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IndustryArena Forum > MetalWorking Machines > Uncategorised MetalWorking Machines > converting an old beat up grinder into a horizontal mill
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  1. #21
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    Jan 2005
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    Re: converting an old beat up grinder into a horizontal mill

    Quote Originally Posted by machinedude View Post
    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

    Attachment 474414
    Why put the Encoder on the motor, the spindle is the best place to add an Encoder, usually just one 4"fan is more than enough to replace the original fan, here is an Encoder and fan I did on a Bridgeport, the Horizontal build also has an Encoder on the Spindle and works very well.
    Mactec54

  2. #22
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    273

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

    1:1 ratio and the motor shaft has the room to make mounting easy enough was my thoughts. as for two fans i have a bunch of them sitting around so i figured 2 can't hurt. i honestly don't know how warm this motor will run so i figured to much air flow is better than not enough.

    that Bridgeport looks nice, mine has seen better days but it was a scrapyard rescue too i would be afraid to get that one dirty

  3. #23
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    Re: converting an old beat up grinder into a horizontal mill

    Quote Originally Posted by machinedude View Post
    1:1 ratio and the motor shaft has the room to make mounting easy enough was my thoughts. as for two fans i have a bunch of them sitting around so i figured 2 can't hurt. i honestly don't know how warm this motor will run so i figured to much air flow is better than not enough.

    that Bridgeport looks nice, mine has seen better days but it was a scrapyard rescue too i would be afraid to get that one dirty
    Not sure what you mean by being afraid to get the machine dirty, that one also was a scrap yard rebuild 20 years ago, I used it more than 12 hours a day for 8 years and it still looked like that, the epoxy paint is easy to wipe down or clean once in a while, that is the same machine that has the Horizontal spindle also, it does not get the same amount of use that it used too because I have other CNC machines with tool changers, it is still the best machine I have with .0001" cut part accuracy
    Mactec54

  4. #24
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    Re: converting an old beat up grinder into a horizontal mill

    looks like it is in good shape is all. much better than the one i have. i got mine for $250 and it worked as is so i did not waste to much time on it since i was making money with it right away. i did not have the time to do a lot with it. tossed a quick coat of paint on it and added a DRO and that was then end of it, that was 15 years ago or better.

    i would like to go over it and make it look nice i just don't have the time since i have other projects i'm working on at the moment. full time job limits me to weekends for home projects so things move slow at home

    when your not making money with machines building them is slow picking up a little bit here and there in the parts needed department. everything adds up fast even with the big stuff being out of the way. nickel dime stuff gets expensive once you start adding it all up

    curious to see how this motor does this is my first time going the VFD route. seems like this method has some decent torque with a better motor over a decent range of speed. some of these motors can get expensive fast but this one was reasonable since they were phasing it out. i saved a few hundred dollars, something similar cost around $600.
    the ones with a better constant torque rating were out of my price range but 10:1 is not bad for this one. i have a DURA PULSE GS21-23P0 VFD to run it with. so the expensive bits are bought at least. i just need to decide on an encoder type but need to look into them some more. electronics are not my strong point

  5. #25
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    Re: converting an old beat up grinder into a horizontal mill

    Quote Originally Posted by machinedude View Post
    looks like it is in good shape is all. much better than the one i have. i got mine for $250 and it worked as is so i did not waste to much time on it since i was making money with it right away. i did not have the time to do a lot with it. tossed a quick coat of paint on it and added a DRO and that was then end of it, that was 15 years ago or better.

    i would like to go over it and make it look nice i just don't have the time since i have other projects i'm working on at the moment. full time job limits me to weekends for home projects so things move slow at home

    when your not making money with machines building them is slow picking up a little bit here and there in the parts needed department. everything adds up fast even with the big stuff being out of the way. nickel dime stuff gets expensive once you start adding it all up

    curious to see how this motor does this is my first time going the VFD route. seems like this method has some decent torque with a better motor over a decent range of speed. some of these motors can get expensive fast but this one was reasonable since they were phasing it out. i saved a few hundred dollars, something similar cost around $600.
    the ones with a better constant torque rating were out of my price range but 10:1 is not bad for this one. i have a DURA PULSE GS21-23P0 VFD to run it with. so the expensive bits are bought at least. i just need to decide on an encoder type but need to look into them some more. electronics are not my strong point
    For an Encoder check to see what your controller can use, that is the important part, I built many of the Bridgeport Boss machines, for customers and to sell.

