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Hi Mike,

Thanks for the info on the FET -- I didn't know what it was for sure.
I understand that there is a more rugged FET which can be used for a
replacement so I'll talk to Homier about that when they call.

Like you, I found the controller worked nicely (until it failed).
I've stalled it several times at low speeds (parting mostly) and it
just hums -- I quickly turn it off with the pot and release the tool.

Since my lathe is inactive anyway I'm taking advantage of the down
time to fiddle with some of the suggested mods. I've lapped the
gibs/dovetails on the cross and compound slides and they seem a bit
smoother now although they were not bad to begin with. Now I'm
trying to adjust the backlash out of the cross slide without causing
binding, which isn't as easy as I expected...

John

--- In 7x12minilathe@..., "Mike Nash"
<mnfwd2.minilathe@m...> wrote:

It sounds like you have the newer (Sieg made) Homier with a mosfet

type

controller. I have the older Homier with the SCR controller and

these would

fail to zero speed with blown fuses.

Yep, it's a mosfet controller:
Description:
2SK 790
N-FET/500V/15A/150W

I find these failures strange. My Homier mini mill uses a mosfet

drive and

(so far) it has simply "tripped" when overloaded. Turning the speed

pot to

zero (click) and back on resets it.

Mike Nash



----- Original Message -----
From: "John" <moran03@e...>
To: <7x12minilathe@...>
Sent: Sunday, March 23, 2003 10:32 AM
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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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

What other machines do you have Bill?
I have a Burke #4 mill to go with my Homier 7x12.
One of the most impactful changes I made to my lathe to overcome
the "crudities," as you put it so well, was to install a real
toolholder. I went with the Series 100 Phase II QCTP, after making
the JWE compound mods. This dramatically reduced chatter and
improved rigidity. I don't find myself fiddling with those gib
adjustment set screws all the time now. (That never seemed to
accomplish much!)
Next thing I want to do is make some tapered saddle gibs.
B Flint

--- In 7x12minilathe@..., "bwmsbldr" <BWMSBLDR@J...>
wrote:

I moved to this list from a similar one that suffered from an
excess of Off Topic posts. I am hoping to participate in a list

that

is focused on the small chinese hobby lath. I have been machining
as a hobby since starting in HS in 1953 and own a selection of

machine

tools. Bought my HF 7x10 at a garage sale for $100 last year. I

have

added a number of accessories from HF lacking only a four jaw

chuck.

the current effort is to eliminate the play and adjustment

crudities

in the machine and repair it up to optimum condition. Fortunatly
having other machines will ease that project.

Bill Williams (Bill in

Boulder)

Tom,
I looked at your photos. Nice work. I think you made the right
move going with 4 screws to hold the tools. I like the height
adjustment arrangement you used too.
Are those titanium coated carbide inserts in your pictures? I
recently got some and have been experimenting with them, but
haven't found the right combination of speed and depth of cut
to make them work well. What are you doing on steel and aluminum?
B Flint



-- In 7x12minilathe@..., "tomdoyle123456789"
<tdoyle@m...> wrote:

I recently completed the Cam Action QCTP project described on
mini-lathe.com. It works very well and I am very happy with it.
I made a few changes you might want to consider if you decide to
build it. I added a parting tool holder and changed the way the
height adjusting screw is tensioned. The height adjusting screw
tensioning described on mini-lathe.com would not work with the
parting tool so I used a more traditional method on all the tool
holders including the parting tool. Used a 3/4" 10-34 set screw
threaded 1/4" into the tool holder.
A knurled 3/16" thick adjusting screw is made from 1/2" brass rod.
A split washer and 10/32 nut hold the adjusting screw in place.

I used 4 screws to hold the tools in place rather than two.
Made the cam shaft from 1/2" drill rod which allowed the use of
1/4" rod for the handle. I posted some fairly nice photos in the
photos section. The close up photo of the parting tool (look at
it in full size) should tell the story If anyone needs more info
on the parting tool holder let me know.

tom ...

--- In 7x12minilathe@..., Boris Tolkachev
<btolkachev@y...> wrote:

My name is Boris, I live in Jersey City, NJ.

