¿ªÔÆÌåÓý

Date

Re: unusual tap

bbftx
 

Rich,
Here's a place that has all sorts of weird taps>


B Flint


--- In 7x12minilathe@..., Richard Kleinhenz
<woodnpen@o...> wrote:
Would anyone know where I can find an M9x0.5 metric tap? I checked
MSC, J&L and Travers, I don't think any of the std places would have
this. Is there someone specializing in out of the ordinary taps liek
this?

--
Regards,
Rich
========================================
Richard Kleinhenz
mailto:woodnpen@o...


========================================


unusual tap

Richard Kleinhenz
 

Would anyone know where I can find an M9x0.5 metric tap? I checked MSC, J&L and Travers, I don't think any of the std places would have this. Is there someone specializing in out of the ordinary taps liek this?

--
Regards,
Rich
========================================
Richard Kleinhenz
mailto:woodnpen@...


========================================


Re: cutting speeds

Richard Kleinhenz
 

Thank you both, looks like I am in the ballpark, in general. Maybe I need to try HSS rather than carbide inserts.
m
--
Regards,
Rich
========================================
Richard Kleinhenz
mailto:woodnpen@...


========================================


Re: cutting speeds

Bril Flint
 

Richard,
Definitely try HSS, as an experiment for your own education under your own shop circumstances if nothing else. HSS just seems more forgiving to me, and I get better results since I haven't seemed to crack the "carbide code" yet. HSS will wear faster, but for me, that's a small price to pay for better, more consistent results.

B Flint

----- Original Message -----
From: Richard Kleinhenz
To: 7x12minilathe@...
Sent: Tuesday, April 01, 2003 6:33 PM
Subject: Re: [7x12minilathe] Re: cutting speeds


Thank you both, looks like I am in the ballpark, in general. Maybe I need to try HSS rather than carbide inserts.
m
--
Regards,
Rich
========================================
Richard Kleinhenz
mailto:woodnpen@...


========================================



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just got a lathe

 

I'm a retired engineer in the milwaukee area. Just bought a mini
lathe from Frank who has a booth at 7 mile fair. I think its the
same as the Homeier unit.
I'm new at actually cutting metal, although I've had model makers
build me things for years.
I bought Joe Martin's book on Tabletop Machining. Turning metal to
size is not too hard.
When the tool comes, we'll see if i can cut inside threads.
I'd love to hear from others in the milwaukee area and could use
immediate advice on where to get small amoounts of material to turn
Thanks
mike Aita
414 962 1878


Re: cutting speeds

lomahoney55
 

Relative newbie chiming in here. I've had a bunch of experience with
this lately, turning some 1 inch Al down to 0.5 inch in the center of
a shaft. I'm finding that these 7x12s can hog out up to 0.020 inch
with either a HSS or a cemented carbide bit, but the finish is not
very good. I use this for a roughing cut to remove a lot of material
quickly. The speed is about at the 9:30+- position in the LOW range
using a slow and even hand feed on the carraige.

Then, back off the bit and skin off 0.001 or 0.002 on each pass with
the speed dial about 12:00-1:00 until I arrive at my final diameter.
I find I can get a good finish with the carbide bits, a better finish
with a sharpened HSS. Patience is the key. Dry or lubed with TapMagic
seems to make no difference on the Al. Finish it off with emory cloth
(s). Another Yahoo group recommended using polish while the piece is
still on the lathe, but I haven't gotten that far yet.

In general, I'm not too pleased with the commercial carbide bits, but
I think they are cheapy Enco bits. If I buy carbides in the future,
I'm going to buy some top quality ones and see how they do.

