KeeponDragon
no problems... just challenges
Definitely watching this one...I'm curious what, if any issues I'll have converting my 9x20 over to VFD...
A couple of points to consider in your lathe conversions: it is a good practice to use a motor rated at about 1 1/2 times you single phase motor if you use a VFD. You end with better starting torque.
When I use a GE TECO 510, I match the HP rating and the VFD rating, as they have extra electrical and thermal headroom built in to their design. When I use a very inexpensive VFD, (offshore, etc) I run a 1HP motor on a 2HP VFD, to get some thermal buffer. On a 3HP motor, I'd use a 4HP VFD if it were one of the cheap ones.
Putting a VFD on a lathe requires considerable wiring changes - doing it on a mill is a couple of hours at worst. It's like night and day.
That's what I added to my old lathe...
Nice!I mounted the magnet to a disc, and the disc to the spindle with a taper loc fitting...
I’ve seen that on a friends unit but I don’t think any of mine have that feature? At least I don’t recall seeing it in the manuals. I have an older Teco on my mill and the lathe will have a GE/Fuji.Most VFDs have a conversion factor parameter to display a close approximation of RPM instead of Hz. This is very good if you don't change the belts/gears.
I have an older Teco on my mill
Thats where I got mine for 200 bucks, picked up local. Easy peasyeMotorsDirect.ca is a good source for VFD's and motors. The TECO brand VFD is one used often, it's not cheap or inexpensive but has all the options and support.
I'm not really sure I really need a VFD Rated motor since I'm mostly interested in obtaining slower speeds. My lowest speed is 70rpm now and I'd like to hit 40 - but 50 would do. A VFD Rated motor would take me to 10 or even lower.
Looks like there are a lot of like minded members here. @TorontoBuilder , @Rauce , @YotaBota , @curmudgeon , @KeeponDragon , @cjmac , @phaxtris , @lucsimoneau ,
@Dabbler and I have chatted about just such a conversion on my 1440 lathe too.
I already have the 3Hp TECO L510 VFD for this job. I've been shopping for a 3HP VFD Rated 3phase motor for quite some time now to replace the 2HP single phase motor that is there. I also plan to install a DRO.
My spindle sticks out of the rear of my lathe head by about 2-3/4 inches.
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The reason for multiple magnets is to speed up the data acquisition, improve low speed resolution (where it is needed most), and provide better balance in the spindle. Although I doubt balance is really an issue, it's free with multiple magnets so why not.
I'm not really sure I really need a VFD Rated motor since I'm mostly interested in obtaining slower speeds. My lowest speed is 70rpm now and I'd like to hit 40 - but 50 would do. A VFD Rated motor would take me to 10 or even lower.
Although my VFD does have the RPM function that @Dabbler described, I won't be using it because I still want to be able to use my gearing. I'd prefer a direct rpm reading from the spindle.
I have Arduino code and basic design for a tachometer / SFM using a 20x4 LCD display. Its configured for a mill, but could be easily modified for a lathe.Note: Anyone buying a cheap rpm meter from amazon will likely be limited to single magnet low resolution capability, because well the manufacturer is cheap. Not a big deal, I tested my old tachometer against several very costly analog and digital tachometers at 100 rpm and so no greater than 3% variance. It only really matters for very low speeds where accuracy is critical. Not often the case on a lathe
Multi-magnets require a DRO with that option, or an arduino or other controller based custom job. My buddy is making us a few to beta test and then we will likely offer some to community members. Ours will have multiple encoder options and multiple magnet option and surface feet per minute calculation. One other item I requested to be built into the tachometer is a revolution counter for winding coils for electric motors and solenoids etc... this will require high accuracy at low rpm.
Yes shameless plug... mods feel free to delete that second paragraph if it offends
Multi-magnets require a DRO with that option, or an arduino or other controller based custom job.
We paid extra to get the more expensive DRO option for the lathe JUST to be sure that we didn't have to learn anything different between the two machines.The Ditron D80 DRO on my mill can be set to use multiple magnets. I plan to get a Ditron for my lathe too. I'd like to keep them the same for commonality. So no worries there.
A while back I looked at the code that @whydontu provided. It shouldn't be a problem to add multi sensors to that. If it is a problem, I'll have fun working it out. I've already wired up a box to play with.
I'm not fond of the Amazon/Ali tachs so no worries there.
A bit back to my original question - if the VFD set at 30Hz would put the RPM range of the 3450 RPM motor at 1725, that would mean that I'm back with the original motor's speed range with the belts and back gear. What would be the best position of the belt in this situation? Later on I could always switch out the motor for a slower RPM model pretty easily if this caused a problem. Thanks!
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A bit back to my original question - if the VFD set at 30Hz would put the RPM range of the 3450 RPM motor at 1725, that would mean that I'm back with the original motor's speed range with the belts and back gear. What would be the best position of the belt in this situation? Later on I could always switch out the motor for a slower RPM model pretty easily if this caused a problem. Thanks!
View attachment 28839