Re: RideTheGearTran has a new feature
Hi Everyone, Well that is a LOT of very helpful feedback. I really appreciate it.? A lot of the points are things that I have thought about. I have been thinking of considering the number of turns on the thread in the information about torque/stress/strain etc, but I really like this comment from Chris, as I hadn't twigged to it:
?As soon as the amount of metal is the same as the screw's minor diameter cross-section then the threads?are as strong as the screw
I will incorporate that when I finish my next topic on turning tapers by the tailstock offset method. There are a lot of ways to skin a cat and many of them are easier than pulling up an online program. I find I do just remember the common metric ?sizes. The object of the percent tables is to give a hobbyist an idea about whether the non-ideal drill he happens to have is good enough. If it gives 30% thread depth or 100% it probably isn't good enough and it may be time to buy the right drill. It is more problematic with small threads. I wanted to mount a carbide tip which has an M2.5 x 0.45 thread which requires a 2.2mm drill. It seems too expensive to buy the right drill and tap for a single screw. The program made that clear. So I will redesign the ball turner with a clamp to hold the carbide tip. RideTheGearTrain needs the thread pitch to calculate the gear train. As an improvement to the program I decided to include some standard thread tables so that the user could easily find the pitch. ?Then I realized that these thread tables include a lot of extra information, which I started playing with. The specs in these tables include the flat or radius at the root and crest of the profile as well as the angle. ?Those are taken into account in calculating the thread depth. Then the depth can be used in calculating percentage thread depth for drill sizes. So it all grew like Topsy.? I am not an engineer, but a hospital doctor and computer programmer and inherited a lathe from my father in 2014. So the feedback is important to make sure my ideas aren't plain wrong! ?So thanks everyone for the tips! Oh yes, I will read this too; http://tapmatic.com/tapping_questions_torque_vs_thread_strength.ydevEvan Lathe: 1955 Boxford Model A with screw cutting gearbox and power feed. My Free Online Geartrain Software: My YouTube Channel and Playlist about using an engineers lathe: ? Project to build a Greek Hero steam engine and measure its power output:?
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Re: Saddle/Carriage adjustments
I remember Ted Hansen's article about correcting the carriage when it appeared in Home Shop Machinist. If the book is the same, I was not impressed.? In the HSM article, Hansen designed an additional gizmo to help the carriage stay straight, but that ignores the real problem.
The problem is the original gizmo that's on there -- the spring-loaded device?that holds the carriage down on the minilathe bed. It's a Mickey Mouse design, but it's there for a reason.? The factory didn't machine the underside of the bed, which was left as a rough cast iron surface. This surface didn't have a constant distance from the top surface of the bed, so the spring device compensated for that by pulling the carriage down no matter what the thickness?of the?bed was.
But the?real solution isn't to keep this gizmo or to add extra?gizmos, but to get?the underside of the bed parallel to the top side. Then you can? get rid of the spring loaded device and use shims to adjust the keeper plates. I did that decades?ago, and my carriage remains smooth and shake-free, and so stable I haven't needed to adjust the shims in years.
Here?(Under the section called "the carriage") is a link to the procedure that I used in 2002, which Frank Hoose conveniently put on his? site:? ?? I'd mostly do it the same now, but there are a few changes I would make:
1. First, I did this on? my?original 2002 bed, which was very bad, but some newer beds are much better and don't require much lapping (or perhaps any lapping). About 5 years ago I replaced my original 10" bed with a 14" bed from LMS, and I was pleased to discover that the underside of the bed was finished pretty well.? But those beds are part of the 14" bed kits that LMS sells. I don't know if the typical beds sold on minilathes are as good as that.
2.? In these directions, I used Mother's Metal Polish, which is extremely fine.? That was tedious and took hours, but I was trying to do it really slowly because I was inventing the procedure as I went along and wanted to be able to catch myself if I was screwing up.? Now this method is fairly well known, and I would recommend valve-grinding compound instead.
3.? Also, I should stress that this is to lap the UNDERSIDE of the lathe bed, NOT the top of the bed, which is precision ground.? The top side should be kept clean and lubricated, but no abrasive should get there at any time.
