converting an old beat up grinder into a horizontal mill


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Thread: converting an old beat up grinder into a horizontal mill

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    Default converting an old beat up grinder into a horizontal mill

    this project has been going on for a few months now when time permits. this all started when my employer decided to get a different small surface grinder since this one has seen better days. by the time i ended up with it some key parts had been taken off the machine so restoring it would have cost to much and to be honest i am not a fan of swinging handles on a grinder. so after looking at it for a bit i decided to work on converting it into a small horizontal mill. i had a lot of spare parts so buying parts was not needed so much. if nothing else the 1,500lbs of machine made for a good base to build from for a small mill.

    the cast iron head of the grinder was big enough to fit a BT30 spindle tapper in so that's the plan for the spindle. the original motor was only 1 HP so that is being upgraded to a 3HP 3 phase inverter duty motor running off a VFD and am planning on a power draw bar with an air cylinder. no plans for any ATC just something set up for quick manual tool changes.

    if nothing else this should be interesting at the very least it gives me something to tinker with and keeps me out of trouble some pictures of the busted down machine. if the machine was not free i don't think i would do this but since it was nothing ventured nothing gained is basically how i look at it now.

    converting an old beat up grinder into a horizontal mill-base-top-view-jpgconverting an old beat up grinder into a horizontal mill-base-casting-saddle-length-jpgconverting an old beat up grinder into a horizontal mill-bearing-assembly-jpg

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    Attached Thumbnails Attached Thumbnails converting an old beat up grinder into a horizontal mill-column-length-jpg   converting an old beat up grinder into a horizontal mill-column-bearing-assembly-width-jpg  


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    Default Re: converting an old beat up grinder into a horizontal mill

    this just a progress pictures over the last 3 1/2 months of me working here and there on the weekends. the mechanics of the lower end is pretty much sorted out, the Y axis for a horizontal configuration is probably the most difficult. direct drive of a screw to lift the head is not an option so that part is on going at this point, this was just a rough assembly to get an idea of travel and where things will fall when i get done.

    converting an old beat up grinder into a horizontal mill-rough-assembly-jpg



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    Default Re: converting an old beat up grinder into a horizontal mill

    thought i had the inside nailed down but once i took my shaft out and test fit the draw bar i soon realized i had to go back in and rework the section that allows the pull stud clamp to open up. i'm not sure what happened there but it's fixed now. it's easier to take a little more off than to put a little more back on with out messing something up

    only thing to do with the shaft at this point is to add some drive dogs for the holders. it would be nice if i can avoid cutting into the taper but that would have probably been easier to be part of the shaft. the older machines seemed to have bosses milled into the taper but the newer machines all seem to have a one
    piece construction and the taper is not touched.

    knowing me i will just probably cut into the taper since that would be the easiest way for me to add them. i can keep the bosses shallow and still have good engagement with the two drive dogs.

    working on the labyrinth seal for the front now but just started working on that part before i ran out of gas for the day

    converting an old beat up grinder into a horizontal mill-spindle-shaft-almost-done-jpg
    converting an old beat up grinder into a horizontal mill-spindle-shaft-almost-done-2-jpg



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    Default Re: converting an old beat up grinder into a horizontal mill

    i guess i should have included a picture of the cast iron head the original spindle was in but did not think to include it. since the head was set up for a grinding wheel rather than a cutter spindle i ended up taking about 3.5 inched off the length of the casting. some of the length i will get back and by the time you add a tool holder to the spindle it will probably end up sticking out to about the same place as the original. but the altered casting should make for a more rigid machine. after the holiday i hope i can get the casting bored out and start putting things together so i can see a final result for run out. it looks pretty good so far but it's hard to tell for sure until things start going together. i am hoping for about .0002 or better but time will tell.

    converting an old beat up grinder into a horizontal mill-top-view-shotened-head-jpg



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    Default Re: converting an old beat up grinder into a horizontal mill

    i managed to get a decent amount done over the weekend but not as much as i would have liked too. i added some drive dogs to the spindle finished up the labyrinth seal and mounting to the casting for the head. i then realized i would need some kind of spring retention cap on the drive side of the spindle shaft so i sorted that out. when i had things together for what ever reason i decided to check the amount of ejection stroke needed and noticed the stoke was longer than expected. so to fix that i will have to rework one section of the internal work on the shaft to shorten that up some. the shorter the better so you can keep as much of the spring holding force as possible and not waste it on travel for the holder ejection. so getting that nailed down is the next step and then some kind of end cap on the draw bar to protect the treads then i will have the shaft finished completely.