    All projects take time, and the cost of materials now makes you think about the best way to do things.
    Mactec54

  6. #26
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    Re: converting an old beat up grinder into a horizontal mill

    Quote Originally Posted by mactec54 View Post
    For an Encoder check to see what your controller can use, that is the important part, I built many of the Bridgeport Boss machines, for customers and to sell.

    All projects take time, and the cost of materials now makes you think about the best way to do things.
    material costs these days are no joke. 1 foot of 3" 1/4 thick wall DOM tube was over $40 and the 2 3/4" 1/4 thick wall was over $37 for a foot. just shy of $100 with shipping for 2 feet of tube. that's just crazy. i looked at McMaster-car and they wanted $130 for a foot of the 3" alone. so it pays to shop around with material. i have a couple of local suppliers but they are always low on tube because of prices these days.

    the only good thing about prices of material these days is the scrap prices are way up. i have 2 cars that need to go and talked to a scrap yard and they are willing to haul them away and pay me $850 for both of them so i figured its funding for this thing not that $850 goes that far with this sort of stuff but it will keep me busy for a bit at least

  7. #27
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    Re: converting an old beat up grinder into a horizontal mill

    i think i have what i need as far as an encoder for this kind of set up. i am no expert on the electrical side of this stuff but always seem to fumble my way through it sooner or later i won't have it in hand until next week but have enough to work on for a while until i can get to it anyways. Mcmaster-Carr is a different story i have a new timing belt and taper lock hub of the right size for this motor and should have it in less than 24 hours from now.

    i decided to go with a hollow shaft encoder in the line driver version they appear to work the same way as a glass linear scale which should be a fit for a Mesa board and Linux CNC. I'm not an expert n Linux cnc either but it is one of the few options that will do what i want to try out with this project. this is a learning experience for things that appear interesting to me and i have been looking at duel loop systems and wanted to learn more about them so that's how this project started. right now i am thinking this is going to be all analog to control it all. i could be wrong but that's the direction it appears to be pointing me in so i'm running with it

    that part of it is still a ways off yet so i'm not getting to involved in exact details until i am ready too. the mechanical stuff is my main focus the rest is just enough to keep me going in the right direction at this point. here is some basic info on the encoder for the spindle. i won't make any modifications to the motor shaft until i have this encoder in hand.

    Attachment 474610

  8. #28
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    Apr 2007
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    Re: converting an old beat up grinder into a horizontal mill

    started working on the cooling for the motor and took some quick pictures while i was testing fits of everything. So I figured i would share some progress pictures. still work to do but it's moving along some.
    Attachment 475524Attachment 475526

  9. #29
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    Re: converting an old beat up grinder into a horizontal mill

    got the encoder mount sorted out and figured i would post some pictures.

    Attachment 475596
    Attachment 475598
    Attachment 475600
    Click image for larger version. 

Name:	motor complete view.jpg 
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ID:	475602

  10. #30
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    Re: converting an old beat up grinder into a horizontal mill

    It's still going to be a few weeks before i get into the drive and lead screw to raise and lower the head but i started to take a look in more detail. The original machine used spur gears at a 4:1 ratio but that ratio is not ideal for what i would like to see. but from the original parts i was able to determine the center line spacing of the two shafts in parallel. the gears were from Boston gear and i have 2 options that would keep the same center line distance. keep the 4:1 ratio and have slow rapids and lots of torque to lift the head up and down or switch to a 2:1 ratio and have a max rapid rate of around 500 IPM.

    looking at some info from Boston gear i want to say the backlash is around .003 for a D.P.16 gear size based on a standard center spacing. so going with what i have there is not much i can do to adjust for backlash there but i could get an extra gear for the screw side and do a couple of different things to get the backlash better. i don't know exactly how much could be adjusted out but i might be able to get better than .003?

