DIYAPASON-L Digest #521 - Monday, February 18, 2002
 
Solenoids
  by "Pieter Smit" <pieter@cadence-engineering.co.za>
Re: [Residence Organs]  Re: Winding magnets
  by "Tony Newnham" <organist@tsnp.fsnet.co.uk>
Re: Repeat messages
  by <Jess4203@aol.com>
 

(back) Subject: Solenoids From: "Pieter Smit" <pieter@cadence-engineering.co.za> Date: Mon, 18 Feb 2002 08:28:34 +0200   Hi Christopher,   A local organ builder here in SA tried building magnets many years ago. They also did not work, but on analysing the problem, I found that the curvature of the armature was wrong. When the magnetic field is applied, the armature would rather move halfway out, instead of in. This can be fixed. In your case, make sure that the air gap between the armature and the field coil iron actually DECREASES when the armature moves towards its intended open position. Anything where the armature increases the air gap, will cause the armature to stick to the position where the air gap is at a minimum and this may not be fully open or may even be just off the closed position.   The next thing is to use a material that is magnetically "conductive" - a soft iron type of material. It however should be treated against rust. The magnets that did not work were made from a very hard steel (I do not know the composition), but the material is not very magnetic. Another fault was the total magnetic path - the field iron inside the coil has a certain cross sectional area. That same area (or more) should in cross section exist along the magnetic path, firstly where that field rod is joined (without air gap!) to the base, then where the base goes over to = the armature (a small air gap unfortunately is needed here for movement).   What I have described here is the typical pallet magnet. I do not know = what type you have - there are other designs. You may send me a scan or photo or diagram of the set-up, then I can recommend on that.   Hope it helps, Pieter Smit pieter@cadence-engineering.co.za    
(back) Subject: Re: [Residence Organs] Re: Winding magnets From: "Tony Newnham" <organist@tsnp.fsnet.co.uk> Date: Mon, 18 Feb 2002 09:04:33 -0000   Hi   It crosses my mind that some older electronic construction books have details of coil winding - the principal is exactly the same. I also think I've seen a design for a small coil-winding machine. If I can remember where it is - or if I come across it - I'll let you know.   A company that I worked for in the past actually manufactured a coil winder - basically a motor with a clamp assembly to hold the coil bobbin, and a frame to hold the supply spool. There was some sort of arrangement = to feed the wire across the bobbin to get neat turns, but I can't remember = how that worked - I had no cause to use it. There was also a mechanical turns counter - loosing count at 2,000+ turns is no joke!   It strikes me that the arrangement must be similar to that used for = winding bobbins of cotton on a sewing machine.   Hope this helps   Every Blessing   Tony    
(back) Subject: Re: Repeat messages From: <Jess4203@aol.com> Date: Mon, 18 Feb 2002 07:36:40 EST   Hi Group:   Sorry to have sent yesterday's message three times. I thought the mouse = was stuck, but evidently it was working way too well!   Regards, Roy Kersey