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Member postings for Bob

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

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Thread: Fritz Werner Universal Mill
29/08/2013 10:31:04

Hi all

I have just aquired a Fritz Werner Universal mill. The mill is marked 2.210 on the main body and 210F on the vertical head. It has a Siemens Schuckert 2 speed (710/1430 rpm) three phase 415 v motor and some complex switch gear. The wiring diagram is 2.210/84. Both tapers are Int 30 and the machine is imperial.

I would be interested in any information relating to the machine or older Fritz Werner mills in general. I would be especially keen to find the circuit diagram for this machine.

Bob

Thread: Portable Engine Model Engineer Article by Tony Webster
03/06/2012 18:04:05

It would be a great shame if this project was pulled from the magazine at this stage. Although I have not started to build one I have been following the articles. It is a model that I would consider seriously in the future.

Bob

Thread: Which Universities do people recommend for Mechanical Engineering?
10/04/2012 07:33:21

Hi Andy

First point to consider is is the course accredited by the Institute of Mechanical Engineers. See this link for more details http://www.imeche.org/membership/professional-registration/eligibility/academic-requirements/accrediteddegrees

Not all University Engineering degrees are equalin the eyes of the Institution and choosing the wrong degree course may delay achieving CEng status by several years and entail a lengthy process of gaining postgraduate experience.

Remember, just because it has got engineering in its title it is not necessarily an accredited degree course.

Another resource you should consult is the Engineering Council. They produce a very clear document on pathways to CEng status http://www.engc.org.uk/professional-qualifications/chartered-engineer/about-chartered-engineer

You should also look at the Royal Academy of Engineering website http://www.raeng.org.uk/ and the Arkwright Trust http://www.arkwright.org.uk/

Another helpful organisation is the Engineering Education Scheme http://www.etrust.org.uk/eese/what_is_ees.cfm (This link is for England and Scotland) or The Engineering education Scheme Wales http://www.stemcymru.org.uk/en/getinvolved/eesw/default.php if you are based in the Principality.

It is sad to relate that in my experience the Careers Service (I am being vague here) are ill-informed about routes to achieve CEng status and may not give the best advice on this matter.

Bob

Thread: Ian Bradley Heinrici Engine ME 3741
06/04/2012 10:59:39

Hi all

Well I now own one of the torque tube bearings. The exact item quoted by Ian Bradley in his ME (Model Engineer) magazine article. I have to say that I am none the wiser about how the con rod grips the bearing outer race. There are no holes or dimples in the periphery of the outer race for any pegs to engage in.

Bob

17/03/2012 07:42:44

Hi Mark et al

I find it difficult to understand how tightening the pinch bolt will cause the end of the con rod to grip the bearing outer race. The con rod as drawn would only touch the outer over about a quarter of its circumference so it looks to me a bit like a child with a small hand trying to pick up a basketball using just one hand. No matter how hard he trys the ball will always spring away. I would think that the conrod end needs to cover more than half the circumference of the bearing outer to afford any grip.

 Ian, I think the strange bearing with its large internal diameter is to give a very free running eccentric with minimal out of balance mass. Remember friction (and air leaks) are the enemy of hot air engines.  I believe that Ian Bradley had a background in aircraft engineering and I think that this style of bearing were used in aircraft control systems. I have seen them advertised as 'torque tube' bearings.

I agree it is a fine looking engine. I am thinking about water cooling the cold end and using either gas or spirit firing.

Bob

Edited By Bob on 17/03/2012 07:48:01

15/03/2012 20:05:11

I am considering building a version of the Ian Bradley Electrically Heated Heinrici engine published in ME 3741 to 3751 in five parts (1984/5). I have sourced the torque tube bearing from the original supplier that Ian Bradley suggested back in 1985. My question is how is the connecting rod (Part O in Fig 31 ME 3747 p 214 connected to the outer of the eccentric bearing.

The drawing shows two holes which would be radial to the bearing outer and a suggestion that a pinch bolt causes the end of the conrod to grip the bearing outer race when it is tightened.

Is there something, not mentioned in the article? Do torque tube bearings (Ransome and Marles type CA1 1 9/16" bore by 2" OD by 9/32" wide) have protruding lugs on the outer that could fit into the radial holes? The size of these holes does not seem to be dimensioned in the plans.

Has anybody other the the author built an engine to these plans?

Bob

Thread: ISCAR tipped parting tool
26/05/2011 16:50:38
We have a Boxford 250 CNC lathe which uses an ISCAR SGAHL parting tool. I believe it takes GTN-2A tips.
 