    was able to see a collection of parts together to see what the front end is going to look like finished so i figured i would share some more pictures to anyone following this project

    converting an old beat up grinder into a horizontal mill-spindle-parts-top-jpg
    converting an old beat up grinder into a horizontal mill-spindle-parts-jpg
    converting an old beat up grinder into a horizontal mill-spindle-parts-side-jpg
    converting an old beat up grinder into a horizontal mill-spring-end-cap-top-jpg
    converting an old beat up grinder into a horizontal mill-spring-end-cap-side-jpg
    converting an old beat up grinder into a horizontal mill-spring-end-cap-angle-jpg



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    Default Re: converting an old beat up grinder into a horizontal mill

    Quote Originally Posted by machinedude View Post
    i managed to get a decent amount done over the weekend but not as much as i would have liked too. i added some drive dogs to the spindle finished up the labyrinth seal and mounting to the casting for the head. i then realized i would need some kind of spring retention cap on the drive side of the spindle shaft so i sorted that out. when i had things together for what ever reason i decided to check the amount of ejection stroke needed and noticed the stoke was longer than expected. so to fix that i will have to rework one section of the internal work on the shaft to shorten that up some. the shorter the better so you can keep as much of the spring holding force as possible and not waste it on travel for the holder ejection. so getting that nailed down is the next step and then some kind of end cap on the draw bar to protect the treads then i will have the shaft finished completely.

    was able to see a collection of parts together to see what the front end is going to look like finished so i figured i would share some more pictures to anyone following this project

    converting an old beat up grinder into a horizontal mill-spindle-parts-top-jpg
    converting an old beat up grinder into a horizontal mill-spindle-parts-jpg
    converting an old beat up grinder into a horizontal mill-spindle-parts-side-jpg
    converting an old beat up grinder into a horizontal mill-spring-end-cap-top-jpg
    converting an old beat up grinder into a horizontal mill-spring-end-cap-side-jpg
    converting an old beat up grinder into a horizontal mill-spring-end-cap-angle-jpg
    Looking Good, similar to my horizontal build.

    Mactec54


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    Default Re: converting an old beat up grinder into a horizontal mill

    Quote Originally Posted by mactec54 View Post
    Looking Good, similar to my horizontal build.
    i wish i could move faster and get things done but spindles are are precise and that takes time. i wanted to have the head bored out and start thinking about putting things together but the rework and extra parts were not expected so that has me set back another weekend at least. the labyrinth seal was being difficult since it was 316 S.S. and the material i had was way to thick and needed cut down a lot, things were moving around as result so that sucked up some of my time as well chasing that around to get flat always something it seems



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    Default Re: converting an old beat up grinder into a horizontal mill

    Quote Originally Posted by machinedude View Post
    i wish i could move faster and get things done but spindles are are precise and that takes time. i wanted to have the head bored out and start thinking about putting things together but the rework and extra parts were not expected so that has me set back another weekend at least. the labyrinth seal was being difficult since it was 316 S.S. and the material i had was way to thick and needed cut down a lot, things were moving around as result so that sucked up some of my time as well chasing that around to get flat always something it seems
    This is normal when you build something like this, time is something you should not think about. one off parts, take longer as if you mess up you have to start all over again.

    As you can see in my Horizontal build the Spindle is similar.

    why the use of 316ss?

    Attached Thumbnails Attached Thumbnails converting an old beat up grinder into a horizontal mill-spindle-assembled-3-jpg  
    Mactec54


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    Default Re: converting an old beat up grinder into a horizontal mill

    Quote Originally Posted by mactec54 View Post


    why the use of 316ss?

    it was the only thing i could find that was big enough to make it from and i did not want to have to buy something. i did not really have a budget for this project so any way to save is a plus. takes more time but i save a few bucks here and there which adds up over time. so to sum your question up in a nut shell i'm cheap



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    Default Re: converting an old beat up grinder into a horizontal mill

    Quote Originally Posted by machinedude View Post
    it was the only thing i could find that was big enough to make it from and i did not want to have to buy something. i did not really have a budget for this project so any way to save is a plus. takes more time but i save a few bucks here and there which adds up over time. so to sum your question up in a nut shell i'm cheap
    I don't believe that is being cheap, using what you have, is good, material is expensive, I have been doing the same, for some time. it's better to turn the material you have, into something than it just sitting on the shelf, gathering dust.