]

Have you tried vo tech schools or community colleges in your area.
Maybe even some high schools offer night courses and will allow use
of their machines.

It sounds like you have the newer (Sieg made) Homier with a mosfet type
controller. I have the older Homier with the SCR controller and these would
fail to zero speed with blown fuses.

Yep, it's a mosfet controller:
Description:
2SK 790
N-FET/500V/15A/150W

I find these failures strange. My Homier mini mill uses a mosfet drive and
(so far) it has simply "tripped" when overloaded. Turning the speed pot to
zero (click) and back on resets it.

Mike Nash

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

I have made a couple of small modifications to improve my 7 x12.
Using a small piece of hyfax plastic from the junk box I made a flag
for the tail stock so that I could mount a dial indicator and measure
the depth of a hole I am boring. (photo in photo section) The dial
indicator is a cheapy from Harbor Freight mounted on a magnet using a
small piece of 3/4" aluminum angle.

I have also added some short legs to boost the height of the lathe.
My lathe sits on a counter height bench and placed it at the wrong
height for me so I made short legs from 1 1/2" Aluminum to raise the
lathe. Much better. (photo in photo section)

Lee Brown

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

For those not on the 7x10minilathe group:

I moved to this list from a similar one that suffered from an
excess of Off Topic posts. I am hoping to participate in a list that
is focused on the small chinese hobby lath. I have been machining
as a hobby since starting in HS in 1953 and own a selection of machine
tools. Bought my HF 7x10 at a garage sale for $100 last year. I have
added a number of accessories from HF lacking only a four jaw chuck.
the current effort is to eliminate the play and adjustment crudities
in the machine and repair it up to optimum condition. Fortunatly
having other machines will ease that project.

Bill Williams (Bill in Boulder)

I recently completed the Cam Action QCTP project described on mini-
lathe.com. It works very well and I am very happy with it. I made a
few changes you might want to consider if you decide to build it. I
added a parting tool holder and changed the way the height adjusting
screw is tensioned. The height adjusting screw tensioning described
on mini-lathe.com would not work with the parting tool so I used a
more traditional method on all the tool holders including the parting
tool. Used a 3/4" 10-34 set screw threaded 1/4" into the tool holder.
A knurled 3/16" thick adjusting screw is made from 1/2" brass rod. A
split washer and 10/32 nut hold the adjusting screw in place.

I used 4 screws to hold the tools in place rather than two.
Made the cam shaft from 1/2" drill rod which allowed the use of 1/4"
rod for the handle. I posted some fairly nice photos in the photos
section. The close up photo of the parting tool (look at it in full
size) should tell the story If anyone needs more info on the parting
tool holder let me know.

tom ...

My name is Boris, I live in Jersey City, NJ.

I need to build a prototype of my invention. Unfortunately, due to my recent relocation and long process of job seeking, my funds are not in good condition yet. I can't buy simple lathe I need now, and I'm looking for access to lathe belonging to somebody else. I'm a handyman, from my High school times I remember how to use lathe and I have some money to pay for the access or for parts manufacturing
if it will be affordable to me. I do not have many friends here in NJ and nobody I know can tell me where I can access rotating lathe.

All parts I want to make now are small (all dimensions less than 4 inches). I evaluate time I need as 6 - 8 hr of work.

I will be grateful for advise regarding places in NJ/NY where rotating lathes might be accessible.

Thanks

Boris




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Thanks Bob. If I read you right if I bought an Asian 7x12 or 9x20
I'd have these same issues, right?

Thanks a bunch.

Paul





--- In 7x12minilathe@..., Bob Sunley <rosunley@s...>
wrote:

With the exception of the Micromart lathes and the leadscrews on

the US

model 7xX they all have metric cross slide and compound screws, so

no big

problem there. You have to cut to size anyway so if you have inch
measuring tools you are ok, or bring your calculator. If the

graduations on

the lathe are 40 per turn or 0.025mm per division, that is just a

hair under

0.001" by 0.0004 mm. per division.