Larry
New Orleans

--- In 7x12minilathe@..., "Ed Paradis" <eparadis@a...>
wrote:
Rich, I wouldn't say that the speeds are totaly inappropriate for
the
7x's, but I would use them as a general guide. For most steels, I
generally run at a lower speed, typically between 9:00 and 11:00 on
the dial (in low range), and with aluminium, I run at higher
speeds,
typically 10:00 to 1:00 on the dial. The finish is more of a
function of how deep you're cutting and the type of toolbit you're
using. I use predominatly carbide (brazed/cemented & inserts) and
get a pretty decent finish. On the roughing cuts, I'll go anywhere
from about .015 to .020 on steel, as much as .050 on Al. I let the
machine tell me when I'm a little too aggressive, usually groans or
chatters if I'm taking too much (or stalls when it hogs in)... For
my finishing cuts, I generally only go .001 - .002 deep and speed
up
the machine (around 11:00 to 01:00 for steel, 01:00 to 05:00 for
Al)
and manually advance the carriage. I always use some form of lube,
usually "tapmagic", applied with a small brush to the rotating
piece
and I'm usually pretty happy with the result. I keep some strips
of
400 grit wet/dry close by to polish a little while rotating also
(be
careful it doesn't pull you in). The finish is generally better
also
if you use a more blunt or rounded radius on the toolbit with light
cuts rather than a sharp pointed one, in my experience.

Ed

--- In 7x12minilathe@..., Richard Kleinhenz
<woodnpen@o...> wrote:
I understand that cutting speeds published in the books are
generally used for large machines, and that they are totally
inappropriate for our 'toys'. (I have a 7x12). We should go by
what
feels right.

I am looking for a little guidance here. Say I machine 3/8" or
1/2" 1018 steel. Where should I be approximately? I have an
inexpensive indexable toolset from LMS. The surfaces I get are
nothing to write home about... Can anyone with some experience
steer
me in the right direction? Should I always apply cutting oil? How
much to remove in a pass? What speed? I am on the low range.
What
dial setting appr.? It seems easier to take a heftier cut than a
small cut... something seems wrong ;-) Is there something like a
lower limit for a lathe cut?

I get by, because I don't need a good finish on these simple
bushings I make, but I sure would like to do it better eventually.

Thanks for any pointers!

--
Regards,
Rich
========================================
Richard Kleinhenz
mailto:woodnpen@o...


========================================


Re: cutting speeds

Ed Paradis
 

Rich, I wouldn't say that the speeds are totaly inappropriate for the
7x's, but I would use them as a general guide. For most steels, I
generally run at a lower speed, typically between 9:00 and 11:00 on
the dial (in low range), and with aluminium, I run at higher speeds,
typically 10:00 to 1:00 on the dial. The finish is more of a
function of how deep you're cutting and the type of toolbit you're
using. I use predominatly carbide (brazed/cemented & inserts) and
get a pretty decent finish. On the roughing cuts, I'll go anywhere
from about .015 to .020 on steel, as much as .050 on Al. I let the
machine tell me when I'm a little too aggressive, usually groans or
chatters if I'm taking too much (or stalls when it hogs in)... For
my finishing cuts, I generally only go .001 - .002 deep and speed up
the machine (around 11:00 to 01:00 for steel, 01:00 to 05:00 for Al)
and manually advance the carriage. I always use some form of lube,
usually "tapmagic", applied with a small brush to the rotating piece
and I'm usually pretty happy with the result. I keep some strips of
400 grit wet/dry close by to polish a little while rotating also (be
careful it doesn't pull you in). The finish is generally better also
if you use a more blunt or rounded radius on the toolbit with light
cuts rather than a sharp pointed one, in my experience.

Ed

--- In 7x12minilathe@..., Richard Kleinhenz
<woodnpen@o...> wrote:
I understand that cutting speeds published in the books are
generally used for large machines, and that they are totally
inappropriate for our 'toys'. (I have a 7x12). We should go by what
feels right.

I am looking for a little guidance here. Say I machine 3/8" or
1/2" 1018 steel. Where should I be approximately? I have an
inexpensive indexable toolset from LMS. The surfaces I get are
nothing to write home about... Can anyone with some experience steer
me in the right direction? Should I always apply cutting oil? How
much to remove in a pass? What speed? I am on the low range. What
dial setting appr.? It seems easier to take a heftier cut than a
small cut... something seems wrong ;-) Is there something like a
lower limit for a lathe cut?

I get by, because I don't need a good finish on these simple
bushings I make, but I sure would like to do it better eventually.

Thanks for any pointers!

--
Regards,
Rich
========================================
Richard Kleinhenz
mailto:woodnpen@o...


