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Member postings for Oily Rag

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

Thread: Converting fractions to decimals
27/09/2021 22:27:57

What's this about calculators - I thought modern phones had replaced cameras and calculators in one fell swoop!


Thread: Machining Cylinder Head Chamber Roof - DIY or Shop Tool
27/09/2021 22:20:22


From the picture in your last post it looks like the head is in dire need of a skim to remove the bruise across the water transfer plug! Not to mention the dints across the rest of the head face.

I'm also surprised that you are not modifying to 11 stud fixing (the cores are in place in the head to allow these to be drilled thru ).

Is this an A+ head? If so, is it the 'improved water flow type' with the increased size galleries; these had a rather negative affect on water flow when combined with the blanked off rear heater feed outlet (using a sandwich plate under the thermostat housing to take off the water feed to the cabin heater ). The rear two cylinders ran considerably hotter due to the 'decreased water flow' at the rear of the engine which could result in seizure or valve problems - another Longbridge 'faux pas'!!

Also I would question your chamber capacity requirements - you stated 25 odd cc was required, have you added in the deck height and gasket capacity to the 8cc piston bowl. By my reckoning for 9.75:1 CR you will need a total chamber capacity (including piston bowl, deck height allowance and gasket ) of 36.5cc. Must admit it has been nearly 60 years since I worked on 'A' series though.


Thread: Back to Imperial
17/09/2021 16:17:46

Better still the Chinese tailors Inch!

I had a suit made in Shanghai and when they measured me up my waist was 30" and inside leg was 27" - I was delighted that my waist had shrunk but not so pleased about the loss of 5" height! On questioning the tailor it turned out their Inch is based on 30mm!!!!


17/09/2021 15:31:56

Try getting a replacement 2' x 18" manhole cover!

When the galvanised steel one in my garden rotted away (taking with it into the sewer the wife's prize plant pot and contents) I was unable to buy a replacement. To get over this I had a mate with a bending machine make me up one in 2.5mm plate. The Builders Merchant told me the only way to replace these manhole covers was to fit the metric ones which meant rebuilding the top of the brickwork to suit the new cover and its frame. My mate now knocks out batches of imperial covers of 50 a time and they sell like hot cakes!


Thread: Standard Surveying Thread?
17/09/2021 15:20:25

Posted by SOD:-

I'm sure part of the problem is that standard threads are intended for fasteners rather than the screw on fittings found on lens, bottle tops, and proprietary attachments.

According to my thread 'bible' (P.A.Sidders - Guide to World Screw Threads - ISBN 0-89381-1092-9) there is a welter of standards for threads covering 'fittings' other than straight forward fasteners. For example, the 'German Bottle Closure Thread series', the 'British Bottle Closure Thread - Glass and Plastic containers', the Cordeaux thread for telegraph insulators, Water Well casing threads, Fire Hose Coupling threads, Edison Screw thread for Lamps, and a real odd one the 'British Water Tap shank rope thread'. These all being of non Whitworth form. Miscellaneous Whit forms are listed as - Condenser tube glands, Oil Drum plugs, Endoscope Lamp housings, Microscope Objectives and nose pieces, Oil Switchgear (?), Optical Instruments (Fine motion and Adjustment), Optical Instruments (metal tubes, cells and fittings), Camera Lens fitting flanges (R.P.S Standards) and finally Electrical Conduit Thread!

I remember that many moons ago when working at Alfred Herberts there was a tooling job for either India or Malaysia (but could have been China) where they wanted to manufacture water taps, the shank of the tap was the aforementioned 'British Water Tap shank rope thread' - we found the standard to this was a very early BS number (something like BS14 or so) dating from the earliest days of the BSI.


Thread: Yet another scam
17/09/2021 14:34:57

I have just had a call from Virgin Media (allegedly) informing me that my router had a serious problem, a very pleasant Indian fellow told me - they had detected the problem in my connection speed. He said he was a technician that needed to check my router software as there was a definite problem with it. I played him along (I have Sky Internet!)

