Re: Cutting with rotating cutter
Hi Johannes. You don’t need an extra crank. ? As your dividing disc uses the outer edge for measurement. Just drill a suitable hole in the disc, with a suitable bolt and handle, this can be attached when you need it and removed when you don’t. ? ??????????????? Ellis ? ? ? I have a big dividing disk on the left side of my lathe. ?So no space for the crank. However, after some days use, I will use my new crank much more.
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Re: Cutting with rotating cutter
I have a big dividing disk on the left side of my lathe. ?So no space for the crank. However, after some days use, I will use my new crank much more.
Johannes ? Lavoll. ? ? ? ? ? ? ?
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On 13 Feb 2025, at 11:15, John Mattis via groups.io <john.mattis@...> wrote:
? I have found that to get the best finish when turning I hand feed toward the head stock and power feed toward the tail stock. By the way, high?speed?steel?is better than carbide on?our mini lathes. For cutting thread I use a 9-inch diameter hand wheel that is secure to the spindle bore. I have also made a modification to the change?gears to allow them to be adjusted easier. Drawings and photos are available if you request, just email me. Regards, John Mattis (retired mechanical engineer) Over the years, I've also considered doing this mod to add a crank to the end of the leadscrew, even though I've rarely had the "need" for this feature. But, in a recent hack, I did add a crank, but on the left-hand end of the lead-screw. (see photo). Just a thin metal arm secured underneath the cap screw that holds the plastic gear. Not sure if this arrangement is any better or worse than attaching a crank on the right-hand end of the leadscrew, but my hack did not require any permanent mods to the lathe, and can be quickly installed and removed if needed.
?
<IMG_20250213_105432.jpg>
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Re: Cutting with rotating cutter
I have found that to get the best finish when turning I hand feed toward the head stock and power feed toward the tail stock. By the way, high?speed?steel?is better than carbide on?our mini lathes. For cutting thread I use a 9-inch diameter hand wheel that is secure to the spindle bore. I have also made a modification to the change?gears to allow them to be adjusted easier. Drawings and photos are available if you request, just email me. Regards, John Mattis (retired mechanical engineer)
Over the years, I've also considered doing this mod to add a crank to the end of the leadscrew, even though I've rarely had the "need" for this feature. But, in a recent hack, I did add a crank, but on the left-hand end of the lead-screw. (see photo). Just a thin metal arm secured underneath the cap screw that holds the plastic gear. Not sure if this arrangement is any better or worse than attaching a crank on the right-hand end of the leadscrew, but my hack did not require any permanent mods to the lathe, and can be quickly installed and removed if needed.
?
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Re: Cutting with rotating cutter
Over the years, I've also considered doing this mod to add a crank to the end of the leadscrew, even though I've rarely had the "need" for this feature. But, in a recent hack, I did add a crank, but on the left-hand end of the lead-screw. (see photo). Just a thin metal arm secured underneath the cap screw that holds the plastic gear. Not sure if this arrangement is any better or worse than attaching a crank on the right-hand end of the leadscrew, but my hack did not require any permanent mods to the lathe, and can be quickly installed and removed if needed.
?
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Re: Cutting with rotating cutter
The fitted thrust washer to reduce axial play was part of my overly elaborate sealing arrangement to keep swarf out of the control box.
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Roy
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Re: Cutting with rotating cutter
Your setup looks a lot like mine.? In addition to the crank, I made a replacement block that has pockets for thrust bearings.? That reduced the backlash quite a bit.? The OEM design has a lot of "slop" between the blocks and lead screw, which permits a LOT of backlash.
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A custom-made washer the right thickness would do much the same thing.
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Cutting with rotating cutter
Hi Roy
Thanks, I have now made an external lead screw crank.
Let see what happens after 144 teeth cuts on a 3.465 inch ? wheel .
Johannes Lavoll.
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Re: Here list of charts & Tables
When purchased my copy they did not? have small book. The small book came years later.?
The three ring binder works better because only has what I need.?
?
Dave?
