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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.

Thread: Carbon fibre pendulum rod
11/08/2020 15:52:47

I did measure the Q factor of my pendulum with all fittings. I can't find my notes just now but I think it came out at about 6000. Easy enough - set it going and count the number of cycles it takes to decay to 37% of it's starting amplitude. Multiply that number by 2 x Pi to get the Q. The most important factor is the air resistance so best to use lead or even uranium for the bob and an aerodynamic shape. I stuck with steel not having uranium to hand!


10/08/2020 19:30:55

The supplier of the pultruded CF tube I used for my regulator quoted -0.1 to -0.3 ppm/C. I used a threaded bottom fitting for the rod for use with a regulator nut at the bottom of the bob. I calculated that making the transition from CF to steel 30mm below the centre of the bob would compensate for 0.2 ppm/C for the rod with a small positive contribution from the suspension.

Seems to work fine.


Thread: Another new member
09/08/2020 11:47:41
Posted by Peter Cook 6 on 09/08/2020 11:13:26:

Thanks. No plans for clockmaking! I have rather too many clocks as it is. In any case clockmaking would involve gear cutting and (after so many years in IT) I am averse to highly repetitive activities. That is what computers are for.

So clock making probably lies on the far side of a timeline that includes CNC - and I have a LOT to learn before I even contemplate that.

Hello and welcome Peter

I was always interested in clocks having taken old alarm clocks apart as a teenager to see how they worked. Most of them went back together and continued working!

In my retirement my wife bought me a Vienna regulator (American) on Ebay and I restored that and was pleased to get it working. Later, on researching my family tree, I discovered that three generations of my ancestors were watch and clock makers so I took the plunge and started clock making as well as repairing clocks for friends. Making gears (more correctly called wheels and pinions) isn't that tedious.

Your new mill is very good for small items and could be converted for CNC. I have an SX2P which I have converted for CNC and find it very useful for crossing out wheels which is more difficult than cutting the teeth.

Have fun.


Thread: Cleaning emergency !
04/08/2020 19:52:13

Replacing the floor covering in a camper van is by no means easy. The flooring is usually laid before the installation of the furniture so everything must be removed including the kitchen sink!

A possible alternative is to use floor paint. This is a useful guide: **LINK**


02/08/2020 21:42:34

Try Googling "Plasticiser migration". I think you're stuffed.

When manufacturing electronic products we used to have to be carefull how they were packaged to prevent the plasticiser from the power cable ruining the plastic case of the unit.


Thread: Opions sought on using the USB Photo Stick for photo storage
30/07/2020 10:24:38

Have a look at MEGAsync. Will automatically sync any folders on your computer with cloud storage. You can also set it up on your mobie phone to automatically upload photos (only when the phone is on charge so as not to flatten the battery). All free of charge for up to 50 Gb IIRC.


Thread: Why is there no side relief on a wheel cutter
28/07/2020 10:30:07
Posted by Clive Steer on 28/07/2020 09:45:44:

To see the machine check out Petermann on the site.


Some other fantastic machines in the Petermann range. Lathes with tool setting thimbles calibrated to one micron diameter!


Thread: Slitting Saw Arbor
19/07/2020 11:57:01
Posted by JasonB on 19/07/2020 07:00:16:

MC B, the stepped ones work OK if reasonable quality though I think there have been some poor ones about in the past which has given them a bad name.

Yes, I bought one several years back and it was absolute rubbish. The stepped circles were far from concentric. I stick to single size ones now.


Thread: Carbon fibre pendulum rod
19/07/2020 11:41:51
Posted by Emgee on 18/07/2020 23:26:52:

I'm sure that if anyone on here needs any specific shape or size of carbon rod/tube it could be produced by some of the current membership, at reasonable cost of course.


That is if anyone has the equipment to do pulltruding. A normal lamination will not be stable enough.


19/07/2020 11:40:27
Posted by Alan Crawley on 18/07/2020 17:41:45:

I have one other small query about the CF rod, will it be ok where it is subjected to the friction of the crutch? This consists of two 3mm silver steel pins in a brass disc that can be rotated to adjust clearance to the pendulum rod. I would like to thank everyone who has taken the trouble to help me with my project.

