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Re: Bolt queries
Hello Peter:
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Machinery's Handbook also has Metric information, it will tell you USA measurements are based on the meter. Check Ebay or bookstores for a copy, even the early editions are useful. New they are about $100, but I've found used for $10. The book is a great read, everything from flooring to finance. It's size has stayed the same to fit in that small drawer in Girshner tool boxes.?
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In tool making we always used stronger bolts. Aluminum would only be used for appearance or weight. Stainless bolts in stainless are prone to galling, this week I had a 1/4" screw gall in a stainless flange and I had to saw it free. I'm on the road with no grease so I used butter and finished the job.?
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Re: Bolt queries
Hi Peter, we have the book (Engineers Bible) over here in the UK it's about 80mm thick so it has every bit of information you could need in it keep a look out for a copy.
On another note over the use of stainless bolts I use nothing else in many different metals and have done so for many years, but I always brush a film of copper grease on them and have never had any problems at all. Phill? |
Re: Bolt queries
Lay hands on a copy of Machinery's Handbook, and you will find several hundreds of pages of tables, discussion, and formulae. I keep picking at it, but I'm mathematically challenged, and unlikely to live long enough to understand it all even if I live a hundred years longer. :) Bill in OKC? William R. Meyers, MSgt, USAF(Ret.) Aphorisms to live by: Good judgement comes from experience. Experience comes from bad judgement.? SEMPER GUMBY! Physics doesn't care about your schedule. The only reason I know anything is because I've done it wrong enough times to START to know better. Expect in one hand, expectorate in the other. See which one gets full first.
On Monday, August 14, 2023 at 12:40:47 AM CDT, Peter Brooks <peter@...> wrote:
Some queries about bolts. - common sense would say that a bolt should be softer than (or equal in hardness to) the thread that is is going in to, the bolt being replaceable where the threaded item is maybe not. If threading into aluminium there seems little option than to use an aluminium bolt but in the back of my mind I am highly suspicious of aluminium (like it might meld back together like the Terminator!). It¡¯s strange stuff. I¡¯ve heard that you shouldn¡¯t use stainless steel in aluminium (galvanic reaction apparently), are there any other combinations of metals that are unadvisable? ?I have anti-seize compounds, one copper based and another, from bicycle maintenance days, do folks use these in general engineering? - is there a standard formula for the size (width and thickness) of bolt hex heads? ?(I¡¯m making some M14x1 bolts). - given light loadings (we¡¯re not dangling stuff from cranes, or pulling supertankers) is there any difference in the strength of fixing between (say) a 10mm, a 20mm and a 30mm bolt? Is there any point to the length of a bolt apart from reaching down to a thread? (I think this nearly qualifies for the ¡®Dumb questions¡¯ thread !) |
Bolt queries
Some queries about bolts.
- common sense would say that a bolt should be softer than (or equal in hardness to) the thread that is is going in to, the bolt being replaceable where the threaded item is maybe not. If threading into aluminium there seems little option than to use an aluminium bolt but in the back of my mind I am highly suspicious of aluminium (like it might meld back together like the Terminator!). It¡¯s strange stuff. I¡¯ve heard that you shouldn¡¯t use stainless steel in aluminium (galvanic reaction apparently), are there any other combinations of metals that are unadvisable? ?I have anti-seize compounds, one copper based and another, from bicycle maintenance days, do folks use these in general engineering? - is there a standard formula for the size (width and thickness) of bolt hex heads? ?(I¡¯m making some M14x1 bolts). - given light loadings (we¡¯re not dangling stuff from cranes, or pulling supertankers) is there any difference in the strength of fixing between (say) a 10mm, a 20mm and a 30mm bolt? Is there any point to the length of a bolt apart from reaching down to a thread? (I think this nearly qualifies for the ¡®Dumb questions¡¯ thread !) |
Re: Unimat Vertical Column
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On 14 Aug 2023, at 4:26 am, Peter Brooks <peter@...> wrote:
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Unimat Vertical Column
Is the vertical column diameter the same on both the DB200 and the Unimat 3?