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Re: Here list of charts & Tables
The Machinery's Handbook I bought included a pocket reference, perhaps to reduce wear & tear on the big everything-but-the-kitchen-sink book.
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Re: Here list of charts & Tables
The file #8 is hardness testing I finally got down load and the unloaded.
Like Mohs hardness testing for material hunting just like pencil.? The other was magnic and tape now read to hunt materials for mini lathe?
?
The best part of a magnic is for stainless steel series 300 in non magnic easy to machine.?
If magnic then 400 and will work harden not fun in mini lathe?
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Dave?
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Here list of charts & Tables
?I found to be very useful with mini lathe is this list of charts & Tables
It keeps from having to get? Machinist Hand Book out. I first by going machinist Hand Book but found myself washing hands a lot so costly stay new.
?
I have in ?" binder like said before and keep never the mini lathe? in plastic protector to keep oil hands off the pages. ,
?
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Re: Dismounting the headstock bearings
How does thd plastic gear holdup over the years?
?
Dave?
?
On Sun, Feb 9, 2025 at 08:59 PM, Jon Rus wrote:
?
PR Here is a last photo,
Maybe you have a stack up of plastic spacers that are flexing under momentary instantaneous load?? They seem to be tight, but they might flex and return to their tight look--lye to you about being tight?
?
?
?
On 2/9/2025 10:23 AM, Pierre-Raymond Rondelle via groups.io wrote:
On 08.02.25 21:38, Ryan H via groups.io wrote:
1/100mm is about .0003". Over what distance are you trying to maintain that? Just curious as it shouldn't be a problem on shorter lengths with everything properly adjusted and aligned especially the saddle and headstock. I may have missed where you said but if you're saddle travel isn't perfect you're not gonna get .0003" unless you work only in the "good" area of travel. Then the headstock has to be done but anyway...
?
The inner race of the inner bearing can be an interference fit on the spindle albeit very slight. Like tap it with a wooden hammer handle only to fully seat it.?
?
?The inner race of the outer bearing should be a very snug slip fit on the spindle. That race has to be able to slide just like on a vehicle. ?It's fairly time consuming process. ?Sounds like your spindle wasn't properly fit for the bearing. If it was the race would move so you can set it. I think you're first step is going to be to rectify that and from there you're going to be set on that part.
?
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Re: German screws / pencil sharpener
I remember this post past .
How is your mini lathe doing .
If need good chart on imperial to metric drill sizes. I first one just left of my lathe see photo
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I send one. I have real good wall chart for metric threading on mini lathe I have too .? It on the other wall very handy.
?
Dave?
?
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Re: Dismounting the headstock bearings
Ryan,
We're on the same wave length !
I already checked the lead screw for longitudinal deformation and
else as well as the half nuts plus the whole alignment. I can't say
that it's perfect because there are no centering pins but I didn't
find any hard spot nor anything else to be relevant.
All the gears are made of steel, a bit noisy. The clearance
adjustment (paper sheet of different thicknesses method) between
spurs doesn't visually improve anything but taking away the first
gear eliminates the ghost thread. At the moment, it might be the
influence of the lead screw, amplified or not by the gear train or a
kind of resonance of the whole gear train. As mentioned yesterday,
different ratios need to be checked in priority. In addition, to
suppress any doubt about the lead screw, I also have to check its
decoupling from the last gear, all the other gears remaining
connected to the spindle. Not an easy troubleshooting but a greasy
one !
It came into my mind that if I use the compound, the slide being
locked, there's no ghost thread but same amount of roughness. Also
to be checked again, plus with more accuracy. The nature of the
cutting tools may also impact the roughness. Comparison between
carbide and HSS cutters with the same metal & speed.
Before all that, an FMECA written procedure, addressing two entries
roughness and ghost thread, is mandatory !
For the rest, it's more or less what I'm intending to do. But, since
it's a no-return operation, everything needs to be clarified before
and the possible causes identified or eliminated.
I'm not in a hurry and, in //, I'm on a Quorn construction project,
so all this work will probably take weeks or even months. I saved
all the messages, which I'll respond when the job is done.
Thanks, Have a nice day.
