three phase coolant pump

[powderblast]

the coolant pump runs fine left it on practical all day so im happy with the way its running and the vfd on the lathe is great m well happy i did contact qualified elections to do the job and no one was interested i eventually got some one from a motor rewind place but there was to much money the way the lathe is now is just as good as original i will be getting the safety shut working on it though.

i am not a qualified electrician that is not my trade hence why im asking for abit of advice and all is greatly appreciated.

thanks for all your input guys

 

[Darkwood]

This is an electrical engineering project hence you struggled getting any electricians to get involved, I assume this is your own project and for personal use only as you have probably contravened so many regulations and safety standards here in converting this lathe that you will probably have put yourself at risk given an emergency situation, so just for my own curiousity here, since you have lost the original controls built to old standards and effectively upgraded the machine, how does the Emergency stop system operate, how does the lathe brake itself and if applicable the electro-mechanical clutch system work, making a control circuit functional is easy, making it safe to use takes a lot of knowledge and experience...
I'm guessing this is a small lathe gauging the size of that motor frame but even so there is a lot of geared torque on the spindle and it could do a lot of damage with all respect in an emergency but as this is personal use you really don't have anyone to answer to so I only comment on it as an advisory note here in that you consider the consequences of dabbling in this kind of stuff, something you-tube often fails to mention if you are actively using it to get this lathe upgraded.

 

[Rocboni]

Most of these lathes don't actually come with Emg operating systems, or mechanical brakes as they are aimed at hobby use. My lathe came from a educational establishment and simply had a low level Emg button installed to drop out the start Contactor, I have a vfd installed now, the Emg button stops the lathe in about a 2Seconds, this is fully programmable.

Come to think of it the lathes at school didn't have any automatic braking facility if an Emg button was pressed to actually stop the lathe immediately, other than a foot bar which cut the power and applied brakes depending on how hard you pushed on the bar.

I have seen larger lathes with DC injection type braking installed.

 

[Darkwood]

The requirements for schools and colleges has changed dramatically over the last decade as far as I know, considering safety only extended to wearing googles in my school days it wasn't uncommon for kids to be injured on workshop machinery.
I deal mainly with the large lathes usually 30kw upwards where you cannot achieve a stop on a dime piece without creating a larger safety risk so extra user training and awareness is usually needed, electromagnetic braking is usually the choice of larger lathes not DC injection, the issue with DC injection is it has a timed injection rate at a given voltage which is effective for known loads but lathes are variable in their loads and speeds so not suitable in most cases as damage to the motor could be done by simply changing the load or speed.
The smaller lathes can be brought to a quick stop quite safely even when loaded up thus a moderate inertial load with limited risk of total mechanical failure like shearing the shaft which of course would present a higher danger than having a longer run down.
As for my previous post, he is changing the controls of the lathe and thus anything he does must comply to the latest regulations, the size of the lathe is irrelevant here as even with the student sized lathes there is a risk or injury and/or death but like I said, it is for his own use and he is not selling it so he has no one to answer to if all goes Pete Tong and he is injured or worse. Imagine getting clothing caught by the spindle, there is more than enough torque available even when it is stopping to pull you over the lathe or under the spindle (rotation dependent) and often the outcome will not be pretty.

 

[Rocboni]

A young girl was actually caught in a lathe locally at a school, lucky it was not fatal, however she did suffer facial injuries, I think it was her tie which got caught. I'm only taking 5 years ago max when I was at school, there was a global Emg stop system but it simply cut power to all machines if any was activated, the school tech dept was built in 1997.

I think you have to consider the circumstances, it's only going to be used as a hobby machine so he poses a risk only to himself, buy disconnecting the original control system and connecting to an inverter has not likely made it less safe then it originally was unless they machine guarding has not been integrated as it was when I converted my lathe.

 

[Darkwood]

As I expressed, as this is a private project there is no real body that he has to comply to but like you touch on here, their are often electric clutch systems and/or braking that can be lost without you realising when you convert such machines, some lathes have mechanical clutching and some electrical this in itself has a great bearing on safety when upgrading the machine, I have seen this done badly so many times, I have seen Hi/Lo speed clutch control lost and compensated by overspeeding the motor thus leading to mechanical failure as excessive stresses are played through the gearing etc, I have seen drive clutches powered permanently to allow VSD control which means the motor starts up under heavy gearing and not what it was designed for, luckily setting up the drive can assist the starting and limit any damage caused by this.
As for the girl getting caught in the lathe with her tie... it beggers belief that kids are allowed anywhere near such machinery with loose clothing, said school should be fined with the full force of the H&S, not sure what school this was but we all had to wear full overalls over our uniforms when in the workshop and that was 30yrs ago never mind 5yrs.

 

[Chris1234]

I think at my school (mid 90’s) we had a global e-stop system that simply cut power to everything. So presumably any electrical braking system would have not worked.

I was left operating a 3hp lathe at school after only a few minutes training!

I believe there was a school girl killed using a lathe in the last 7 years or so after her hair got caught.