Oct. 2018
Bluewater Bulletin
Bluewater Model Engineering Society Sarnia, Ontario
Vol. 34 No.1 October 2018 Editor John Lovegrove
Our next meeting will be on
November 12th, 2018 @ 7:30 pm
Northern Collegiate Room 125, Indian Road, Sarnia.
The October Meeting
As usual we started with the treasurer’s report and again we are OK financially. The annual subscription has been reduced to $10 until further notice but this may have to be revised at some point because of what will be discussed next.
As mentioned in the notice sent out prior to our first meeting; the school board has made some further changes which make things more difficult for us.Firstly, they have made another room change so that we are now in room 125. This is a regular class room and fortunately it did work out very well. The second is that we are now having to pay for rental of the room in addition to insurance and admin fees. Costing is therefore as follows: Insurance $20, insurance processing fee $10, permit application fee $15, then,we will be paying $7.50/h for the room, which means$15 each month for the 2 hours we normally have.
There must have been some squawks from other user groups because they have now waived the fee for the first 4 meetings this season but we will still have to pay $15 for each of the remaining 5. Next year we will probably have to pay for every meeting. They have also changed the user categories somewhat so that to qualify for free usage we would have to be a registered charity (which we are obviously not.) We are in fact treated as a not-for-profit organization(category 5) but Bruce has had to provide an affidavit
to that effect, along with a financial statement for the club. (Oh joy!)
There was some discussion about, whether other
facilities may be available that are free of charge but I personally do not know of any: City facilities are$20/h and the church halls I know of are
~$35/session. Insurance is in addition to this. If
anyone knows of any other facility that may be a
lower cost option please go and fully check it out and send me the details.
Being the first meeting of the season, it was also the occasion for election of the club officers. Following this, the executive will mainly remain the same with Bruce Mannerow as President, Nick Jonkman as Treasurer and me (John Lovegrove) as Secretary/Newsletter Editor. Don Hayes will take over Librarian duties from Keith Orr.
The only activity the club was involved with during the summer was Hobbyfest. This had been moved from the third Sunday in July to the last Saturday in
August. It was also moved from Centennial Park to
Germain Park and with shorter hours. A few of us
went along with our models but attendance was
disappointing and towards the end of the morning the rain started pouring down. Fortunately, our tent kept the water off our exhibits but when there was a break in the weather we packed up and went home. A side from the weather, the whole set-up was not very satisfactory with some exhibitors inside the building and others scattered in different locations around the grounds. Many thanks to those who did come along but we were not left with much enthusiasm for exhibiting next time (assuming there is one.)
Bruce did have a few workshop items to discuss: One was a Joe Pi tip for holding undersize stock in a 5C collet. Unlike ER collets they do not accommodate a very wide diameter range so if the stock is a little under the nominal size the difference can be made up using a piece of paper wrapped around it.
Another item he mentioned was the low-cost air
powered “die filer” that is available from Harbor
Freight. In fact, Tony Koolen and I each bought one
while we were on a trip in the US. I have tried mine
and it does work fairly well but it is quite crudely made and the air consumption is high. (My 5hp compressor barely keeps up.) It is about what you would expect for ~$US17.
CNC mills provide what is known as “rigid tapping”
whereby the rotation and downward movement of the head are synchronized to correspond with the thread pitch of the tap being used. This happens both while cutting the thread and withdrawing the tap. Again, I wonder how this works out with very small taps.
As often happens there was discussion that started on one topic then morphed through several others. In this case it started with how the Henry Ford Museum in Dearborn has been “hollowed out” since it was sold off by Ford. There was concern that other museums
of a technical nature may be going the same way.
Larry Stevens had visited the National Maritime
Museum in Greenwich, London, England and
commented on the quality of the exhibits – particularly the collection of chronometers (sea clocks) made by John Harrison that were on display at the time. Harrison basically solved one of the more pressing problems of the period; that of being able to determine the longitude of a ship by accurate time keeping and observing the position of the sun. However, he was never given the credit he deserved mainly because he was a craftsman and not one of the scientific elite. A few years back there was a television series about this and an excellent book entitled “Longitude” by Dava Sobel. The key to accurate timekeeping in a conventional (mechanical) clock is mainly compensating for the effects of temperature. As I recall, Harrison started with pendulum type clocks and the problem with these is that the rod supporting the pendulum bob gets slightly longer in warmer weather so the oscillation slows and the clock loses time. His solution was the
so-called grid-iron pendulum which uses an iron rod going down so far, brass rods coming back up some way, then iron rods going down from the top of the brass rods to the pendulum bob itself. With the thermal expansion of brass being greater than that of iron, by choosing suitable lengths for the iron and brass parts, one can (theoretically) keep the effective length of the pendulum constant, irrespective of temperature.
