Kit 302- C170: Magnets for Cowling?

[tpwpny]

I've seen some online pieces about fastening a cowling on with Neodymium magnets to make it easily removable. I'm working on my first model and wondering whether this is worth trying. My plan so far is not to embed the magnets into the firewall, as I've seen many do. Instead, I want to try adding 2 or 4 small friction(?) blocks on the firewall edges with tiny magnets on each... then gluing small metal washers to the inside cowling near the edge. Thoughts? Anyone try anything similar?

Any other techniques appreciated...!

[dirk gently]

I did that in this model:


I can post pictures of the cowling removed if required.

[tpwpny]

Very nice! And yes- would love to see what it looks like with the cowling removed. Thanks!

[dirk gently]

I have to get back from work first, but I'll try to remember to do it in the (European) evening.

[tpwpny]

Sorry - I should have added in my original post that I plan to use the default plastic cowling. Don't know if I'm skilled enough yet to create a decent wooden one.

[dirk gently]

I don't think there's much difference as far as magnet mounting is concerned.

[Bill Gaylord]

The embedding is probably the most straightforward, although I've used offset magnets before, which will pull the cowling into position, as the magnets are never fully "satisfied" and are trying to pull it rearward as much as possible. I can't find a photo of it however. I know I also used that idea with a t-slotted cowl design, that rotates into position.
I've done this (below) with several Guillow's planes. I use dowel pins, along with RE magnets. The magnets are quite powerful, where using washers on one side provides adequate grip, even for electric r/c. The magnets and washers are CA glued in place. Scuffing them up a bit with sandpaper helps the glue grip to them. My Zero has the same setup.

[dirk gently]

Here are the mounting details. you can also use locating pins if you like, I don't have them:

DSCN0564.JPG

Another example:

DSCN0568.JPG

And the (somewhat) finished product:

DSCN0569.JPG

[dirk gently]

For a guillows, I would make a copy of the firewall and glue it permanently to the cowling. Then I would mount the magnets in both the mirror firewall and the actual firewall. Here's an example (you have to imagine the magntes, this one is still unfinished):

DSCN0573.JPG

[tpwpny]

If I embed the magnets flush, as seems to be the usual practice, what do you advise I use to make the hole? I'm worried a drill or Dremel bit may be too harsh and rip up the wood....or maybe a special knife? Or is it as simple as cutting the hole with an Exacto?

[dirk gently]

I do it with an exacto knife. I make the hole a bit smaller than needed. Then I take a rolled piece of sandpaper and sand to size.

[Bill Gaylord]

I've seen some online pieces about fastening a cowling on with Neodymium magnets to make it easily removable. I'm working on my first model and wondering whether this is worth trying. My plan so far is not to embed the magnets into the firewall, as I've seen many do. Instead, I want to try adding 2 or 4 small friction(?) blocks on the firewall edges with tiny magnets on each... then gluing small metal washers to the inside cowling near the edge. Thoughts? Anyone try anything similar?

Any other techniques appreciated...!

I probably shouldn't have shown the firewall embedded magnet photo, as it took it in that direction. I've been using tabs glued onto the firewall that fit flush with the inner cowl surface, using screws to attach on the smaller models. The offset magnets should work well though with that scheme, instead of the screws. Again, using a magnet on one part and washer on the other, with them intentionally offset so that the magnet is never fully "satisfied" with it's location, always trying to pull the cowl further rearward. When I used the offset magnet scheme before, you could get a good feel for the ideal offset distance that would create the greatest pull.

[tpwpny]

I probably shouldn't have shown the firewall embedded magnet photo, as it took it in that direction. I've been using tabs glued onto the firewall that fit flush with the inner cowl surface, using screws to attach on the smaller models. The offset magnets should work well though with that scheme, instead of the screws. Again, using a magnet on one part and washer on the other, with them intentionally offset so that the magnet is never fully "satisfied" with it's location, always trying to pull the cowl further rearward. When I used the offset magnet scheme before, you could get a good feel for the ideal offset distance that would create the greatest pull.

That's the route I'm planning... I think I'll wait till wings are mounted though... Hopefully in the next few days...

[tom arnold]

Why do you want to remove the cowl in the first place?

[tpwpny]

Why do you want to remove the cowl in the first place?

To change the rubber motor if necessary.