========================================


Re: No longer a wannabe

bflint
 

Larry,
For a drill chuck for the mini lathe tailstock, you can't beat Little
Machine Shop. They have a an arbor and 1/2 drill chuck for $25. The nice
thing about it is that it is a shortened arbor that fits in the mini lathe
tailstock. Most MT2 arbors out there need to be cut off to mount in the
short tailstock.


LMS also has faceplates and chucks. You might be able to find chucks a
couple bucks cheaper elsewhere, but if you're ordering a drill chuck and
arbor, you might as well get it all from one place to minimize shipping
costs.
B Flint

----- Original Message -----
From: <toolroomtrustee@...>
To: <7x12minilathe@...>
Sent: Thursday, March 27, 2003 9:55 AM
Subject: [7x12minilathe] No longer a wannabe
Who currently has best price on faceplates, 4-jaw chucks, #2MT drill chuck
arbors?
Larry Murray








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Re: cutting speeds

bflint
 

Rich,
I'm getting good results on mild steel like 1018 using HSS tools with no
coolant. What type of inserts are you using? I haven't gotten as good
results with coated carbide inserts no matter what I seem to try. Carbide
generally likes higher speeds and deeper cuts.

The HSS inserts from LMS in indexable tool holders have worked well for me,
as have ground HSS bits.
I'm getting a good finish with relatively light cuts anywhere from .001" up
to about.020". For 1/2" diameter, I'd have the dial on my machine about
halfway on the low range. Assuming that's about 600 rpm, I think we're
talking about 75 feet per minute surface speed, which is well under the
recommended max for turning mild steel.

I'm also getting better results with steel now that I have completed the JWE
compound mods and have a good size QCTP (series 100). It's more massive and
more rigid than the stock mini lathe toolposts. You also have to make sure
you have the gibs on the cross slide and compound snug.
Also, if you're turning a workpiece longer than about 2 or 3x the diameter,
you probably need to have the tailstock end supported by a center.
Otherwise it will deflect and give you a bad finish.

I'm sure other people may use different setups, but that's what has worked
best for me.
B Flint

----- Original Message -----
From: "Richard Kleinhenz" <woodnpen@...>
To: <7x12minilathe@...>
Sent: Sunday, March 30, 2003 5:37 PM
Subject: [7x12minilathe] cutting speeds


I understand that cutting speeds published in the books are generally used
for large machines, and that they are totally inappropriate for our 'toys'.
(I have a 7x12). We should go by what feels right.

I am looking for a little guidance here. Say I machine 3/8" or 1/2" 1018
steel. Where should I be approximately? I have an inexpensive indexable
toolset from LMS. The surfaces I get are nothing to write home about...
Can anyone with some experience steer me in the right direction? Should I
always apply cutting oil? How much to remove in a pass? What speed? I am
on the low range. What dial setting appr.? It seems easier to take a
heftier cut than a small cut... something seems wrong ;-) Is there
something like a lower limit for a lathe cut?

I get by, because I don't need a good finish on these simple bushings I
make, but I sure would like to do it better eventually.

Thanks for any pointers!

--
Regards,
Rich
========================================
Richard Kleinhenz
mailto:woodnpen@...


========================================




To unsubscribe from this group, send an email to:
7x12minilathe-unsubscribe@...



Your use of Yahoo! Groups is subject to


cutting speeds

Richard Kleinhenz
 

I understand that cutting speeds published in the books are generally used for large machines, and that they are totally inappropriate for our 'toys'. (I have a 7x12). We should go by what feels right.

I am looking for a little guidance here. Say I machine 3/8" or 1/2" 1018 steel. Where should I be approximately? I have an inexpensive indexable toolset from LMS. The surfaces I get are nothing to write home about... Can anyone with some experience steer me in the right direction? Should I always apply cutting oil? How much to remove in a pass? What speed? I am on the low range. What dial setting appr.? It seems easier to take a heftier cut than a small cut... something seems wrong ;-) Is there something like a lower limit for a lathe cut?

I get by, because I don't need a good finish on these simple bushings I make, but I sure would like to do it better eventually.

Thanks for any pointers!

--
Regards,
Rich
========================================
Richard Kleinhenz
mailto:woodnpen@...


========================================


Re: 7x12 Blows Fuses ?

