Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work.

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
  #1   Report Post  
rashid111
 
Posts: n/a
Default Building CNC Surface grinder - whole lotta questions

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

  #2   Report Post  
Adam Smith
 
Posts: n/a
Default

I'd ask this same question on yahoogroups DIYCNC (not instead, but as well).

Adam Smith
Midland, ON

"rashid111" wrote in message
oups.com...
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).

snip


  #3   Report Post  
Eric R Snow
 
Posts: n/a
Default

On 25 May 2005 11:10:15 -0700, "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

If I was going to spend that much time on a project I'd use servo
motors and stay away from steppers. For lotsa good reasons. However,
for good advice call Gecko Drives. They sell both stepper and servo
drives. Their servo drives take step and direction commands and uses
them to drive a servo with encoder feedback. That way you can use
cheap or free stepper software.
ERS
  #4   Report Post  
Don Foreman
 
Posts: n/a
Default

On 25 May 2005 11:10:15 -0700, "rashid111" wrote:

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.


You will have a substantial shatter shield around that fast-spinning
wheel, right?



  #5   Report Post  
DoN. Nichols
 
Posts: n/a
Default

In article .com,
rashid111 wrote:
Here's what I am trying to accomplish:

when making accordion reeds, the highest notes (piccolos) are


O.K. With reed making, you have my attention. (Though my focus
is on concertina reeds, not accordion reeds. They are different in the
mounting (concertina reeds mount on individual dovetailed carriers,
sometimes called "shoes" from the shape.

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).


O.K. More width taper than a similar concertina reed.
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)


Lower concertina reeds may be similarly thickness tapered along
the length, or may be thinner at about the 1/3 point from the root to
the tip, depending on which specific reed, as about four consecutive
reeds use the same physical dimensions of reed and reed shoe.

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


CNC sounds like fun ...


Agreed.

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).


O.K. First suggestion -- design in ways to keep the grinding
swarf out of the ball screws. It will *kill* them fairly quickly.
Grinding is dirty and nasty. You'll want bellows around the ball-screw
-- both sides of the nut, or some other protective shape. There are
some which look like a clock spring which has been stretched out from
the center. You want to mount those so the cracks are on the bottom, so
there is less likelihood that grit will work its way to the inside.

Even Acme screws have special protective housings around them of
some form or other.

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.


Ball screws take an amazingly low amount of torque under normal
circumstances.

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.


That sounds good.

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.


Again -- look for ways to enclose it to protect it from the
swarf. My Sanford grinder (manual) has the table running on one
inverted V way and one flat way, held in place by gravity only (not much
lifting force in a grinder), but has a lot of overhang in all
directions, so the ways are never exposed to the swarf.

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).


Note that you can get mag chucks with either a fine pitch pole
spacing or a coarse one. The coarse one is fine for holding big chunks
of metal, but for something as thin as your spring stock, you will want
a fine pitch one. And you will want a permanent magnet one, not an
electromagnet, to allow you to use coolant while grinding without
opening a shock hazard (Of course, a well isolated power supply will do
that too, but a permanent magnet just does not *have* any high voltage
to worry about.)

And in terms of the travel -- understand that when you mount the
chuck, you will have to grind the entirity of its top surface to assure
that it is truly parallel to the travel of the table. This is important
to me because the nice fine-pole Permanent Magnet chuck which I got from
eBay is about 1/2" longer than the X-axis travel, so I will have to take
it to the milling machine to remove some of the ends to allow a proper
complete dressing. So -- for now, I still have the electro-magnetic
chuck in service -- and *no* coolant.

Not a
whole lot in terms of accuracy reqs for linear travel - definitely not
anywhere close to vertical axis.


Agreed.

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).


I disagree here. You will want to take multiple passes at right
angles to the reed stock, with the rim of the wheel dressed to a gentle
curve to avoid steps in the thickness of the reeds, which could act as
stress concentrators, leading to fatigue cracks after hard playing. The
X-axis could carry the wheel over a whole row of reed stock, and the
Y-axis is changed with the Z-axis in small steps to make the contour you
wish.

