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Ken Cutt
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rashid111 wrote:
Here's what I am trying to accomplish:

when making accordion reeds, the highest notes (piccolos) are
extremely critical to profile dimension. Typical piccolo reed will be
made out of .012 thick blue steel (48-50 RC), .4" in length, .050 in
width (they are typically narrower toward the tip, may be .050 @
root,.040 @ tip).

The reed gets to be about 0.0015 thin @ the tip and has a profile where
the thickness will linearly decrease from .012 @ root to .002 halfway
and then it will be 0.0015 the rest of the way toward the tip. Filing
by hand is extremely time consuming (for piccolos only, other, lower
reeds, can be easily filed by hand)

So I am thinking about 2 possibilities: a) pantograph-type surface
grinder b) CNC driven SG.

CNC sounds like fun ...

Most important thing is vertical accuracy - need to have downfeed
accuracy of .0005 or thereabouts. To that end I have bought a complete
liner assembly: 1.5mm pitch precision ground ballscrew, linear rails
complete with NEMA motor Sanyo Denki 103-540-0351
(from what I could read from the image of the assembly on the Web).

Today being my second day into CNC exploration I understand this is
unipolar motor(more than 4 wires) . What I am not sure about is the
torque. I am hoping it will be sufficient, as travel weight of grinder
head assembly will be around 6-7 pounds and I don't see much in a way
of forces acting on it - unlike typical mill Z-drive. I hope to grind
around one thou per pass - not to overheat the steel.

Assuming I can get CNC to drive half-step mode, I am looking at
downfeed resolution of 1.5mm/400 = 0.00015" which is great . 1/4 or
1/8 get me into sub-angstrom area Of course I will never get close
to these tolerances as other components will not allow for it.

In terms of linear travel I need about 3" tops ( in case I want later
to grind longer, lower reeds). I am thinking about acquring
and building a liner slide assembly: small ball screw, linear slide. I
am not sure what I want to drive: the grinder head assembly or the base
with mag chuck ( 5x7" are available new on Ebay for $100 or so). Not a
whole lot in terms of accuracy reqs for linear travel - definitely not
anywhere close to vertical axis.
I only need X-travel, no Y (with 2" OD of the wheel and .040 wide
contact area the grinding plane will be flat enough).

Thinking about DIY Xylotex $87 3-axis unipolar kit. I might get into
building a CNC-mill down the road, so I should be able to re-use the
Xylotex for it. I will need to get a stepper for X-axis. Will probably
shoot for something like 140+Oz so, again, I will be able to re-use it
for future CNC machinery (I ordered some Oldham couplers so swapping
these in and out should be easy).

I am planning on using a speed-controlled router/rotary head with 1/4"
- 1/2" shank and may be 1/8 - 1/4" thick 2" OD grinding wheel @
4000-10000 rpms. For my accuracy reqs I will definitely need to true it
up nicely. Spindle will need to be accurate as well. Really hoping that
typical $50 rotary tool variety will work for me. Does anybody know a
nice router type motor that can, ideally, be face mounted ? Otherwise I
will need to bore out a mounting collar. I don't see much in a way of
power reqs here - 1/4 HP should work fine ? I don't care if it will
take few secs to bring the spindle up to required RPMs. From what I see
in HD, Sears and Lowes almost all of the routers/rotary tools nowdays
use plastic outer shell ... not good

So what do you think ? Any advice is most welcome

Not exactly what you are asking and no where near as cool as CNC but ,
why not make up a reverse die and set that on the mag base , then just
use a regular surface grinder ? Luck
Ken Cutt