Speeds, Feeds, and Strategies for Bench Top Mills - Page 12


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Thread: Speeds, Feeds, and Strategies for Bench Top Mills

  1. #221

    Default Re: Speeds, Feeds, and Strategies for Bench Top Mills

    I've been machining all sorts of stuff, things are going really well. I am dialing in a lot of parts that I made in the past as a result of the tool changer. Since I am no longer worried about being there to change tools, I run all sorts of finishing ops with devoted finishing tools. Luxurious!

    I need more TTS ER20 holders and that supply chain looks like a mess, I am not sure what I am going to do there.

    My PM 1127 lathe conversion is starting to cook. I have been making a lot of stuff on the lathe, I have a few parts to cook up for the mill. Then, I will do the servo conversion on the mill as well install the new spindle, new ATC parts, and just generally clean and adjust it. The steppers will come off, they will go on the lathe. I haven't decided what control I am going to use on the lathe. I am torn between Acorn and LinuxCNC. If UCCNC had a lathe control i'd do that without hesitation,.

    As for feeds and speeds. I have been shredding it lately. Running at around 5 cu/in/min with 3/8" 3 flute ebay carbide in Aluminum. The thing is incredibly quiet at those speeds. Tool life is great too. With finishing tools on the tool changer I get to come back through and clean up with really nice finish and tolerance. As we know the 0704 is a bit loose, so for finishing runs I like to run the machine at about 1/3 the roughing pace.



  2. #222

    Default Re: Speeds, Feeds, and Strategies for Bench Top Mills

    It took me three tries but I am happy with this. The first try I machined the M8 tapped holes 8mm (not my model, I should have checked it). So I couldn't tap the holes and had to try again. The second try I broke the m3 tap off in one of the holes, doh. The third try I got it all squared away. I am fighting a bit of dimension issue, I suspect that Z axis ballnut block is loose on the carriage again. Next time I have the machine apart I am going to have to revise that design. Oddly, Y axis was coming out spot on but X is a little large versus the model. I checked calibration and X was like .005" off over 6", I calibrated, but it made basically no difference in final dimensions (still larger than i'd like). I have never struggled with good dimensions on this machine, so I need to take a look at the mechanical bits. I nailed the chamfers on both sides despite flipping the part. Perhaps a fairly simple process for better machinists than me, but I've always struggled with A/B machining and getting the B side chamfers really spot on. I also really dialed in my Drewtronics probe, which helped a lot get that B side perfectly lined up. The ProbeIt UCCNC plugin and probe calibration routine certainly helps too. Finally, my programming really took a big leap on this part. Again, the tool changer allows for so much more versatility. I can keep 15 tools around, 10 on the carousel, the rest on the back burner, and it lets me do all sorts of steps that I would have skipped in the past.

    Anyways, ultimately the part came out pretty great.







  3. #223

    Default Re: Speeds, Feeds, and Strategies for Bench Top Mills

    I've revised the ATC carousel design a bit. There was always a good bit of extra space on the carousel. Since the G0704 spindle is small, the space between the tools can be reduced. I figure I can get at least 14 tools on it, maybe 16. Additionally, I've alway disliked how the carousel accumulates chips and debris despite the umbrella and door. One solution, I figure, is to leave some gaps in the carousel so that chips and coolant can wash through the fingers instead of accumulating on top.

    Current setup with 10 tools.



    New design with 14 spots. The finger design uses 2" by .25" aluminum bar stock, much easier to machine than the wedge designs too.


    I am going to revise the coolant ring, or maybe get rid of it all together. I am working on a spray bar that will mount on the side of the head, the coolant ring nozzles have clearance issues with the ATC as it is, with 14 tools it's going to get worse.