And -- you will want both axes to be capable of moving a greater
distance than the dimensions of the mag chuck, so you *can* grind it
flat at the start. (Just after you mount the chuck on the table, and
just after any time you remove and re-mount the chuck.

One way around this, at least for production of a single reed
profile, would be to dress the wheel (a wider wheel) to produce the
profile in a single path over the reed stock. But that has two
disadvantages that I can see:

1) It will take more horsepower (and at least a 1/2" thick wheel).

2) Cutting the full width in a single cut (even if you sneak up
on the depth) will put a lot more longitudinal force on the
reed stock, and is likely to overcome the grip of the mag chuck,
thus destroying that reed, and perhaps wedging and shattering
the wheel.

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 ?


A router motor has the disadvantage of lots of bulk too close to
the mag chuck, so it might limit your travel.

And I'm not sure that the bearings in any router will be
sufficiently precise for surface grinding.

My Sanford, and other surface grinders that I have seen, have a
long spindle with precision bearings at both ends (well sealed, to
protect them from the swarf, again), and a belt drive to a motor set
behind the column and much lower, so the weight distribution is better.

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 think that the motor on my Sanford is a 1HP -- but it is
driving a wheel of 4" diameter.

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


The time to spin up is not a serious problem. The ability to
drive a full width wheel dressed to the profile would be, however --
even if you downfeed by only 0.0001" per pass. You can use lower power
if you dress the wheel to a '(' profile, and cut only a narrow path per
pass -- but that needs Y-axis automation in addition to the X and Z
which you were planning.

So what do you think ? Any advice is most welcome


You have the things which have occurred to me above -- some of
them based on my experience running the Sanford as a manual surface
grinder, which helps to get a feel for what is happening.

Harold Vrodos (or should that be Howard?) will be able to offer
lots of information on grinding, but he has managed to avoid the CNC
side of things, so perhaps some of my thoughts will be of help.

Good Luck,
DoN.


P.S. FWIW, I think that my Sanford might be a good candidate for
CNC conversion on the X and Z axis (with ball screws), but the
Y-axis is a rack-and-pinion drive, which would take a bit more
motor to drive it.
--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---


  #6   Report Post  
Ken Cutt
 
Posts: n/a
Default

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
  #7   Report Post  
rashid111
 
Posts: n/a
Default

Ken -

do you mean use a pantograph style device to transfer dimension of a
die
to the target ? Can you elaborate a bit here ?

I did look around on the Web and have quite an extensive collection of
metalworking literature @ home, so I do have a pretty good
understanding
of a what an industrial SG looks like and how it works etc.

My whole setup is in a garage and I can not get a used SG from Ebay in
there,
unfortunately. But then again, my work envelope is tiny (1x3"),
compared to even the
smallest industrial SGs (6x12")

I thought about making a belt driven spindle for the grinding wheel
and it does look like
something I can tackle (I have a mill and a lathe and some spare time).
Just might
go that route if the router spindle is too bad. I am trying to keep the
size and weight
of the Z assembly down.

In my dreams I see myself loading a (pre-cut) strip of blue steel
onto the chuck and carefully
aligning it with the X -0 point, loading particular reed's profile into
Mach2 and hitting "go".
Minute later I have a complete reed, tuned to within 50 cents of target
or, may be, dead on



I don't really have to spin @ 4000rpm, can probably go much lower.

About X-Y travel: just might have to go that route. Ideally as long as
I am doing it,
I'd like to build a X-Y-Z CNC assembly that I can use for milling or
grinding. One immediate
problem is the grinding dust - it will be offly hard to absolutely keep
it out of the ballnut.

Another is price: my very limited grinding envelope doesn't require a
whole lotta of travel,
there is no forces to speak of - and it means I can go with short
5-10mm ballscrews and
linear rails.

Building milling-capable assembly is a whole different ballgame - 3-4
times more expensive.
Much longer and beefier rails and ballscrews.

  #8   Report Post  
DoN. Nichols
 
Posts: n/a
Default

In article .com,
rashid111 wrote:

[ ... ]

I did look around on the Web and have quite an extensive collection of
metalworking literature @ home, so I do have a pretty good
understanding
of a what an industrial SG looks like and how it works etc.

