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Re: Found this photo - anyone has more information about it?
Hello Carl:
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On Tue, Jan 10, 2023 at 11:26 AM, Carl wrote: Maybe I am missing something, I am not versed in screw geometry or standards. If I understand correctly, what would be happening is that the 7.0mm hole made to tap the M8x1.0 LH thread would get a lengthwise slit, say maybe a max of 0.3/0.4mm wide, would then be clamped so as to close that slit/gap and then threaded to M8x1.0 LH. I think that the result would be a smaller albeit not precisely round (ie: slightly oval) hole to thread but as we are talking brass and not steel, this would not be a problem when making threading, provided due care was taken. If for the sake of this exercise we take the slit+clamped hole to be just as round as the un-slit one, I think that what we would end up with would be an M8x1.0 LH thread made in a hole a wee bit smaller than usual practise advises, say M6.80 instead of M7.0. When the clamp is released, the slit will then spring open and as a result the now threaded hole will go from the (estimated) 6.80mm to the nominal 7.00mm, taking the both the crest and root of the M8x1.0 LH thread further away from the lead screw's axis. If I am correct, I think that the screw would have quite a bit of play. Make sense? Thanks a lot for your input. Best, JHM |
Re: Found this photo - anyone has more information about it?
¿ªÔÆÌåÓýHello Julius and Jay: What if you slit the nut before tapping the M10x1 LH? Then when you tap it crush the slit in the nut closed. Then when the clamp is removed and the slit springs open you will have your slack removed. Carl. On 1/10/2023 6:14 AM, Julius Henry Marx
wrote:
Hello Jay: |
Re: Found this photo - anyone has more information about it?
Hello Jay:
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On Tue, Jan 10, 2023 at 04:30 AM, Jay Perez wrote: Thank you very much for your detailed CADs.? 8^D Much obliged. ? 8^D My bad. I should have detailed it properly. Here's a quick & dirty sketch, approximately to scale. No match for your CADs but I think it gets the idea across: As you can see, there's really not much room for anything but oil and swarf. Even so, brass has a way of constantly setting up residence in there. Yesterday I attempted an idea similar to the one shown on your second drawing but using a small piece of silicone sheathing from some high temperature cable, just to see how it behaved. The silicone cable was (as expected) too soft and quickly deteriorated, but I think we may be on to something. I have to see where I can get small teflon/delrin balls. With this flawed OEM design and with no room around the nut, I think that the only possible way for something to press against the feed screw threads is from above. But it has to be separate from the screw that holds the nut in place, unless the solution is something with very tight tolerances. ie: it would have to work with the screw in place and as tight as it should be, maybe a tiny piece of hard teflon in the right shape. The screw is M4, rather small, but if an M6 flat head screw like this one ... ... with a concentric M2 grub screw running inside were used, there's may be a possibility. The grub screw could have a 60¡ã point, like this one but would have to be made from brass or hard teflon and just plain slot type, no allen head required. You would first tighten the nut in place with the M6 screw and after the sloide is in place, thegib is properly adjusted and the feed screw/ways oiled, you would tighten the brass/teflon grub screw till it runs on top of the feed screw thread and the backlash is acceptable.? Eventually the grub screw would wear down and have to be replaced. The problem with this is that all those allen screws are impossible to drill/thread. Don't ask me how I know.? 8^¡ã It is a rather complicated solution but there may be a way to do it. Have to play a bit with fire, water and oil. Thnak a lot for your input. Best, JHM |
Re: Found this photo - anyone has more information about it?
Based on Julius' and other comments I modeled some of the other options discussed. I'm not familiar with the machine and not sure I'm correctly visualizing the clearances?around the nut from the verbal descriptions. Two of the designs seem pretty plausible if you have the taps and equipment to fabricate your own nut. I think you could probably get away with cutting the slot with a hacksaw blade or a jeweler's?saw. Jay True Split Nut Design. Slot in line with the threads. ?? Modified version of my earlier design. Set screw on the bottom pushing a plastic plug into the thread. On Sun, Jan 8, 2023 at 7:47 PM Julius Henry Marx <sawbona@...> wrote: Hello Jay: --
Jay |
Re: Found this photo - anyone has more information about it?
