Edited By Windy on 19/05/2011 14:55:54

Edited By Windy on 19/05/2011 10:57:16

Finally bit the bullet and bought a new Warco VMC at Harrogate.

Had spoken to some VMC owners and found out about its limitations.

Eventually I will put a raising block on the head.

Please has anybody got drawings of the head dimensions that I could borrow?

I realise that it is a relatively light machine and was told end mills above 0.5” could cause vibration of the head.

It has been suggested that the head could maybe be filled with possibly epoxy filler to dampen any vibration.

Any advice gratefully accepted.

Windy

Edited By Windy on 19/05/2011 00:01:12

Edited By Windy on 03/05/2011 23:26:53

Edited By Windy on 30/04/2011 13:43:59

Edited By Windy on 29/04/2011 19:36:00

Edited By Windy on 29/04/2011 19:38:27

According to a magneto specialist this was a common problem with some of the carbon brushes from India.

Edited By Windy on 16/04/2011 15:13:51

Edited By Windy on 01/04/2011 13:25:52

Edited By Windy on 05/03/2011 23:34:52

Windy.

Edited By Windy on 11/04/2010 09:57:24

Thanks all for your comments it seems the cheap optical one comes out tops.

Have tried reflective tape, white paint and black tape on a bright background as suggested, the readings on the 2800rpm motor where all very close to 3000rpm.

Will borrow my mates old ignition strobe and do a comparison.

Edited By Windy on 22/02/2010 23:58:27

I have bought a new £26 optical rev counter and would like to check the accuracy of it at high rpm and how can it be checked in a home workshop.

My mechanical counter reads 2850rpm
On a quality 25,000-rpm motor minimum optical reading was 30,000 over 5,000 revs out.

An article that I read on speed testing of electric motors says a strobe should be used?
I require to check a speed range around 70,000 rpm the optical goes up to 99,000rpm.

A visual slow  speed test was done on my lathe i.e. Slowest back gear was selected and a mark placed on the chuck backplate then rpm counted against a stopwatch for a minute.

The lathe speed plate says 50rpm, my stopwatch test gave just over 62rpm, the optical rev counter read 62.4rpm and a mechanical rev counter said 60rpm

My mechanical counter only goes to 20,000rpm.

At slow speeds the optical counter is reasonably accurate but when the revs go above about 2000rpm there are large discrepancies compared to the mechanical counter.

Any suggestions or are these lower priced optical rev counters unreliable at high speeds.

Windy

Edited By Windy on 22/02/2010 17:00:45

Edited By Windy on 22/02/2010 17:01:53

Edited By Windy on 22/02/2010 17:05:24

Edited By Windy on 22/02/2010 17:11:16

Hi Meyrick, I haven’t had much to do with Viton O rings of that size as alternatives to metal piston rings but would PTFE ones be any better there is also Kalrez it has the same advantages as Viton but it has greater chemical and temperature resistance. However Kalrez is considerably more expensive than Viton.

Windy

Edited By Windy on 17/02/2010 01:06:41

Sorry about shooting off at a tangent from small hole drilling.

Amazing that something that Gustaf de Laval in 1888 did for use on an impulse steam turbines is now used on the majority of rocket engines today.

One of my 1911 books shows a gas turbine design not too different to a modern one.

It seems that a lot of mechanical and theoretical ideas are very old but with modern materials become a reality.

I have a great deal of information on the delaval nozzles for impulse steam turbines and am using that as a basis for the design of them.

Edited By Windy on 14/02/2010 20:17:49

Edited By Windy on 14/02/2010 20:21:49