On 09.02.25 21:17, Ryan H via groups.io
wrote:
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Gotcha. If it was me, I'd start with two things. First
would be pulling the headstock apart and addressing the
bearing adjustment problem. The inner race on the outer
bearing needs to be able to slide on the spindle to set the
preload. I did mine the old fashioned way like you'd polish
engine crankshaft journals. If you haven't done that it done
by bolting the spindle down firmly, wrapping sand paper around
the spindle, wrapping a long shoelace or the like around the
paper a few times and pulling the ends of the laces to turn
the paper. There are probably YouTube videos that show what
I'm describing. It works better than just trying to hand sand
as it keeps pretty even pressure all the way around the part.
If you decide to do it use fine grit paper, like no courser
than 800 to start, as yours is probably pretty close. I may
even start with 1,000 as yours is probably within fractions of
a thousandth if the bearing already goes on but doesn't slide.
Go slow and check fit often. As we know It's easier to remove
material than put it back. :-) ?You just want it slide, just.
If you go too far then the spindle can move in the inner race
and we don't want that. It's a time consuming process, lots of
cleaning and testing for maybe only two or three rotations of
the paper before cleaning and testing again but it's worth the
time. You'll be able to set it perfectly.?
?
My second thing to check would be the lead screw and half
nuts to see if there's a burr or anything causing irregular
movement and adjust of the base, compound and cross slides.
That may cause the ghost thread. You can check if it's from
the compound or cross slides by locking them down tight with
the gib adjustment screws and taking a test cut. I'm sure you
know it's really a process of eliminating variables until you
find which part is causing the problem and then addressing
that part to eliminate the issue.
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Re: Dismounting the headstock bearings
Thank you for your time.
I explored a lots of solutions, it seems that the reason is
merely the tight adjustment of the left bearing on the arbor. The
dismounting operations are going soon, When done, I'll send a
report of what occurred.
On 10.02.25 05:59, Jon Rus via
groups.io wrote:
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PR Here is a last photo,
Maybe you have a stack up of plastic
spacers that are flexing under momentary instantaneous load??
They seem to be tight, but they might flex and return to their
tight look--lye to you about being tight?
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Re: Dismounting the headstock bearings
Thanks Jon,
I don't think so because the two bearings are #30206 as per the
drawing / BOM, please refer to the documents I sent with one or my
first messages (2025 01 25). Apparently, there's no spacer in
between.
All this needs to be checked while dismounting the headstock, of
course, because it's not possible to 100% trust this kind of
equipment nor the manual. I already noticed several errors.
have a nice day.
On 10.02.25 05:19, Jon Rus via
groups.io wrote:
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Hello PR,
I found this image
This photo of a shaft clearly shows a
stepped section near the shaft bearing area of the spindle.? If
yours has a similar area, you will not win easily.
Did you disassemble and review yours
lately for burrs or "out-of-round" tight tolerance problems to
see why you can not create preload?
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Re: Dismounting the headstock bearings
PR Here is a last photo,
Maybe you have a stack up of plastic
spacers that are flexing under momentary instantaneous load?? They
seem to be tight, but they might flex and return to their tight
look--lye to you about being tight?
On 2/9/2025 10:23 AM, Pierre-Raymond
Rondelle via groups.io wrote:
toggle quoted message
Show quoted text
On 08.02.25 21:38, Ryan H via
groups.io wrote:
1/100mm is about .0003". Over what distance are you
trying to maintain that? Just curious as it shouldn't be a
problem on shorter lengths with everything properly adjusted
and aligned especially the saddle and headstock. I may have
missed where you said but if you're saddle travel isn't
perfect you're not gonna get .0003" unless you work only in
the "good" area of travel. Then the headstock has to be done
but anyway...
?
The inner race of the inner bearing can be an
interference fit on the spindle albeit very slight. Like tap
it with a wooden hammer handle only to fully seat it.?
?