    Mactec54


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    Default Re: converting an old beat up grinder into a horizontal mill

    ...interesting build....have you had any thoughts about a counter balance for Y axis?



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    Default Re: converting an old beat up grinder into a horizontal mill

    Quote Originally Posted by machinehop5 View Post
    ...interesting build....have you had any thoughts about a counter balance for Y axis?
    i may not need any kind of counterweight so as of now my plan is to just try without one and see how it does? i plan on using 750W servo's all around with a 5mm pitch screw so they can handle the weight i think but i will have to see first hand how it does and go from there. the Y axis is going to have some weight to it no doubt but i think it should only be around 400lbs at the very most taking a guess of course the 3hp motor alone is close to 50lbs but about the same as the original direct drive 1hp that was on the grinder to begin with.

    i will cross that bridge when i get to it right now i have a long list in front of that part but the possibility has crossed my mind that i could have a need for a counter weight of some sort.



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    Default Re: converting an old beat up grinder into a horizontal mill

    Quote Originally Posted by machinedude View Post
    i may not need any kind of counterweight so as of now my plan is to just try without one and see how it does? i plan on using 750W servo's all around with a 5mm pitch screw so they can handle the weight i think but i will have to see first hand how it does and go from there. the Y axis is going to have some weight to it no doubt but i think it should only be around 400lbs at the very most taking a guess of course .
    after getting into the shop at home i checked some weights and the over all weight is less than i thought it was. i think 200lbs to 225lbs is closer to a finished weight, the columns were lighter than i thought they were, i have not touched them since i got the machine, they only weigh 40lbs each. the cast iron head i was not able to get a weight on since i have it set up on the mill working on the bores for the bearings.

    so i honestly think it will be fine without any kind of counter weight. when i bought the servo's a while back i was asking about these kind of concerns and was told they can move around 900lbs paired with a 5mm screw. if i remember right i was told they get used on knee mills often to lift the knee so if they can handle that that's way more than what i am lifting here.



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    Default Re: converting an old beat up grinder into a horizontal mill

    Quote Originally Posted by machinedude View Post
    after getting into the shop at home i checked some weights and the over all weight is less than i thought it was. i think 200lbs to 225lbs is closer to a finished weight, the columns were lighter than i thought they were, i have not touched them since i got the machine, they only weigh 40lbs each. the cast iron head i was not able to get a weight on since i have it set up on the mill working on the bores for the bearings.

    so i honestly think it will be fine without any kind of counter weight. when i bought the servo's a while back i was asking about these kind of concerns and was told they can move around 900lbs paired with a 5mm screw. if i remember right i was told they get used on knee mills often to lift the knee so if they can handle that that's way more than what i am lifting here.
    They would be using 3:1 or more to move that weight with a 750w servo

    Mactec54


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    Default Re: converting an old beat up grinder into a horizontal mill

    Quote Originally Posted by mactec54 View Post
    They would be using 3:1 or more to move that weight with a 750w servo
    i would think you are right in the need for some kind of reduction to increase the torque taking a guess. so i would take the comment with a grain of salt from DMM without knowing all the details of an extreme application like this.

    but my case is not that extreme so i will just see what happens and go from there. if i need a counter weight so be it if need be.