Keith,
I agree that a double nut could be used effectively to adjust and control backlash. That in my experience, is preferable to a ¡°split¡± nut that has to be squeezed or forced together by some means to effect the adjustment. A double nut simply uses two nuts that are in line with one another, but opposed. The space between the two nuts is adjusted to control backlash. Thanks for mentioning this method as offers precise adjustments. Dick |
Re: Found this photo - anyone has more information about it?
Hello Jay:
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First of all, thank you very much for taking the time to put this together.? 8^)? On Sun, Jan 8, 2023 at 08:44 PM, Jay Perez wrote: There are quite a few variants and all have the same principle: a spring. Ahh, Brigdeport milling machines. Serious stuff. Many intelligent solutions are. But it doesn't look crude to me.? 8^) There would be no problem with that. Just maybe, given the size of the nut, finding a thin enough saw blade. That's the exact moment at which the elephant enters the room. Like I mentioned previously, the OEM nut is a 10mm cube and the way it moves in is 10.5mm high. So there's only ~ 0.50mm vertical space available. As the saddle is made from die cast aluminium, the way is shaped like a flat bottomed inverted cone to facilitate the separation from the die during manufacture. It measures 13.5mm at the top and 12.5mm at the bottom. So the nut moves along the centre of the way with barely any wiggle room. ie: ~ 0.50mm at the bottom, ~1.50mm to each side at the top and ~1.00mm at the bottom. I'm afraid I don't see room for a clamp + set screws there. 8^/ Idea: I have been wondering if the M4x0.7 screw than holds the nut in place could push a very small brass/teflon/? bearing against the 8.0x1 thread and help reduce the backlash. Or maybe the screw could be made from very hard brass and have an acute/pointed end. ie: by design (in theory), the feed screw axis and the M4 screw axis intersect at 90¡ã and as a consequence of that, the screw's point would run inside the thread and (hopefully) reduce or eliminate the existing backlash. Make sense? Obviously (if it works) such a screw would have to be replaced when the point gets worn and start to slip. But anything is better than this incredible design flaw from Emco's engineers. Once again, thanks for your input. Best, JHM |
Re: Found this photo - anyone has more information about it?
Hey All, I like that approach Julius and have used something similar on the Z axis of my 3D printer. Bridgeport mills use a 'split nut' to adjust for backlash. Crude but effective. I drew one up for the Unimat in Fusion 360?based on the dimensions of the 10mm nut someone posted for sale. Basic operation is the same, you have to cut a gap into the nut to allow it to be compressed together and then have a mechanism that allows you to squeeze it slightly to adjust the fit of the nut onto the leadscrew. I don't have this machine so don't know how much room there is in the area where this is used so it may not work as designed. You might be able to rotate the clamping mechanism 90* to get it to fit in the space. You would have to relocate the set screws and drill a 10+ mm hole in the bottom of the clamp to allow the leadscrew?to pass through. I've attached some pictures and a drawing (some dimensions) and the CAD file in native Fusion format and as a STEP file. On Sun, Jan 8, 2023 at 2:52 PM Julius Henry Marx <sawbona@...> wrote: Hello Richard: --
Jay ![]()
Unimat Split Nut - Set Screw Cross Section 2.png
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Unimat Split Nut - Mid Plane Cross Section.png
Unimat Split Nut with Clamp and Set Screws.f3d
Unimat Split Nut with Clamp and Set Screws.f3d
Unimat Split Nut with Clamp and Set Screws.step
Unimat Split Nut with Clamp and Set Screws.step
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Unimat Split Nut - Set Screw Cross Section 1.png
Unimat Split Nut Drawing with Clamp and Set Screws.pdf
Unimat Split Nut Drawing with Clamp and Set Screws.pdf
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Re: Added album New to me SL1000
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There are brackets as well as the whole assembly on eBay. I might make the post, your drawings look simple enough. Thanks!
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Re: Added album New to me SL1000
#photo-notice
Thanks! I bought the second one. With a sleeve I could even use it in my Craftsman. Maybe¡
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Re: Found this photo - anyone has more information about it?