-- http://www.homemadetools.net/ ?SMALL TURRET TOOL POST PLANS? ?LARGE TURRET TOOL POST PLANS ?MINI- ?SMALL QC TOOL POST PLANS? ?QUICK CHANGE LATHE TURRET ?MINI LATHE COMPOUND PIVOT MODIFICATION |
Re: Unimat 3 belting tightness
Hello Bill:
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On Sat, Aug 12, 2023 at 05:27 PM, Bill in OKC too wrote: Indeed ... It would not have been any trouble (taking apart and assembling the headstock spindle was) to just change the Bellvilles. Now I not only have to source them but I have to do it all over again. ... always enough time to do it over.Not really, as I still have a lot of fixing/replacing/tuning on my U3 so I can actually use it to finish a project. Thanks for your input. Best, JHM |
Re: Unimat 3 belting tightness
The aphorisms to live by, 1st & 5th, are basically how I learned these things. That and working on, and occasionally actually fixing stuff. Always replace gaskets and springs, if at all possible! Particularly where there are bearings involved! I'm a cheap bastrich, but it's a false economy to not do it right the first time. One of my bosses in the USAF once told me that there is never enough time to do it right, but always enough time to do it over. Which was not a positive in his opinion!? Glad I could help even a little bit! Bill in OKC William R. Meyers, MSgt, USAF(Ret.) Aphorisms to live by: Good judgement comes from experience. Experience comes from bad judgement.? SEMPER GUMBY! Physics doesn't care about your schedule. The only reason I know anything is because I've done it wrong enough times to START to know better. Expect in one hand, expectorate in the other. See which one gets full first.
On Saturday, August 12, 2023 at 01:57:33 PM CDT, Julius Henry Marx <sawbona@...> wrote:
Hello Bill: On Sat, Aug 12, 2023 at 02:33 PM, Bill in OKC too wrote:
Indeed ... As with any tool/part made of steel. That's what I was getting at. Thinking it was enough, I replaced the pair of OEM Unimat 3 bearings (as I mentioned, totally gone) with a new pair of SKFs but did not think to replace the eight OEM Belleville springs. Undoubtedly ignorance/lack of experience on my behalf. But then I would not think twice about replacing the thrust bearing in a car's gearbox when replacing the clutch, even if it was newish. Dumb is dumb. What I don't understand is that, of the many articles/web pages I have read on the subject of replacing the U3 spindle bearings,why not one mentions the need to replace the springs. If you took into account the age of the lathe (in this case 43 years) and the existing bearings being the original ones, there are more than sufficient reasons to do so. But I digress ... Fortunately, the parts list indicates that they are part # ZFD 94 3461 and the DIN number is 34.6x20.4x0.4 (in this case the part's dimensions) for the springs on the spindle. A quick look at a brought me up to speed, these chaps call them Bearing PreLoad Disk Springs. "With dimensions to suit most standard roller bearings (radial ball bearings), this range of plain bearing preload disc springs are manufactured from CK75 Carbon Steel (DIN 1.1248) with a zinc phosphate and oiled finish. The preload disc springs (or washers) assist in maintaining positioning accuracy of the bearing (with no end play) and also minimise vibration and shaft deflections. Correct preloading will also increase bearing rigidity and negate excessive running noise." So there you go: if there's fatigue (leading to incorrect preloading) bearing rigidity will decrease and and running noise will increase.The part number for the 34.6x20.4x0.4 size is and they are manufactured in the UK. I'll have to look up a local manufacturer first, I have the feeling that a set of eight won't cost me less than US$60.00/75.00 Thanks for your input. Best, JHM |
Re: Unimat 3 belting tightness
Hello Bill:
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On Sat, Aug 12, 2023 at 02:33 PM, Bill in OKC too wrote:
Indeed ... As with any tool/part made of steel. That's what I was getting at. Thinking it was enough, I replaced the pair of OEM Unimat 3 bearings (as I mentioned, totally gone) with a new pair of SKFs but did not think to replace the eight OEM Belleville springs. Undoubtedly ignorance/lack of experience on my behalf. But then I would not think twice about replacing the thrust bearing in a car's gearbox when replacing the clutch, even if it was newish. Dumb is dumb. What I don't understand is that, of the many articles/web pages I have read on the subject of replacing the U3 spindle bearings,why not one mentions the need to replace the springs. If you took into account the age of the lathe (in this case 43 years) and the existing bearings being