    I have a new PDB lever design worked out. Same basic lever action as the existing setup, just an improved geometry that hopefully will allow it to travel further, have less clearance issues, and will last longer. The current setup was prototyped then modified ad hoc to make it work, this design fixes the flaws I sussed out over the last year or so with the PDB. I am also going to cut a new drawbar, I made the current one out of stainless, it looks great and has done okay, but it's too soft. It's starting to deform fairly heavily where the drawbar lever contacts the top of the drawbar itself.



    Next up is the PDB base plate, this will fix a few issues, but mostly it will strengthen the lever arm mount. It's been working fine, but it's just not quite strong enough. There's a bit too much flex in the PDB assembly and the draw bar release isn't as snappy as it used to be. Between the flex and the slop the release is a bit slow. Getting it all tight should mean I can get away with higher drawbar pressure (marginally) but also it should make tool changes just a little bit more reliable. Not that they've been unreliable (they've been great), but any little bit of refinement I can get is a win. A little bit snappier release should let me speed up the tool changes a bit too.

    After those items, I hope to be able to do the servo conversion. I am probably a month out on that yet. This G0704 project just keeps evolving.



  4. #224

    Default Re: Speeds, Feeds, and Strategies for Bench Top Mills

    New ATC gripper is designed an on the mill. It should better accommodate the wide range of TTS style tool holders I have. They vary wildly in OD. The existing ATC grippers don't accommodate the smaller tool holders (too loose), as a result my tools rattle on the carousel and it's kind of annoying. This new gripper is much better and it tightly grips the small OD holders, and can flex enough to hold the large OD holders without creating too much resistance. As soon as I get the patience to mess with my piece of junk 3d printer (Ender 3 V2) I will finish printing the rest of the grippers.

    I also got the material for the new ATC fingers and new ATC hub. I need to check backlash on X, i suspect the ballnut is giving up, or at a minimum something is loose. Then i'll do the approximately 40 hours of machining to clear customer orders and get the new parts made. I will then be fitting double nut screws and the Clearpath servos.





  5. #225

    Default Re: Speeds, Feeds, and Strategies for Bench Top Mills

    So, i've got about .0022" backlash on both X and Y. Hmmmm. That's about twice what I would like, but it's also not all that bad for a single nut.

    I still don't know why I had dimension issues on the part above. The X system is getting noisy, but it runs all day long without issue. I think the screw isn't particularly straight and the couplers just deal with it.

    I setup backlash compensation in UCCNC. I am not particularly confident in it. Mach probably ruined me on this, but when I play around with backlash using my pendant, the backlash comp does some crazy stuff. I need to do more tests with MDI to see if moving an axis via steps and the odd results correlate to actual machine movement when backlash comp is enabled.

    I have some new end mills coming. They are Shars Gorilla chip breakers, incredibly expensive at $60 for a single 3/8" end mill. My favorite carbide is half that price. Godspeed to me, I guess. I have the spindle power, I have the feed rate, I'm pretty sure I can't run the machine at 1" DOC because it becomes a noodle. I suppose I will try again.

    The experiment rages on.



  6. #226
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    Default Re: Speeds, Feeds, and Strategies for Bench Top Mills

    The cost of tooling is crazy. I found this really nice little lathe, its a miniature precision second op, and when I bought it, I never gave a thought to the collets. It uses these crazy little 4NS collets, and they are finicky; so not all of them work on all applications. Many of them were made by Rivetts for their precision grinders, and they are a couple of tenths larger than the Hardings, which is what this lathe uses. Some Rivetts fit, but not all of them. Anyway they are 256 dollars each new, from Harding. I finally bought 70 of them, off of ebay, for 450 dollars, and about 50 of them fit.

    Then I happened upon a mini mill, a beautiful Little Machine Shop High torque CNC conversion for 950 dollars, so I'm trying to get it set up and I needed a 12 TPI threadmill so I can put a spindle on the little lathe, and theyre like 150 bucks apiece! A 2-3 inch long 1/4 inch with a .200 inch neck and a single profile tooth is 150 bucks! I found a used 3/8ths 4 flute with a 2mm pitch for 25 bucks, I think it will work, but man, the cost of tooling is just too much!