John
 

Hi Frank,

I also turn speed to zero before using any other control. But I am
leery of a failure causing the chuck to move while I have a grip on
the key, unlikely as that may be. Note that when I inserted the
extra fuse and turned the power on with the speed control set to OFF
that the chuck went to full speed for a half second or so before the
fuse blew -- this is the type of thing I don't want to happen while
I've got a grip on the chuck or the work. Also, I sometimes use the
tailstock chuck to start taps and noted that the headstock chuck is
more difficult to turn if the power is applied even though the speed
control is set to zero -- the big red button fixes this too.

Like you, I turn the power completely off when I'm done using the
machine. This is good practice because otherwise the lathe's
electronics are exposed to line transients from passing T-storms,
etc. I wired my shop so all the wall outlets are on one wall switch
and the radio is a reminder that ensures I turn it off when leaving.
During the summer I will pull the plug as further transient
protection.

Some further news on the FET failure: I removed the shorted FET and
tried the unit with the single remaining FET in place -- it works
normally, at least for the short term. I assume it won't run too
long this way because the FET will over heat. I did add a number of
air holes to the case below the FET heat sink and will monitor the
temp while awaiting replacement parts.

As a guess about why some controllers last and others fail: if the
parallel FET's both conduct the same amount of current while ON then
the controller will last but if the FET's are grossly mismatched then
one will conduct the bulk of the current and eventually fail -- the
time to failure will depend on the degree of mismatch. The
replacement IRFP460 FET's have a lower ON resistance than the
original 2SK790's so they should dissipate less heat under all
circumstances (including mismatched device characteristics).
Probably, the 460 FET's would survive if used singly although I will
install two to ensure long term viability.

John



--- In 7x12minilathe@..., Frank Hoose <fhoose@y...> wrote:
I don't know for sure if it makes a difference, but I
always turn the speed down to zero before switching
direction or turning off the lathe. I have not had a
FET failure in over 2 years following this procedure
and I use my lathe about 10 hours per week or more. I
never use the big red button since I power off the
lathe from a power strip it is plugged into when I'm
done working with it.

Frank Hoose



--- John <moran03@e...> wrote:
Hi Chris,

Thanks for the info. Unfortunately I have already
ordered the
IRFP460 replacement FET's from an electronics
supplier -- they have a
minimum $ order so I'll wind up with a LOT of
transistors and fuses
(in case anyone else runs into the same problem,
contact me for a
good deal on these items...).

Homier is sending a replacement board but it may
take up to 2 weeks
so I'll probably try to repair the present board in
the interim.

I found a schematic for the Grizzly 7x12 in the 7x10
group photos
section in a folder titled ESC. This confirmed what
I had determined
from looking at the ckt board: the output FET's are
in parallel but
they do not use source resistors to ensure equal
current sharing. My
theory on why my unit failed is that this particular
board has 2SK790
FET's from different manufacturers; I suspect that
the device
characteristics were sufficiently different that
they didn't share
the current equally causing the device which took
the bulk of the
current to eventually fail. Others who experience a
similar failure
might check to see whether both devices have the
same manufacturer's
logo as a check on my supposition.

Also, I had gotten into the habit of putting the
fwd/rev switch into
the center=off position when fiddling with the
chuck, this to ensure
that the chuck wouldn't move in the unlikely event
of a failure
occurring while my hands were in harm's way. I can't
decide whether
this may have contributed to the failure. Based on
examining the
schematic I will in the future use the big red
button instead of the
fwd/rev switch to ensure the chuck can't move --
don't know whether
this will help but it certainly won't hurt.

Further, I intend to add some holes in the case
below the heat sink
and to add a spacer to ensure the clear plastic
shield is held away
from the heat sink so air can circulate past the
sink. These holes
will also help any metal chips which wander into the
electronics
enclosure find their way back out. Again, this may
not help but it
won't hurt.

Having had my favorite toy disabled by an
electronics failure I'm
trying to avoid a repetition.

John



--- In 7x12minilathe@..., Chris Wood
<chrisw@s...> wrote:
John:

It sounds like the MOSFETs have blown. We have
replacements that
are higher
capacity.

