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IndustryArena Forum > MetalWorking Machines > Benchtop Machines > Mini Lathe > HF 8x14 linear rail conversion....and maybe more...
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  1. #1
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    HF 8x14 linear rail conversion....and maybe more...

    So I've had a harbor freight 8 x14 lathe for a while, and I cnc'd it a while back, but after converting my mill to linear rails it had to happen to the lathe too. so this is what I'm starting with


    And while a lot of work has already been done, such as ballscrews and spindle motor upgrades, there is so much more that can be done and this upgrade is a great excuse to do it. So I don't know where this build thread will take me yet, but ignorance is bliss at the moment. So on with the destruction! First step, strip it all down to the little bits.


    Next up I have to mill the saddle rib off the bed. There's no place for that where we are going. But of course it's not as easy as just slapping it on the mill and going at it with some scrap carbide. Of course there's a whole bunch of gunk on the bottom of the feet. I bought the lathe used and I think the previous owner had glued around the mounting holes for some reason.


    A little elbow grease later and both pads are clean as a whistle.


    So on the mill she goes. I'm lucky to have a makerspace local to me with the needed tools to help out as it's a bit large to fit on my CNC mill. Tramming it in took quite a while. There are no real good reference surfaces to align too. I ended up using the saddle rib which isn't ideal, but worst case I can go back and reamachine the rib. I'm only keeping a small portion of it anyways.


    obligatory action shot! I used a 3" indexable face mill to do all the heavy lifting.


    Lest thing for today was to drill the linear rail mounting holes. They will get tapped for M4 bolts, but there just isn't enough hours in a day. thank goodness for my Albrecht drill chuck. it made swapping back and forth from the sop drill to the drill a snap.



    Ok, I lied...I've been playing around with some sanding brushes I got off amazon, so after spotting nad drilling, I ran both surfaces back over with an 80 grit brush. Here you can see the before and after differences between the two legs.


    the pictures don't really do it justice, but they look significantly better in person.

  2. #2
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    Re: HF 8x14 linear rail conversion....and maybe more...

    How hard to machine the lathe bed ?

  3. #3
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    Re: HF 8x14 linear rail conversion....and maybe more...

    Quote Originally Posted by asuratman View Post
    How hard to machine the lathe bed ?
    the actual machining was easy. It was a paint to square it up on the mill though.

  4. #4
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    Re: HF 8x14 linear rail conversion....and maybe more...

    What do you plan for cnc control ? You plan to use mach3 or acorn or linux ... ?

  5. #5
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    Re: HF 8x14 linear rail conversion....and maybe more...

    i'm currently using mach3, but depending on how things go i may switch to linuxcnc or kmotion

  6. #6
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    Re: HF 8x14 linear rail conversion....and maybe more...

    So i haven't been taking as many pictures as i should, but i have been working on this when I have time. I have the saddle plate made, as well as the top slide. Rails are temporarily mounted as is the saddle.





    Here's the bottom side of the cross slide table. I machined strips for the rails to sit in as well as a pocket for the ball nut clearance. I had a bit of an issue with my tool pulling out. as a result there is that unsightly "L" shape. Luckly it's on the bottom side and isn't really an issue.




    top side of the cross slide table was skimmed and machined for a combination of dowel pins and 1/4-20 threads. Hopefully this will make installing and aligning tools pretty easy


  7. #7
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    Re: HF 8x14 linear rail conversion....and maybe more...

    Hello,
    How about the progress ?

  8. #8
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    Re: HF 8x14 linear rail conversion....and maybe more...

    Quote Originally Posted by CS900 View Post
    So i haven't been taking as many pictures as i should, but i have been working on this when I have time. I have the saddle plate made, as well as the top slide. Rails are temporarily mounted as is the saddle.

    Here's the bottom side of the cross slide table. I machined strips for the rails to sit in as well as a pocket for the ball nut clearance. I had a bit of an issue with my tool pulling out. as a result there is that unsightly "L" shape. Luckly it's on the bottom side and isn't really an issue.



    top side of the cross slide table was skimmed and machined for a combination of dowel pins and 1/4-20 threads. Hopefully this will make installing and aligning tools pretty easy
    The aluminum cross slide gang tool table looks very nice, but have you considered using a t-slot table? If you think the weight won't be an issue you could just buy a replacement table for a mini mill.
    Bob La Londe
    http://www.YumaBassMan.com

  9. #9
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    Re: HF 8x14 linear rail conversion....and maybe more...

    Quote Originally Posted by Bob La Londe View Post
    The aluminum cross slide gang tool table looks very nice, but have you considered using a t-slot table? If you think the weight won't be an issue you could just buy a replacement table for a mini mill.
    My concern was height. I'm already closer to the center line of the spindle than I would like, and T slots would take up even more space. As it is, I'm going to be limited to around a 4" working diameter.

  10. #10
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    Re: HF 8x14 linear rail conversion....and maybe more...

    If you position a QCTP right at the edge of the table (whichever table) you can do a little turning in front of the table. Particularly if you maintain the ability to swivel the tool post, but yes I get where you are coming from. I'm into a conversion on a 7x10-16 and I'm looking at a 2.5 in max work piece over the cross slide myself.
    Bob La Londe
    http://www.YumaBassMan.com

  11. #11
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    Re: HF 8x14 linear rail conversion....and maybe more...

    who said I was planning on using a QCTP?

    you doing linear rails as well? Have a build thread for it?

  12. #12
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    Re: HF 8x14 linear rail conversion....and maybe more...