    Speeds, Feeds, and Strategies for Bench Top Mills-minimill-jpgSpeeds, Feeds, and Strategies for Bench Top Mills-collets-jpgSpeeds, Feeds, and Strategies for Bench Top Mills-minimillcloseup-jpgSpeeds, Feeds, and Strategies for Bench Top Mills-takaoseiki-jpg

    Halfnutz


  7. #227
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    Quote Originally Posted by CL_MotoTech View Post
    So i've progressed a bit further. I got the ATC running, the PDB seems well sorted. I made a bunch of parts, including a large run on a cylinder head that was quite a neat project.

    Here's the ATC going:
    Wow man I'm sure digging that atc. Is there any chance you have those plans to the atc for sale?? Great job



  8. #228

    Default Re: Speeds, Feeds, and Strategies for Bench Top Mills

    I bought the ATC as a kit from a guy here on the forum. I haven't seen him around for a while... I think he got annoyed with the talking heads.

    I think the guy that made mine started with plans from a Canadian guy that sells the plans, or at a minimum the two designs are very similar. Somebody here posted the link to those plans a long time ago, I tried to find them again, but couldn't. Of course the tool changer is only half the story. I built the power drawbar, and while it's been working well for over a year now, the second iteration will be welcomed. The design work is done, I just have to machine the parts and assemble it.



  9. #229

    Default Re: Speeds, Feeds, and Strategies for Bench Top Mills

    Quote Originally Posted by Halfnutz View Post
    The cost of tooling is crazy. I found this really nice little lathe, its a miniature precision second op, and when I bought it, I never gave a thought to the collets. It uses these crazy little 4NS collets, and they are finicky; so not all of them work on all applications. Many of them were made by Rivetts for their precision grinders, and they are a couple of tenths larger than the Hardings, which is what this lathe uses. Some Rivetts fit, but not all of them. Anyway they are 256 dollars each new, from Harding. I finally bought 70 of them, off of ebay, for 450 dollars, and about 50 of them fit.

    Then I happened upon a mini mill, a beautiful Little Machine Shop High torque CNC conversion for 950 dollars, so I'm trying to get it set up and I needed a 12 TPI threadmill so I can put a spindle on the little lathe, and theyre like 150 bucks apiece! A 2-3 inch long 1/4 inch with a .200 inch neck and a single profile tooth is 150 bucks! I found a used 3/8ths 4 flute with a 2mm pitch for 25 bucks, I think it will work, but man, the cost of tooling is just too much!
    When I started with this project I would buy end mills by the pound on eBay. You could get like 5lbs of used carbide end mills for like $20. I still have a bunch of those end mills and occasionally pull them out when I'm in a bind. Tool prices are a bit scary right now though.



  10. #230
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    Default Re: Speeds, Feeds, and Strategies for Bench Top Mills

    I finally found a decent single tooth thread mill with a large enough profile to cut a 12TPI thread for less than 150 dollars and with enough meat that I dont have to worry about snapping it off. Its a 3/8in. with a .251 neck for around $25. Between that and the form mill, I should be able to figure it out. The price of those little 4NS collets from Harding, $250 bucks each, just shocked me. Unbelievable, but hey, thats probably what I would charge to make one. Everything is crazy right now.

    Halfnutz


  11. #231

    Default Re: Speeds, Feeds, and Strategies for Bench Top Mills

    Hopefully you get a good run out of it. Even at inflated prices it will probably be worth it in the long run, especially since tooling prices aren't likely to go down any time soon.

    I've been looking at buying more TTS tool holders and am trying how to get like 10 without spending $600. By the time I buy the ER20 holders and decent collets the prices really add up.