the original ones, there are more than sufficient reasons to do so. But I digress ... Fortunately, the parts list indicates that they are part # ZFD 94 3461 and the DIN number is 34.6x20.4x0.4 (in this case the part's dimensions) for the springs on the spindle. A quick look at a brought me up to speed, these chaps call them Bearing PreLoad Disk Springs. "With dimensions to suit most standard roller bearings (radial ball bearings), this range of plain bearing preload disc springs are manufactured from CK75 Carbon Steel (DIN 1.1248) with a zinc phosphate and oiled finish. The preload disc springs (or washers) assist in maintaining positioning accuracy of the bearing (with no end play) and also minimise vibration and shaft deflections. Correct preloading will also increase bearing rigidity and negate excessive running noise." So there you go: if there's fatigue (leading to incorrect preloading) bearing rigidity will decrease and and running noise will increase.The part number for the 34.6x20.4x0.4 size is and they are manufactured in the UK. I'll have to look up a local manufacturer first, I have the feeling that a set of eight won't cost me less than US$60.00/75.00 Thanks for your input. Best, JHM |
Re: Unimat 3 belting tightness
They are springs. All springs deteriorate over time. Corrosion, stress fractures, etc. Get them wet, and let them rust, and it happens pretty quick. Keep them clean and dry and protected, it takes longer, but it will still happen. Happens faster when they're under constant compression or tension. Think of it as cheap insurance!? Bill in OKC William R. Meyers, MSgt, USAF(Ret.) Aphorisms to live by: Good judgement comes from experience. Experience comes from bad judgement.? SEMPER GUMBY! Physics doesn't care about your schedule. The only reason I know anything is because I've done it wrong enough times to START to know better. Expect in one hand, expectorate in the other. See which one gets full first.
On Saturday, August 12, 2023 at 02:52:18 AM CDT, Unimat Matt <matthewtay2020@...> wrote:
I am not sure about the Belleville washers to be honest, I would have thought they would be way too strong for the belts to overcome, especially when the forces from the belts are in the opposite (vertical) direction. That said, the washers are inexpensive so it my be worth a try. If you are having issues with play, you might want to also check your bearings, even though they are new! Unfortunately there is a massive problem with fake bearings. I've had fake ones that felt like they were worn out straight from the box! |
Re: Unimat 3 belting tightness
Hello:
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On Sat, Aug 12, 2023 at 04:52 AM, Unimat Matt wrote: ... not sure about the Belleville washers ...I have had a brief look on the web and it seems that they can suffer from fatigue. It is all way over my head, can't begin to grasp any of it. But one thing I understand: a Belleville washer is a disk spring made from a special steel to certain specificacions eg: DIN2093. And just line any other spring, it is designed (and tested) to work to spec up to a certain number of cycles.? Not the same scenario, but think shock absorber springs in a car/truck. At one point in time and depending of their use history they may have to be replaced. ... would have thought they would be way too strong for the belts to overcome ...Well, that's why I asked, I thought so too. Although overcome would not be the adequate term for what the belt does, it is just a small difference in the reading while measuring runout. But they are designed to be overcome is cases like the one I described in the OP. eg: a tool jamming. ... forces from the belts are in the opposite (vertical) direction.The forces from a tool would be perpendicular to the rotation axis ie: along the X axis, like in any other lathe. If we trace a line from the motor spindle axis to the lathe spindle axis (standard U3), it seems that it is at a ~ 30¡ã below the X axis. So I think that is the direction of the belt tension. ... washers are inexpensive so it my be worth a try.Of course, but I want to check on what is the right/expected behaviour in a properly working U3 before taking the spindle out. It is a bit of a hassle. ... issues with play ...I detect no play in the bearings ie: no runout and they were puchased from a SKF distributor. Thanks for your input. Best, JHM |
Re: Unimat 3 belting tightness
I am not sure about the Belleville washers to be honest, I would have thought they would be way too strong for the belts to overcome, especially when the forces from the belts are in the opposite (vertical) direction. That said, the washers are inexpensive so it my be worth a try.