ProductID=1221

Regards,
Chris Wood
LittleMachineShop.com <www.littlemachineshop.com>
The premier source of parts and accessories for
mini lathes and
mini mills.
221 E. Walnut St. #110, Pasadena, CA 91101
(800)981-9663 * Fax (626)584-5844



-----Original Message-----
From: John [mailto:moran03@e...]
Sent: Sunday, March 23, 2003 8:32 AM
To: 7x12minilathe@...
Subject: [7x12minilathe] 7x12 Blows Fuses ?


My 7x12 which is now 2.5 months old popped its
fuse shortly after
startup Friday, just as I was beginning a parting
cut at low
speed.
I installed the replacement fuse and , with the
speed control in
the
OFF position and the tool backed away, the lathe
started as if it
was
at full speed and the fuse popped again in less
than a second.

This is a relatively new unit so I called Homier
and they promised
to
call me back on Monday. I'm just wondering if
this is a common
problem; my understanding is the Homiers use an
SCR based
controller
which is less prone to failure than the MOSFET
types. My ckt board
has a sticker with FC250J/110V and the large power
devices are
identified as K790 -- the board uses surface mount
devices except
for power handling which are thru-hole. Anybody
have more info on
the Homier controller?

Up until this happened I was very happy with the
controller since
it
allowed speed to be reduced to 12rpm, slower than
most references
in
the 7x10 group specify. I did notice that when
the speed control
was
in the OFF position that rotating the knob
slightly(as alowed while
OFF) made the chuck would move slightly and groan
a bit. Since it
seems to be live even while OFF I always turn the
wall outlet off
after use.

John



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desktop!


Re: 7x12 Blows Fuses ?

Richard Albers
 

--- In 7x12minilathe@..., "John" <moran03@e...> wrote:
<Big Snip>

Further, I intend to add some holes in the case below the heat sink
and to add a spacer to ensure the clear plastic shield is held away
from the heat sink so air can circulate past the sink. These holes
will also help any metal chips which wander into the electronics
enclosure find their way back out. Again, this may not help but it
won't hurt.
I think those holes would just let more chips IN. I don't have any
extra holes in there (on my Grizzly 7x12) and have never had a FET
fail.

Since you will have extra FETs, try it without the holes, first.

Just my opinion...

RA


Re: 7x12 Blows Fuses ?

 

I don't know for sure if it makes a difference, but I
always turn the speed down to zero before switching
direction or turning off the lathe. I have not had a
FET failure in over 2 years following this procedure
and I use my lathe about 10 hours per week or more. I
never use the big red button since I power off the
lathe from a power strip it is plugged into when I'm
done working with it.

Frank Hoose



--- John <moran03@...> wrote:
Hi Chris,

Thanks for the info. Unfortunately I have already
ordered the
IRFP460 replacement FET's from an electronics
supplier -- they have a
minimum $ order so I'll wind up with a LOT of
transistors and fuses
(in case anyone else runs into the same problem,
contact me for a
good deal on these items...).

Homier is sending a replacement board but it may
take up to 2 weeks
so I'll probably try to repair the present board in
the interim.

I found a schematic for the Grizzly 7x12 in the 7x10
group photos
section in a folder titled ESC. This confirmed what
I had determined
from looking at the ckt board: the output FET's are
in parallel but
they do not use source resistors to ensure equal
current sharing. My
theory on why my unit failed is that this particular
board has 2SK790
FET's from different manufacturers; I suspect that
the device
characteristics were sufficiently different that
they didn't share
the current equally causing the device which took
the bulk of the
current to eventually fail. Others who experience a
similar failure
might check to see whether both devices have the
same manufacturer's
logo as a check on my supposition.

Also, I had gotten into the habit of putting the
fwd/rev switch into
the center=off position when fiddling with the
chuck, this to ensure
that the chuck wouldn't move in the unlikely event
of a failure
occurring while my hands were in harm's way. I can't
decide whether
this may have contributed to the failure. Based on
examining the
schematic I will in the future use the big red
button instead of the
fwd/rev switch to ensure the chuck can't move --
don't know whether
this will help but it certainly won't hurt.

Further, I intend to add some holes in the case
below the heat sink
and to add a spacer to ensure the clear plastic
shield is held away
from the heat sink so air can circulate past the
sink. These holes
will also help any metal chips which wander into the
electronics
enclosure find their way back out. Again, this may
not help but it
won't hurt.