4. Finally, lapping two things together with abrasive always changes both surfaces, so you're changing the keeper plates also.? You don't want those changed, but this isn't a problem because they can easily be flattened on sandpaper after the lapping is over.
Mike Taglieri
On Mon, Jan 31, 2022, 10:41 PM Stan Gammons via <buttercup11421= [email protected]> wrote:
Hi Bruce,
I have that book. What you are talking about is in chapter 5. I've
considered doing that but being a newbie I've been a bit
apprehensive about trying some of the upgrades/mods I've read about.
I'm not so comfortable with trying to true surfaces by scraping
that's described in chapter 11.
I don't subscribe to HSM, but yes it would be nice if they would
offer back issues in PDF format that could be downloaded from their
website. Perhaps even a DVD of all issues from the beginning up to
the current issue. Yeah, I'm dreaming...
Stan
On 1/31/22 21:21, Bruce J wrote:
I kinda feel like a broken record on this subject :-) but Ted
Hansen's ¡®Complete MiniLathe Workshop¡¯ (available from Village
Press
?) has a discussion of this very problem, and two solutions: one
quick and dirty, basically shimming the existing saddle plates to
provide better contact, and a more robust fix, switching to
u-shaped saddle plates, similar to those on bigger lathes like
South Bend, that considerably improves the rigidity of the mini
lathe.?
Also a custom wrench: a bit of an allen wrench
brazed to the top of a C-shaped piece of rod, allowing you to
tighten the saddle plate screws without removing the front
apron.?
I find myself again wishing they¡¯d sell HSM in digital
archive form, because there¡¯s all sorts of references out
there to this or that other back issue and it would really be
nice to be able to just call it up, instead of having to troll
through eBay for some well-thumbed old copy.?
All my woodworking magazines offer this and it¡¯s very
convenient. ?
I¡¯d even be happy with just an online access instead of a
portable copy.?
Thanks everyone for the replies on this.?
The backsplash is still in place. I'll remove it and see
if I can adjust the carriage so it moves easier once I
have some more time.
Stan
On 1/31/22 08:53,
GadgetBuilder wrote:
The adjustment scheme for the carriage slide plates
works better on large lathes than it does on our small
machines.? Most 7X owners find that shimming the slide
plates is easy and works well.? In addition, it often
helps considerably to refine the bed thickness where
the slide plates run.? See:
John
--?
Bruce Johnson
The less a man knows about how sausages and laws are
made, the easier it is to steal his vote and give him
botulism.
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Re: Saddle/Carriage adjustments
Bruce, it is not being a broken record when what you are saying is worthwhile advise. And I completely agree that Ted Hansen¡¯s book is very worthwhile and very reasonably priced. Check out ¡°Machine Tool Reconditioning¡± for a shock! Any minilathe owner Could profit from some of the projects he very clearly describes. And as for HSM references, I completed my collection by purchasing the first six issues. A complete collection is easy if you started 39 years ago!?? Bill in Boulder ? Sent from for Windows 10 ?
toggle quoted message
Show quoted text
From: Bruce JSent: Monday, January 31, 2022 20:22 To: [email protected]Subject: Re: [7x12MiniLathe] Saddle/Carriage adjustments ? I kinda feel like a broken record on this subject :-) but Ted Hansen's ¡®Complete MiniLathe Workshop¡¯ (available from Village Press ?) has a discussion of this very problem, and two solutions: one quick and dirty, basically shimming the existing saddle plates to provide better contact, and a more robust fix, switching to u-shaped saddle plates, similar to those on bigger lathes like South Bend, that considerably improves the rigidity of the mini lathe.? Also a custom wrench: a bit of an allen wrench brazed to the top of a C-shaped piece of rod, allowing you to tighten the saddle plate screws without removing the front apron.? I find myself again wishing they¡¯d sell HSM in digital archive form, because there¡¯s all sorts of references out there to this or that other back issue and it would really be nice to be able to just call it up, instead of having to troll through eBay for some well-thumbed old copy.? All my woodworking magazines offer this and it¡¯s very convenient. ? I¡¯d even be happy with just an online access instead of a portable copy.?