Hello Richard:
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On Sun, Jan 8, 2023 at 03:17 PM, Richard wrote: ... available from Arc Euro in the UK as a spare ...Indeed ... Thanks for the heads up, I had seen it last week while looking for a solution for the backlash in my U3, thinking that maybe a part from some other lathe could be modified/adapted. Good to know this one fits.? 8^) ... make my own from 1/2" bronze bar ...Last year I made a nut (sans the spigot) to use along with the original nut and a coiled spring to separate them, making a device such as those used in hobby CNC machines to reduce backlash: But it was a failure as there is very little space between the top of the feed screw and the bottom of the slide: It is ~ 0.90mm without counting the crest of the feed screw thread, so it is probably down to ~ 0.70mm. A coiled spring expands under tension and altough I managed to file/sand one and make it work to reduce the backlash, at some point the slide would jam. The nut is a ~10mm cube and the way it moves in is 10.5mm high by 12.5mm at the bottom and 13.5mm at the top. Not much room below the nut and not much to either side. Thank you very much for your input. Best, JHM |
Re: Added album New to me SL1000
#photo-notice
On Sun, Jan 8, 2023 at 02:34 PM, Kit Maira wrote:
When I bought my Craftsman lathe I spent a lot of time and dough chasing down all the accessories for it. Looks like I¡¯m going to be repeating that with the Unimat.I doubt very much that you will need all the accessories for the SL, and you could waste a lot of time and money finding them. It is more useful to get what you need when you need it, or make it if you can't buy it at a reasonable price. The main thing I wanted but never found was soft jaws for the three jaw chuck. I know they were made once, but now I am using the U3, and the chuck is accurate enough not to need soft jaws. I am also well tooled up for collets. Lots of users think they need the four jaw independent chuck. I've never needed one in more than fifty years of intermittent workshop experience, in industry and at home, and I've never seen anyone else use them either. Other accessories, as you've already realised with the threading attachment, are too rare and expensive for the problem they solve. For drilling you will need a column, which I drew up a while back. See: /g/Unimat/files/MILLING-POST.pdf Also the locking screw for the headstock:?/g/Unimat/files/Locking%20Screw%20DB501-8.pdf Finding the bracket for the headstock is a different matter, but it shouldn't be too difficult to make one given a reasonable size lump of Ali. |
Re: Found this photo - anyone has more information about it?
Hi Julius,
That nut is available from Arc Euro in the UK as a spare for the Sieg C0 lathe: I have used those in the past but now make my own from 1/2" bronze bar (squared off to 10mm).?? That needs a standard M4 tap and a M8x1LH tap of course! Rgrds,?? Richard. |
Re: Added album New to me SL1000
#photo-notice
I bought one of these for my Unimat:??they don't seem to have the one I got, which came with an MT2 arbor, but it's a nice little 4-jaw chuck. Price has gone up by about $15 since I got mine early last year.? Well heck!??this looks exactly like the one I got. ;)? Cheaper than just the 4-jaw chuck alone, too!. 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
On Sunday, January 8, 2023 at 08:34:59 AM CST, Kit Maira <kit.maira@...> wrote:
I would like to find a drill chuck to fit this. I have a drawer full of chucks, none of which fit it. I see a few milling attachments on eBay. A 4 jaw chuck would be nice. When I bought my Craftsman lathe I spent a lot of time and dough chasing down all the accessories for it. Looks like I¡¯m going to be repeating that with the Unimat.? I have been going through the copious amount of literature that is on this site, and the Facebook group as well. I¡¯m impressed by the versatility of this little machine. Always wanted a sensitive drill press for one, now it looks I have one.? I was looking at the threading feature, it looks like that would require a lot of expense to get multiple threading capability, and I doubt that would be easy to find.? I¡¯m excited to clean this up, and make a few bits. |
Re: Added album New to me SL1000
#photo-notice
I would like to find a drill chuck to fit this. I have a drawer full of chucks, none of which fit it. I see a few milling attachments on eBay. A 4 jaw chuck would be nice. When I bought my Craftsman lathe I spent a lot of time and dough chasing down all the accessories for it. Looks like I¡¯m going to be repeating that with the Unimat.? I have been going through the copious amount of literature that is on this site, and the Facebook group as well. I¡¯m impressed by the versatility of this little machine. Always wanted a sensitive drill press for one, now it looks I have one.? I was looking at the threading feature, it looks like that would require a lot of expense to get multiple threading capability, and I doubt that would be easy to find.? I¡¯m excited to clean this up, and make a few bits. |