Having had my favorite toy disabled by an
electronics failure I'm
trying to avoid a repetition.

John



--- In 7x12minilathe@..., Chris Wood
<chrisw@s...> wrote:
John:

It sounds like the MOSFETs have blown. We have
replacements that
are higher
capacity.

ProductID=1221

Regards,
Chris Wood
LittleMachineShop.com <www.littlemachineshop.com>
The premier source of parts and accessories for
mini lathes and
mini mills.
221 E. Walnut St. #110, Pasadena, CA 91101
(800)981-9663 * Fax (626)584-5844



-----Original Message-----
From: John [mailto:moran03@e...]
Sent: Sunday, March 23, 2003 8:32 AM
To: 7x12minilathe@...
Subject: [7x12minilathe] 7x12 Blows Fuses ?


My 7x12 which is now 2.5 months old popped its
fuse shortly after
startup Friday, just as I was beginning a parting
cut at low
speed.
I installed the replacement fuse and , with the
speed control in
the
OFF position and the tool backed away, the lathe
started as if it
was
at full speed and the fuse popped again in less
than a second.

This is a relatively new unit so I called Homier
and they promised
to
call me back on Monday. I'm just wondering if
this is a common
problem; my understanding is the Homiers use an
SCR based
controller
which is less prone to failure than the MOSFET
types. My ckt board
has a sticker with FC250J/110V and the large power
devices are
identified as K790 -- the board uses surface mount
devices except
for power handling which are thru-hole. Anybody
have more info on
the Homier controller?

Up until this happened I was very happy with the
controller since
it
allowed speed to be reduced to 12rpm, slower than
most references
in
the 7x10 group specify. I did notice that when
the speed control
was
in the OFF position that rotating the knob
slightly(as alowed while
OFF) made the chuck would move slightly and groan
a bit. Since it
seems to be live even while OFF I always turn the
wall outlet off
after use.

John



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7x12minilathe-unsubscribe@...



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No longer a wannabe

 

Wednesday I was in Chehalis, WA to have lunch date with a woman I met at a
dance. I told her HOMIER was having a sale there and she was pleased to go
with me before we had lunch.

We got there about 12:30 and they were still sticking stuff on the shelves.
Our first pass through I saw a 7x12 lathe out of it's box. A little later we

went by again and they had one in the box, I asked a worker if they'd help me
get it
in my truck, he said yes so I bought it for $299.99. Somebody put it in my
truck, I blue tarped it and secured it and off to lunch. Later I cuddled
with her leaving only when she had to get ready to have dinner with friends,
as I told her, she is a very attractive lady for a guy with a new lathe to
prefer to be with her
than getting lathe home to clean and set up.

I got home, pushed crap around on my workbench and managed to egt it up
and then mounted feet and chip tray. Not much grease on it and that was red
rather than the usual black gunky grease I have seen or worse the cosmoline
found on surplus military rifles. I was careful to put all the paper towel
grease wipers in outside garbage. I haven't turned it on yet, may be a few
days.

Seems a little silly to buy it since I already have a Unimat (originally
bought in 1968) and an Enco 9x20 bought 13-14 years ago, But I wanted it.
The only thing about buying it today was I had the pleasure today and I saved
the $70
or more UPS charges and instead paid $25 sales tax. I had WLS nearly six
months ago, had Lasiks eye surgery 12 days ago. I am starting community
college after 35 years away from school, I don't need this lathe but i want
it. I am already manufacturing rationales for it, one is my youngest brother
is gaving me his 1980 Vanagon, now I have a lathe that will fit in it.

I'll likely start out using drill chuck from the 9x20 and adapting things as
I can.
Who currently has best price on faceplates, 4-jaw chucks, #2MT drill chuck
arbors?


"Have lathe will travel" is the card of a man....

Anyway, I have a 7x 12 and am pleased.

Larry Murray


Lathe Storage

 

Hi,

On the subject of storing a bench lathe, has anyone come up with a
novel way of having a lathe bench and hauling crate combined. I am
thinking of perhaps combining the two features so one can use the
bottom of the crate for a lathe bench. Also combining features to
make it easier to haul up a set of steps by the single user/mover
would be really neat too.

