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Member postings for Russell Eberhardt

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

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Thread: Wheel cutting depth of feed
11/02/2012 21:02:46
Found this useful site: Designing Cycloidal Gears . It gives all the equations based on the recommendations in BS 978. The BS calls for a bottom clearance of 0.4M and thus the ratio of tooth height (cutting depth) to modulus will be constant.
 
Working through the equations I get:
Depth = 3.06 x M
 
This is close enough to the factor of 2.95 given for the smaller and larger sizes. I can only assume that the cutters sold for M 0.5 to M 1 have a non standard form, perhaps to give greater bottom clearance for some reason. I can't see why though.
 
Russell;
10/02/2012 19:06:39
Not really. I cn cut the wheels OK. I was just looking for a technical explanation of the tables.
 
Russell.
Thread: Metal work at schools
10/02/2012 11:14:10
Posted by David Clark 1 on 09/02/2012 15:27:28:
Hi Ady 1
I would disagree that they are going to be the safest.
Not having learnt the hard way, I doubt they have any safety sense.
regards David
 
 
Absolutely! If kids aren't exposed to any danger they never learn to spot it and avoid it. While I was at school I made fireworks and various explosives and had many electric shocks from my home projects. Wouldn't be allowed now.
Posted by jason udall on 09/02/2012 22:20:40:
new problem added...It has been stated that "Any firm taking on under 18s. Need to have all staff CRB checked and "Child Protection" trained...apprentiships or even employment for under 18's looks dead in the water.
When this idiocy was introduced I was teaching martial arts to children and adults as a volunteer for many years. I stopped teaching the children rather than pay for the checking and training. It's the children who suffer.
 
Russell.
Thread: Wheel cutting depth of feed
10/02/2012 11:04:19
Posted by Stub Mandrel on 09/02/2012 21:34:54:
My ageing Machinery's Handbook gives the total depth (i.e. cutter feed) as 2.157xmoduls or 2.167xmodule depending on whether clearance is 0.157xmodule or module/6 (the former being the American standard).
 
Whatever the source both of your figures seem way to high as the addendum =module and dedendum =module+clearance i.e. feed depth is module x 2 + clearance.
 
What is your source for these figures?
 
Neil
I think your figures are for involute gears as opposed to the cycloidal gears used in clocks.
 
The figures come from here: clock-works and the Meadows and Passemore catalogue.
 
Russell.
Thread: Metal work at schools
09/02/2012 14:01:47
If he wants to be an engineer keep encouraging him in your workshop but also encourage him to learn as much maths and physics as possible.  Engineering isn't just about manual skills.
 
Oh, and take him to the Science Museum and other engineering rich visits.
 
Russell (retired chartered engineer)

Edited By russell eberhardt on 09/02/2012 14:02:50

Thread: Wheel cutting depth of feed
09/02/2012 13:53:32
Can anyone explain why the depth of feed for modules 0 to 1.5 is given as 2.95 x M except for the range 0.5 to 1.0 where it is given as 3.38 x M?
 
This doesn't seem logical to me. I could understand a smaller module being different to a larger one but changing back again seems strange Or is there a misprint in the tables?
 
Russell.
Thread: old Simplex articles
09/02/2012 13:43:52
Joa,
 
Sorry, I haven't seen a suitable redesign. This is a bit of a grey area as different boiler inspectors have different ideas. A commercially made boiler is CE marked and complies with the pressure vessels directive and should be accepted anywhere in Europe whatever it's construction.
 
If you want to make a boiler youself and have it tested and used in the UK it is best to discuss it with the inspector you will be using before starting.
 
Russell.
08/02/2012 19:58:17
When considering the boiler you will have to consider any rules laid down in Germany for model boilers. The Simplex boiler as described will not be accepted by UK boiler inspectors and insurance companies as they don't like the T section crown stays. It is acceptable here in France but has to be fitted with a fusible plug which means you have to change the superheater design.
 
Russell.
Thread: Power Hacksaw run off
08/02/2012 19:48:54
Posted by Les Jones 1 on 08/02/2012 18:30:32:
I am impressed by its accuracy.