  12. #232

    Default Re: Speeds, Feeds, and Strategies for Bench Top Mills

    I've been using Oldham couplers for years, which does not support the screw like the Lovejoy units, but I found they have less backlash. I have gotten the system down to .0012" after a repack on the nut. Anyways, I always had in the back of my mind where for The Grizz build they sent the screw back to Dave and he straightened them, and on The Grizz they supported the screw at the stepper. My X screw slapped at high RPM especially when the stepper end was far from the nut, but it always worked, not optimal but it ran for years. The screw obviously not straight, and not supporting that end isn't perfect.

    So I took the screw out, stuffed it the lathe. It had .07" runout from about 7" to the end coupler side. It was pretty nice from 7" back, with very little ronout. So I bumped it (pretty hard) with the cross slide, placing the bend just at the apex of the chuck. I got it down to like .02" runout. I could have done better but I didn't want to damage the screw as I don't really have good tools for this.

    Here's the 3d printed support. It snaps on, and uses two existing holes from Dave's mount. The nice thing about it snapping on the screw is that you don't have to mess with couplers to take it off. I should have taken a photo with it off the mill, oh well. Between straightening the screw and this support the X travel is damn smooth and quiet now. A definite improvement.

    I can provide a model for anybody that may want to print one.





  13. #233

    Default Re: Speeds, Feeds, and Strategies for Bench Top Mills

    Oh, and I made this AC bearing cover for the outside X axis bearing. The plastic ones always fall apart, it seems they don't like my coolant. The bearing seal also fell out... the bearing wasn't pretty dang notchy. I cleaned it and repacked it. Even with the table surrounds stuff was getting in there. So the new bearing cover should help get by until the new bearings arrive, and being aluminum it will last.

    There have been a few other improvements that aren't quite complete. I should have an update next week.







  14. #234

    Default Re: Speeds, Feeds, and Strategies for Bench Top Mills

    New PDB lever is in place. I also finally got around to truing up the spindle, especially the top bearing surface. On my spindle I turned off the threads on the very top of the spindle and use a 17mm ID bearing on that. This supports the spindle and belleville stack. To get this true, I mounted the spindle in the 4 jaw, indicated off the existing bearing surfaces, then brazed the third bearing surface to build it up, using the steady rest on the top bearing surface to support the spindle I was able to turn the third bearing surface true to under .0005". I wish I could have halved that, but it was tricky given the length of the spindle. The spindle is now rather smooth, no tight spots, and it runs quiet and smooth. I'd still like to get a bit of vibration out of it, but now i think it's down to the drawbar and belleville stack itself, it's all a spot loose, and that means it likely doesn't run particularly concentric while spinning. That turns into vibration. That said, it's quite smooth at 6k. The smoothest it has been since adding the power drawbar anyways. If I can get it a bit smoother, I will turn some pulleys for 8k spindle operation.

    Old PDB lever. It was never intended to last as long as it did. It made it almost two years, but is looking pretty rough.



    New lever. It solves all the clearance issues of the old one, and solves all of the issues the old one had with wall thickness issues and what not.





  15. #235

    Default Re: Speeds, Feeds, and Strategies for Bench Top Mills

    While I was in there I also adjusted a number of the bits, greased the 3/4" collet, all that good stuff. The collet releases quite swiftly now. I think I am going to buy a reamer, rebore the spindle ID, then ream it, and cut a new drawbar on the lathe to suit. With a nice round ID on the spindle, it should make for a really consistent push on the draw bar and improve things further. It should also help reduce runout on the stack and further reduce vibration. It's very close now. It's just a matter of time, money, and willpower. I may look into reducing the size of my Belleville stack some, but I get good travel with this system and that aids in ATC reliability.



  16. #236

    Default Re: Speeds, Feeds, and Strategies for Bench Top Mills

    Not sure what happened here, but this end mill had enough. It's a Shars house brand carbide 5 flute. I was machining stainless, I heard a crunch, took a look inside and this was the result. I love machining stainless though, it's like butter.



    I got the new coolant system on. I am going to change it, but proof of concept is there. This works really well actually. It's printed in PETG and I did a pressurized seal of the manifold using some West epoxy.