If you are having issues with play, you might want to also check your bearings, even though they are new! Unfortunately there is a massive problem with fake bearings. I've had fake ones that felt like they were worn out straight from the box! |
Re: Unimat 3 belting tightness
Hello:
> ... formula for correct belt tightness. > ... change between different manufacturers ... > ... "snap fit" and you won't go far ... Yes, I have read abot 5%, 10%. But the thing is that I have seen small lathes run with loose belts and wonder if that isn't the right way or if it dependent on lathe size/load factors And then there's the issue of the Belleville washer fatigue on the U3. eg: mine was 43 years old last month and like I mentioned, the bearings were shot, (really shot) when I got it. If the bearings were shot beyond use, in what state are the Belleville washers? They are there to interact with the spindle/bearings arrangement and if they suffer (or not) fatige is something to be considered. A belt that is too tight will force the spindle's axis and the washers counteract that force. Thanks for your input. Best, JHM |
Re: Unimat 3 belting tightness
There is a formula for correct belt tightness. I can't remember off hand, but it is something like, belt circumference minus 10%
This will change between different manufacturers and different grades of belting.? If you want to be less technical, aim for a moderate "snap fit" and you won't go far wrong. |
Unimat 3 belting tightness
Hello:
I make the belts for my U3 from ? 5mm green textured PU, material I found on Aliexpress. Works fine and slips much less since I turned a new spindle pulley in Al to replace the lousy plastic OEM pulley. First thing I did when I purchased it (a year ago or so), after a thorough cleaning and taking stock of what was what, was to replace spindle bearings which were shot and install a new 24V/200W PWM regulated motor, later upgraded to a 400W one. From then on, the U3 slowly has morphed into a project in itself as I am still adjusting issues that kept cropping up every time I started to do something. eg: carriage, tailstock and headstock alignment, saddle/carriage gibs, new carriage leadscrew, new carriage handwheel arrangement and so on. Not unexpected from a 43 year old unit with an evident lack of maintenance and an unknown number of previous owners. Had I known ... But I digress. While taking spindle runout readings I noticed that the belt (on or off) had a marked influence on the spindle, albeit noticeable only with the dial in place. I assume (?) that the Bellville washers fitted along with the bearings are directly related to this axial movement, their being some sort of protection for the bearings/tool if and when the tool would decide to dig into the material being turned. Not that something of the sort would ever happen to me ...? 8^¡ã Refecting on this, a couple of questions popped up: 1. I have seen photos/videos of other round belt driven lathes where they actually seem to be loose. Just how tight does the spindle belt have to be on the U3? How can this tightness be measured? There is no provision to regulate it, has anyone ever found a way to do it in a simple and efficient manner? 2. Do the Bellville suffer material fatigue? ie: would they need replacing after many years' use? Thanks in advance. Best, JHM |
Re: Show us yer boring tools!
If you have inserts with dull edges or chips, all you have to do is touch the top surface to a diamond composite wheel. If you apply a small angle, you can easily create a razor sharp edge and top rake.? This gives all old inserts a second life and results in mirror smooth surfaces.? On Wed, Aug 9, 2023 at 10:26 PM Keith S. Angus <keithsangus@...> wrote: On Mon, Aug 7, 2023 at 08:21 PM, Jkle379184 wrote: |
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