My whole setup is in a garage and I can not get a used SG from Ebay in
there,
unfortunately. But then again, my work envelope is tiny (1x3"),
compared to even the
smallest industrial SGs (6x12")


Try the Sanford, which is 4x7" envelope. It is a benchtop
machine, not a floor-standing one. I just checked on eBay, and they
don't have one at the moment -- but one would be an excellent starting
point for your CNC machine.

[ ... ]

In my dreams I see myself loading a (pre-cut) strip of blue steel
onto the chuck and carefully
aligning it with the X -0 point, loading particular reed's profile into
Mach2 and hitting "go".
Minute later I have a complete reed, tuned to within 50 cents of target
or, may be, dead on


That level of accuracy is possible, but I don't see it happening
in 60 seconds -- especially with your low power spindles.



I don't really have to spin @ 4000rpm, can probably go much lower.


Probably not. The cutting behavior of the stones is a function
of the SFM (Surface Feet per Minute). A smaller stone needs to go
*faster* to cut as well.

About X-Y travel: just might have to go that route. Ideally as long as
I am doing it,
I'd like to build a X-Y-Z CNC assembly that I can use for milling or
grinding. One immediate
problem is the grinding dust - it will be offly hard to absolutely keep
it out of the ballnut.

Another is price: my very limited grinding envelope doesn't require a
whole lotta of travel,


Remember my comments in another followup about needing to grind
in the entire top of the magnetic chuck prior to putting it into
service.

there is no forces to speak of - and it means I can go with short
5-10mm ballscrews and
linear rails.


Good Luck.

Building milling-capable assembly is a whole different ballgame - 3-4
times more expensive.
Much longer and beefier rails and ballscrews.


But -- no grinding swarf to destroy your ways (linear rails).
Grinders are *nasty*.

Good Luck,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---
  #9   Report Post  
Ken Cutt
 
Posts: n/a
Default

rashid111 wrote:
Ken -

do you mean use a pantograph style device to transfer dimension of a
die
to the target ? Can you elaborate a bit here ?

I did look around on the Web and have quite an extensive collection of
metalworking literature @ home, so I do have a pretty good
understanding
of a what an industrial SG looks like and how it works etc.

My whole setup is in a garage and I can not get a used SG from Ebay in
there,
unfortunately. But then again, my work envelope is tiny (1x3"),
compared to even the
smallest industrial SGs (6x12")

I thought about making a belt driven spindle for the grinding wheel
and it does look like
something I can tackle (I have a mill and a lathe and some spare time).
Just might
go that route if the router spindle is too bad. I am trying to keep the
size and weight
of the Z assembly down.

In my dreams I see myself loading a (pre-cut) strip of blue steel
onto the chuck and carefully
aligning it with the X -0 point, loading particular reed's profile into
Mach2 and hitting "go".
Minute later I have a complete reed, tuned to within 50 cents of target
or, may be, dead on



I don't really have to spin @ 4000rpm, can probably go much lower.

About X-Y travel: just might have to go that route. Ideally as long as
I am doing it,
I'd like to build a X-Y-Z CNC assembly that I can use for milling or
grinding. One immediate
problem is the grinding dust - it will be offly hard to absolutely keep
it out of the ballnut.

Another is price: my very limited grinding envelope doesn't require a
whole lotta of travel,
there is no forces to speak of - and it means I can go with short
5-10mm ballscrews and
linear rails.

Building milling-capable assembly is a whole different ballgame - 3-4
times more expensive.
Much longer and beefier rails and ballscrews.

Sorry I missed the part about space being an issue . I was thinking
conventional surface grinder . Still I think it would be cheaper to make
up the die and have them ground at a shop or a friends grinder . The
time and expense of building a " high tolerance " machine would cover
the cost of a box load outsourced . Still pretty cool to have your own
CNC set up but business wise I think other solutions might be more
profitable . Luck
Ken Cutt
  #10   Report Post  
James Waldby
 
Posts: n/a
Default

Ken Cutt wrote:
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


rashid111 wrote:
Ken -
do you mean use a pantograph style device to transfer dimension
of a die to the target ? Can you elaborate a bit here ?