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    Default Re: converting an old beat up grinder into a horizontal mill

    Quote Originally Posted by machinedude View Post
    after getting into the shop at home i checked some weights and the over all weight is less than i thought it was. i think 200lbs to 225lbs is closer to a finished weight, the columns were lighter than i thought they were, i have not touched them since i got the machine, they only weigh 40lbs each. the cast iron head i was not able to get a weight on since i have it set up on the mill working on the bores for the bearings.

    so i honestly think it will be fine without any kind of counter weight. when i bought the servo's a while back i was asking about these kind of concerns and was told they can move around 900lbs paired with a 5mm screw. if i remember right i was told they get used on knee mills often to lift the knee so if they can handle that that's way more than what i am lifting here.
    ...if, only a few 100 LBS and depending Y axis travel a Gas Spring assist would be an easy option. Just need a place to mount them in your build design.
    https://www.google.com/search?q=gas+...t=gws-wiz-serp



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    Default Re: converting an old beat up grinder into a horizontal mill

    Quote Originally Posted by machinehop5 View Post
    ...if, only a few 100 LBS and depending Y axis travel a Gas Spring assist would be an easy option. Just need a place to mount them in your build design.
    https://www.google.com/search?q=gas+...t=gws-wiz-serp
    Yes, you can make your own using an air cylinder which can be better than these gas springs

    Mactec54


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    Default Re: converting an old beat up grinder into a horizontal mill

    Quote Originally Posted by machinedude View Post
    i would think you are right in the need for some kind of reduction to increase the torque taking a guess. so i would take the comment with a grain of salt from DMM without knowing all the details of an extreme application like this.

    but my case is not that extreme so i will just see what happens and go from there. if i need a counter weight so be it if need be.
    DMM; may have miss understood what you were wanting to do, they have done many manual milling machines conversions, X and Y axis can normally be direct drive or a 1:1 drive but Knee or Z axes normally need gearing or a counter spring / weight, or a bigger motor

    Sure, the motor can probably push 900LBs. the Y axis on my mill with the table loaded, has been more than that at times, without any problems.

    Mactec54


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    Default Re: converting an old beat up grinder into a horizontal mill

    i started working on the casting bores for the new spindle. this casting seemed to be hard when it came to machining so i'm not sure if it was hardened or not? roughing in the bores was not to much trouble but finishing was a royal pain in the butt. i don't really have a great way to machine the head since it is an odd shape but managed to get the angular contact bearing side done. the problem i had was keeping the shoulder square and even all the way around. i ended up doing the bore first then setting up a rotary table to kiss the shoulder off flat with a long reach end mill. it was a bit of a treat to get bolted down on a rotary table since i did not have much room for clamping.

    the bore depth was not so important but keeping the depth even was very important since this will cage the bearings in the bore on this end. so when the labyrinth seal gets bolted down the angular contact bearings are locked in. doing it this way means the deck height of the bearing in the bore have to be about perfect. so only a few tenths at most is what i am looking for. to much and you run the risk of distorting the bearings. this will all get set with the bearing spacer since that is what i have the most control over so i can produce the best results. the spacers have to be parallel to .0001 so once i get them set to get that i can then focus on the final over all length. then i will have the most important side finished.

    the bores i ended up finishing with a hone as well. this was the only way i had enough control to keep things where i wanted them. old school no doubt but effective at least.



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    Default Re: converting an old beat up grinder into a horizontal mill

    i have been waiting for 3 weeks for some DOM tube so i can make outer race spacers and this material still has not shipped yet? prices are a bit out of control on tube and everything else for that matter but it is what it is i guess.

    i do have enough finished that i can sort the motor mounting and everything else. this is still in the rough design phase and i still have a few things to sort out but the major stuff i think i have sorted out and did a screen grab to post for the basic plan.

    since i would like to do rigid tapping this 3 phase motor needs some feed back so coming up with a way to get an encoder on the motor was a bit of a thinking process but i think i have a good plan, the motor has a plastic fan for cooling on the back side of the shaft so the plan is to attach an encoder directly to the shaft and loose the plastic fan altogether. these motors cool ok at high speeds but when you run slower the cooling drops off. so to make it better at all speeds the plan is to heatsink the motor and use 2 DC fans to cool everything. most likely they will just run all the time when the machine is running.

    i have a simple belt tension system worked out and now know what length of belt i need. the one belt i have is too short but getting one that will work is not a problem.

    this is still a work in progress but the screen grab explains things better than i can i think

    converting an old beat up grinder into a horizontal mill-spindle-drive-rough-design-png



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converting an old beat up grinder into a horizontal mill

converting an old beat up grinder into a horizontal mill

converting an old beat up grinder into a horizontal mill