Keyboard Shortcuts
Likes
- 7x12MiniLathe
- Messages
Search
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?
?
Dave? |
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. ,
?
|
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:
|
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
?
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?
? |
Re: Dismounting the headstock bearings
开云体育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:
|
Re: Dismounting the headstock bearings
开云体育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:
|
Re: Dismounting the headstock bearings
开云体育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:
|
Re: Dismounting the headstock bearings
开云体育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:
|
Re: Dismounting the headstock bearings
开云体育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:
|
Re: Dismounting the headstock bearings
toggle quoted message
Show quoted text
|
Re: Dismounting the headstock bearings
开云体育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:
|
Re: Dismounting the headstock bearings
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.?
?
Ryan
On Feb 9, 2025 at 10:23?AM -0500, Pierre-Raymond Rondelle via groups.io <pierreraymondrondelle@...>, wrote:
|
Re: Dismounting the headstock bearings
开云体育Ryan, I'm not speaking of alignment accuracy that would mainly lead to
a machine a taper instead of a cylinder but of runout of the chuck
that is currently resulting in an irregular machined surface. And
you're right in your rationale, telling that, depending on the
location the machining is preformed, the effect is greater when
the distance to the chuck is increased. I admit not having checked
the conjunction of the bad surface with the distance from the
chuck. I take note to do that during the final verification after
fixing the trouble. I don't also remember if I said this : the roughness is
drastically improved as well by decoupling the gear train from the
40-teeth drive gear at the end of the spindle. This phenomenon
lets me thinking that the two bearings aren't pre-constrained
enough. I don't understand yet why the ghost thread it's close to
the lead screw pitch (2mm). I gonna change the ratio of the gear
train to check it. On 08.02.25 21:38, Ryan H via groups.io
wrote:
|
Re: ANSWER TO GUIDE RULE - OT
开云体育Not bothered about having flat spaces next to the tools, that’s what benches are for.? They’ll be roughly the same height as my current benches so it’ll work out. ?There might be some depending on how things work out, but smaller is better is it frees up more space. ? I find those flat spaces that the Crasftsmans has are a bit clunky, having to take them off & on whenever you switch tools is probably more trouble than they’re worth. ? Tony ? From: [email protected] <[email protected]> On Behalf Of Charles Kinzer via groups.io
Sent: Saturday, 8 February 2025 11:23 am To: [email protected] Subject: Re: [7x12MiniLathe] ANSWER TO GUIDE RULE - OT ? You have to consider that the Craftsmen "rotary triple" gizmo for three tools also provides a little flat workbench space on each side of the tool.? That is probably useful.? It is true that you could probably fit two doubles in the same space, but you would have next to zero flat working space.? Of course, that may not matter to somebody if they have some flat space elsewhere. ? Charles E. "Chuck" Kinzer ? On Friday, February 7, 2025 at 04:02:05 PM PST, Tony Smith via groups.io <ajsmith1968@...> wrote: ? ? The lathe & mill are roughly the same weight (45kg & 55kg?) and the centre of gravity would be roughly at the pivot point (biased towards the mill as it’s heavier & taller) so flipping wouldn’t involve too much effort. ? Most of these set-ups let you go in both directions, mine would only go one way so less chance of it getting away from me. ? I’ve got a CAD model of the lathe, if I had one for the mill I could model the whole thing and see how it balances. ? Tony ? ? From: [email protected] <[email protected]> On Behalf Of Ralph Lehotsky via groups.io ? Unless it would have an assisting motor, I don't think that I would be able to flip a mini-lathe or a mini-mill.? I can barely lift one, and usually have to disassemble parts of them when considering a location move.? Otherwise, for lighter bench tools, I think it's a great idea. ? ralphie |
Re: cutting with rotating cutter
开云体育
Thanks Roy
I am cutting clock wheels for my private clocks.
Even though the Carriger has a very tight fit when I cut wheels, I feel there are a little bit twist when I return the cutter for next tooth.
One way is to stop the cutting wheel before return.
Anyway, I needed your words before making this crank.
(an interesting project)
Johannes
Mexico
?
From: [email protected] <[email protected]> on behalf of Roy via groups.io <roylowenthal@...>
Sent: Saturday, February 8, 2025 17:46 To: [email protected] <[email protected]> Subject: Re: [7x12MiniLathe] cutting with rotating cutter ?
Yes!
?
Either method works, The carriage wheel gives more rapid carriage movement, a leadscrew crank gives more precise movement. Adding a leadscrew crank is pretty easy & gives you the option of using? whichever works best on a particular project.
?
Roy
|
Re: Dismounting the headstock bearings
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.?
?
?
On Feb 8, 2025 at 1:59?PM -0500, Pierre-Raymond Rondelle via groups.io <pierreraymondrondelle@...>, wrote:
|
cutting with rotating cutter
开云体育
Question:
Is lead screw a better tool to move the carriage correct in both direction than use the hand feed wheel?
If so, I will make a crank on the right side of the leadscrew.
(I am lazy, I do not want to stop the cutting wheel after a cut before returning it for the next cut.)
Johannes
Mexico
|
Re: Dismounting the headstock bearings
开云体育Hi Jon, Thank you for your reply. For your information, my lathe chuck is a 100mm (4"). As far as I know the bearings are of the tapered type but I didn't verify, just referring to the drawing and the BOM. I have neither any problem with the dismounting / mounting jigs nor the procedure but I'm only concerned by the fact that I can't manage to tighten the spindle nut farther, hence I can't adjust the clearance. This is exactly the same on the milling machine spindle except that the bearings have angular contact. On another spindle (the Unimat lathe's one, w/ angular contact) tuning the clearance is not an issue at all. I considered again the design rules and I compared them : the
conclusion is that it fits with the situation but contradicts the
common sense ! - bearings are normally of class 0. Internal rings : n6 rotating arbor on the gear side and p6 on the chuck side where the load is heavier. => press needed. This doesn't allow any adjustment ??? So what's the use of the adjustment nut couple ? Another question waiting for response: Since the spindle id hard to dismount, how can the spindle bearings be maintained, cleaned and greased ? The manual doesn't tell anything about that. - Should I consider the reverse (fixed arbor and rotating like on a car) external cage : rotating bore, P7 or R7 for heavy loads (no adjustment) internal rings : fixed arbor, g6 or h6 (adjustment allowed on the arbor) On 07.02.25 19:20, Jon Rus via
groups.io wrote:
[...] |
Re: Dismounting the headstock bearings
开云体育Ryan, I agree with you and I'd like to add some comments. Concerning the use of tapered bearings, my lathe came with them and I didn't touch them until I decided to get rid off a bad surface aspect. A little bit rough with a ghost wave of the same pitch as the lead screw. I slightly improved this situation but I can't manage to tighten the spindle nut enough to go further. Hence this thread. On to the other hand, I'm not looking at a thou but 1/100mm and a
good surface aspect and ... the very last 1/100 are extremely
harder to reach ! On a mini lathe, the tapered bearings are there more for reducing the stray movements than to withstand loads. The sole difference I noticed is that on a wheel hub, the adjustment is very easy because the inner ring is not pressed in but slipping on the spindle. I found an explanation for that, please, read my other post. On 08.02.25 07:05, Ryan H via groups.io
wrote:
|