 
From the video it looks as if his foot was impressed by that large lump he cut!
 
Russell.
Thread: old Simplex articles
08/02/2012 10:06:58
Posted by Jo Thoms on 07/02/2012 20:00:44:If you search on http://freespace.virgin.net/simplex.steam/the simplex website: the guys should be able to help you with everything you need (including helping by identifying the numerous corrections to the published articale/drawings)

Unfortunately this site hasn't been updated for several years. There is useful information there but there does'nt seem to be anyone to contact.
 
Russell.
07/02/2012 15:27:15
David,
 
What is your line on people requesting or sending PDF copies of articles for personal use? Is there a copyright problem?
 
Russell.
Thread: Digital Issues
07/02/2012 10:26:55
Are there any plans to expend the issues of M.E. further back? I would love to be able to put my back numbers out of the way in the attic.
 
Russell.
Thread: Serendipity
05/02/2012 14:19:55
A few years back, when I moved into a rented house I also found an engineers square - along with some toolmakers clamps, files, a micrometer, and best of all bench shears. Spoke to the landlord and he didn't want them so they left with me.

Russell
 
Thread: Is this scrap?
05/02/2012 14:08:11
Harold Hall published a design for a jig (or is it a fixture?) for sharpening slitting saws on his grinding rest. I have built one and it only takes a few minutes to sharpen the saw while it takes several days to get a new one sent mail order!
 
Most small mills run the spindle much too fast on their lowest speed for using a slitting saw. That was my initial reason for fitting a variable speed drive.
 
Russell.
Thread: 9x20 Lathe Parts
04/02/2012 21:10:40
Thanks for all the replies. I now have the manual.
 
Russell.
Thread: Quality of Engineer's squares
04/02/2012 10:48:53
A cheap source of cylindrical squares is old gudgeon pins from a car scrapyard. I have a pair of Rover 2000 ones that I have used for years. They are precision ground to a couple of tenths under 1" dia. and just under 3" long. I'm sure something bigger could be found from a truck.
 
Russell.
Thread: 9x20 Lathe Parts
04/02/2012 10:31:41
Posted by wotsit on 13/01/2012 20:20:58:

This site has a good copy of a rebuild manual from Cletus Berkeley (it used to be in the Yahoo Group at one time) - it refers to the Grizzly version, but fits most makes.

 

Does anyone have a copy of this file or a working link? The above link is broken.
 
Russell.
Thread: Lidl cast steel vice-16.99
04/02/2012 10:15:21
Posted by John Stevenson on 04/02/2012 00:49:42:

Same with printers, these are sold with 30% filled cartridges and they make their money on new consumables. So now just buy one, run it until it runs out of ink then bin it.
.
..or just refill the cartridges with ink or toner yourself. It's a bit meesy but much cheaper.
 
Russell.
Thread: graphite yarn no thanks o-rings yes please
04/02/2012 10:04:17
Posted by JasonB on 04/02/2012 07:38:04:
Get a copy of "Model Engineers Handbook" the tables in that give sizes specifically for our use on pistons as well as the usual type seals.

I agree. It's a very useful book by "Tubal Caine" and full of indispensable info.
 
Regarding the "O" rings, There shouldn't be any "nip" between the bottom of the groove in the piston and the bore as suggested by some. This will just give excessive wear.
 
The bore should be exactly the nominal OD of the ring. This will give slight compression of the ring. There should be less than about 5 thou diametrical clearance between the piston and bore to prevent the ring from extruding between the bore and piston. The depth of the groove should be sufficient to give a slight clearance to the ring, just a few thou deeper than the ring section. The groove width should be about 10 thou greater than the ring section to allow movement.
 
The seal isn't produced by pinching between bore and piston. The steam pressure pushes the ring against the side of the groove to obtain a seal, hence the necessity for the groove to have some side clearance.
 
However, don't believe me, get Tubal Cain's book.
 
Russell.
Thread: 15-day Skeleton Timepiece
27/01/2012 17:03:52
Thanks
 
Russell.
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