?The inner race of the outer bearing should be a very
snug slip fit on the spindle. That race has to be able to
slide just like on a vehicle. ?It's fairly time consuming
process. ?Sounds like your spindle wasn't properly fit for
the bearing. If it was the race would move so you can set
it. I think you're first step is going to be to rectify that
and from there you're going to be set on that part.
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Re: Dismounting the headstock bearings
PR, Here is another image, perhaps the
change in size of the shaft is interfering with the tightening of
the nut and the outer stack of gears and spacers and aligning
shaft keys?
Again, Good Luck!
On 2/9/2025 10:23 AM, Pierre-Raymond
Rondelle via groups.io wrote:
toggle quoted message
Show quoted text
On 08.02.25 21:38, Ryan H via
groups.io wrote:
1/100mm is about .0003". Over what distance are you
trying to maintain that? Just curious as it shouldn't be a
problem on shorter lengths with everything properly adjusted
and aligned especially the saddle and headstock. I may have
missed where you said but if you're saddle travel isn't
perfect you're not gonna get .0003" unless you work only in
the "good" area of travel. Then the headstock has to be done
but anyway...
?
The inner race of the inner bearing can be an
interference fit on the spindle albeit very slight. Like tap
it with a wooden hammer handle only to fully seat it.?
?
?The inner race of the outer bearing should be a very
snug slip fit on the spindle. That race has to be able to
slide just like on a vehicle. ?It's fairly time consuming
process. ?Sounds like your spindle wasn't properly fit for
the bearing. If it was the race would move so you can set
it. I think you're first step is going to be to rectify that
and from there you're going to be set on that part.
|
Re: Dismounting the headstock bearings
PR, Here is another image
On 2/9/2025 10:23 AM, Pierre-Raymond
Rondelle via groups.io wrote:
toggle quoted message
Show quoted text
On 08.02.25 21:38, Ryan H via
groups.io wrote:
1/100mm is about .0003". Over what distance are you
trying to maintain that? Just curious as it shouldn't be a
problem on shorter lengths with everything properly adjusted
and aligned especially the saddle and headstock. I may have
missed where you said but if you're saddle travel isn't
perfect you're not gonna get .0003" unless you work only in
the "good" area of travel. Then the headstock has to be done
but anyway...
?
The inner race of the inner bearing can be an
interference fit on the spindle albeit very slight. Like tap
it with a wooden hammer handle only to fully seat it.?
?
?The inner race of the outer bearing should be a very
snug slip fit on the spindle. That race has to be able to
slide just like on a vehicle. ?It's fairly time consuming
process. ?Sounds like your spindle wasn't properly fit for
the bearing. If it was the race would move so you can set
it. I think you're first step is going to be to rectify that
and from there you're going to be set on that part.
|
Re: Dismounting the headstock bearings
Hello PR,
I found this image
This photo of a shaft clearly shows a
stepped section near the shaft bearing area of the spindle.? If
yours has a similar area, you will not win easily.
Did you disassemble and review yours
lately for burrs or "out-of-round" tight tolerance problems to see
why you can not create preload?
Good Luck in your solution....
On 2/9/2025 10:23 AM, Pierre-Raymond
Rondelle via groups.io wrote:
toggle quoted message
Show quoted text
On 08.02.25 21:38, Ryan H via
groups.io wrote:
1/100mm is about .0003". Over what distance are you
trying to maintain that? Just curious as it shouldn't be a
problem on shorter lengths with everything properly adjusted
and aligned especially the saddle and headstock. I may have
missed where you said but if you're saddle travel isn't
perfect you're not gonna get .0003" unless you work only in
the "good" area of travel. Then the headstock has to be done
but anyway...
?
The inner race of the inner bearing can be an
interference fit on the spindle albeit very slight. Like tap
it with a wooden hammer handle only to fully seat it.?
?
?The inner race of the outer bearing should be a very
snug slip fit on the spindle. That race has to be able to
slide just like on a vehicle. ?It's fairly time consuming
process. ?Sounds like your spindle wasn't properly fit for
the bearing. If it was the race would move so you can set
it. I think you're first step is going to be to rectify that
and from there you're going to be set on that part.
|
Johannes
John Mattis
davesmith1800