    the current gears have a 14.5 pressure angle which is the better choice i think if i am stuck with a gear drive. from what i seen they run smoother than the 20 degree pressure angle and do better with higher speeds. but what i have not seen to much info on is what kind of speed you can run a spur gear? the servo's i have can do 5,000 RPM. so at this stage is doing a gear drive feasible at high speeds? keeping a 4:1 ratio would mean running the servo's wide open just to get 250 IMP max but is a 750W servo driving a 5mm pitch screw running a 2:1 ratio going to provide enough Torque to lift a 250lbs of head up and down ? i'm thinking it would but if someone has more experience chime in by all means.

    going 2:1 on the ratio gives me some wiggle room on the top speed of a gear drive and not have things fly apart if i would hit a speed limit on the gear drive and still have a decent rapid rate. 18" x 18" work space is not very big but a 4:1 ratio is only going to do around 250 IMP if the gear can run at 5,000 rpm?

    looking for any input if anyone cares to chime in

  11. #31
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    Re: converting an old beat up grinder into a horizontal mill

    problem solving on my own this is the only thing i could find on speed limitations of spur gears. if this is what i am after then in my case with a 1.25 pitch diameter of the smaller gear it seems to hit the limit at 4,500 rpm in my case. so if this is the case i could back it off some even more and still get 400 IPM, but running that fast i'm thinking this needs to be housed in oil rather than grease and that is a whole new issue to figure out i guess if it's housed in oil that would keep the noise level down some as an added plus.

    Attachment 475748

  12. #32
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    Re: converting an old beat up grinder into a horizontal mill

    i found a sizing tool from ABB that was helpful. what i landed on was aa 2:1 ratio on the Y Axis seems the servo's should work fine with the screw i have and the weight of the head which is roughly 250Ibs. the 2:1 ratio was pretty simple since the center spacing on the gears stayed the same from the original set up which was 4:1 making for a really slow axis. so i switched the original Boston gears with some new ones from Boston gear. the typical backlash on the DP 16 gears is typically .003 but that can be adjusted with the center spacing, the ball screw mount floats along with the mount to the head so you have some wiggle room to adjust to keep the backlash as small as possible. my best guess is it was designed this way for this reason.

    i did put the head back on the machine to see how well the plain split bearings worked and they work just fine but back driving is going to be an issue on the Y axis with the head weight. so i need to find some kind of solution to keep things from crashing down. it may develop enough resistance once the pinion gear is in place but until i get that part sorted out the back driving could be an issue?

  13. #33
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    Re: converting an old beat up grinder into a horizontal mill

    by the time i added the pinion gear and adjusted the gear spacing with the clearance of the ball screw mounting points the back driving went away but i bought a large air cylinder to balance the weight of the head anyways. i am not sold on the gas springs since the cycles per minute on those are pretty limited from what i seen. the air cylinders seemed like a better approach since you can set them where every you need to with the amount of air pressure so that's why i decided to go this route. a dewalt cordless drill is able to raise and lower the head as is so i should be sized well with a 750W servo i think. i can't really see or feel any backlash but until things are powered it's hard to tell. i think things are tight enough for a duel loop to deal with so i'm not too concerned with a small amount if it would show up on an indicator when i get to this point. i ended up with about 14" of total travel 12" above the table top and 2"below so i lost some with the linear rails but still good enough to be useful.

  14. #34
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    Re: converting an old beat up grinder into a horizontal mill

    my spin on the air cylinder as a counter balance. works the same way the Haas system works just not as heavy duty. the Haas machines are dealing with a lot of weight so they did an air over oil system.

    after paying around with it i landed around 200lbs for force in the upward direction to even out the force needed to lift and lower the head. i don’t have an exact weight of the head but everything is in the ballpark of 275 to 300lbs.

    i was going to have a regulator oiler combo on the counter balance but decided it probably would not do much since the air is not moving around very much and just used a regulator water trap on that part and put the oiler on the section that controls the air pressure for the power drawbar. you need two regulators since the system operates at 2 different pressures.

    basically you turn a air cylinder into a adjustable constant force air spring doing this. the upper zone just either push out air on that side or pulls air in depending on the direction your moving but does not enter the pressurized zone of the air cylinder. pretty basic system. the portable air tank is just a collection point to store the air pressure and your tank has to be 10 to 15 time the volume of the air in the air cylinder. being bigger would not hurt anything just takes more space.

    Attachment 478288

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