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METAL LATHE SMOKE, RPM LOSS, NEW LATHE MOTOR?
- Thread starter MooseMeat
- Start date
MooseMeat
Super User
I err'd on the side of caution on clough42's 120htz test setup, tomorrow I'll install the proper length belt and tension and tone down the htz.
I cannot really comment on the belt tension thing. I have always felt some ability to deflect the belts was required. But I don't know what higher than normal v-belt tension would do.
I probably would not recommend running the motor at 100hz. Other than testing, my max for your motor would be 75 or 80.
The forum does not directly support videos. Most members upload to their private YouTube channel and then add a link to it in their post.
I probably would not recommend running the motor at 100hz. Other than testing, my max for your motor would be 75 or 80.
The forum does not directly support videos. Most members upload to their private YouTube channel and then add a link to it in their post.
On my machines I set up the VFD for 30-120Hz. The torque drop off at 120Hz is less than expected: I expected 50%, but I think it is less than 30%. The drop off for torque is hardly noticable at 30Hz. In theory, I could go to 6-10 Hz, but I'm not that bold.
MooseMeat
Super User
Well I was all set for a picture debut of all the lathe happenings but for some reason the new tach would not hold rpms and jumped all over the board, mind you it looked really cool none the less mounted in the case. This was an amazon tach with the hall sensor and magnet. I mounted the magnet in a piece of pvc pipe I bored out and friction fit it over the end of the spindle that sticks out of the cover, I modified the cover and made a jb weld passthrough that is threaded to adjust the sensor but noting I did would get it to read correctly. Three wires to the sensor and plug and two power wires, I wired itfor 120, powers up fine but no amount of tinkering would make it happy. I tried the magnet both ways troubleshooting but I did have it correct the first time.
I watched a video of a mill with the same setup and it was noted the fella had to use his own magnet as the supplied one didn't cut it, so back it went to the amazon recycle bin.
I watched a video of a mill with the same setup and it was noted the fella had to use his own magnet as the supplied one didn't cut it, so back it went to the amazon recycle bin.
I was all set to suggest that, but I see you got it covered.
I've had bad magnets too. The other thing that is important is the gap.
Lastly, sometimes the count doesn't work well over long periods of time. Most tachs allow you to have several magnets and then divide to get rpm. That way you can get over the minimum frequency bar.
I limited my lathe to 75Hz, not because of motor torque but because I didn't want to exceed the RPM rating of the chucks, or have the bearings and gears get overheated. My old mill I ran to 120Hz. The torque drop off is usually irrelevant, as you are usually wanting that speed for some tiny shaft (lathe) or tiny cutter (mill) and theres still way more torque available than you can reasonably transfer to the cut in a useful way.
If the motor is slowing down (i.e. not keeping the 100Hz), then that's probably quite the load its experiencing andif you say that the belt is way too tight, then as it heats up its probably grabbing in the pulley and slowing things down.
If the motor is slowing down (i.e. not keeping the 100Hz), then that's probably quite the load its experiencing andif you say that the belt is way too tight, then as it heats up its probably grabbing in the pulley and slowing things down.
MooseMeat
Super User
The magnet would stick to things and when the sensor was inline with the magnet the red light on the sensor lights up, also watched a video of the same sensor and the red light was on all the time and blinked when the magnet passed it, I guess we'll see what the new one does, I tapped into the ground and the hot on the filter on the "in" side, not sure if this makes a difference
Just think of all the experience one gains breaking, fixing and modding things....🙂
For me, this a much bigger piece of why I do it. Learning is my real hobby.
MooseMeat
Super User
I very much agree, learning should be in part enjoyable as well, bloody frustrating at times but when the motor smoke clears, all fingers and vision intact and when you turn that little black knob for the first time and things happen, that's the gravy on the potatoes.
MooseMeat
Super User
Tach question here;
So I tried to install a tach, the numbers are all over the board, sent the dam thing back and ordered a new one. Tried almost everything thinking the wires were messed up from the manufacturer as this can be an issue as reported by other people.
I wired the new one up and same problem with the lathe running on the vfd, vfd, vfd, hmmmmmmm, so I turned the vfd off and ran the lathe chuck off a drill to trigger the sensor, well then, I'm gonna give you one guess as to what happened, YAH IT WORKED. I have a filter on the power line in before the vfd but now I'm thinking ferrite rings will/may kill the interference??
thoughts??
cheers and thanks..
So I tried to install a tach, the numbers are all over the board, sent the dam thing back and ordered a new one. Tried almost everything thinking the wires were messed up from the manufacturer as this can be an issue as reported by other people.
I wired the new one up and same problem with the lathe running on the vfd, vfd, vfd, hmmmmmmm, so I turned the vfd off and ran the lathe chuck off a drill to trigger the sensor, well then, I'm gonna give you one guess as to what happened, YAH IT WORKED. I have a filter on the power line in before the vfd but now I'm thinking ferrite rings will/may kill the interference??
thoughts??
cheers and thanks..
If you look at what Clough42 did in the same video you referenced earlier, it might help.
Personally, I'd run stuff like Tachs and DROs off of their own circuit not the one that the VFD is running from.
MooseMeat
Super User
good point, if the ferrets fail then I will do just that, I more or less have the same setup as C42 except the ferrits.
I'll report back.....😉
once I get this bug fixed I'll drop some machine porn pics, my wife say's you all have to stop enabling me btw..
Sorry mate, there's a clause in the group rules that stipulates we must enable. So <shrug/> it's the rules 😀
MooseMeat
Super User
the tach is 110-240 so I wired it into the incoming 120 part, the fwd/rev, potentiometer for speed and the emergency stop is all that is wired into the vfd
MooseMeat
Super User
I'll let the wife know, she'll want real names, addresses and the names of your wives or partners and full contact details.
anyone got a spare cave I can rent??
BaronJ
Ultra Member
Hi MM, Guys,
The Tach should be wired before the VFD and should be using shielded cable. The ferrite rings in the tach lead should help as will a capacitor of about 1000 pf wired across the tach. There should also be a mains filter either built into the VFD or in the mains supply directly before it. There should also be a mains earth terminal that should be used on the VFD and continued to the lathe metalwork.
VFD's are basically very electrically noisy things, its a function of how they work. In Europe it is mandated that things like VFD's, have mains filters built in as have many other electrical appliances.
The Tach should be wired before the VFD and should be using shielded cable. The ferrite rings in the tach lead should help as will a capacitor of about 1000 pf wired across the tach. There should also be a mains filter either built into the VFD or in the mains supply directly before it. There should also be a mains earth terminal that should be used on the VFD and continued to the lathe metalwork.
VFD's are basically very electrically noisy things, its a function of how they work. In Europe it is mandated that things like VFD's, have mains filters built in as have many other electrical appliances.
I have an old shop, no power though. Oh yes the roof leaks. Rent is very reasonable though.🙂
Her phone already has all that information and much more. 😵
Hiding in somebody else's shop won't help.
The best thing to do is to buy more tools and more machines and confuse her by putting them in piles or covering them with piles and lots of chips. I like to add stock drops. That way she never asks what they are worth.
If you organize stuff or put them neatly in drawers, they will get classed as joint property in the divorce.