Reaming

"Fortunat1" wrote in message
.. .

OK, which brings me to another side of this, I guess. I'm hand reaming. By
that I mean I'm putting a tap handle on the reamer, sticking the work
piece
in a vice and going at it by twisting the thing by hand. Needless to say
it's nearly impossible to keep the reamer absolutely straight. Am I doing
this right? One suggestion I got was to use my drill press by rigging
something up to hand turn the drill spindle (no way I can get it to turn
slowly enough for reaming) in order to get the reamer straight in.

If you look at the top of your hand reamer, I'll bet you'll find a centering
hole. Chuck up a tapered center in the drill press and use it to steady the
top of the reamer.

Rich S.

"Rich S." wrote in
:

"Fortunat1" wrote in message
.. .

OK, which brings me to another side of this, I guess. I'm hand
reaming. By that I mean I'm putting a tap handle on the reamer,
sticking the work piece
in a vice and going at it by twisting the thing by hand. Needless to
say it's nearly impossible to keep the reamer absolutely straight. Am
I doing this right? One suggestion I got was to use my drill press by
rigging something up to hand turn the drill spindle (no way I can get
it to turn slowly enough for reaming) in order to get the reamer
straight in.

If you look at the top of your hand reamer, I'll bet you'll find a
centering hole. Chuck up a tapered center in the drill press and use
it to steady the top of the reamer.



Hmm, good one. I could alos use the press to regulate the pressure on the
tool easily enough that way..

What's so hard about reaming? I get reamed at work every other day


Scott
http://corbenflyer.tripod.com/
Gotta Fly or Gonna Die
Building RV-4 (Super Slow Build Version)

Fortunat1 wrote:
"Morgans" wrote in
:



Of course, getting a real chart with the tool, material, and the
correct tool speed and feed speed or pressure it the "best" way to
go at it. g




--

Fortunat1 wrote:
"Morgans" wrote in
:


Of course, getting a real chart with the tool, material, and the
correct tool speed and feed speed or pressure it the "best" way to
go at it. g

OK, which brings me to another side of this, I guess. I'm hand reaming. By
that I mean I'm putting a tap handle on the reamer, sticking the work piece
in a vice and going at it by twisting the thing by hand. Needless to say
it's nearly impossible to keep the reamer absolutely straight. Am I doing
this right? One suggestion I got was to use my drill press by rigging
something up to hand turn the drill spindle (no way I can get it to turn
slowly enough for reaming) in order to get the reamer straight in.

Is this unneccesarily complicated? We're talking about .090 4130 here with
a 5/16" hole. Wing attach and strut brackets for mounting onto a wooden
spar for the most part..


You could chuck the reamer, and use the chuck key to turn it. A piece
of 1/4" rod (cut threads off long bolt) also make a nice turning handle.



--
"Life is not a journey to the grave with the intention of arriving
safely in
a pretty and well preserved body, but rather to skid in broadside,
thoroughly used up, totally worn out, with chocolate in one hand and
wine in
the other, loudly proclaiming 'WOO HOO What a Ride!'"
--Unknown

On Tue, 14 Aug 2007 02:03:28 +0000, Scott
wrote:

What's so hard about reaming? I get reamed at work every other day



I was waiting for that comment :-)

a very good use for an old large reamer...

clean it up and mount it in a varnished ornamental base.
tack on the side a plaque.
"for excellence in the field of motivation"

make a really neat job of it and present it to the office bully at the
next office occasion :-)

I still have the reamer and plaque of one presented to the boss many
years ago :-)
stopped him in his steps.

Stealth Pilot

Ernest Christley wrote in
:



Is this unneccesarily complicated? We're talking about .090 4130 here
with a 5/16" hole. Wing attach and strut brackets for mounting onto a
wooden spar for the most part..


You could chuck the reamer, and use the chuck key to turn it. A piece
of 1/4" rod (cut threads off long bolt) also make a nice turning
handle.


Excellent suggestion. In fact the end of my tap handle did the job
perfectly.
Interpolating all the suggestions here, here's what I did to improve my
reaming.
First, I got some bits to cut the holes a tad larger than they already
were. A 7.7 mm bit got me much closer to the final size. I found some
7.9 mm whcih were also undersize, but I was afraid it was a little too
close and that the drilled hole might leave the corners of the
triangular hole eating past the final reamed size.
Second I used proper cutting oil. I also used the drill press suggestion
which was perfect as it allowed me fine regulation of the pressure on
the reamer and also kept it nice and straight going in.
Now for the next stage. I have to install these on the spars. I have two
possible plans. One, I drill it on the press ensuring that everything is
as square as possible. the other that I use a made up drill guide which
clamps around the spar and "feels" the hole in the plate on the other
side. In either case I plan to use a bit of tubing with an OD the same
size as the ultimate size of the hole in order that it fits in the holes
on the plates so that after the first hole is drilled and I can slip a
bolt in there I can drill the others in precisely the right place using
the plate itself as a guide. In either case I'd drill out to a sixe
under the final dia and then use the reamer to cut the final bit of wood
away. Any pitfalls with this plan?

"Fortunat1" wrote

In either case I'd drill out to a sixe
under the final dia and then use the reamer to cut the final bit of wood
away. Any pitfalls with this plan?

