalyst' in inverted comma's was because that is how the Times reported it!

In hindsight I should have probably written 'sic' to show it was how the message was reported. It seems you just cannot get the technical journalists these days.

I do like your idea of using plastic though - out of the box thinking there. But what of all the fumes given off by burning plastic? Isn't one of the gasses released formaldehyde?

Martin

My point entirely - I would have thought it would have been better to modify a 16mm drill to 'Blacksmith's Drill' specification by reducing the shank to suit the largest capacity of the chuck currently available. Even then I would want to ensure the MT taper was not bruised and the tailstock barrel female taper was in top condition (i.e not ribbed by a previously spinning taper ) - worth a pre-emptive clean up with a MT reamer?

Posted by Michael Gilligan on 25/07/2021 14:50:36

… and like many ‘rationalisations’ perhaps it fed the European gravy train

Undoubtedly Michael! it seems completely superfluous to enact yet another tooling taper to join the many already proven over the years. If they wanted a 'European Taper' why not just resurrect the Jarno (assuming it was a Swedish / Finnish invention! )

Martin

There was also a report a few months ago that coffee grounds could be used as a 'carbon catalyst' in the steel making process, developed by, I believe, a Brazilian University no less! Not sure I want my steel smelling of coffee when I'm machining it though.

So after all those milk bottle tops we saved as kids (remember that?) the new generations will be saving coffee grounds. Problem is most folk use 'instant' coffee which has no connection to a coffee bean and is purely a chemical extract - the reason I only drink tea made with real leaf.

Martin

I would be surprised if there is such a thing as a MT1 to JT6 shank available. In my experience MT1 usually only comes with either JT0 or JT1 for fitting the smaller Jacobs chucks. I have a genuine Jacobs manufactured MT1 to Jacobs JT1 arbor on which the box states - Models 1, 1A, 2A-1A, 7-1A, 30-1A, 250-1A, and 25S. Another genuine Jacobs manufactured arbor (MT2) for JT2 states - Models 2, 2A, 6-2A, 7, 8 1/2N (that is eight and a half), 11N, 30, and 32.

I have a Rohm keyless 1/32" to 1/2" with a JT6 back taper and also a Jacobs Model 34 mounted on a MT2 to JT6, and a MT3 - JT6 fitted with a 1/16" to 5/8" Rohm keyless.

The only example I have of the JT0 taper is a Model 0 chuck (0 - 5/32" )

From this I would reckon that a JT6 is best suited to a MT2 or MT3 arbor, it would seem a MT1 with a JT6 is considered as 'overloading'? Subsequently you have proved me wrong Peter! Looks like someone considers an MT1 to JT6 is within the bounds of possible, but I doubt Jacobs would agree!!

Martin

Edited to get rid of grinning buffoon emoji - and again to update with last sentence.

Edited By Oily Rag on 25/07/2021 13:33:55

Edited By Oily Rag on 25/07/2021 13:38:07