alan00463 wrote:
>--- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan"
><stefan_trethan@g...> wrote:
>
>
>>As i said those are old pictures.
>>
>>The stop screw is now right at the drill clamp, so that it comes
>>
>>
>down on
>
>
>>the PCB. This holds the PCB down and it prevents the frame from beeing
>>tilted when reaching the stop and breaking the drill.
>>
>>There is a counterweight clamped to the back of the frame, it is
>>
>>
>balanced
>
>
>>so that it just thinks down, but around neutral seems good so you
>>
>>
>have a
>
>
>>good feeling for the force.
>>
>>Also, the bearing is not in the same hight as the drill tip, this
>>
>>
>prevents
>
>
>>it going in a perfect tangent. I now put a wood block under the PCB
>>
>>
>and
>
>
>>have angled the drill holder forward to make it straight again (this
>>
>>
>angle
>
>
>>is adjustable with a screw). The two red plastic rods are no longer
>>
>>
>used
>
>
>>to hold the drill, the front clamp is sufficient.
>>
>>Added light and vacuum.
>>
>>
>>If i had to do it again, i would use two plates, the upper one
>>
>>
>triangular,
>
>
>>with a piano hinge at the back.
>>
>>ST
>>
>>
>
>Thanks, Stefan, for your comments. I got my Proxxon drill and am
>getting ready to build the drill press.
>
>I am seriously considering the two-plate design, using two pieces of
>half-inch thick (12.5mm) wood or plywood with a wood spacer and a
>piano-hinge. I would probably make it about 25 cm (10in) wide.
>Not sure how long of a lever arm to use--what do you think? I
>suppose that I will just let the drill bit eat into the lower board
>when top plate is pressed down. I suppose that I will place springs
>between the two plates to hold the drill bit slightly elevated above
>the workpiece when the operator lets go. Then when the operator
>applies downward pressure, the drill bit will be exactly vertical when
>the drill bit contacts the upper surface of the workpiece.
>
>I think this design would be even better than the one you built,
>Stefan. It would be lighter and occupy less space. I might have to
>attach an L-shaped pieces of wood to the upper wood plate to make sure
>the drill bit is always held perpendicular to the upper wood plate.
> I guess the longer the lever arm the better, so long as it isn't too
>hard to store when not in use.
>
>Alan
>
>
>
Put a hole somewhere, and make it where you can easily hang it up on a
wall etc. Sized to fit inside a closet or back side of a closet door
might be good too. Other holes to lighten the wood are probably a good
idea too, need stiff but doesn't have to be 100% solid, 50% would
probably be just as sturdy..
3/8" project planks from Lowe's etc make a good backer board, if
you're making a spacer anyway might take a look at it. If you screw in
a piano hinge you might not want to have to mess with it again changing
the bottom board. Angle brackets should work out as cheap and easier
for the L's than using all wood for a right angle.
1x deflection one way, vertical in the center of the board, and 1x
deflection the other way should be slightly better as a general rule
than vertical at top and 2x deflection a single way. With a decent
length arm it really shouldn't matter for this, but still good to keep
in mind for a general rule.
Alan