? Thanks everyone for the replies on this.? The backsplash is still in place. I'll remove it and see if I can adjust the carriage so it moves easier once I have some more time.
Stan
On 1/31/22 08:53, GadgetBuilder wrote: The adjustment scheme for the carriage slide plates works better on large lathes than it does on our small machines.? Most 7X owners find that shimming the slide plates is easy and works well.? In addition, it often helps considerably to refine the bed thickness where the slide plates run.? See:
John
? --?
Bruce Johnson
The less a man knows about how sausages and laws are made, the easier it is to steal his vote and give him botulism. ?
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Re: Saddle/Carriage adjustments
Hi Bruce,
I have that book. What you are talking about is in chapter 5. I've
considered doing that but being a newbie I've been a bit
apprehensive about trying some of the upgrades/mods I've read about.
I'm not so comfortable with trying to true surfaces by scraping
that's described in chapter 11.
I don't subscribe to HSM, but yes it would be nice if they would
offer back issues in PDF format that could be downloaded from their
website. Perhaps even a DVD of all issues from the beginning up to
the current issue. Yeah, I'm dreaming...
Stan
On 1/31/22 21:21, Bruce J wrote:
toggle quoted message
Show quoted text
I kinda feel like a broken record on this subject :-) but Ted
Hansen's ¡®Complete MiniLathe Workshop¡¯ (available from Village
Press
?) has a discussion of this very problem, and two solutions: one
quick and dirty, basically shimming the existing saddle plates to
provide better contact, and a more robust fix, switching to
u-shaped saddle plates, similar to those on bigger lathes like
South Bend, that considerably improves the rigidity of the mini
lathe.?
Also a custom wrench: a bit of an allen wrench
brazed to the top of a C-shaped piece of rod, allowing you to
tighten the saddle plate screws without removing the front
apron.?
I find myself again wishing they¡¯d sell HSM in digital
archive form, because there¡¯s all sorts of references out
there to this or that other back issue and it would really be
nice to be able to just call it up, instead of having to troll
through eBay for some well-thumbed old copy.?
All my woodworking magazines offer this and it¡¯s very
convenient. ?
I¡¯d even be happy with just an online access instead of a
portable copy.?
Thanks everyone for the replies on this.?
The backsplash is still in place. I'll remove it and see
if I can adjust the carriage so it moves easier once I
have some more time.
Stan
On 1/31/22 08:53,
GadgetBuilder wrote:
The adjustment scheme for the carriage slide plates
works better on large lathes than it does on our small
machines.? Most 7X owners find that shimming the slide
plates is easy and works well.? In addition, it often
helps considerably to refine the bed thickness where
the slide plates run.? See:
John
--?
Bruce Johnson
The less a man knows about how sausages and laws are
made, the easier it is to steal his vote and give him
botulism.
|
Re: Saddle/Carriage adjustments
I kinda feel like a broken record on this subject :-) but Ted Hansen's ¡®Complete MiniLathe Workshop¡¯ (available from Village Press ?) has a discussion of this very problem, and two solutions: one quick and dirty, basically shimming the existing saddle plates to provide better contact, and a more robust fix, switching to u-shaped saddle plates, similar to those on bigger lathes like South Bend, that considerably improves the rigidity of the mini lathe.?
Also a custom wrench: a bit of an allen wrench brazed to the top of a C-shaped piece of rod, allowing you to tighten the saddle plate screws without removing the front apron.?
I find myself again wishing they¡¯d sell HSM in digital archive form, because there¡¯s all sorts of references out there to this or that other back issue and it would really be nice to be able to just call it up, instead of having to troll through eBay for some well-thumbed old copy.?
All my woodworking magazines offer this and it¡¯s very convenient. ?
I¡¯d even be happy with just an online access instead of a portable copy.?
Thanks everyone for the replies on this.? The backsplash is still in
place. I'll remove it and see if I can adjust the carriage so it
moves easier once I have some more time.