Sounds to me like you are seriously splitting toadstools.

If you were to just drill the wood so the bolt fits, and then put some epoxy
or varnish or whatever you want to use to make sure the bolt and wood do not
interact, won't that fill the voids?

I always thought that the strength in a fitting like this was in the
squeezing of the fitting on the wood, not the sheer of the bolt against the
wood. Am I wrong?
--
Jim in NC

"Morgans" wrote in
:


"Fortunat1" wrote

In either case I'd drill out to a sixe
under the final dia and then use the reamer to cut the final bit of
wood away. Any pitfalls with this plan?

Sounds to me like you are seriously splitting toadstools.

If you were to just drill the wood so the bolt fits, and then put some
epoxy or varnish or whatever you want to use to make sure the bolt and
wood do not interact, won't that fill the voids?

I always thought that the strength in a fitting like this was in the
squeezing of the fitting on the wood, not the sheer of the bolt
against the wood.


Not according to the info I have, anyway. I can't see the friction on the
plates giving much strength at all. One of the engineering manuals i have
is pretty specific about how the size of the bolt makes a large difference
in regards to how much material it's pulling (iow a small bolt will pull
through the wood more readily than a large one because it's applying the
same pressure over a smaller area) Same manual goes to pains to point out
that the hole should be as perfect as possible a fit in order to spread the
load as evenly as possible over the material it's resting against. Seems to
me I may have seen something similar in an old Sport Aviation and maybe one
of the Bengelis books.
But your question brings up a good point. How tight a fit do I want in the
wood and the steel? Too tight will mean I won't be able to fit the bolts
through the steel after painting. I wouldn't be as worried about the wood
as the pourousness of the wood would allow for some retention.

"Fortunat1" wrote

Not according to the info I have, anyway. I can't see the friction on the
plates giving much strength at all. One of the engineering manuals i have
is pretty specific about how the size of the bolt makes a large difference
in regards to how much material it's pulling (iow a small bolt will pull
through the wood more readily than a large one because it's applying the
same pressure over a smaller area) Same manual goes to pains to point out
that the hole should be as perfect as possible a fit in order to spread
the
load as evenly as possible over the material it's resting against. Seems
to
me I may have seen something similar in an old Sport Aviation and maybe
one
of the Bengelis books.

Is your engineering manual wood aircraft specific?

I am NOT sure of how this applies to your situation, but I KNOW that with
wood propellors, the amount of torque (squeeze) is critical in not having
the prop slip. If the torque is not maintainted, it will allow the prop to
slip around until it bears against the bolts and failure occurs. Anyone
else?

It would seem like the way I have heard that many people do it, is to fill
the space between the bolt and the wood with epoxy. It spreads the loads,
and prevents wood to steel contact, which is critical to prevent corrosion
and decay.

But your question brings up a good point. How tight a fit do I want in the
wood and the steel? Too tight will mean I won't be able to fit the bolts
through the steel after painting. I wouldn't be as worried about the wood
as the pourousness of the wood would allow for some retention.

Morgans wrote:
"Fortunat1" wrote
Not according to the info I have, anyway. I can't see the friction on the
plates giving much strength at all. One of the engineering manuals i have
is pretty specific about how the size of the bolt makes a large difference
in regards to how much material it's pulling (iow a small bolt will pull
through the wood more readily than a large one because it's applying the
same pressure over a smaller area) Same manual goes to pains to point out
that the hole should be as perfect as possible a fit in order to spread
the
load as evenly as possible over the material it's resting against. Seems
to
me I may have seen something similar in an old Sport Aviation and maybe
one
of the Bengelis books.

Is your engineering manual wood aircraft specific?

If you read the literature, I think you will find that tearout is an
issue for bolted wood connections on aircraft, so the bearing stress is
important(and is equally applicable to metals as well). If the hole is
oversize the bearing stress goes up. If the bolt size and hole size
are reduced, the bearing stress goes up. So the bolts are generally
sized based on the bearing stress on the wood, not the shear stress of
the bolt. There was even some experimentation with aluminum and hollow
steel bolts at one point.

As to the importance of fit...from an older ANC and FPL study on bolted
wood joints for aircraft.....

"1) bolt holes with visibly smooth side walls have bolt-bearing
properties far superior to those with visibly rough side walls;
2) in order to produce a smooth hole, the drill must be well sharpened
and the rate of feed in drilling must be slow enough to enable the drill
to cut rather than tear its way through the piece; and
3) in the materials used in this study, Douglas-fir plywood and Sitka
spruce, the twist drill produces a smoother hole than does a machine bit.

Because the area of wood in actual contact with the bolt is reduced, a
bolt hole with its wall visibly scored or with material torn or
otherwise removed beyond the true cutting line of the drill will be more
seriously deformed at loads less than the proportional limit, will have
a lower load at proportional limit and a reduced ultimate load, and will
be more seriously deformed at the ultimate load than a hole with a
smooth, truly drilled wall. "

Further findings of the study were that machine sharpened bits were
superior to hand sharpened bits, a slow feed was critical to getting the
best hole quality ala one inch per minute with a twist drill was best.
Also, it mentioned that the drill should be producing shavings, not
small chips or granules, these latter being evidence the bit was tearing
and not cutting the wood.


Charles