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Member postings for David Davies 8

Here is a list of all the postings David Davies 8 has made in our forums. Click on a thread name to jump to the thread.

Thread: Inverter connection problems
11/10/2020 06:02:07

Zan

you have readings for 7-8 & 8-9 of 4.1 ohms. You don't show one for 9-7. If this also reads 4.1 ohms this proves that there is a star point buried in the motor windings. (The value of 4.1 ohms is equal to 1.732 x 2.4 ohms).

Following your link diagram taken from the motor, the low speed connection is double star, where 4,5 & 6 form the other star point and linking 1-7, 2-8 and 3-9 puts the two star configured winding sets in parallel.

If I knew how to attach my sketch I would.

HTH

Dave

Thread: Standard steel tube sizes vs bearing sizes
25/09/2020 08:14:05

If you can get hold of some schedule 160 pipe, nominal 63.5 od, that has a wall thickness of 9.52 so plenty of material to form a shoulder. Try local tube stockists or hydraulic engineering firms for an off cut.

HTH

Dave

Sorry mis-read table. Nom 50.8 bore schedule  160 tube has  60.3 od and a wall of 8.7. This gives a bore of approx 43. Would that suit?

Edited By David Davies 8 on 25/09/2020 08:22:51

Thread: Strength of Beams
10/09/2020 11:28:13

''The I girder can be modified to become a castellated beam yielding greater depth and stiffness for the same or slightly less weight.''

 

As often seen on frames for HGV semi-trailers.

 

Dave

Edited By David Davies 8 on 10/09/2020 11:29:29

Thread: New Moderators
07/09/2020 07:51:21

Yesturday I cudnt spel injuneer, 2day i are wun. cheeky

Dave

Thread: COMPRESSION RATIOS
02/09/2020 16:46:10

"Doesn't seem that much to crow about, Harley at 1200cc being faster than Manx at 500cc"

Duncan

the side valve Harleys in question were KR 750s not 1200s . The Manx was an overhead cam motor.

Cheers

Dave

Thread: Boiler
30/08/2020 19:22:33

Kevin

Tubal Cain's 3 inch boiler is listed as a kit of parts and drawings by AJ Reeves. Possibly this is the one referred to above by Clive Brown.

HTH

Dave

Thread: Is a hand scraper pulled or pushed?
21/08/2020 17:38:34

Bob

on Youtube, if you search for 'lookcreations' you can watch Matt Look scraping no end of things including the ram on his Elliot shaper, beam straight edges and various parts of his Holbrook lathe whilst being renovated.

HTH

Dave

Thread: Burnerd ec collets...dismantling
17/08/2020 10:30:46

Just a thought, Caustic Soda would soften even the most obstinate dried oil/grease. Remember to add the caustic to water not the other way round and note that it will get hot when being mixed. Don't use it on aluminium. I know Caustic is nasty stuff but acetone is highly flammable.

HTH

Dave

Thread: Cowell Hand Shaper
13/08/2020 08:36:05

I have just had a shock upon seeing the prices being asked for secondhand copies of the above book. Assuming Mytime Media holds the copyright of the book would it be viable to reprint?

Any comment Neil?

Dave

13/08/2020 08:20:39

Gents

An auto downfeed is described by Ian Bradley in his book 'The shaping machine'', published by MAP many years ago. Secondhand copies are around.

HTH

Dave

Thread: Vfd sizing
09/08/2020 23:13:41

To elaborate on Emgee,s post, always use the full load current to determine the inverter size not motor power. Six and eight pole motors may have higher magnetizing currents than the usual two or four pole motors and hence will have higher flc which the vfd must be able to provide.

I found this out the hard way in work.

Dave

Thread: Viking Link Interconnector
09/08/2020 22:54:25

Because of the distributed inductance and capacitance of a long cable, with ac a distance is reached where the current carrying capacity of the cable is wholly taken by the charging current. You can,t get any power out at the end. Charging only occurs once, not every 10ms, with a dc cable and from then on power can be transmitted.

Dave

Thread: Melting bronze
02/08/2020 20:53:13

I can't answer your question directly as I have only cast bronze into sand moulds. l coated my skimmer and stirrer with "ladle paint" which prevented th bronze from sticking to the tools. It is available from all good foundry equipment stockists.

I have used your angle iron with end plates method many times when recovering lead.

hth

Dave

spelling!

Edited By David Davies 8 on 02/08/2020 21:13:21

Thread: Jobs
30/07/2020 23:04:35

Bazyle

surely politicians should be at the top of your list?

Dave

30/07/2020 22:57:07

Re parsimony.

I read the following some time ago:-

An engineer is someone who can do for 50p what any old fool can do for a pound.

Dave

Thread: Making sense of big numbers
25/07/2020 20:17:23

Hopper,

IIRC it was the entire works of Shakespear not The Lord's Prayer!

Cheers

Dave

Thread: Engineers' Level adjustment - why 4 holes?
20/07/2020 22:03:12

Gary

at the risk of me stating the obvious the level must be swapped end for end on your reference surface after each iteration. The reference need not be level but the bubble must be in the same position for both orientations.

regards

Dave

20/07/2020 06:17:14

Gents

I have a M & W ELS in bits in front of me. I still haven't got round to replacing the vial though I have obtained a spare vial. The outer screws hold the vial carrier to the level frame. The heads of the inner screws are beneath the vial carrier and 'jack' the carrier away from the frame..

Both bottom holes in the vial carrier are clearance holes, only the frame is tapped.

The replacement vial was obtained from Cromwell tools. (I have no connection)

HTH

Dave

Thread: VFD/Lathe fault
08/07/2020 10:50:01

"Now when I power up the VFD I get a reading of 0.00 but there seems to be no communication between VFD and the remote control panel, fwd/rev switches, the on/off switches and the speed control pot are all doing nothing."

Ron

Check the following parameters on the VFD or compare with any written setup data that you were given with the machine.

F01 Frequency command =1 , this enables voltage input to terminal 12.

F02 Run/Stop/Direction. =1, this enables external Fwd/Rev

F03 Max Frequency = 50.0, this is a basic setting , you may wish to increase but then you are into field weakening

F04 Base frequency = 50.0, (this should be set as the figure given on the motor rating plate)

F16 Minimum frequency = 10.0, not too low, when running slowly the fan is non-effective

taken from Cub handbook pages 5-3 and 5-4.

HTH

Dave, yes, another one.

Edited By David Davies 8 on 08/07/2020 10:50:42

Thread: Message from the prime minister
07/07/2020 16:11:27

Well, it made me laugh Duncan!

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