Bob

On 11 Mar 2003, at 11:49, pkklathe wrote:

I am looking at a lathe that is set up to metric scale - the

dials

are all in metric gradations and so are the threads. How much

of a

problem is using such a machine if turning to Imperial measure?

I want to make working model steam and internal combustion

engines

from castine kits and bar stock, and assume many of the kits are
from overseas sources and come with metric drawings anyway...

It is a nice machine otherwise and a good value...

Thanks,

Paul





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_________________________________________________________________

One other thing, if a lot of inch threading is required, pick up an inch
leadscrew conversion kit from
along with a set of inch changegears. Solves any almost fits threading
problems.

Bob

--- In 7x12minilathe@..., "pkklathe" <pkk@o...> wrote:

I am looking at a lathe that is set up to metric scale - the dials
are all in metric gradations and so are the threads. How much of a
problem is using such a machine if turning to Imperial measure?

I want to make working model steam and internal combustion engines
from castine kits and bar stock, and assume many of the kits are
from overseas sources and come with metric drawings anyway...

It is a nice machine otherwise and a good value...

Thanks,

Paul

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The graduations aren't much of a problem, threading in the system
other than the leadscrew is cut to can be a nuisance. To cut
Imperial threads, you may need different change gears than the lathe
comes with and the thread indicator probably won't work properly.
They're not insurmountable problems, more a convenience issue.

Roy

With the exception of the Micromart lathes and the leadscrews on the US
model 7xX they all have metric cross slide and compound screws, so no big
problem there. You have to cut to size anyway so if you have inch
measuring tools you are ok, or bring your calculator. If the graduations on
the lathe are 40 per turn or 0.025mm per division, that is just a hair under
0.001" by 0.0004 mm. per division.


Bob

I am looking at a lathe that is set up to metric scale - the dials
are all in metric gradations and so are the threads. How much of a
problem is using such a machine if turning to Imperial measure?

I want to make working model steam and internal combustion engines
from castine kits and bar stock, and assume many of the kits are
from overseas sources and come with metric drawings anyway...

It is a nice machine otherwise and a good value...

Thanks,

Paul

All good points, one other thing that I have found is that there is a
tendency to be too timid with the feed.You need too keep up a constant
pressure. On aluminum and brass you should be able to get a constant
curl of metal coming off.

Mark




On Thu, 2003-03-06 at 23:25, Ed Paradis wrote: WD, a little late in the
response, but I'll add my 2 cents worth,
maybe it's already been covered. I had some trouble initially with
parting, but here's what I did. I double checked the height, making
sure of the centerline, then I made sure that the parting tool was as
sharp as possible. I have found that right out of the package, many
of the cut off blades need sharpening. Check for a good relief angle
on the tip, approx 7 to 11 deg angle. Be careful not to overheat the
tip, as it will anneal and soften the end of it. Use the grind -
dip - grind - dip method,and you should be OK. You mention that
you're using the HF QCTP. I have heard of others having parting
problems with the HF cutoff tools. Maybe you can try some other
blades. You may want to make sure also, that you're parting off as
close to the chuck as possible, and that the saddle is locked to the
ways tightly. This will insure that all of the forces are applied to
the parting tool. You may wish to play with the centerline issue
slightly, with some scrap to get the feel of it. Especially on the
softer material (i.e. Aluminium, brass) you shouldn't be having this
problem...

Ed

--- In 7x12minilathe@..., "wdannhardt <wdannhardt@y...>"
<wdannhardt@y...> wrote:

I recently purchased a 7 x 12 mini lathe, and so far it has been
wonderful, I am very satisfied. I purchased a quick change tool
holder from HF, and with a modification to the compound, now have
easy tool height adjustment. The only tool I have problems with is
the cut off tool.

I am using a .062" x .5" HSS tool, cutting brass and Aluminum. I
always seem to get terrible chatter. I made sure the saddle, cross
slide and compound are very tight to the ways, but it still

happens.

Does anyone have any suggestions to make this better? I've not

heard

of anyone else complain about this, so I think it must be something

I

am doing.

Thanks for your help,
WD

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