Any suggestions would be appreciated.

Thanks in advance

Too_many_Tools


Re: 7x12 Blows Fuses ?

John
 

Hi Chris,

Thanks for the info. Unfortunately I have already ordered the
IRFP460 replacement FET's from an electronics supplier -- they have a
minimum $ order so I'll wind up with a LOT of transistors and fuses
(in case anyone else runs into the same problem, contact me for a
good deal on these items...).

Homier is sending a replacement board but it may take up to 2 weeks
so I'll probably try to repair the present board in the interim.

I found a schematic for the Grizzly 7x12 in the 7x10 group photos
section in a folder titled ESC. This confirmed what I had determined
from looking at the ckt board: the output FET's are in parallel but
they do not use source resistors to ensure equal current sharing. My
theory on why my unit failed is that this particular board has 2SK790
FET's from different manufacturers; I suspect that the device
characteristics were sufficiently different that they didn't share
the current equally causing the device which took the bulk of the
current to eventually fail. Others who experience a similar failure
might check to see whether both devices have the same manufacturer's
logo as a check on my supposition.

Also, I had gotten into the habit of putting the fwd/rev switch into
the center=off position when fiddling with the chuck, this to ensure
that the chuck wouldn't move in the unlikely event of a failure
occurring while my hands were in harm's way. I can't decide whether
this may have contributed to the failure. Based on examining the
schematic I will in the future use the big red button instead of the
fwd/rev switch to ensure the chuck can't move -- don't know whether
this will help but it certainly won't hurt.

Further, I intend to add some holes in the case below the heat sink
and to add a spacer to ensure the clear plastic shield is held away
from the heat sink so air can circulate past the sink. These holes
will also help any metal chips which wander into the electronics
enclosure find their way back out. Again, this may not help but it
won't hurt.

Having had my favorite toy disabled by an electronics failure I'm
trying to avoid a repetition.

John



--- In 7x12minilathe@..., Chris Wood <chrisw@s...> wrote:
John:

It sounds like the MOSFETs have blown. We have replacements that
are higher
capacity.
ProductID=1221

Regards,
Chris Wood
LittleMachineShop.com <www.littlemachineshop.com>
The premier source of parts and accessories for mini lathes and
mini mills.
221 E. Walnut St. #110, Pasadena, CA 91101
(800)981-9663 * Fax (626)584-5844



-----Original Message-----
From: John [mailto:moran03@e...]
Sent: Sunday, March 23, 2003 8:32 AM
To: 7x12minilathe@...
Subject: [7x12minilathe] 7x12 Blows Fuses ?


My 7x12 which is now 2.5 months old popped its fuse shortly after
startup Friday, just as I was beginning a parting cut at low
speed.
I installed the replacement fuse and , with the speed control in
the
OFF position and the tool backed away, the lathe started as if it
was
at full speed and the fuse popped again in less than a second.

This is a relatively new unit so I called Homier and they promised
to
call me back on Monday. I'm just wondering if this is a common
problem; my understanding is the Homiers use an SCR based
controller
which is less prone to failure than the MOSFET types. My ckt board
has a sticker with FC250J/110V and the large power devices are
identified as K790 -- the board uses surface mount devices except
for power handling which are thru-hole. Anybody have more info on
the Homier controller?

Up until this happened I was very happy with the controller since
it
allowed speed to be reduced to 12rpm, slower than most references
in
the 7x10 group specify. I did notice that when the speed control
was
in the OFF position that rotating the knob slightly(as alowed while
OFF) made the chuck would move slightly and groan a bit. Since it
seems to be live even while OFF I always turn the wall outlet off
after use.

John



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7x12minilathe-unsubscribe@...



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Re: Installed a Digital Readout on Lathe

 

Yes. Zietlowdesign.com should do the trick.

