what to do with a free scrap dumpster find ?

if i knew a lot about them i would probably go cheap but for me the more and better documented the unit is the better i will be at making heads and tails of it. i think Hitachi might be a good choice Japan makes good stuff and they have support if needed as well. not all drives have the same control method and the more advanced ones seem to have sensorless vector control as a control method which i think might be something you might want for spindle control. i started looking through the manual and it's 420 pages of information so that's going to take some time to read through.

seems like the sensorless vector control is like an open loop servo and if there was encoder feedback it would then be a closed loop system

the Hitachi are around $300 i think. just about everything on Amazon is made in China these days and the price difference is not as much as you would think. i don't mind paying a little more for something for the extra support and better documentation.

i think this is what i would need to do what i want. might be higher in price but you get what you pay for. if you wanted you could add a encoder to the motor and provide feed back for a more complex system if needed? but this one does have that option.

these drives are pretty simple for basic manual operation of a motor. they can get complicated pretty quickly once you add control logic in the mix so that part will take me a while to sort out.

but this looks like a winner hitachiacdrive.com/hitachi-wj200-series-wj200-022sf/

and her is the motor i was looking at to pair with this inverter.
www.automationdirect.com/adc/shopping/ca...er_duty/4_in_1/d396a

i thought this was interesting when you over speed a motor by running it past the the rated 60 Hz. The ratio of decrease is the same as a mechanical gearing in the torque department. So running a a 60 Hz motor at 120 Hz cuts the torque in half at 120 Hz the same way a pulley 2 times the size of the other would in a mechanical system. 24 N/m of torque at 100% 16 N/m running at 90 Hz @ 67 % and 12 N/m running at 120 Hz @ 50% torque

AT the lowest torque @12 N/m that's quite a bit of spindle force and in theory that is spinning the motor @ 7200RPM other factors play into these number so in reality they will be lower but that seems about on track for a machine tool .

i seen this Hitachi drive has a boost feature for low speed and can go as low as .5 HZ or about 30 RPM in th-s case. this drive might be pricey but it does quite a bit. should be able to add an encoder and be able to do rigid tapping from what i can tell so far. it will take a PP/R of up to 1024.

i have to admit HP is misleading when it comes to spindles and it's more about the range of torque over the range of speed you can get from your set up. 3HP might be overkill but i don't think a cushion will hurt. i would rather have more than needed than not enough

happen to come across this video on spindles with VFD drives and rigid tapping. this young fellow is spot on with my findings and put together i very nice video to stream line the process. the set up he has is basically the same as what i was thinking about doing with the exception of my spindle being a horizontal rather than vertical like his.

i have noticed a few going with a 4 pole motor with a base speed of 1800 rpm. so to talk about that. the 4 pole motors do better at low rpm torque so slower speeds will have better torque but the need to have great low end torque at very low speeds is a trade off at the torque at higher speeds. with a base speed at 1800rpm by the time you get to 3600 rpm the base 60 Hz is now running at 120 Hz and the torque has been cut in half already from the rated torque.so it's true they can deliver full torque at 6 Hz or a 180 rpm if it's a 4 pole motor but they suffer on the top end as a result it seems. and not to mention the price is about double compared to the one i am looking at.

so that would be the only difference in choices i would make. i will have to look at drives a little more at automation direct since that was where i found the motor i like.

i got to starting attaching the table to the saddle and adding rails adds about 1 5/8 of a inch to the table height; i would imagine i will pick up another 1 5/8 once the ways are attached to the box ways. so some sort of way cover are probably going to have to be dreamed up for this project later on. the extra height will cut into the travel some i would think too but i never know how much until i build something but the height is actually a good thing since once a table top is on the Y axis on a horizonal configuration would be useful to go slightly under the table top. i could see it coming in handy doing weld preps or just edge breaks. so this will be something to think about as i go.

on a plus note i did check with an indicator across the grinders table just sitting on the rails not attached and in 2 directions the surface was flat within .0007 at the most. it might get better once the rails are attached? regardless it was a good sign things are pretty flat. the spacing was based on the location of the oil ports in the casting so i may end up spreading them apart more and drilling and tapping new holes? just depends on any flex once extended? the table casting is 2" thick and i was planning on mounting a steel sub plate over top of the entire table for a 9" x 31" table top so it might be fine as is? will check to see if it deflects any once the rails are attached to the table bottom.

in case your wondering yes i'm flying by the seat of my pants on this project seems to be a common theme for me        

since this machine had a flat on flat way and a V way on the other side the two rails will not be on the same plane. so in order to get things set i had to figure out the offset height between the two. since my indicator only moved .0007 over 6" i would say i am probably about as close as i can get with a tired old Bridgeport

Very nice.