Stan
On 1/31/22 08:53, GadgetBuilder wrote:
The adjustment scheme for the carriage slide plates works better
on large lathes than it does on our small machines.? Most 7X
owners find that shimming the slide plates is easy and works
well.? In addition, it often helps considerably to refine the bed
thickness where the slide plates run.? See:
John
--?
Bruce Johnson
The less a man knows about how sausages and laws are made, the easier it is to steal his vote and give him botulism.
|
Re: Saddle/Carriage adjustments
Thanks everyone for the replies on this.? The backsplash is still in
place. I'll remove it and see if I can adjust the carriage so it
moves easier once I have some more time.
Stan
On 1/31/22 08:53, GadgetBuilder wrote:
toggle quoted message
Show quoted text
The adjustment scheme for the carriage slide plates works better
on large lathes than it does on our small machines.? Most 7X
owners find that shimming the slide plates is easy and works
well.? In addition, it often helps considerably to refine the bed
thickness where the slide plates run.? See:
John
_._,_._,_
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Re: Unwanted taper when turning
Thank you all for the suggestions. I¡¯d summarize them as:
- Turn between centers (I wasn¡¯t) / Don¡¯t extend the work to far (I was based on Ryan¡¯s description)
- Check cutting tool (I will take a pic, but I don¡¯t think it was ground for brass)
- Check headstock alignment. (Are we talking about using Rollie¡¯s Dads Method or is there a step I should do before that? I¡¯ve been doing some reading about it).
- Check compound angle
- Check slop
Some answers for the questions asked:
- Material diameter is 1/4 inch
- I was using the carriage hand wheel to move the cutter. I have the compound slide locked tight
- As far as depth of cut, I¡¯m figuring that out. My cross slide is pretty tight and right now I¡¯m having a hard time figuring out exactly what I¡¯m doing as far as depth. I was just trying to make a chip and backing off if it didn¡¯t work.
I¡¯ll make some adjustments and let the group know how it goes. Again, thank you for the responses.
Jack
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Re: Unwanted taper when turning
I agree, it sounds like the cutter is "not dubbed" on top rake as we used to call it, grind it neutral correct and it shouldn't "suck in", same idea with drill bits in brass and bronze, the taper you are showing is the possibly the backlash in the cross slide being taken up as the cutter pulls the slide in
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Re: Unwanted taper when turning
You are using carriage handwheel to advance the carriage, and not the
compound to advance the cutter. Your photo almost looks like your compound
is set at an angle, and you are feeding using the compound instead of the
carriage. Another possibility is that you have a lot of slop in your cross
slide and/or compound. Have you tried locking the cross slide and compound
by tightening one of the gibs on them both? Also check the carriage. See if
you can grab the left and right sides, and try to twist, lift, rotate, see
if there is any movement in it that needs to be addressed. And as others
have stated, no back rake on the cutter when cutting brass.
Michael - California, USA
Micro-Mark MicroLux 7x16
LMS 3990 Hi-Torque Mill with power feed
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-----Original Message----- From: [email protected] < [email protected]> On Behalf Of Jack Lunn via groups.io Sent: Sunday, January 30, 2022 2:33 PM To: [email protected]Subject: [7x12MiniLathe] Unwanted taper when turning Just getting started with a new to me HF 7X10 (extended to 16). Trying to practice on brass and the bit ¡°digs¡± in as i move the saddle to the left. This results in an inward taper. I¡¯ve tried to adjust the cross slide to remove any play. What should i check? Thank you for any assistance! Attachments: image0.jpeg: /g/7x12MiniLathe/attachment/115637/0
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Re: Unwanted taper when turning
When you said ¡°digging in¡± the first thing I thought of is the back rake is zero for Brass and Bronze in this online reference: ? Jim Lynch ?
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Re: Saddle/Carriage adjustments
The adjustment scheme for the carriage slide plates works better on large lathes than it does on our small machines.? Most 7X owners find that shimming the slide plates is easy and works well.? In addition, it often helps considerably to refine the bed thickness where the slide plates run.? See:
John
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Re: Saddle/Carriage adjustments
Certainly begin by looking at and adjusting the saddle.? ?The saddle adjustment is a rather crude arrangement - you will have to remove the apron and the back splash (if still in use).