First thing I said was "send me a new router then, if there is a problem with it". "Oh, but I need to check the software on it first" he said. "But you told me you have checked it already - just send me a new router, you have the address" "No, I need to check it remotely, please switch on your device and go to the following address".

Now this is where they take control of your PC and search for all your bank details and data. I carried on playing him along by pretending to switch on and doing as he said. I told him the address he had given me was blocked as being an insecure and dangerous site. "What fire wall do you have?" he asked. I told him "Double Ace" - this threw him as he had never heard of it (neither have I - I made it up on the spur of the moment). I then said if you are a technician you should have heard of it - it is to stop scammers and fraudulent people. He then asked if I had a internet speed reader programme - I said yes - he asked me to run it and tell him the upload and download speeds, I made him wait while I pretended to load the programme. The told him the speeds were 350 Mbs download and 415 Mbs upload - he said "there is the proof that there is a problem!" - I told him that the reason is down to internet bandwidth usage within my area and background programmes running on my PC. I again told him to send me a new router if there was a problem and if there is an issue with the software you can re-programme it from his end, no need for me to intervene.

After keeping him on line for the best part of 30 minutes he eventually hung up on me! It's a great game to play on these bar stewards!


Thread: Back to Imperial
17/09/2021 13:02:29

Regarding wood - I've never understood why it is sold in 1.2 mtr, 2.4 mtr lengths! I assume it is because it is impossible to divide by 3 in the 1, and 2 mtr lengths. Strange that they should decide on such an anomaly in a 10 base system.

Likewise there is little uptake of the metric 400 grad divisions within a circle, although I have come across this weird division for circular definition in the Bosch engine management system for engine control to define crankshaft angularity - it caused mayhem before it was realised that a grad was not comparable to degrees.


Thread: The "Lost art of hardening copper"
20/08/2021 09:58:26

An interesting 'discovery'! I liked the bit in the NBS letter Circular about the alloying of copper - one of the most difficult materials I have ever had to machine has been CuBe (Copper Beryllium alloy of 1.5% Beryllium) which would blunt a HSS hacksaw in a few strokes and would require the very sharpest carbide to stand a chance of lasting. It has some amazing properties such as a very high capability to dissipate heat allied to a high wear resistance, hence its use as a valve seating material and guides in race ICE engines. Meanwhile Beryllium when alloyed with Aluminium (with small amounts of Nickel, Magnesium, Copper and Titanium) makes an exceptionally strong piston material with exceptionally high strength at elevated temperatures.

The sad aspect of all this is that Metallurgy as a subject has all but disappeared from British University courses, one of the UK's leading establishments was Sheffield's Metallurgy Department which closed a number of years ago.


Thread: QDM750/Kerry Super 8 spindle bearings
19/08/2021 18:21:59


Sorry for the delay in responding.

I have now had a chance to dig my workshop notes out on this rebuild - unfortunately I no longer have any photographs (the curse of mobile phones that get broken, lost, or stolen!) but from my notes I measured the distance between the bearing shoulders of the spindle quill and also the depth of the retaining circlips, the upper (AC bearing) clip gave a +0.004" clearance on bearing outer race width. I did consider packing this but eventually settled for 'as it was' condition.

The way I see it the AC bearing supports the mandrel and the lower DGB 'floats' to accommodate the upper bearing. I used a Hoffman RLS8-V3 DGB and a SKF 7302 BEP AC. With it all assembled the end float was zero - I believe the end float you have experienced may have been caused by the AC bearing wearing through lack of lube, this will introduce end float. I would certainly recommend you check the gap between the top retaining circlip and bearing to ensure a close fit. A spring 'wobble' washer could be used if it is excessive. Also worth replacing the circlip if it is damaged in any way.

Let us know how you get on.

Have you any response about a manual?