Pendulum clocks do not work at sea because of the ship’s motion so he used an oscillating balance wheel in the sea clocks, essentially the same as those used in mechanical watches. However, thermal expansion is still an issue because the wheel expands with temperature increasing the moment of inertia and slowing the oscillation rate. (A similar issue to that with pendulum clocks.) I did see the collection of clocks in Greenwich during a visit to England but I
cannot remember the details of the temperature
compensating arrangement he used.
The discussion then morphed to the subject Invar.
This is an alloy of iron with 36% nickel, formulated to have a minimal thermal expansion and would
Show and Tell
Bruce seems to have been the only one to get very much done during the summer. (Looking back, I made the same comment last year.) The picture shows progress on his 4½” Howitzer. The rather tricky component is the worm box that is part of the system used to elevate the gun barrel. Most worm gears have the shaft axes at right angles but in this case the worm is offset from this by its (mean) helix angle. This means that the teeth on the wheel can be straight cut. Bruce is making this a simple spur gear; the contact areas may not be as great as in a proper worm and wheel arrangement but it is good enough
for these purposes.
He also talked about an article in Popular Mechanics on a reversible tapping head. This prompted some discussion because a few of us have bought/obtained versions of these to use in a mill etc. I wonder whether anyone has had the courage to use one with a very small tap in a component where breaking the tap would be a disaster? As an aside, the higher end
therefore be a good material for making critical clock components. Out of interest I did look up some thermal expansion data in Engineering Toolbox. This is a table of some common materials.
Material μ
(10-6 m/(m.K))
Aluminum 21 - 24
Brass 18 - 19
Borosilicate Glass 4
Invar 1.5
Pure Iron 12
Nickel 13
Plastics 40 - 120
Fuzed Quartz 0.55
Steel 11 - 12.5
316 Stainless Steel 16
Wood, parallel to grain 3
Wood, across grain 30
The units may seem strange but translating to a
readily understandable form, the number is basically how many millionths of an inch a 1 inch length of the material expands for each degree centigrade rise in temperature.
The information shows just how much better Invar is compared with most other materials. It is also
interesting that a combination of metals in the right proportions gives a coefficient almost an order of magnitude lower than either of the component materials. I have included quartz in the table because electronic clocks and watches rely on a quartz crystal oscillator for their time base. Wood is included because this has been used in clocks and it has some obvious virtues for making the pendulum rod.
Finally, just a few links of things that may be of
interest; from Bruce:
This one shows some fantastic craftsmanship.
https://vimeo.com/288711470
This is the web site mentioned at the meeting. It has free calculators for gear and belt lengths.
https://www.wmberg.com/resources/tools
He also mentioned that Joe Pie is making a small
brass cannon
https://www.youtube.com/watch?v=ZuxYcbxPuiI&inde
x=3&list=PL4wikbEbcE3LKMZi5aP5JbYfBYVxFXMw
Z
and here is the video showing how to make chain for the cannon.
https://www.youtube.com/watch?v=BjM4AZXAZo8&lis
t=PL4wikbEbcE3LKMZi5aP5JbYfBYVxFXMwZ
This is another site about engineering history etc.
https://www.youtube.com/channel/UCfsznjef2zGJnrC
RQBXqo6Q
From Nick Jonkman; this one is about making steel:
https://www.popularmechanics.com/technology/infrast
ructure/a20722505/history-ofsteel/?
src=nl&mag=pop&list=nl_pnl_news&date=0709
18
occasionally there are some new items. I knew that
they had an early diesel engine there and my
recollection was that it came from the Henry Ford
museum. I checked this out and in fact it did:
The other item, brought along by Tony Koolen, was really another in the “what the heck is it” category.
It is a 1903, 12hp engine made by MAN Maschinenfabrik Augsburg-Nürnberg) and is directcoupled to a generator. After this, I took a closer look at the information they have on some of the other engines and found two more that came from the Ford museum; an Otto Gas Engine and a Crossley Gas Engine. These three items have at least found a good home where they are looked after by knowledgeable people and can be seen by engine enthusiasts.
Remaining Meetings this Season
2018
December 10th
2019
January 14th
February 11th
March 18th (11th is March break)
April 8th
May 13th
June 10th
Our Website
https://sites.google.com/site/bluewatermes/
John Lovegrove
No one really knew what it was but it was certainly very nicely made. The best guess was that it was part of some kind of grinding jig.
Visit to the Coolspring Power Museum
Tony Koolen and I went to the October open day at the museum in Pennsylvania. We have been before
but it is always good to have another look around and