--
Lone Tree, Colorado? ?USA
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Re: Unwanted taper when turning
Judging from what you have said, my question is ¡®are you using a lathe tool designed for steel and having top rake¡¯? If so, turning tools for brass should be 0 deg top and side rake ie a flat top. Otherwise they dig in and cause all sorts of problems. Best wishes and stay safe. ?????? Ellis ?
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Just getting started with a new to me HF 7X10 (extended to 16). Trying to practice on brass and the bit ¡°digs¡± in as i move the saddle to the left. This results in an inward taper. I¡¯ve tried to adjust the cross slide to remove any play. What should i check?
Thank you for any assistance!
Attachments:
image0.jpeg: /g/7x12MiniLathe/attachment/115637/0
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Re: RideTheGearTran has a new feature
For the standard of threading that most of us machine, the easiest method of finding out tap drill sizes, is to look at a chart ! The next easiest is to subtract the pitch of the thread from the diameter and adjust for the nearest drill size ¨C up or down. eg M6 x 1, tap drill 5 dia, !¡± BSW 8tpi, tap drill 7/8¡± dia. I use the first method for standard threads and the second for non standard. No problems in over 50 years of work. Best wishes and stay safe. ???????? Ellis ? ? ? And just to provide a little data on this, I found this at Tapmatic and it covers the topic succinctly with an eye-opening chart. ?
? Chuck K.
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Re: Unwanted taper when turning
Also, what type of cutting tool are you using???How much material do you have sticking out of the chuck???What depth of cut are you taking???Material diameter???I've learned there's a lot that can cause a taper especially like your describing. There's a ton of knowledge in this group and they've helped me sort out a bunch of stuff that was at least me doing something wrong and to be honest that's lot easier to fix, LOL!??Thin material sticking out will want to flex away from the tool causing a taper. I turn custom orifices out of 3/8" brass and it cuts nicely with very sharp tooling and keeping the stick out to about an inch and a half. Over that and I have to take very light cuts or the material deflects from the tool. A little more information on what you're trying and I'm sure it can be sorted out.?
Ryan
On Jan 30, 2022, 11:34 PM -0500, mike allen <animal@...>, wrote:
??? ??? are you turning between centers ? or just using the chuck ? Is
the headstock aligned with the lathe bed ?
animal
On 1/30/2022 2:33 PM, Jack Lunn via groups.io wrote:
Just getting started with a new to me HF 7X10 (extended to 16). Trying to practice on brass and the bit ¡°digs¡± in as i move the saddle to the left. This results in an inward taper. I¡¯ve tried to adjust the cross slide to remove any play. What should i check?
Thank you for any assistance!
Attachments:
image0.jpeg: /g/7x12MiniLathe/attachment/115637/0
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Saddle/Carriage adjustments
Hi All.
I'm finally? getting back into the machinist hobby after recovering from
back surgery and other health issues.? From day one it seemed like the
saddle/carriage didn't move as well as it should.? Nothing like as easy
as the cross slide.? Seems like the gibs/retainers need to be adjusted.?
Lathe is a HF 93212.? Any tips/instructions on going about this for a
newbie?
Stan
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Re: Unwanted taper when turning
are you turning between centers ? or just using the chuck ? Is
the headstock aligned with the lathe bed ?
animal
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Show quoted text
On 1/30/2022 2:33 PM, Jack Lunn via groups.io wrote: Just getting started with a new to me HF 7X10 (extended to 16). Trying to practice on brass and the bit ¡°digs¡± in as i move the saddle to the left. This results in an inward taper. I¡¯ve tried to adjust the cross slide to remove any play. What should i check?
Thank you for any assistance!
Attachments:
image0.jpeg: /g/7x12MiniLathe/attachment/115637/0
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Re: RideTheGearTran has a new feature
"real engineers" are likely?working with metric holes and you don't need a table to figure stuff out.? It is simple enough you can just remember?it for common sizes. There are not so many metric drill sizes.? Most drill sets go in 0.5 mm steps, a few in 0.1 mm steps.? But that's it.