Lee



--- In 7x12minilathe@..., "bbftx" <bflint@a...> wrote:
Lee
Do you have a web address for Zietlow?
I couldn't find it with a Google search.
Thanks
B Flint

--- In 7x12minilathe@..., "trainman80005"
<Trainman4@h...> wrote:
Hi:

I have just completed the installation of a digital readout on my
Grizzly 7 X 12 and could not be happier. I purchased the DRO
from
Zietlow Design off of the internet and got the Quill Kits for the
machine off of Ebay. On the Zietlow website there are complete
instructions on how to make the mounts required for the
installation
and how to set everything up. It is really nice to now be able
to
know exactly where your cutter is located on the x and y axis and
not
have to make a guess by reading the dials and worring about
backlash. The entire project was completed for less than
$250.00.
I
am placing some pictures in the photo section of the installation.

Lee Brown


Re: Installed a Digital Readout on Lathe

 

Yes. Zietlowdesign.com should do the trick.

Lee



--- In 7x12minilathe@..., "bbftx" <bflint@a...> wrote:
Lee
Do you have a web address for Zietlow?
I couldn't find it with a Google search.
Thanks
B Flint

--- In 7x12minilathe@..., "trainman80005"
<Trainman4@h...> wrote:
Hi:

I have just completed the installation of a digital readout on my
Grizzly 7 X 12 and could not be happier. I purchased the DRO
from
Zietlow Design off of the internet and got the Quill Kits for the
machine off of Ebay. On the Zietlow website there are complete
instructions on how to make the mounts required for the
installation
and how to set everything up. It is really nice to now be able
to
know exactly where your cutter is located on the x and y axis and
not
have to make a guess by reading the dials and worring about
backlash. The entire project was completed for less than
$250.00.
I
am placing some pictures in the photo section of the installation.

Lee Brown


Re: 7x12 Blows Fuses ?

Chris Wood
 

John:

It sounds like the MOSFETs have blown. We have replacements that are higher
capacity.


Regards,
Chris Wood
LittleMachineShop.com <www.littlemachineshop.com>
The premier source of parts and accessories for mini lathes and mini mills.
221 E. Walnut St. #110, Pasadena, CA 91101
(800)981-9663 * Fax (626)584-5844

-----Original Message-----
From: John [mailto:moran03@...]
Sent: Sunday, March 23, 2003 8:32 AM
To: 7x12minilathe@...
Subject: [7x12minilathe] 7x12 Blows Fuses ?


My 7x12 which is now 2.5 months old popped its fuse shortly after
startup Friday, just as I was beginning a parting cut at low speed.
I installed the replacement fuse and , with the speed control in the
OFF position and the tool backed away, the lathe started as if it was
at full speed and the fuse popped again in less than a second.

This is a relatively new unit so I called Homier and they promised to
call me back on Monday. I'm just wondering if this is a common
problem; my understanding is the Homiers use an SCR based controller
which is less prone to failure than the MOSFET types. My ckt board
has a sticker with FC250J/110V and the large power devices are
identified as K790 -- the board uses surface mount devices except
for power handling which are thru-hole. Anybody have more info on
the Homier controller?

Up until this happened I was very happy with the controller since it
allowed speed to be reduced to 12rpm, slower than most references in
the 7x10 group specify. I did notice that when the speed control was
in the OFF position that rotating the knob slightly(as alowed while
OFF) made the chuck would move slightly and groan a bit. Since it
seems to be live even while OFF I always turn the wall outlet off
after use.

John



To unsubscribe from this group, send an email to:
7x12minilathe-unsubscribe@...



Your use of Yahoo! Groups is subject to


Re: Installed a Digital Readout on Lathe

John
 

Check this address, it may be what you want:






--- In 7x12minilathe@..., "bbftx" <bflint@a...> wrote:
Lee
Do you have a web address for Zietlow?
I couldn't find it with a Google search.
Thanks
B Flint

--- In 7x12minilathe@..., "trainman80005"
<Trainman4@h...> wrote:
Hi:

I have just completed the installation of a digital readout on my
Grizzly 7 X 12 and could not be happier. I purchased the DRO
from
Zietlow Design off of the internet and got the Quill Kits for the
machine off of Ebay. On the Zietlow website there are complete
instructions on how to make the mounts required for the
installation
and how to set everything up. It is really nice to now be able
to
know exactly where your cutter is located on the x and y axis and
not
have to make a guess by reading the dials and worring about
backlash. The entire project was completed for less than
$250.00.
I
am placing some pictures in the photo section of the installation.

Lee Brown