I am looking for a UK supplier of these tips or an equilvalent tip. I feel sure that the price quoted by the lathe supplier (£9.00) a piece can be bettered.
 
Bob
Thread: Dangerous Practices
16/09/2010 20:01:25
Hi All
 
May be I am missing something, but I can't see why the steam chest could not be held conventionally in the 4 Jaw to turn the bosses and end faces?  In Photo 28 the steam chest is shown gripped conventionally so the chuck must have the capacity to accommodate the width of the steam chest. As to settling the casting back against the body of the chuck then in Photo 31 there is nothing to be gained over just gripping the work in the jaws as at this stage the rear face is still a rough casting. My concern would be gripping the machined surfaces with those nasty chuck jaws. I would pack a piece of shim between the work and the finished faces just to be on the safe side. If the concern was that the top and bottom faces were only gripped close to the chuck then use some parallel steel packers between the chuck jaws and these faces about half way up the chuck jaws. (I always find these tricky to balance in place while setting the work up).
 
The chuck jaws on any half-way tidy 4 Jaw should hold work parallel to the axis of the lathe without reference to the chuck face. Most of us rely on this with the 3 jaw without stopping to question the fact. The mechanism of the 4 Jaw is not much different regarding the arrangement of sliding surfaces to ensure the jaws move parallel to the face of the chuck.
 
As for the unconventional use of the diagonal grip in the 4 jaw this will grip work very tightly, but I would worry about the stresses imposed on the chuck body by this sort of (ab)use. I would avoid doing it with my best 4 jaw.
 
Bob
Thread: Lusus Naturae - Drawing Revisions
19/08/2010 19:28:48
Just a quick update on my version of Lusus. I am building it at 1.667 times the original size to suit material I had to hand.
 
Point 1   I made the swinging arm exactly to to the drawing. I then measured the centre height of the top bearing with the arm set vertical. I used this height to mark the centre positions on the supports for the radius rods on top of the cylinder. I fitted the material to the cylinderhead to do this. Once this was established I marked out the remaider of the supports and drilled and filed to shape. This ensured that at mid stroke I could get everything in line and level.
 
Point 2 I have changed the design to make the radius rods fit inside the supports on top of the cylinder head. I have fitted counterbored bronze bushes to the radius rods to save some space as it is a bit tight here. The radius rods are 2.5" between centres, exactly the same distance as between the end eye of the beam and the mid- centre of the beam.
 
Point 3 My piston rod is a nice sliding fit in the cylinder head. ( 5/32 " reamed hole and commercial 5/32 " stainless rod lightly polished.
 
Point 4 Con rod made of two pieces of steel. The top fork has a tapped M4 thread inside. The rest of the rod is turned (between centres) and left slightly over length. Once installed it can be adjusted by turning a bit off the threaded portion and extending the thread. This process is repeated until the engine can turn over without the top of the piston fouling the cylinder head. Once the length has been established it is taken apart, degreased and then threadlocked in place with Loctite. Put two pieces of rod through the con rod eyes and set the assembly on a pair of parallels to cure. This ensures that the axes of both ends are parallel.
 
So the good news is that once assembled everything runs very smoothly!
 
Next challenge is to sort out the valve gear.
 
Bob

Edited By Bob on 19/08/2010 19:30:45

Thread: Removing a chuck...
11/08/2010 20:03:48
Fig 5 Page 43 is labelled Removing a chuck, but the strap wrench is shown in the correct position for tightening the chuck.
 
I always find that  jambing a block of wood between a chuck jaw and the rear shear of the lathe and then engaging back gear and pulling the belt in reverse (by hand) will loosen even the most stubbon chuck.
 
It would seem to me that there is something wrong if you need a strap wrench to put the chuck on.
 
Bob
Thread: Lusus Naturae - Drawing Revisions
11/08/2010 19:52:10
Hi Phil
 
I am looking at moving the radius rods to the inside of the supports. I don't think there is any prototypical president for doing so, but there seems to be room if the rather ungainly nuts are omitted from the beam end pivots. I am planing to use tiny circlips to retain the pivot pins and as these will not be visible no one will be any the wiser! This will also allow me to make the radius rods straight.
 
Bob
09/08/2010 10:50:29
Hi Phil
 
Situation regarding vacuum/compression above piston now eased by 2 mm hole in top pf cylinder head.
 