I supposed he meant:
Cut out a cavity in a block, like a mold for the reed.
Put your stock in the cavity, hold both down via magnet,
and grind top surface flat (on ordinary surface grinder),
leaving proper cross-section.

With this approach, the hard parts are making the die
and getting the stock to hold down well enough. To see
if the process would work, I think you could make up a
quick-and-dirty die by a couple of cuts on a mill, with
a fairly arbitrary profile rather than an accurate one,
and take that die and some stock to a "shop or a friends'
grinder" (as Ken suggested in later post) to see if the
process would work, before going to the trouble of making
up an accurate die. If it worked ok, then you could make
an accurate die and a miniature SG with manual downfeed
and motorized X axis.
-jiw


  #11   Report Post  
DoN. Nichols
 
Posts: n/a
Default

In article ,
James Waldby wrote:
Ken Cutt wrote:
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


rashid111 wrote:
Ken -
do you mean use a pantograph style device to transfer dimension
of a die to the target ? Can you elaborate a bit here ?


I supposed he meant:
Cut out a cavity in a block, like a mold for the reed.
Put your stock in the cavity, hold both down via magnet,
and grind top surface flat (on ordinary surface grinder),
leaving proper cross-section.

With this approach, the hard parts are making the die
and getting the stock to hold down well enough. To see
if the process would work, I think you could make up a
quick-and-dirty die by a couple of cuts on a mill, with
a fairly arbitrary profile rather than an accurate one,
and take that die and some stock to a "shop or a friends'
grinder"


Hmm -- accordion (and concertina) reeds are very sensitive to
the contour of the bottom surface. Your method would be forcing the
flat bottom surface to curve to allow the removal of material from the
top side. When you release it, you may have a curve which will make
getting the reed to "speak" quickly (or at all) more difficult. I can
see you spending the time saved in the machining carefully bending the
reed back to the correct profile. (A curve near the tip will result in
a shift in pitch as the reed goes from a dead stop to a stable pitch --
and more of a shift with each increment in bellows pressure. There is
always some shift as a function of bellows pressure, but it is
beneficial to make that as small a shift as possible.

And aside from that -- at least some concertina reeds (I know --
the original question was about accordion reeds, but there are
similarities) will start out at a constant thickness where the reed is
clamped into the carrier, then a fairly sharp step, curving down to a
minimum thickness at about the 1/3 distance from the clamp to the tip,
and then gradually increasing in thickness towards the tip. I don't
know if any accordion reeds do this -- though I would expect it more of
the bass reeds on the left-hand end. Anyway -- such a shape would
require a rather massive magnetic field to achieve the initial
pull-down, and then a lot of work straightening the back when the
grinding is done.

And -- the contour of a reed may need to be changed from
instrument to instrument (as well as from note to note), so the number
of dies would quickly get out of hand, I fear. (Unless this is for
production -- the manufacturing of a single line of accordions, instead
of making replacement reeds for instruments from here and there.

Another consideration is that while the die and hold-down field
might work for the shape, it would still need quite a few passes of
gradually increasing depth to avoid burning the temper of the reeds with
the grinding heat (thus making the reeds duller and less responsive).

But -- it still might be an interesting experiment.

Enjoy,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---
Reply
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules

Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Looking for info on a Delta "toolmaker" surface grinder Waynemak Metalworking 3 April 8th 05 01:06 AM
FS: Boyar Schultz 612 Surface Grinder Marty Escarcega Metalworking 3 February 13th 05 02:15 AM
FA Nice little surface grinder ( ebay ) AZOTIC Metalworking 6 January 14th 05 01:46 AM
Building an Extension (Preparation Stage) Andrew UK diy 7 December 29th 03 11:48 PM
Building Warrants - Buying Flat Without L Reid UK diy 6 July 16th 03 03:54 PM


All times are GMT +1. The time now is 11:30 AM.

Powered by vBulletin® Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright 2004-2024 DIYbanter.
The comments are property of their posters.
 

About Us

"It's about DIY & home improvement"