I had the same worry at first but my regulator has the same type of crutch and, after five years of running, I can't see any mark on the CF tube.


18/07/2020 17:20:37

I used a pultruded carbon fibre tube for the pendulum of my regulator. I used 7 mm O.D. and 1 mm wall thickness. It has supported a 5 kg bob for the last five years without problems. I used slow cure Araldite to glue steel fittings to the ends. The fibre tube manufacturer quoted -0.1 to -0.3 ppm/°C and I have no reason to doubt that. You have to remember that the bob, suspension, and rod end fittings will all have a positive expansion coefficient but the threaded end of the rod for the regulating nut, combined with the bob itself can be made to approximately balance the expansion of the suspension.

The only unexpected effect I noticed was that the clock gradually slowed down over the first six months or so as the rod crept under load but it then settled down. I guess that was a result of the stress being redistributed from the epoxy to the carbon.

Hope that helps.


Thread: Vfd sizing
14/07/2020 16:57:13

I would go with the 0.5 kW one. De-rating electronics generally leads to improved reliability.


Thread: Con rods, stressman needed
14/07/2020 16:45:26
Posted by Dave Smith 14 on 14/07/2020 14:33:19:

The other thing is they lighter, you remove mass from the point where you do not not want it. Buckling comes down to stiffness again for a given load which is controlled by the cross section as you say. In my racing days we did as much as we could to take the mass out of the pistons and the little end of conrods.


Yes. Many years ago I restored a vintage sports racing car that had the OHV push rods originally produced by a knitting needle manufacturer as they were experienced in making fish bellied rods!


Thread: Hose thread queery
14/07/2020 16:31:54
Posted by fizzy on 13/07/2020 21:04:01:

well im none the wiser...just read that it might relate to NPT.....who knows?

I'm pretty sure that you will find that the 3/4" refers to the OD of the connector and that it will be 1/2" BSP.


Thread: Classic Cars - Driving London to Edinburgh in Top Gear
14/07/2020 16:24:06
Posted by john halfpenny on 14/07/2020 10:12:31:

Russell has omitted to say that this classification applies to cars, but motorcycles are treated differently.

and, of course, here in France vintage has a totally different meaning hic!

14/07/2020 08:57:20
Posted by not done it yet on 11/07/2020 16:35:09:

These vehicles of pre WWI are classed as ‘veteran’, not ‘classic’,

The accepted terminology ( according to the VCC and VSCC) is:

Pre 1905 - Veteran

1905 to 1920 - Edwardian

1920 to 1930 - Vintage

Certain makes and models 1931 - 1939 - Post Vintage Thoroughbred

Classic - I don't know of any official designation.


Thread: Hose thread queery
13/07/2020 15:39:24

It gets more confusing. Here in France 1/2 in BSP thread is called 21 mm, 3/4 BSP is called either 26 or 27 mm.

Note - Colin, 3/4 BSP has thread OD about 33 mm not 20 mm.


Edited By Russell Eberhardt on 13/07/2020 15:54:46

Thread: Pulley Sizes For An X2 Clone Conversion
23/06/2020 11:13:05

Have a look at timing belts and pulleys. The pulleys are available down to 10 tooth. I used a pair for my cnc conversion of an SX2P to enable me to move the motor closer to the spindle and give room for the z-axis drive. No problems with it.


Thread: Wooden Gears
14/06/2020 17:07:43

Robbibs Timber supply marine ply to BS standards from 1.5 mm up. 5 mm up is available in five or more ply. Varnishing with epoxy resin should give good strength. They can supply full sheets or cut to size. I've had excellent service including delivery to France.


Thread: Beginner's engine build. Simplex 5"g.
09/06/2020 11:26:21

I may have missed it but I don't think anyone has mentioned yet the need to aneal the frame material before cutting. If you are using BMS it tends to distort after cutting out for the axle boxes.


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