Some years ago I put a short article in INAV on a post sanding gadget. It is two flat blocks of hard wood, about 2" square, with 320 paper glued to opposing faces. The blocks have holes drilled near the corners. One block has clearance holes for 4-40 screws, the other is tapped for this screw. The blocks are counterbored (larger drilled holes) on the inside faces to take compression springs. Long screws are used to join the blocks. When the screws are snugged down so the sandpaper faces touch each other, the heads of the screws are marked in a common spot (eg. bottom). Then they are backed off evenly until the somewhat rounded post (eight-sided is fine) fits between the faces. The post is put in an elecrtric drill chuck and run at 500 to 1000 RPM. The block is moved along the post. After one pass, the screws are tightened about 1/8 turn and the sanding is repeated.
When the post is round, check the size with a dial gage. Finer cuts can be made until the right size is reached. The post can be uniform to at least .0002", and perfectly round. Always start with a post that is at least .010 oversize. When finished, the fit to a tissue tube can be snug to the right degree.
This technique is good for posts down to about .045 " dia. The balsa should be at least 7# stock.
While this gadget takes the work out of making round posts, note that the plastics people often use a technique of putting a square peg in a round hole to get the right friction. We can do that too. The round peg needs to be very accurately sized to work well, but the square peg is less demanding.
Finally, if you do have a loose post in a model, take it out, wet it with water and let it dry completely. It might expand enough to get the right fit in the tissue tube. If it still needs more, some people have used rubber cement instead of water to build some bulk and add friction. I haven't done that, so I can't comment further.
Ray
--- In Indoor_Construction_at_yahoogroups.com, Rey Mazzocco <aprivpilot@...> wrote:
>
> Thanks!
>
>
> I also have trouble making my round posts consistent in diameter. Is there an easier way to do this besides rolling between sanding blocks? I've thought of using a drawplate, similar to this: http://www.micromark.com/jewelers-draw-plate,6942.html (which I don't have). I may try square posts using 1/16" sq brass tubing as a mandrel for the paper tubes. I know I can cut and shape consistent square posts.
>
>
> Rey
>
>
> -----Original Message-----
> From: William Gowen <wdgowen_at_...>
> To: Indoor_Construction <Indoor_Construction_at_yahoogroups.com>
> Sent: Thu, Mar 7, 2013 11:25 am
> Subject: Re: [Indoor_Construction] Re: Wing Tube Mounting
>
>
>
>
>
> Nice Rey!
>
>
> On 3/6/2013 11:26 PM, aprivpilot wrote:
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>
>
> Thanks for posting this, Bill. Just what I needed to make a fiddly job (for me) a lot easier.
>
> Rey
>
> http://groups.yahoo.com/group/Indoor_Construction/photos/album/1944973591/pic/1818506490/view?picmode=&mode=tn&order=ordinal&start=1&count=20&dir=asc
>
> --- In Indoor_Construction_at_yahoogroups.com, William Gowen wrote:
> >
> > Well JP a blind squirrel finds a nut every once in a while. (I just made
> > that up)
> >
> > On Mon, Mar 4, 2013 at 8:16 PM, J P Kish wrote:
> >
> > > **
> > >
> > >
> > > **
> > > Hey Bill, when you make things this simple, you take the "mystique" out of
> > > the "difficult challenge" of indoor. Thanks!
> > > jp
> > >
> > >
> > >
> > >
> > > ----- Original Message -----
> > > *From:* Bill
> > > *To:* Indoor_Construction_at_yahoogroups.com
> > > *Sent:* Monday, March 04, 2013 12:24 PM
> > > *Subject:* [Indoor_Construction] Re: Wing Tube Mounting
> > >
> > >
> > >
> > > I put a picture of my tube attachment jig in my photo album. Here's the
> > > link:
> > >
> > >
> > >
> > > http://groups.yahoo.com/group/Indoor_Construction/photos/album/1791606911/pic/2135511843/view?picmode=&mode=tn&order=ordinal&start=1&count=20&dir=asc
> > >
> > > The posts are 1/16" brass tubes which is the size I use for paper tubes
> > > and wing and stab posts. The brass tube on the left is attached to the
> > > base. The one on the right is attached to a balsa slider. There are
> > > aluminum tubes at the bottom of the brass tubes that I use to push the
> > > paper tubes off after they are glued to the wing or stab.
> > >
> > > I put the paper tubes on the brass tubes at the top of the brass tubes.
> > > Then I put the wing or stab between the brass tubes and adjust the slider
> > > to put a little bit of pressure on the wing or stab. For small parts this
> > > is usually enough to hols the part while I glue the tubes. For larger parts
> > > I will prop up the wing or stab to get it aligned.
> > >
> > > When everything looks right I use a small amount of glue to tack the tubes
> > > to the wing or stab. When that is dry I add more glue. When the gluing is
> > > finished I use the aluminum tubes to push the paper tubes off of the brass
> > > posts.
> > >
> > > The whole jig takes about 10 minutes to build and has been in use for
> > > several years.
> > >
> > > --- In Indoor_Construction_at_yahoogroups.com, "LeRoy Cordes" wrote:
> > > Does anyone have a trick or two to make the operation easy and consistent?
> > > LeRoy Cordes
> > >
> > >
> > >
> >
>
Received on Sat Mar 09 2013 - 05:44:57 CET