    The next version is either going to go around the front of the mill, so probably 3 on the side and 2 on the front. Or I may just add more down the side. That said, it worked great when I was making some gears. So a new version isn't a priority.



    The new spindle is also slick as all get out. So quiet, so smooth. It's blowing me away. I need to get around to making the final drawbar bits and I'm certain it's going to be incredible.



  17. #237

    Default Re: Speeds, Feeds, and Strategies for Bench Top Mills

    This was a fun one. The impeller required large stick out on a .25" end mill. I had the tool 1.6" outside of the ER20 holder to avoid a crash. The only major issue with the part was that the center hold ended up slightly small at the bottom, I should have just sent the tool back through for a finishing pass. It was easily fixed up with some sand paper on a pencil and the lathe. I got to use a .25" lollipop for the profiling and it turned out pretty nice I'd say. I've never used that tool before, just kind of had it sitting around for a rainy day, and it paid off. Run time wasn't super long, maybe an hour or so, which considering the finishing path for the profiling was taking tiny steps isn't too bad. I ran typical F&Ss on all tools except for the lollipop which I ran at a crawl even with 6k at the spindle. Looking at the flat surfaces on the lower face of the impeller shows that my spindle balance and runout is looking sweet. The machine is nice and square too. That surface was machined with the 3 flute carbide at 1.6" stickout. Stock impeller on the right for comparison.





  18. #238

    Default Re: Speeds, Feeds, and Strategies for Bench Top Mills

    I turned a 5.25" by 6.5" by 1.25" piece of aluminum into something smaller, though it isn't done. I think the spindle is a spot loose now, but the work is still good.

    Side B is yet to come, custom soft jaws pictured (though not exactly obvious what they do they are for side B). Total machine time on this is going to be about 4 hours. I will do all the contouring with a .25" lolli. I could reduce that run time by a ton but I'm not doing volume parts so I don't really even try. I ate dinner while this thing cooked. I used 6 tools for the cover.





  19. #239
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    Default Re: Speeds, Feeds, and Strategies for Bench Top Mills

    I hope dinner was good, but that piece looks better than a filet mignon to me. good work....WTF is that thing?

    "THE GRIZZ" photo album - https://goo.gl/photos/yLLp61jooprtYzFK7
    Youtube - https://www.youtube.com/channel/UCT2lq9obzEnlEu-M56ZzT_A


  20. #240

    Default Re: Speeds, Feeds, and Strategies for Bench Top Mills

    lol, thanks! My wife says it is a penis, shows where her mind is. It is what I hope to be the final version of my high capacity Suzuki GT750 water pump. The high capacity impeller shown above, this pumps about 3.5 times the amount of the stock setup. The cover has to be larger to allow for the larger impeller, they are a matched set. The engine powers our race car and as it is in a rather extreme state of tune it generates way more heat than a stock motor, hence the need for way more cooling.

    Version 1 of the cover here, which is a slighter lower volume pump than this new one - https://www.cnczone.com/forums/bench...ml#post2445258

    You can see the internal work, side B machining will do the same on this one. On the first cover I did the bare minimum, it's a slab, and while it worked for two years it was hard to get in and out because the bolts were long. It's also heavy for what it is. Really, this part should be a casting, but that's a lot of work. I stylized the new cover, reduced the bolt tabs, removed material where I could as to lighten it, and generally just cleaned up the design. It should pump an additional 15%.

    A high capacity cast cover shown below, it didn't last (note the large hole that let all the water out) and cost a ton of money as we had to import it from the UK. My cover is higher capacity yet and won't suffer the same porosity issues as a cast one.



    Finally, these parts are one off parts for this thing, it is a vintage sports racer my father built in the 70's and that him and I campaign for fun at various events. We built the trailer too, we completed it back in 2001.





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Speeds, Feeds, and Strategies for Bench Top Mills

Speeds, Feeds, and Strategies for Bench Top Mills