Regarding the layout of grasshopper engines in general, looking at Antony Mount's drawing  (Historic Engines Worth Modelling Vol 2 General Arrangement Page 30) it shows the beam horizontal and the centres of the end holes equidistant from the centre of the end of the radius rod. The radius rod is also horizontal and in this position the fixed centre of the radius rod coincides with the centre of the end hole of the beam. The swinging arm is then perpendicular to the beam. This means that the centre of the cylinder must be the same distance from the centre of the swinging arm bearing as the centres of the end holes in the beam.
 
Using the drawing of the base for Lusus published on this website and the Imperial dimensions from the article in The Best of Model Engineering Vol 2,  the distance between the centre of the cylinder to the centre of the swinging arm bearing is 2 31/32" but the end holes on the beam centres are 3" apart.
 
Further, the radius rods (aka Beam Support Arms) are dimensioned at 1 5/8" but made to suit the job. Is the 1 5/8" dimension the undeveloped length before the jog is put in? I would have expected these centres to be 1 1/2" apart.
 
The relationship between the length of the radius rod and the main centres on the beam should be:
 
AB = Length of radius rod
BP = Distance between mid hole centre and piston rod eye centre
CB = Distance between mid hole centre and swinging arm centre
 
AB x AB = CB x BP
 
I am sure that if CB = BP them AB = CB = BP
 
I wonder if the loose fit between the gland and piston rod may be important in more ways than just allowing the escape of pressure above the piston, could it also easy any lack of true parallel motion of the piston rod eye?
 
(The drawings show both the piston rod and the bores in the cylinder head and dummy gland to be 3/32")
 
Bob
08/08/2010 17:23:49
I am building this engine at 1.667 times the original size (to suit a piece of material I had to hand).
 
I have just completed the cylinder and cylinder head and fitted a piston. I am concerned at the amount of compression/vacuum at the top end of the cylinder. Have I missed something? Should there be an air vent in the top of the cylinder head?
 
Bob
Thread: Safety
21/11/2009 19:17:34
(Second attempt to post this, I was sure I was logged in, hit the post button only to be informed that you must be logged in to use this feature so here is a much shortened version)
 
One or two points of fact (I hope)...
 
Almost any metal will burn if it is sufficiently finely divided and mixed with air or oxygen. The classic chemistry demonstration was pyrophoric lead made by heating lead tartrate and excluding oxygen as the lead dust cooled. This powder would spontaneously burst into flames when poured from the phial ito the air. The white sparks seen when F1 cars bottom out are the result of titanium being abraded away from the underside skid plates. (probably see lots more of those next season with the banning of refuelling during the races)
 
So I am not surprised to learn that titanium swarf can catch fire. I know of an incident in a local engineering firm (now, alas, closed) where an expensive CNC lathe was destroyed by a magnesium fire.
 
I suspect there are more issues than inflamability surrounding machining titanium as I have tried drilling holes in the stuff and find it work hardens like some stainless steels.
 
Minor point, but when magnesium burns in air the main product is white magnesiun oxide ( and smaller amounts of magnesium nitride and possibly trace amounts of carbon) I would not worry too much about the basic nature of this oxide as it is the active ingredient in many antacids used to treat indigestion (Milk of Magnesia)
 
Carbon Tetrachloride is very nasty and should be avoided at all costs. It is thermally decomposed to carbonyl chloride, also known as phosgene. The mustard gas reference is an understandable misconception as both were used in chemical warfare. The long term dangers of carbon tetrechlorde include cancers so find another safer solvent.
 
In general, treat all organic solvents with respect. They are miscible with the fatty membranes that surround cells, especially nerve cells in your body so it should be no surprise that they are bad news. I remember seeing glue sniffers at Birmingham New Street station in the late 1970s. An image that should serve as a reminder of the dangers of solvents.
 
A couple of things that have not be mentioned yet in this thread are cadmium (found in Easyflo No.2 silver solder) and the dangers of welding galvanised steel.
 
I remember a lot of information in the Model Engineer about the nature of the dangers from cadmium in silver solders. As I recall there was a fatality where the engineer had been engaged in silver soldering, but I don't know if it was the cadmium to blame. I think the advice at the time was to avoid cadmium bearing alloys, but if you needed to use cadmium bearing alloys to not use oxy-acetylene (too hot for silver brazing anyway) and to work in a well-ventilated space. I think Tubal Cain published some estimates of the air-bourne levels of cadmium that seemed very low as long as common sence precautions were followed, but I wonder how they stand up against modern advice. Cadmium is a nasty cumulative poison and suspected carcinogen.
 
Welding galvanised steel is another bad idea.
 
