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Post by modeng2000 on Jul 25, 2006 6:02:52 GMT
I would appreciate it if someone would look up a couple of items printed in ME so I would know if I have the right references before trying to get copies.
They are from Smoke Rings and are titled 'Sparking oddity'. Volume 178, Number 4044, Page 729 and Volume 179, Number 4048, Page 189.
If my memory is not playing tricks the items should be about a spark engraver and I believe Ted Jolliffe was the originator.
Many thanks in anticipation.
John
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Post by baggo on Jul 25, 2006 8:02:55 GMT
Hi John,
The oddity referred to is actually a hot vulcanising clamp, not a spark engraver as you thought,
John
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Post by modeng2000 on Jul 25, 2006 10:42:28 GMT
Hi John,
Many thanks for that.
I guess I'll have to keep looking.
John
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Post by baggo on Jul 25, 2006 12:17:37 GMT
Hi again John,
I did do a search through my index which covers all of ME from the first issue but could find no mention of spark engraving. I remember an article on building a spark erosion machine but not engraving.
John
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Post by modeng2000 on Jul 25, 2006 18:52:57 GMT
Thanks John for your interest.
This gadget I am trying to find out about was a hand held spark engraver much like a conventional vibrating engraver in design. It worked by having a plunger vibrate up and down against the work piece, this vibration was achieved by an armature inside a solenoid. The engraving point attached to the armature was electrically in series with the coil and workpiece. When contact was made with the work, the armature would be attracted into the solenoid and so break the circuit. Each time the gap appeared there was a spark caused by the back emf due to the collapsing magnetic field in the solenoid. Then the engraving point would fall back onto the work and so it would start over again.
It would seem to be a fairly strait forward device but I did not want to re-invent the wheel if I didn't have to!
John
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Post by houstonceng on Jul 26, 2006 21:39:39 GMT
John
I remember that type of engraver from early days at work. We "Juniors" were required to mark our tools with it. Sorry. Can't remember the make after 40 years.
Andy
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Post by modeng2000 on Jul 27, 2006 11:52:23 GMT
The thing aboit the spark engraver is that it can mark hard materials which is really why I am interested.
John.
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jbrv
Member
Posts: 3
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Post by jbrv on Aug 17, 2006 9:04:42 GMT
I remember the article in M.E., if I have timi in the weekend I will look at my index to see if I did a note about the article.
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Post by modeng2000 on Aug 17, 2006 15:33:39 GMT
Thanks, that would be most helpful. I still have not found it.
John
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Post by colinabrey on Aug 18, 2006 18:41:46 GMT
Hi John, There is an "Electro Etch" marking tool described in Trade Topics, Vol 162 (No 3848) 5th May 1989 page 577. Perhaps that is what you are looking for.
Regards
Colin
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Post by modeng2000 on Aug 18, 2006 19:10:58 GMT
Colin,
Thanks for the reference. I shall go to the library next week to look it up.
Off to Thornbury tomorrow for the Bristol exhibition.
Regards,
John
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jbrv
Member
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Post by jbrv on Aug 24, 2006 16:30:22 GMT
The article is "Electromagnetic Etching Pen", nO. 3952 page 292.
Now I know that my index have a good use.
Cheers
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Post by baggo on Aug 24, 2006 17:38:22 GMT
Aha! That's why I couldn't find it - I was searching for engraving rather than etching!
One point to mention about the power supply - I would recommend that one side of the secondary winding from the mains transformer should be connected to earth. Otherwise the whole equipment could become live if the transformer developes a fault.
John
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Post by modeng2000 on Aug 24, 2006 19:03:45 GMT
Many thanks folk.
I am well aware of the potential to get a shock if the part you hold is not insulated or at earth potential. The spark is generated by the back emf that arises when the magnetic field collapses on breaking the circuit.
I used to have a SEI shocking coil many years ago that used the same principle.
Many thanks,
John
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Post by modeng2000 on Nov 14, 2006 16:41:34 GMT
At long last I have today been to the library to look up the references for this etching/engraving tool.
Unfortunately one of the references was missing, in fact two volumes were missing from the library's collection. The reference librarian suggested that someone most probably had taken them.
Is there anyone who would email me the item in ME No 3952 page 292 please?
John
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Post by baggo on Nov 14, 2006 17:17:36 GMT
Hi John,
If you send me a pm with your email address I'll do that for you,
John
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Post by Phil Sutton on Nov 14, 2006 20:17:41 GMT
While we are on the subject,does anyone know if "Didcot" was serialized in the ME?I Don't have many back copies,but I may be able to get access to some.
TIA
Phil
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Post by baggo on Nov 14, 2006 20:38:31 GMT
Hi Phil,
No, Didcot did not appear in ME. Martin Evans descibed Dart which is the 7.25" version. I don't think Neville Evans did a write up for Didcot, although I could be wrong,
John
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Post by modeng2000 on Nov 15, 2006 7:09:49 GMT
Thanks for your help John. You can't have much time to do modeling after all the help you give forum members  John |
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Post by baggo on Nov 15, 2006 13:02:16 GMT
Don't worry John, I'm virtually retired and live on my own so I've got plenty of time for actual engineering work ;D It's the money to fund it that's the problem  John |
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