    I was just making a suggestion. No need to get defensive. (Whether you intended to or not it appears defensive.) I suggested a QCTP would have some hang over for turning in front of the table. My sentence started with the word IF. A very strong qualifier. Even IF you use a regular or other fixed tool post and its not keyed in place you can turn it to cut a little in front of the table IF you need to. I assumed that you would have multiple tool posts. One for the turning tool, a couple for drills, and one for a cutoff tool at a minimum. Turning tool in front, drills in the middle at the back edge of the table, and an inverted cutoff tool in the back. With good spindle motor control and control setup the turning tool in the back doesn't even have to be inverted. I think guys just do it that way to save time so they don't have to wait for the spindle to reverse. Of course it has to be fixed so it doesn't get jerked off the tool post if its inverted.

    Nope. No build thread. I hadn't planned linear rails, but after seeing yours I am considering scrappig my prograss and starting over with them. I actually have plenty of rails on the shelf for some other builds I have planned. Actually I do already have linear rails for the cross slide. So, I guess. Yes some linear rails. LOL. I had machined off the top of the saddle to install the cross slide bearings, but going to a linear rail bed and just making a saddle would simplify some of the next steps I was trying to figure out.

    As to my original suggestion. My thought was use a t-slot table INSTEAD of the matix table. Not on top of it. Shopping for a decent t-slot table is expensive, but you can buy a replacement mini mill t-slot table for under $150. I bought a couple to see which one I would like the best. Now that I have picked one I'll just mill the dovetails off the back and drill it for my cross slide bearings. While they aren't perfect tables, they are cheap, easily machined, and have very little flex under load compared to some other materials.
    Bob La Londe
    http://www.YumaBassMan.com

  13. #13
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    Re: HF 8x14 linear rail conversion....and maybe more...

    oh, I wasn't trying to be defensive, thus the little winky face. I was trying to hint that I'm designing a turret to use in place of the QCTP.

    What table did you end up using?

  14. #14
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    Re: HF 8x14 linear rail conversion....and maybe more...

    Yeah, I saw that after my response. My bad.
    Bob La Londe
    http://www.YumaBassMan.com

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    Re: HF 8x14 linear rail conversion....and maybe more...

    no worries, we're all friends here

    What table top did you end up going with for your lathe?

  16. #16
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    Re: HF 8x14 linear rail conversion....and maybe more...

    I don't recall which one it was, but it is one of several availble from Little Machine Shop as replacements for different mini mills.
    Bob La Londe
    http://www.YumaBassMan.com

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    Re: HF 8x14 linear rail conversion....and maybe more...

    Sorry for no progress guys. I'm in the middle of moving my entire shop to my new house!

  18. #18
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    Re: HF 8x14 linear rail conversion....and maybe more...

    Good luck with the move. I'm going to miss the ducks!

  19. #19
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    Re: HF 8x14 linear rail conversion....and maybe more...

    hahahahaha. that actually mad me laugh. Maybe i can find some to put up at the new place.

  20. #20
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    Re: HF 8x14 linear rail conversion....and maybe more...

    So a long time coming, i have finally been working on the lathe again now that i'm semi settled into the new house. First thing done was to finally make a stand for it. I've had the steel sitting around forever but never got around to it.


    I also got some encoders mounted. At some point i'd like to actually use them for position feedback, but for the time being they will be used to help calibrate the lathe and map the ballscrews. The Z axis was pretty easy. the magnetic strip is applied directly to the bed casting and an L bracket holds the sensor.


    The X axis was a bit trickier. I ended up attaching the magnetic strip to the chip cover that protects the linear bearings and mounting the sensor to the cross slide plate. Maybe not super ideal, but it should work for now.


    I also started working on some gang type tool holders. the table is a matrix of 1/4-20 threads and dowel holes so i came up with the modular type holders that locate on the dowels and are secured with the a bolt. They can be mounted in pretty much any direction or location

    I've got a few ready to go for when i'm actually ready to make some chips.

  21. #21
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    Re: HF 8x14 linear rail conversion....and maybe more...

    This is one of those threads I've beren following and looking forward to seeing it run. While not as long in running as the Z2 thread its been a long time coming. Nice to see some progress.

    Uuum... where is the turret?
    Bob La Londe
    http://www.YumaBassMan.com

  22. #22
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    Re: HF 8x14 linear rail conversion....and maybe more...

    The lettering on the toolholders looks really nice. What method did you use?

    Cool project!

  23. #23
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    Re: HF 8x14 linear rail conversion....and maybe more...

    Quote Originally Posted by Bob La Londe View Post
    This is one of those threads I've beren following and looking forward to seeing it run. While not as long in running as the Z2 thread its been a long time coming. Nice to see some progress.

    Uuum... where is the turret?
    You better believe i have one all designed up and ready to make. Haha. I'm excited to see it run too. My original conversion worked fairly well, and while I'm loosing a bit of diameter turning capacity, i think the rails will stiffen things up quite a bit. And to answer the next question everyone will ask, my max diameter I can chuck now is around 3" before it'll hit the table. not super great, but very rarely do i turn anything over 2".

    Quote Originally Posted by burbingus View Post
    The lettering on the toolholders looks really nice. What method did you use?

    Cool project!
    Thanks, they are just engraved on a CNC, filled with nail polish, and sanded down.

  24. #24
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    Re: HF 8x14 linear rail conversion....and maybe more...

    Got a little more done on the lathe today. Tail stock is all mounted up.





    In addition to having to make a new base that will work with the linear rails, the ball screw goes right down the center of the base casting so the original screw and locking clamp would no longer work. So i made a steel version that goes around the ballscrew. It's kind of hard to see, but here's a cross section view of how the new locking clamp looks.

  25. #25
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    Re: HF 8x14 linear rail conversion....and maybe more...

    Squared up the axis today. I clamped my granite square to the "master" Z rail and swept and indicator on it. Maybe a little ghetto of a set-up but it's not stupid if it works! You can also see the new tailstock clamp at the tail end.


    square to within .0002 over 6" not too shabby.

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