Bob
Thread: Milling on a lathe
12/11/2009 13:32:25
Hi All
 
I agree that a slot drill can be used to flat bottom or counterbore a hole, but take great care, especially when counterboring this way. If the lip of the slot drill takes hold of one side of the hole it can exert a lot of force on the work/machine and if there is not sufficient rigidity something will give. Either the work will move or the slot drill will break. Best to use a twist drill to at least start the counterbore before finally squaring off the bottom. A better solution is to use a proper counterbore with a fixed pilot.
 
With regard to holding slot drills, remember if they are not central to their axis if rotation they will cut oversize so collet chucks or accurately bored holders (like FC3 holders) are the way to go.
 
No experience of using ER collets, but as long as the stock you fit into the collet is well finished, parallel and to size or a tiny (say 0.002" under no more) then you should have no problems.
 
Bob
Thread: Non Myford/mini Lathe
28/10/2009 00:56:38

Hi Don
 
I agree, older machine tools are excellent value and in my opinion often out-perform some other well-known machines favoured by many model engineers.
 
But it seems we might be in a minority here!
 
Bob
Thread: Milling collet arbor jammed in milling machine
19/10/2009 12:20:27
Hi John et al
 
I would suggest that good old machines are a viable way ahead for many model engineers. Over the years I have been involved with many machine tools that would be considered small by industrial standards but vast by model engineers. Most of these machines have been ex-industry or ex-education and been lightly used. They are big, they are three phase and they are heavy, but that's what I like.
 
To compare costs my current lathe a Smart and Brown Model A toolroom lathe cost £500 delivered to my door. It takes up about the same floor area as a Boxford CUD (OK just a bit bigger) and needed some work to run on a single phase supply, but compared to my ex-education ML7 is an infinitly better machine, screw-cutting, Norton box, taper turning, good set of collets etc and with a little inginuity most Myford kit can be adaped to fit the S&B. Now that machine stands easily in the end of my single garage workshop and turns very true.
 
Another example was an Archdale vertical mill brought for £200 at auction. A big job moving it but an excellent machine (Int 40 btw)
 
Machine tools like this turn up all the time. Look for auctions in your local paper and be on good terms with your local scrap metal dealers.
 
Remember, you can do a small job on a big mill, but the other way is difficult. 
 
 
Bob
19/10/2009 12:03:40
Posted by chris stephens on 16/10/2009 18:17:47:
Well, Morse 2 was good enough for Mr Westbury, when he re-worked the Dore-Westbury mill, and a great deal of fine work has been produced on that machine over the years. 
Expediency far out ways idealism.
chris stephens
 Hi Chris
 
I would agree with No. 2 Morse on a light vertical mill going upto about a 3/8" or even 1/2" cutter my issue is with No. 3 Morse and larger and longer cutters held in Autolock type chucks. I can only report on What I have observed and I have seen problems with that particular combination. The International type chuck is to be prefered as more of the shank of the tool is accomodated insde the quill of the machine resulting in less overhang and so better surface finish/ less vibration etc.
 
I have used a Dore Westbury mill but I an not a great fan of those either.
 
Bob
16/10/2009 15:58:20
Hi John
 
Quote " Can you name me one benchtop mill or mini mill that has an International 40 taper ?" End Quote"
 
Quite so, but I would avoid a benchtop mill or a mini mill also!
 
Bob
14/10/2009 17:50:31
Posted by Peter Tucker on 22/09/2009 04:54:33:

<snip>
All MT mills will have a slot for a drift; however my meagre experience is that the drift dose not shift a tight taper.
 
<snip>
 
Oh what a thing it is to generalise...
 
The Victoria Universal Mill's vertical head is No. 3 Morse and most definitely has no slot for the ejector drift
 
I would be concerned about any miller with such a quill that would allow a normal drift to be used to eject the taper as I would doubt its rigidity. Fine for drilling machines but not for mills.
 
I also do not think that big collets chucks should be mounted on Morse tapers, there is not enough metal at the point where the chuck joins the taper. I have seen a Clarkson (reputable manufacturer) 1 1/4" autolock mounted on a No. 3 taper bend at the point where the chuck joins the taper after a nasty snarl up.
 
Finally, I would avoid using Morse taper tooling on Milling machines for the reason that it might be impossible to remove from the taper if it is flogged up too tight. That's why mills use 40 International tapers which are much steeper and in my experience do not jamb in the taper. Also the drive is not taken on the taper, but by separate lugs.
 
Bob
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