One thing you left out of the calculation is the number of threads engaged.? ?This is important.
Typically you want the fastener to develop its full strength.?To do this you calculate?the amount of metal that is in shear.? This is the size (area) of the thread times the percent engagement?times the number of turns.? ? So the number of turns is equally?important?as the percent engagement.? ?As soon as the amount of metal is the same as the screw's minor diameter cross-section then the threads?are as strong as the screw.
Engineering is slightly more complex if the threaded?hole is a different material?from the screw.? ?You just need enough?turns to develop?the required strength at the percent engagement.
Normal nuts are designed to be just under this limit.? They will fail just before the screw is about fail.? It is this way so if overtightened the nut fails.? ?If nuts were made longer then the screw would fail first. So you can look at a nut and see about what you need in terms of thread engagement.
No I'm not a mechanical engineer, my area is different but I've read up a little on fastener design
Drill Sizes:?
The latest addition to the menu has an orange border around the button as it is independent of the main program. If you click it you can choose a thread from the metric or imperial thread reference tables, and choose the diameter you want.? The program then displays all the thread specifications and tables of drill sizes that could be used to tap a thread of that size.
I previously thought that a drill equal to the minor diameter at the root of the thread would be ideal to give 100% thread depth. But with ordinary, straight fluted, taps that is not the case. Generally they recommend 75% thread depth. The reason is that there is a forming process, whereby the tap pushes metal up into the crest and can produce a 100% thread depth even though the drill would suggest 75%. Consequently tables recommending drill sizes are typically based on 75% depth. Since they are designed as printed tables they usually only give you one option. But we may not have exactly the right sized drill. Then what.?
The choice of 75% is somewhat arbitrary. Softer materials like aluminium may form more easily and could accommodate drills less than 75%. Harder materials like stainless steel form less readily and ideally should use a higher percentage. On the other hand, if there is little load on the thread the designer might be happy to accept a lower percentage, particularly if the material is strong.
Since the computer program can deal with a single thread without having to produce a table for all threads, it gives us an opportunity to produce tables with a range of common drill sizes showing what percentage of thread depth would be covered. That is what I have done with RideTheGearTrain. The hobbyists can look at the drills they have available and decide whether they are happy with the percent depth they will achieve.
So, what do the REAL engineers think of this idea?? Any comments or suggestions? Is this idea unusual? Unique? Or general knowledge.
PS RideTheGearTrain now has several entries for mini-lathes with or without a thread cutting gearbox.
For those who don't know, the primary purpose of this free program is to calculate what gears are needed in the gear train to cut a thread of any pitch or TPI.
Evan
--
Evan
Lathe: 1955 Boxford Model A with screw cutting gearbox and power feed.
My Free Online Geartrain Software:
My YouTube Channel and Playlist about using an engineers lathe: ?
Project to build a Greek Hero steam engine and measure its power output:?
--
Chris Albertson
Redondo Beach, California
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Unwanted taper when turning
Just getting started with a new to me HF 7X10 (extended to 16). Trying to practice on brass and the bit ¡°digs¡± in as i move the saddle to the left. This results in an inward taper. I¡¯ve tried to adjust the cross slide to remove any play. What should i check?
Thank you for any assistance!
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Re: RideTheGearTran has a new feature
And just to provide a little data on this, I found this at Tapmatic and it covers the topic succinctly with an eye-opening chart. ? ? Chuck K. ? Sent from for Windows ?
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From: Roy via groups.ioSent: Sunday, January 30, 2022 6:47 PM To: [email protected]Subject: Re: [7x12MiniLathe] RideTheGearTran has a new feature ? As Chuck pointed out, 75% is the common depth goal. The detailed thread specs call for a slight flat at both the crests of male threads & the valleys of female threads - aiming for 75% automatically achieves that. There's very little strength gain from 100% depth; more than offset by the difficulty of actually achieving it. Even for interference threads, the interference is in the bulk of the body, not the crests/valleys.
Roy (an actual BSME) ?
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Evan
Jim
GadgetBuilder