Re: Added album New to me SL1000
#photo-notice
Well you have all the basics, plus the slow feed attachment, which is a bit rare these days. With the other machines you have you should be able to make additional tooling or replicate original parts. I have found the Unimats to be very handy, and easy to use, even if the working size is limited. On the other hand with the high speeds I found it fine for small components. Working with collets made precision working easier, and was better for hand work, without those whirling chuck jaws waiting to skin your knuckles. I am trying to get around to making a copy of the spindle nose onto a Morse taper blank to fit into a bigger lathe, so I can make fixtures with good concentricity but larger sizes than are possible on the Unimat itself. If you decide to do this then the first tools you need are an M12 ¡Á 1 tap, 11 mm drill, and a 12.00 mm reamer or D bit to cut the thread and recess for anything to fit the spindle. These can be made on the SL, or roughed out on a bigger lathe and then finishing cuts taken on the SL to give good repeatable concentricity. I got repeatable concentricity to about 0.0005" with some fixtures I made.
These machines are highly adaptable, which is why so many of them are still in use. |
Re: Found this photo - anyone has more information about it?
Hello:
Sorry to revive an old thread ... After getting my set of qctp+holders finished, I am now looking to see about fixing the backlash issues the Unimat 3 cross slide has. From what I seen, it is very tricky business to get involved in as there is very little/no room to do much about it and on top of that the slide nut itself is very small: Not to mention the terrible hassle you are in should you lose the damn thingy: just in case, I wrote the people at Emco last June equiring about the possibility of getting a replacement part but was promptly ignored. It seems the very same part is used in the Unimat Basic, so it may be available somewhere. But I digress ... As we know, the hole in the nut is threaded 8.0x1 LH. The thing (part no. A3A 050 040) is basically a ~10mm x 10mm x 10mm cube, with the threaded cylinder to hold it in place from above with a M4x8 countersunk screw (part no. ZSR 65 0408) being ? ~6.0mm x 5.0mm high .? Hoping not to impose, I was wondering if you'd be kind enough to post a photo of what you have done to the cross slide so I could get an idea of what I was getting into.? ie: the slot you milled into the cross slide and any details you think pertinent. Thanks in advance. Best, JHM |
Re: Added album New to me SL1000
#photo-notice
Only what you see. I got it in an antique shop that was closing. Everything was half off. I don¡¯t know whether $350 was a good deal, it was an impulse purchase. I think I¡¯ll need to disassemble and clean it up. There is a bit of surface rust. In addition to this little lathe I have a 12¡± Craftsman lathe, a South Bend 405 and a Lewis Machine mill that I am working on. I¡¯m curious to learn what the Unimat is capable of. I¡¯m in search of projects to keep me busy. Will probably bring this into the basement for the winter, as my shop is not heated, and the cold is coming. Thanks for responding.?
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Re: Added album New to me SL1000
#photo-notice
Kit, there's a copy of the manual on the 2nd page of files:?/g/Unimat/files/DB-SL%20Manual%20%28Miniature%20Machining%20Techniques%29/DB_SL_Manual_Miniature_Machining_Techniques.pdf Parts and bearings and such are available several places, including the usual suspect, eBay, but Unimat Homestead??is also a good place, and they have a better quality printed copy of the manual, too. I was pretty flush when I got my SL & DB last year, and bought the manual, bearings, and belts from Doug.? We have blueprints/drawings also in files, for many of the machine parts, as well.? They're cool little machines! 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
On Friday, January 6, 2023 at 06:48:53 PM CST, Kit Maira <kit.maira@...> wrote:
Thanks, I¡¯ve been exploring them, as well as the photo albums. Is a manual available that I can download, preferably for free? I noticed that there is a missing snap ring on the shaft that drives the carriage feed.
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