PS - my method of assembly was to press in the AC top bearing into the quill, then supporting the inner race of the AC press in the mandrel which had the DGB bearing pre-fitted to the quill shoulder dimension, when the DGB outer race was ready to go into its housing I tapped it in gently as the mandrel was still under load. The upper bearing was as I said in the earlier post an 'easy' fit due to the corrosion from being in the elements. The drill has been fine with a very quiet spindle and no overheating.

Edit for PS

Edited By Oily Rag on 19/08/2021 18:31:05

17/08/2021 21:59:01


I also have a QDM750 which was gifted to me some years ago (because it had stood outside a famous (now defunct) car factory for many years and had been considered scrap). I rebuilt it and from memory the DGB bottom bearing acts as the locator for the spindle whilst the AC top bearing takes the axial load when drilling. The bearings which came out of mine were totally shot after being weathered and after cleaning up the spindle, the fit into the inner race of the top bearing was less than I would have preferred, Loctite bearing fit coming to the rescue - but it has all worked well enough. Which bearings did you fit as there was a late model change from the earlier bearings which, I believe, was a change to the tolerance class? Never seen anything definitive on this but was told this by a reputable M/C Tool rebuilder.

Have you managed to find an operators manual for it? The Tony site only provides the advertising literature as seen in the write up on the QDM range of drills.

Lovely bit of kit by the way.



Thread: Centec 2B - New arrival and Q&A
13/08/2021 19:27:38


I;m with you on this - I can't abide anything to do with YT as it is totally destroying peoples ability to think things through in a logical manner. This, to a large extent, is reflected in the OP's continual grasping for the Holy Grail as his posts show. I never bother to look at any of the self serving BS that is posted on YT - sorry but it is, to my mind, all 'Anti Socia'l Media with a very dark edge to it.

The only way to get knowledge is through reading and applied conceptual thought, we do not 'deep' learn from visuals because the basic thought process has been by passed.

It used to annoy me intensely when I was told that 'presentations' had to be MPP visuals with plenty of pictures and no detailed writing, just straight forward 'non sentences' abbreviated into bullet points. What utter Twaddle! I persisted in writing 'papers' which started with a proposition, examined the caveats, weighed up the competing arguments and delivered a reasoned conclusion. Problem was the majority of graduates were too thick to comprehend what had been written because they lacked the vocabulary of their mother tongue.


PS I like the analogy!

13/08/2021 16:19:39


Stop faffing about and do the job properly! Bits of brass shim is a 'bodgers' answer to the pulley problem. Bore it out with a slight recess and make a top hat bush which is a good press fit into the pulley, remount and finish bore to the 3/4" bore.

Then put a keyway into the bush to suit - use the toolpost to mount a keywaying tool then by taking 0.005" cuts shave the keyway to size (obviously you don't run the spindle for this and its best to lock the spindle in position ) by hand feeding the tool through the bore.

That gets the pulley sorted!

Re-con the motor with new bearings and refit it. Whilst awaiting the motor mount brackets use a car jack to support the outer overhung end of the motor.

You will need a good vice for using that 3" slab mill! Not my choice for a small hobby machine as they are more suited to high horsepower industrial machines where time is money. I have a wide selection of slab mills that I don't think I've ever used.


Thread: Steel Prices
11/08/2021 18:12:09

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.


Thread: Change Gears Identification
09/08/2021 16:36:28
Posted by Howard Lewis on 09/08/2021 16:16:25:

Unfortunately, there is no easy way of determining the Pressure Angle.

.....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.


Thread: Hahn & Kolb micrometer
28/07/2021 21:01:06

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' !


Thread: cylinder bore lapping
28/07/2021 20:52:12

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.


28/07/2021 18:51:01

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!


Thread: Maximat V10-P Lathe Headstock Gears
27/07/2021 22:13:55

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!!


Thread: Hahn & Kolb micrometer
27/07/2021 22:01:49

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,. )


Thread: Tapers
27/07/2021 21:36:35


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!!


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.


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'.


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